tty: move hvc drivers to drivers/tty/hvc/

As requested by Arnd Bergmann, the hvc drivers are now
moved to the drivers/tty/hvc/ directory.  The virtio_console.c driver
was also moved, as it required the hvc_console.h file to be able to be
built, and it really is a hvc driver.

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

17 files changed, 8795 insertions, 0 deletions

diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile
index c43ef48b1a0f..d3685f071b8d 100644
--- a/drivers/tty/Makefile
+++ b/drivers/tty/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_N_GSM)		+= n_gsm.o
 obj-$(CONFIG_R3964)		+= n_r3964.o
 
 obj-y				+= vt/
+obj-$(CONFIG_HVC_DRIVER)	+= hvc/
diff --git a/drivers/tty/hvc/Makefile b/drivers/tty/hvc/Makefile
new file mode 100644
index 000000000000..e6bed5f177ff
--- /dev/null
+++ b/drivers/tty/hvc/Makefile
@@ -0,0 +1,13 @@
+obj-$(CONFIG_HVC_CONSOLE)	+= hvc_vio.o hvsi.o
+obj-$(CONFIG_HVC_ISERIES)	+= hvc_iseries.o
+obj-$(CONFIG_HVC_RTAS)		+= hvc_rtas.o
+obj-$(CONFIG_HVC_TILE)		+= hvc_tile.o
+obj-$(CONFIG_HVC_DCC)		+= hvc_dcc.o
+obj-$(CONFIG_HVC_BEAT)		+= hvc_beat.o
+obj-$(CONFIG_HVC_DRIVER)	+= hvc_console.o
+obj-$(CONFIG_HVC_IRQ)		+= hvc_irq.o
+obj-$(CONFIG_HVC_XEN)		+= hvc_xen.o
+obj-$(CONFIG_HVC_IUCV)		+= hvc_iucv.o
+obj-$(CONFIG_HVC_UDBG)		+= hvc_udbg.o
+obj-$(CONFIG_HVCS)		+= hvcs.o
+obj-$(CONFIG_VIRTIO_CONSOLE)	+= virtio_console.o
diff --git a/drivers/tty/hvc/hvc_beat.c b/drivers/tty/hvc/hvc_beat.c
new file mode 100644
index 000000000000..5fe4631e2a61
--- /dev/null
+++ b/drivers/tty/hvc/hvc_beat.c
@@ -0,0 +1,134 @@
+/*
+ * Beat hypervisor console driver
+ *
+ * (C) Copyright 2006 TOSHIBA CORPORATION
+ *
+ * This code is based on drivers/char/hvc_rtas.c:
+ * (C) Copyright IBM Corporation 2001-2005
+ * (C) Copyright Red Hat, Inc. 2005
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <linux/console.h>
+#include <asm/prom.h>
+#include <asm/hvconsole.h>
+#include <asm/firmware.h>
+
+#include "hvc_console.h"
+
+extern int64_t beat_get_term_char(uint64_t, uint64_t *, uint64_t *, uint64_t *);
+extern int64_t beat_put_term_char(uint64_t, uint64_t, uint64_t, uint64_t);
+
+struct hvc_struct *hvc_beat_dev = NULL;
+
+/* bug: only one queue is available regardless of vtermno */
+static int hvc_beat_get_chars(uint32_t vtermno, char *buf, int cnt)
+{
+	static unsigned char q[sizeof(unsigned long) * 2]
+		__attribute__((aligned(sizeof(unsigned long))));
+	static int qlen = 0;
+	u64 got;
+
+again:
+	if (qlen) {
+		if (qlen > cnt) {
+			memcpy(buf, q, cnt);
+			qlen -= cnt;
+			memmove(q + cnt, q, qlen);
+			return cnt;
+		} else {	/* qlen <= cnt */
+			int	r;
+
+			memcpy(buf, q, qlen);
+			r = qlen;
+			qlen = 0;
+			return r;
+		}
+	}
+	if (beat_get_term_char(vtermno, &got,
+		((u64 *)q), ((u64 *)q) + 1) == 0) {
+		qlen = got;
+		goto again;
+	}
+	return 0;
+}
+
+static int hvc_beat_put_chars(uint32_t vtermno, const char *buf, int cnt)
+{
+	unsigned long kb[2];
+	int rest, nlen;
+
+	for (rest = cnt; rest > 0; rest -= nlen) {
+		nlen = (rest > 16) ? 16 : rest;
+		memcpy(kb, buf, nlen);
+		beat_put_term_char(vtermno, nlen, kb[0], kb[1]);
+		buf += nlen;
+	}
+	return cnt;
+}
+
+static const struct hv_ops hvc_beat_get_put_ops = {
+	.get_chars = hvc_beat_get_chars,
+	.put_chars = hvc_beat_put_chars,
+};
+
+static int hvc_beat_useit = 1;
+
+static int hvc_beat_config(char *p)
+{
+	hvc_beat_useit = simple_strtoul(p, NULL, 0);
+	return 0;
+}
+
+static int __init hvc_beat_console_init(void)
+{
+	if (hvc_beat_useit && of_machine_is_compatible("Beat")) {
+		hvc_instantiate(0, 0, &hvc_beat_get_put_ops);
+	}
+	return 0;
+}
+
+/* temp */
+static int __init hvc_beat_init(void)
+{
+	struct hvc_struct *hp;
+
+	if (!firmware_has_feature(FW_FEATURE_BEAT))
+		return -ENODEV;
+
+	hp = hvc_alloc(0, NO_IRQ, &hvc_beat_get_put_ops, 16);
+	if (IS_ERR(hp))
+		return PTR_ERR(hp);
+	hvc_beat_dev = hp;
+	return 0;
+}
+
+static void __exit hvc_beat_exit(void)
+{
+	if (hvc_beat_dev)
+		hvc_remove(hvc_beat_dev);
+}
+
+module_init(hvc_beat_init);
+module_exit(hvc_beat_exit);
+
+__setup("hvc_beat=", hvc_beat_config);
+
+console_initcall(hvc_beat_console_init);
diff --git a/drivers/tty/hvc/hvc_console.c b/drivers/tty/hvc/hvc_console.c
new file mode 100644
index 000000000000..e9cba13ee800
--- /dev/null
+++ b/drivers/tty/hvc/hvc_console.c
@@ -0,0 +1,914 @@
+/*
+ * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
+ * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
+ * Copyright (C) 2004 IBM Corporation
+ *
+ * Additional Author(s):
+ *  Ryan S. Arnold <rsa@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/console.h>
+#include <linux/cpumask.h>
+#include <linux/init.h>
+#include <linux/kbd_kern.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/major.h>
+#include <linux/sysrq.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
+#include <linux/delay.h>
+#include <linux/freezer.h>
+#include <linux/slab.h>
+
+#include <asm/uaccess.h>
+
+#include "hvc_console.h"
+
+#define HVC_MAJOR	229
+#define HVC_MINOR	0
+
+/*
+ * Wait this long per iteration while trying to push buffered data to the
+ * hypervisor before allowing the tty to complete a close operation.
+ */
+#define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
+
+/*
+ * These sizes are most efficient for vio, because they are the
+ * native transfer size. We could make them selectable in the
+ * future to better deal with backends that want other buffer sizes.
+ */
+#define N_OUTBUF	16
+#define N_INBUF		16
+
+#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
+
+static struct tty_driver *hvc_driver;
+static struct task_struct *hvc_task;
+
+/* Picks up late kicks after list walk but before schedule() */
+static int hvc_kicked;
+
+static int hvc_init(void);
+
+#ifdef CONFIG_MAGIC_SYSRQ
+static int sysrq_pressed;
+#endif
+
+/* dynamic list of hvc_struct instances */
+static LIST_HEAD(hvc_structs);
+
+/*
+ * Protect the list of hvc_struct instances from inserts and removals during
+ * list traversal.
+ */
+static DEFINE_SPINLOCK(hvc_structs_lock);
+
+/*
+ * This value is used to assign a tty->index value to a hvc_struct based
+ * upon order of exposure via hvc_probe(), when we can not match it to
+ * a console candidate registered with hvc_instantiate().
+ */
+static int last_hvc = -1;
+
+/*
+ * Do not call this function with either the hvc_structs_lock or the hvc_struct
+ * lock held.  If successful, this function increments the kref reference
+ * count against the target hvc_struct so it should be released when finished.
+ */
+static struct hvc_struct *hvc_get_by_index(int index)
+{
+	struct hvc_struct *hp;
+	unsigned long flags;
+
+	spin_lock(&hvc_structs_lock);
+
+	list_for_each_entry(hp, &hvc_structs, next) {
+		spin_lock_irqsave(&hp->lock, flags);
+		if (hp->index == index) {
+			kref_get(&hp->kref);
+			spin_unlock_irqrestore(&hp->lock, flags);
+			spin_unlock(&hvc_structs_lock);
+			return hp;
+		}
+		spin_unlock_irqrestore(&hp->lock, flags);
+	}
+	hp = NULL;
+
+	spin_unlock(&hvc_structs_lock);
+	return hp;
+}
+
+
+/*
+ * Initial console vtermnos for console API usage prior to full console
+ * initialization.  Any vty adapter outside this range will not have usable
+ * console interfaces but can still be used as a tty device.  This has to be
+ * static because kmalloc will not work during early console init.
+ */
+static const struct hv_ops *cons_ops[MAX_NR_HVC_CONSOLES];
+static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
+	{[0 ... MAX_NR_HVC_CONSOLES - 1] = -1};
+
+/*
+ * Console APIs, NOT TTY.  These APIs are available immediately when
+ * hvc_console_setup() finds adapters.
+ */
+
+static void hvc_console_print(struct console *co, const char *b,
+			      unsigned count)
+{
+	char c[N_OUTBUF] __ALIGNED__;
+	unsigned i = 0, n = 0;
+	int r, donecr = 0, index = co->index;
+
+	/* Console access attempt outside of acceptable console range. */
+	if (index >= MAX_NR_HVC_CONSOLES)
+		return;
+
+	/* This console adapter was removed so it is not usable. */
+	if (vtermnos[index] == -1)
+		return;
+
+	while (count > 0 || i > 0) {
+		if (count > 0 && i < sizeof(c)) {
+			if (b[n] == '\n' && !donecr) {
+				c[i++] = '\r';
+				donecr = 1;
+			} else {
+				c[i++] = b[n++];
+				donecr = 0;
+				--count;
+			}
+		} else {
+			r = cons_ops[index]->put_chars(vtermnos[index], c, i);
+			if (r <= 0) {
+				/* throw away chars on error */
+				i = 0;
+			} else if (r > 0) {
+				i -= r;
+				if (i > 0)
+					memmove(c, c+r, i);
+			}
+		}
+	}
+}
+
+static struct tty_driver *hvc_console_device(struct console *c, int *index)
+{
+	if (vtermnos[c->index] == -1)
+		return NULL;
+
+	*index = c->index;
+	return hvc_driver;
+}
+
+static int __init hvc_console_setup(struct console *co, char *options)
+{
+	if (co->index < 0 || co->index >= MAX_NR_HVC_CONSOLES)
+		return -ENODEV;
+
+	if (vtermnos[co->index] == -1)
+		return -ENODEV;
+
+	return 0;
+}
+
+static struct console hvc_console = {
+	.name		= "hvc",
+	.write		= hvc_console_print,
+	.device		= hvc_console_device,
+	.setup		= hvc_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+};
+
+/*
+ * Early console initialization.  Precedes driver initialization.
+ *
+ * (1) we are first, and the user specified another driver
+ * -- index will remain -1
+ * (2) we are first and the user specified no driver
+ * -- index will be set to 0, then we will fail setup.
+ * (3)  we are first and the user specified our driver
+ * -- index will be set to user specified driver, and we will fail
+ * (4) we are after driver, and this initcall will register us
+ * -- if the user didn't specify a driver then the console will match
+ *
+ * Note that for cases 2 and 3, we will match later when the io driver
+ * calls hvc_instantiate() and call register again.
+ */
+static int __init hvc_console_init(void)
+{
+	register_console(&hvc_console);
+	return 0;
+}
+console_initcall(hvc_console_init);
+
+/* callback when the kboject ref count reaches zero. */
+static void destroy_hvc_struct(struct kref *kref)
+{
+	struct hvc_struct *hp = container_of(kref, struct hvc_struct, kref);
+	unsigned long flags;
+
+	spin_lock(&hvc_structs_lock);
+
+	spin_lock_irqsave(&hp->lock, flags);
+	list_del(&(hp->next));
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	spin_unlock(&hvc_structs_lock);
+
+	kfree(hp);
+}
+
+/*
+ * hvc_instantiate() is an early console discovery method which locates
+ * consoles * prior to the vio subsystem discovering them.  Hotplugged
+ * vty adapters do NOT get an hvc_instantiate() callback since they
+ * appear after early console init.
+ */
+int hvc_instantiate(uint32_t vtermno, int index, const struct hv_ops *ops)
+{
+	struct hvc_struct *hp;
+
+	if (index < 0 || index >= MAX_NR_HVC_CONSOLES)
+		return -1;
+
+	if (vtermnos[index] != -1)
+		return -1;
+
+	/* make sure no no tty has been registered in this index */
+	hp = hvc_get_by_index(index);
+	if (hp) {
+		kref_put(&hp->kref, destroy_hvc_struct);
+		return -1;
+	}
+
+	vtermnos[index] = vtermno;
+	cons_ops[index] = ops;
+
+	/* reserve all indices up to and including this index */
+	if (last_hvc < index)
+		last_hvc = index;
+
+	/* if this index is what the user requested, then register
+	 * now (setup won't fail at this point).  It's ok to just
+	 * call register again if previously .setup failed.
+	 */
+	if (index == hvc_console.index)
+		register_console(&hvc_console);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hvc_instantiate);
+
+/* Wake the sleeping khvcd */
+void hvc_kick(void)
+{
+	hvc_kicked = 1;
+	wake_up_process(hvc_task);
+}
+EXPORT_SYMBOL_GPL(hvc_kick);
+
+static void hvc_unthrottle(struct tty_struct *tty)
+{
+	hvc_kick();
+}
+
+/*
+ * The TTY interface won't be used until after the vio layer has exposed the vty
+ * adapter to the kernel.
+ */
+static int hvc_open(struct tty_struct *tty, struct file * filp)
+{
+	struct hvc_struct *hp;
+	unsigned long flags;
+	int rc = 0;
+
+	/* Auto increments kref reference if found. */
+	if (!(hp = hvc_get_by_index(tty->index)))
+		return -ENODEV;
+
+	spin_lock_irqsave(&hp->lock, flags);
+	/* Check and then increment for fast path open. */
+	if (hp->count++ > 0) {
+		tty_kref_get(tty);
+		spin_unlock_irqrestore(&hp->lock, flags);
+		hvc_kick();
+		return 0;
+	} /* else count == 0 */
+
+	tty->driver_data = hp;
+
+	hp->tty = tty_kref_get(tty);
+
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	if (hp->ops->notifier_add)
+		rc = hp->ops->notifier_add(hp, hp->data);
+
+	/*
+	 * If the notifier fails we return an error.  The tty layer
+	 * will call hvc_close() after a failed open but we don't want to clean
+	 * up there so we'll clean up here and clear out the previously set
+	 * tty fields and return the kref reference.
+	 */
+	if (rc) {
+		spin_lock_irqsave(&hp->lock, flags);
+		hp->tty = NULL;
+		spin_unlock_irqrestore(&hp->lock, flags);
+		tty_kref_put(tty);
+		tty->driver_data = NULL;
+		kref_put(&hp->kref, destroy_hvc_struct);
+		printk(KERN_ERR "hvc_open: request_irq failed with rc %d.\n", rc);
+	}
+	/* Force wakeup of the polling thread */
+	hvc_kick();
+
+	return rc;
+}
+
+static void hvc_close(struct tty_struct *tty, struct file * filp)
+{
+	struct hvc_struct *hp;
+	unsigned long flags;
+
+	if (tty_hung_up_p(filp))
+		return;
+
+	/*
+	 * No driver_data means that this close was issued after a failed
+	 * hvc_open by the tty layer's release_dev() function and we can just
+	 * exit cleanly because the kref reference wasn't made.
+	 */
+	if (!tty->driver_data)
+		return;
+
+	hp = tty->driver_data;
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	if (--hp->count == 0) {
+		/* We are done with the tty pointer now. */
+		hp->tty = NULL;
+		spin_unlock_irqrestore(&hp->lock, flags);
+
+		if (hp->ops->notifier_del)
+			hp->ops->notifier_del(hp, hp->data);
+
+		/* cancel pending tty resize work */
+		cancel_work_sync(&hp->tty_resize);
+
+		/*
+		 * Chain calls chars_in_buffer() and returns immediately if
+		 * there is no buffered data otherwise sleeps on a wait queue
+		 * waking periodically to check chars_in_buffer().
+		 */
+		tty_wait_until_sent(tty, HVC_CLOSE_WAIT);
+	} else {
+		if (hp->count < 0)
+			printk(KERN_ERR "hvc_close %X: oops, count is %d\n",
+				hp->vtermno, hp->count);
+		spin_unlock_irqrestore(&hp->lock, flags);
+	}
+
+	tty_kref_put(tty);
+	kref_put(&hp->kref, destroy_hvc_struct);
+}
+
+static void hvc_hangup(struct tty_struct *tty)
+{
+	struct hvc_struct *hp = tty->driver_data;
+	unsigned long flags;
+	int temp_open_count;
+
+	if (!hp)
+		return;
+
+	/* cancel pending tty resize work */
+	cancel_work_sync(&hp->tty_resize);
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	/*
+	 * The N_TTY line discipline has problems such that in a close vs
+	 * open->hangup case this can be called after the final close so prevent
+	 * that from happening for now.
+	 */
+	if (hp->count <= 0) {
+		spin_unlock_irqrestore(&hp->lock, flags);
+		return;
+	}
+
+	temp_open_count = hp->count;
+	hp->count = 0;
+	hp->n_outbuf = 0;
+	hp->tty = NULL;
+
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	if (hp->ops->notifier_hangup)
+		hp->ops->notifier_hangup(hp, hp->data);
+
+	while(temp_open_count) {
+		--temp_open_count;
+		tty_kref_put(tty);
+		kref_put(&hp->kref, destroy_hvc_struct);
+	}
+}
+
+/*
+ * Push buffered characters whether they were just recently buffered or waiting
+ * on a blocked hypervisor.  Call this function with hp->lock held.
+ */
+static int hvc_push(struct hvc_struct *hp)
+{
+	int n;
+
+	n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
+	if (n <= 0) {
+		if (n == 0) {
+			hp->do_wakeup = 1;
+			return 0;
+		}
+		/* throw away output on error; this happens when
+		   there is no session connected to the vterm. */
+		hp->n_outbuf = 0;
+	} else
+		hp->n_outbuf -= n;
+	if (hp->n_outbuf > 0)
+		memmove(hp->outbuf, hp->outbuf + n, hp->n_outbuf);
+	else
+		hp->do_wakeup = 1;
+
+	return n;
+}
+
+static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
+{
+	struct hvc_struct *hp = tty->driver_data;
+	unsigned long flags;
+	int rsize, written = 0;
+
+	/* This write was probably executed during a tty close. */
+	if (!hp)
+		return -EPIPE;
+
+	if (hp->count <= 0)
+		return -EIO;
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	/* Push pending writes */
+	if (hp->n_outbuf > 0)
+		hvc_push(hp);
+
+	while (count > 0 && (rsize = hp->outbuf_size - hp->n_outbuf) > 0) {
+		if (rsize > count)
+			rsize = count;
+		memcpy(hp->outbuf + hp->n_outbuf, buf, rsize);
+		count -= rsize;
+		buf += rsize;
+		hp->n_outbuf += rsize;
+		written += rsize;
+		hvc_push(hp);
+	}
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	/*
+	 * Racy, but harmless, kick thread if there is still pending data.
+	 */
+	if (hp->n_outbuf)
+		hvc_kick();
+
+	return written;
+}
+
+/**
+ * hvc_set_winsz() - Resize the hvc tty terminal window.
+ * @work:	work structure.
+ *
+ * The routine shall not be called within an atomic context because it
+ * might sleep.
+ *
+ * Locking:	hp->lock
+ */
+static void hvc_set_winsz(struct work_struct *work)
+{
+	struct hvc_struct *hp;
+	unsigned long hvc_flags;
+	struct tty_struct *tty;
+	struct winsize ws;
+
+	hp = container_of(work, struct hvc_struct, tty_resize);
+
+	spin_lock_irqsave(&hp->lock, hvc_flags);
+	if (!hp->tty) {
+		spin_unlock_irqrestore(&hp->lock, hvc_flags);
+		return;
+	}
+	ws  = hp->ws;
+	tty = tty_kref_get(hp->tty);
+	spin_unlock_irqrestore(&hp->lock, hvc_flags);
+
+	tty_do_resize(tty, &ws);
+	tty_kref_put(tty);
+}
+
+/*
+ * This is actually a contract between the driver and the tty layer outlining
+ * how much write room the driver can guarantee will be sent OR BUFFERED.  This
+ * driver MUST honor the return value.
+ */
+static int hvc_write_room(struct tty_struct *tty)
+{
+	struct hvc_struct *hp = tty->driver_data;
+
+	if (!hp)
+		return -1;
+
+	return hp->outbuf_size - hp->n_outbuf;
+}
+
+static int hvc_chars_in_buffer(struct tty_struct *tty)
+{
+	struct hvc_struct *hp = tty->driver_data;
+
+	if (!hp)
+		return 0;
+	return hp->n_outbuf;
+}
+
+/*
+ * timeout will vary between the MIN and MAX values defined here.  By default
+ * and during console activity we will use a default MIN_TIMEOUT of 10.  When
+ * the console is idle, we increase the timeout value on each pass through
+ * msleep until we reach the max.  This may be noticeable as a brief (average
+ * one second) delay on the console before the console responds to input when
+ * there has been no input for some time.
+ */
+#define MIN_TIMEOUT		(10)
+#define MAX_TIMEOUT		(2000)
+static u32 timeout = MIN_TIMEOUT;
+
+#define HVC_POLL_READ	0x00000001
+#define HVC_POLL_WRITE	0x00000002
+
+int hvc_poll(struct hvc_struct *hp)
+{
+	struct tty_struct *tty;
+	int i, n, poll_mask = 0;
+	char buf[N_INBUF] __ALIGNED__;
+	unsigned long flags;
+	int read_total = 0;
+	int written_total = 0;
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	/* Push pending writes */
+	if (hp->n_outbuf > 0)
+		written_total = hvc_push(hp);
+
+	/* Reschedule us if still some write pending */
+	if (hp->n_outbuf > 0) {
+		poll_mask |= HVC_POLL_WRITE;
+		/* If hvc_push() was not able to write, sleep a few msecs */
+		timeout = (written_total) ? 0 : MIN_TIMEOUT;
+	}
+
+	/* No tty attached, just skip */
+	tty = tty_kref_get(hp->tty);
+	if (tty == NULL)
+		goto bail;
+
+	/* Now check if we can get data (are we throttled ?) */
+	if (test_bit(TTY_THROTTLED, &tty->flags))
+		goto throttled;
+
+	/* If we aren't notifier driven and aren't throttled, we always
+	 * request a reschedule
+	 */
+	if (!hp->irq_requested)
+		poll_mask |= HVC_POLL_READ;
+
+	/* Read data if any */
+	for (;;) {
+		int count = tty_buffer_request_room(tty, N_INBUF);
+
+		/* If flip is full, just reschedule a later read */
+		if (count == 0) {
+			poll_mask |= HVC_POLL_READ;
+			break;
+		}
+
+		n = hp->ops->get_chars(hp->vtermno, buf, count);
+		if (n <= 0) {
+			/* Hangup the tty when disconnected from host */
+			if (n == -EPIPE) {
+				spin_unlock_irqrestore(&hp->lock, flags);
+				tty_hangup(tty);
+				spin_lock_irqsave(&hp->lock, flags);
+			} else if ( n == -EAGAIN ) {
+				/*
+				 * Some back-ends can only ensure a certain min
+				 * num of bytes read, which may be > 'count'.
+				 * Let the tty clear the flip buff to make room.
+				 */
+				poll_mask |= HVC_POLL_READ;
+			}
+			break;
+		}
+		for (i = 0; i < n; ++i) {
+#ifdef CONFIG_MAGIC_SYSRQ
+			if (hp->index == hvc_console.index) {
+				/* Handle the SysRq Hack */
+				/* XXX should support a sequence */
+				if (buf[i] == '\x0f') {	/* ^O */
+					/* if ^O is pressed again, reset
+					 * sysrq_pressed and flip ^O char */
+					sysrq_pressed = !sysrq_pressed;
+					if (sysrq_pressed)
+						continue;
+				} else if (sysrq_pressed) {
+					handle_sysrq(buf[i]);
+					sysrq_pressed = 0;
+					continue;
+				}
+			}
+#endif /* CONFIG_MAGIC_SYSRQ */
+			tty_insert_flip_char(tty, buf[i], 0);
+		}
+
+		read_total += n;
+	}
+ throttled:
+	/* Wakeup write queue if necessary */
+	if (hp->do_wakeup) {
+		hp->do_wakeup = 0;
+		tty_wakeup(tty);
+	}
+ bail:
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	if (read_total) {
+		/* Activity is occurring, so reset the polling backoff value to
+		   a minimum for performance. */
+		timeout = MIN_TIMEOUT;
+
+		tty_flip_buffer_push(tty);
+	}
+	if (tty)
+		tty_kref_put(tty);
+
+	return poll_mask;
+}
+EXPORT_SYMBOL_GPL(hvc_poll);
+
+/**
+ * __hvc_resize() - Update terminal window size information.
+ * @hp:		HVC console pointer
+ * @ws:		Terminal window size structure
+ *
+ * Stores the specified window size information in the hvc structure of @hp.
+ * The function schedule the tty resize update.
+ *
+ * Locking:	Locking free; the function MUST be called holding hp->lock
+ */
+void __hvc_resize(struct hvc_struct *hp, struct winsize ws)
+{
+	hp->ws = ws;
+	schedule_work(&hp->tty_resize);
+}
+EXPORT_SYMBOL_GPL(__hvc_resize);
+
+/*
+ * This kthread is either polling or interrupt driven.  This is determined by
+ * calling hvc_poll() who determines whether a console adapter support
+ * interrupts.
+ */
+static int khvcd(void *unused)
+{
+	int poll_mask;
+	struct hvc_struct *hp;
+
+	set_freezable();
+	do {
+		poll_mask = 0;
+		hvc_kicked = 0;
+		try_to_freeze();
+		wmb();
+		if (!cpus_are_in_xmon()) {
+			spin_lock(&hvc_structs_lock);
+			list_for_each_entry(hp, &hvc_structs, next) {
+				poll_mask |= hvc_poll(hp);
+			}
+			spin_unlock(&hvc_structs_lock);
+		} else
+			poll_mask |= HVC_POLL_READ;
+		if (hvc_kicked)
+			continue;
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (!hvc_kicked) {
+			if (poll_mask == 0)
+				schedule();
+			else {
+				if (timeout < MAX_TIMEOUT)
+					timeout += (timeout >> 6) + 1;
+
+				msleep_interruptible(timeout);
+			}
+		}
+		__set_current_state(TASK_RUNNING);
+	} while (!kthread_should_stop());
+
+	return 0;
+}
+
+static const struct tty_operations hvc_ops = {
+	.open = hvc_open,
+	.close = hvc_close,
+	.write = hvc_write,
+	.hangup = hvc_hangup,
+	.unthrottle = hvc_unthrottle,
+	.write_room = hvc_write_room,
+	.chars_in_buffer = hvc_chars_in_buffer,
+};
+
+struct hvc_struct *hvc_alloc(uint32_t vtermno, int data,
+			     const struct hv_ops *ops,
+			     int outbuf_size)
+{
+	struct hvc_struct *hp;
+	int i;
+
+	/* We wait until a driver actually comes along */
+	if (!hvc_driver) {
+		int err = hvc_init();
+		if (err)
+			return ERR_PTR(err);
+	}
+
+	hp = kzalloc(ALIGN(sizeof(*hp), sizeof(long)) + outbuf_size,
+			GFP_KERNEL);
+	if (!hp)
+		return ERR_PTR(-ENOMEM);
+
+	hp->vtermno = vtermno;
+	hp->data = data;
+	hp->ops = ops;
+	hp->outbuf_size = outbuf_size;
+	hp->outbuf = &((char *)hp)[ALIGN(sizeof(*hp), sizeof(long))];
+
+	kref_init(&hp->kref);
+
+	INIT_WORK(&hp->tty_resize, hvc_set_winsz);
+	spin_lock_init(&hp->lock);
+	spin_lock(&hvc_structs_lock);
+
+	/*
+	 * find index to use:
+	 * see if this vterm id matches one registered for console.
+	 */
+	for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
+		if (vtermnos[i] == hp->vtermno &&
+		    cons_ops[i] == hp->ops)
+			break;
+
+	/* no matching slot, just use a counter */
+	if (i >= MAX_NR_HVC_CONSOLES)
+		i = ++last_hvc;
+
+	hp->index = i;
+
+	list_add_tail(&(hp->next), &hvc_structs);
+	spin_unlock(&hvc_structs_lock);
+
+	return hp;
+}
+EXPORT_SYMBOL_GPL(hvc_alloc);
+
+int hvc_remove(struct hvc_struct *hp)
+{
+	unsigned long flags;
+	struct tty_struct *tty;
+
+	spin_lock_irqsave(&hp->lock, flags);
+	tty = tty_kref_get(hp->tty);
+
+	if (hp->index < MAX_NR_HVC_CONSOLES)
+		vtermnos[hp->index] = -1;
+
+	/* Don't whack hp->irq because tty_hangup() will need to free the irq. */
+
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	/*
+	 * We 'put' the instance that was grabbed when the kref instance
+	 * was initialized using kref_init().  Let the last holder of this
+	 * kref cause it to be removed, which will probably be the tty_vhangup
+	 * below.
+	 */
+	kref_put(&hp->kref, destroy_hvc_struct);
+
+	/*
+	 * This function call will auto chain call hvc_hangup.
+	 */
+	if (tty) {
+		tty_vhangup(tty);
+		tty_kref_put(tty);
+	}
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hvc_remove);
+
+/* Driver initialization: called as soon as someone uses hvc_alloc(). */
+static int hvc_init(void)
+{
+	struct tty_driver *drv;
+	int err;
+
+	/* We need more than hvc_count adapters due to hotplug additions. */
+	drv = alloc_tty_driver(HVC_ALLOC_TTY_ADAPTERS);
+	if (!drv) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	drv->owner = THIS_MODULE;
+	drv->driver_name = "hvc";
+	drv->name = "hvc";
+	drv->major = HVC_MAJOR;
+	drv->minor_start = HVC_MINOR;
+	drv->type = TTY_DRIVER_TYPE_SYSTEM;
+	drv->init_termios = tty_std_termios;
+	drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_RESET_TERMIOS;
+	tty_set_operations(drv, &hvc_ops);
+
+	/* Always start the kthread because there can be hotplug vty adapters
+	 * added later. */
+	hvc_task = kthread_run(khvcd, NULL, "khvcd");
+	if (IS_ERR(hvc_task)) {
+		printk(KERN_ERR "Couldn't create kthread for console.\n");
+		err = PTR_ERR(hvc_task);
+		goto put_tty;
+	}
+
+	err = tty_register_driver(drv);
+	if (err) {
+		printk(KERN_ERR "Couldn't register hvc console driver\n");
+		goto stop_thread;
+	}
+
+	/*
+	 * Make sure tty is fully registered before allowing it to be
+	 * found by hvc_console_device.
+	 */
+	smp_mb();
+	hvc_driver = drv;
+	return 0;
+
+stop_thread:
+	kthread_stop(hvc_task);
+	hvc_task = NULL;
+put_tty:
+	put_tty_driver(drv);
+out:
+	return err;
+}
+
+/* This isn't particularly necessary due to this being a console driver
+ * but it is nice to be thorough.
+ */
+static void __exit hvc_exit(void)
+{
+	if (hvc_driver) {
+		kthread_stop(hvc_task);
+
+		tty_unregister_driver(hvc_driver);
+		/* return tty_struct instances allocated in hvc_init(). */
+		put_tty_driver(hvc_driver);
+		unregister_console(&hvc_console);
+	}
+}
+module_exit(hvc_exit);
diff --git a/drivers/tty/hvc/hvc_console.h b/drivers/tty/hvc/hvc_console.h
new file mode 100644
index 000000000000..54381eba4e4a
--- /dev/null
+++ b/drivers/tty/hvc/hvc_console.h
@@ -0,0 +1,119 @@
+/*
+ * hvc_console.h
+ * Copyright (C) 2005 IBM Corporation
+ *
+ * Author(s):
+ * 	Ryan S. Arnold <rsa@us.ibm.com>
+ *
+ * hvc_console header information:
+ *      moved here from arch/powerpc/include/asm/hvconsole.h
+ *      and drivers/char/hvc_console.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#ifndef HVC_CONSOLE_H
+#define HVC_CONSOLE_H
+#include <linux/kref.h>
+#include <linux/tty.h>
+#include <linux/spinlock.h>
+
+/*
+ * This is the max number of console adapters that can/will be found as
+ * console devices on first stage console init.  Any number beyond this range
+ * can't be used as a console device but is still a valid tty device.
+ */
+#define MAX_NR_HVC_CONSOLES	16
+
+/*
+ * The Linux TTY code does not support dynamic addition of tty derived devices
+ * so we need to know how many tty devices we might need when space is allocated
+ * for the tty device.  Since this driver supports hotplug of vty adapters we
+ * need to make sure we have enough allocated.
+ */
+#define HVC_ALLOC_TTY_ADAPTERS	8
+
+struct hvc_struct {
+	spinlock_t lock;
+	int index;
+	struct tty_struct *tty;
+	int count;
+	int do_wakeup;
+	char *outbuf;
+	int outbuf_size;
+	int n_outbuf;
+	uint32_t vtermno;
+	const struct hv_ops *ops;
+	int irq_requested;
+	int data;
+	struct winsize ws;
+	struct work_struct tty_resize;
+	struct list_head next;
+	struct kref kref; /* ref count & hvc_struct lifetime */
+};
+
+/* implemented by a low level driver */
+struct hv_ops {
+	int (*get_chars)(uint32_t vtermno, char *buf, int count);
+	int (*put_chars)(uint32_t vtermno, const char *buf, int count);
+
+	/* Callbacks for notification. Called in open, close and hangup */
+	int (*notifier_add)(struct hvc_struct *hp, int irq);
+	void (*notifier_del)(struct hvc_struct *hp, int irq);
+	void (*notifier_hangup)(struct hvc_struct *hp, int irq);
+};
+
+/* Register a vterm and a slot index for use as a console (console_init) */
+extern int hvc_instantiate(uint32_t vtermno, int index,
+			   const struct hv_ops *ops);
+
+/* register a vterm for hvc tty operation (module_init or hotplug add) */
+extern struct hvc_struct * hvc_alloc(uint32_t vtermno, int data,
+				     const struct hv_ops *ops, int outbuf_size);
+/* remove a vterm from hvc tty operation (module_exit or hotplug remove) */
+extern int hvc_remove(struct hvc_struct *hp);
+
+/* data available */
+int hvc_poll(struct hvc_struct *hp);
+void hvc_kick(void);
+
+/* Resize hvc tty terminal window */
+extern void __hvc_resize(struct hvc_struct *hp, struct winsize ws);
+
+static inline void hvc_resize(struct hvc_struct *hp, struct winsize ws)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&hp->lock, flags);
+	__hvc_resize(hp, ws);
+	spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+/* default notifier for irq based notification */
+extern int notifier_add_irq(struct hvc_struct *hp, int data);
+extern void notifier_del_irq(struct hvc_struct *hp, int data);
+extern void notifier_hangup_irq(struct hvc_struct *hp, int data);
+
+
+#if defined(CONFIG_XMON) && defined(CONFIG_SMP)
+#include <asm/xmon.h>
+#else
+static inline int cpus_are_in_xmon(void)
+{
+	return 0;
+}
+#endif
+
+#endif // HVC_CONSOLE_H
diff --git a/drivers/tty/hvc/hvc_dcc.c b/drivers/tty/hvc/hvc_dcc.c
new file mode 100644
index 000000000000..6470f63deb4b
--- /dev/null
+++ b/drivers/tty/hvc/hvc_dcc.c
@@ -0,0 +1,133 @@
+/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+
+#include <asm/processor.h>
+
+#include "hvc_console.h"
+
+/* DCC Status Bits */
+#define DCC_STATUS_RX		(1 << 30)
+#define DCC_STATUS_TX		(1 << 29)
+
+static inline u32 __dcc_getstatus(void)
+{
+	u32 __ret;
+
+	asm("mrc p14, 0, %0, c0, c1, 0	@ read comms ctrl reg"
+		: "=r" (__ret) : : "cc");
+
+	return __ret;
+}
+
+
+#if defined(CONFIG_CPU_V7)
+static inline char __dcc_getchar(void)
+{
+	char __c;
+
+	asm("get_wait:	mrc p14, 0, pc, c0, c1, 0                          \n\
+			bne get_wait                                       \n\
+			mrc p14, 0, %0, c0, c5, 0	@ read comms data reg"
+		: "=r" (__c) : : "cc");
+
+	return __c;
+}
+#else
+static inline char __dcc_getchar(void)
+{
+	char __c;
+
+	asm("mrc p14, 0, %0, c0, c5, 0	@ read comms data reg"
+		: "=r" (__c));
+
+	return __c;
+}
+#endif
+
+#if defined(CONFIG_CPU_V7)
+static inline void __dcc_putchar(char c)
+{
+	asm("put_wait:	mrc p14, 0, pc, c0, c1, 0                 \n\
+			bcs put_wait                              \n\
+			mcr p14, 0, %0, c0, c5, 0                   "
+	: : "r" (c) : "cc");
+}
+#else
+static inline void __dcc_putchar(char c)
+{
+	asm("mcr p14, 0, %0, c0, c5, 0	@ write a char"
+		: /* no output register */
+		: "r" (c));
+}
+#endif
+
+static int hvc_dcc_put_chars(uint32_t vt, const char *buf, int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		while (__dcc_getstatus() & DCC_STATUS_TX)
+			cpu_relax();
+
+		__dcc_putchar((char)(buf[i] & 0xFF));
+	}
+
+	return count;
+}
+
+static int hvc_dcc_get_chars(uint32_t vt, char *buf, int count)
+{
+	int i;
+
+	for (i = 0; i < count; ++i) {
+		int c = -1;
+
+		if (__dcc_getstatus() & DCC_STATUS_RX)
+			c = __dcc_getchar();
+		if (c < 0)
+			break;
+		buf[i] = c;
+	}
+
+	return i;
+}
+
+static const struct hv_ops hvc_dcc_get_put_ops = {
+	.get_chars = hvc_dcc_get_chars,
+	.put_chars = hvc_dcc_put_chars,
+};
+
+static int __init hvc_dcc_console_init(void)
+{
+	hvc_instantiate(0, 0, &hvc_dcc_get_put_ops);
+	return 0;
+}
+console_initcall(hvc_dcc_console_init);
+
+static int __init hvc_dcc_init(void)
+{
+	hvc_alloc(0, 0, &hvc_dcc_get_put_ops, 128);
+	return 0;
+}
+device_initcall(hvc_dcc_init);
diff --git a/drivers/tty/hvc/hvc_irq.c b/drivers/tty/hvc/hvc_irq.c
new file mode 100644
index 000000000000..2623e177e8d6
--- /dev/null
+++ b/drivers/tty/hvc/hvc_irq.c
@@ -0,0 +1,49 @@
+/*
+ * Copyright IBM Corp. 2001,2008
+ *
+ * This file contains the IRQ specific code for hvc_console
+ *
+ */
+
+#include <linux/interrupt.h>
+
+#include "hvc_console.h"
+
+static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance)
+{
+	/* if hvc_poll request a repoll, then kick the hvcd thread */
+	if (hvc_poll(dev_instance))
+		hvc_kick();
+	return IRQ_HANDLED;
+}
+
+/*
+ * For IRQ based systems these callbacks can be used
+ */
+int notifier_add_irq(struct hvc_struct *hp, int irq)
+{
+	int rc;
+
+	if (!irq) {
+		hp->irq_requested = 0;
+		return 0;
+	}
+	rc = request_irq(irq, hvc_handle_interrupt, IRQF_DISABLED,
+			   "hvc_console", hp);
+	if (!rc)
+		hp->irq_requested = 1;
+	return rc;
+}
+
+void notifier_del_irq(struct hvc_struct *hp, int irq)
+{
+	if (!hp->irq_requested)
+		return;
+	free_irq(irq, hp);
+	hp->irq_requested = 0;
+}
+
+void notifier_hangup_irq(struct hvc_struct *hp, int irq)
+{
+	notifier_del_irq(hp, irq);
+}
diff --git a/drivers/tty/hvc/hvc_iseries.c b/drivers/tty/hvc/hvc_iseries.c
new file mode 100644
index 000000000000..21c54955084e
--- /dev/null
+++ b/drivers/tty/hvc/hvc_iseries.c
@@ -0,0 +1,598 @@
+/*
+ * iSeries vio driver interface to hvc_console.c
+ *
+ * This code is based heavily on hvc_vio.c and viocons.c
+ *
+ * Copyright (C) 2006 Stephen Rothwell, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+#include <stdarg.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/console.h>
+
+#include <asm/hvconsole.h>
+#include <asm/vio.h>
+#include <asm/prom.h>
+#include <asm/firmware.h>
+#include <asm/iseries/vio.h>
+#include <asm/iseries/hv_call.h>
+#include <asm/iseries/hv_lp_config.h>
+#include <asm/iseries/hv_lp_event.h>
+
+#include "hvc_console.h"
+
+#define VTTY_PORTS 10
+
+static DEFINE_SPINLOCK(consolelock);
+static DEFINE_SPINLOCK(consoleloglock);
+
+static const char hvc_driver_name[] = "hvc_console";
+
+#define IN_BUF_SIZE	200
+
+/*
+ * Our port information.
+ */
+static struct port_info {
+	HvLpIndex lp;
+	u64 seq;	/* sequence number of last HV send */
+	u64 ack;	/* last ack from HV */
+	struct hvc_struct *hp;
+	int in_start;
+	int in_end;
+	unsigned char in_buf[IN_BUF_SIZE];
+} port_info[VTTY_PORTS] = {
+	[ 0 ... VTTY_PORTS - 1 ] = {
+		.lp = HvLpIndexInvalid
+	}
+};
+
+#define viochar_is_console(pi)	((pi) == &port_info[0])
+
+static struct vio_device_id hvc_driver_table[] __devinitdata = {
+	{"serial", "IBM,iSeries-vty"},
+	{ "", "" }
+};
+MODULE_DEVICE_TABLE(vio, hvc_driver_table);
+
+static void hvlog(char *fmt, ...)
+{
+	int i;
+	unsigned long flags;
+	va_list args;
+	static char buf[256];
+
+	spin_lock_irqsave(&consoleloglock, flags);
+	va_start(args, fmt);
+	i = vscnprintf(buf, sizeof(buf) - 1, fmt, args);
+	va_end(args);
+	buf[i++] = '\r';
+	HvCall_writeLogBuffer(buf, i);
+	spin_unlock_irqrestore(&consoleloglock, flags);
+}
+
+/*
+ * Initialize the common fields in a charLpEvent
+ */
+static void init_data_event(struct viocharlpevent *viochar, HvLpIndex lp)
+{
+	struct HvLpEvent *hev = &viochar->event;
+
+	memset(viochar, 0, sizeof(struct viocharlpevent));
+
+	hev->flags = HV_LP_EVENT_VALID | HV_LP_EVENT_DEFERRED_ACK |
+		HV_LP_EVENT_INT;
+	hev->xType = HvLpEvent_Type_VirtualIo;
+	hev->xSubtype = viomajorsubtype_chario | viochardata;
+	hev->xSourceLp = HvLpConfig_getLpIndex();
+	hev->xTargetLp = lp;
+	hev->xSizeMinus1 = sizeof(struct viocharlpevent);
+	hev->xSourceInstanceId = viopath_sourceinst(lp);
+	hev->xTargetInstanceId = viopath_targetinst(lp);
+}
+
+static int get_chars(uint32_t vtermno, char *buf, int count)
+{
+	struct port_info *pi;
+	int n = 0;
+	unsigned long flags;
+
+	if (vtermno >= VTTY_PORTS)
+		return -EINVAL;
+	if (count == 0)
+		return 0;
+
+	pi = &port_info[vtermno];
+	spin_lock_irqsave(&consolelock, flags);
+
+	if (pi->in_end == 0)
+		goto done;
+
+	n = pi->in_end - pi->in_start;
+	if (n > count)
+		n = count;
+	memcpy(buf, &pi->in_buf[pi->in_start], n);
+	pi->in_start += n;
+	if (pi->in_start == pi->in_end) {
+		pi->in_start = 0;
+		pi->in_end = 0;
+	}
+done:
+	spin_unlock_irqrestore(&consolelock, flags);
+	return n;
+}
+
+static int put_chars(uint32_t vtermno, const char *buf, int count)
+{
+	struct viocharlpevent *viochar;
+	struct port_info *pi;
+	HvLpEvent_Rc hvrc;
+	unsigned long flags;
+	int sent = 0;
+
+	if (vtermno >= VTTY_PORTS)
+		return -EINVAL;
+
+	pi = &port_info[vtermno];
+
+	spin_lock_irqsave(&consolelock, flags);
+
+	if (viochar_is_console(pi) && !viopath_isactive(pi->lp)) {
+		HvCall_writeLogBuffer(buf, count);
+		sent = count;
+		goto done;
+	}
+
+	viochar = vio_get_event_buffer(viomajorsubtype_chario);
+	if (viochar == NULL) {
+		hvlog("\n\rviocons: Can't get viochar buffer.");
+		goto done;
+	}
+
+	while ((count > 0) && ((pi->seq - pi->ack) < VIOCHAR_WINDOW)) {
+		int len;
+
+		len = (count > VIOCHAR_MAX_DATA) ? VIOCHAR_MAX_DATA : count;
+
+		if (viochar_is_console(pi))
+			HvCall_writeLogBuffer(buf, len);
+
+		init_data_event(viochar, pi->lp);
+
+		viochar->len = len;
+		viochar->event.xCorrelationToken = pi->seq++;
+		viochar->event.xSizeMinus1 =
+			offsetof(struct viocharlpevent, data) + len;
+
+		memcpy(viochar->data, buf, len);
+
+		hvrc = HvCallEvent_signalLpEvent(&viochar->event);
+		if (hvrc)
+			hvlog("\n\rerror sending event! return code %d\n\r",
+				(int)hvrc);
+		sent += len;
+		count -= len;
+		buf += len;
+	}
+
+	vio_free_event_buffer(viomajorsubtype_chario, viochar);
+done:
+	spin_unlock_irqrestore(&consolelock, flags);
+	return sent;
+}
+
+static const struct hv_ops hvc_get_put_ops = {
+	.get_chars = get_chars,
+	.put_chars = put_chars,
+	.notifier_add = notifier_add_irq,
+	.notifier_del = notifier_del_irq,
+	.notifier_hangup = notifier_hangup_irq,
+};
+
+static int __devinit hvc_vio_probe(struct vio_dev *vdev,
+			const struct vio_device_id *id)
+{
+	struct hvc_struct *hp;
+	struct port_info *pi;
+
+	/* probed with invalid parameters. */
+	if (!vdev || !id)
+		return -EPERM;
+
+	if (vdev->unit_address >= VTTY_PORTS)
+		return -ENODEV;
+
+	pi = &port_info[vdev->unit_address];
+
+	hp = hvc_alloc(vdev->unit_address, vdev->irq, &hvc_get_put_ops,
+			VIOCHAR_MAX_DATA);
+	if (IS_ERR(hp))
+		return PTR_ERR(hp);
+	pi->hp = hp;
+	dev_set_drvdata(&vdev->dev, pi);
+
+	return 0;
+}
+
+static int __devexit hvc_vio_remove(struct vio_dev *vdev)
+{
+	struct port_info *pi = dev_get_drvdata(&vdev->dev);
+	struct hvc_struct *hp = pi->hp;
+
+	return hvc_remove(hp);
+}
+
+static struct vio_driver hvc_vio_driver = {
+	.id_table	= hvc_driver_table,
+	.probe		= hvc_vio_probe,
+	.remove		= __devexit_p(hvc_vio_remove),
+	.driver		= {
+		.name	= hvc_driver_name,
+		.owner	= THIS_MODULE,
+	}
+};
+
+static void hvc_open_event(struct HvLpEvent *event)
+{
+	unsigned long flags;
+	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
+	u8 port = cevent->virtual_device;
+	struct port_info *pi;
+	int reject = 0;
+
+	if (hvlpevent_is_ack(event)) {
+		if (port >= VTTY_PORTS)
+			return;
+
+		spin_lock_irqsave(&consolelock, flags);
+
+		pi = &port_info[port];
+		if (event->xRc == HvLpEvent_Rc_Good) {
+			pi->seq = pi->ack = 0;
+			/*
+			 * This line allows connections from the primary
+			 * partition but once one is connected from the
+			 * primary partition nothing short of a reboot
+			 * of linux will allow access from the hosting
+			 * partition again without a required iSeries fix.
+			 */
+			pi->lp = event->xTargetLp;
+		}
+
+		spin_unlock_irqrestore(&consolelock, flags);
+		if (event->xRc != HvLpEvent_Rc_Good)
+			printk(KERN_WARNING
+			       "hvc: handle_open_event: event->xRc == (%d).\n",
+			       event->xRc);
+
+		if (event->xCorrelationToken != 0) {
+			atomic_t *aptr= (atomic_t *)event->xCorrelationToken;
+			atomic_set(aptr, 1);
+		} else
+			printk(KERN_WARNING
+			       "hvc: weird...got open ack without atomic\n");
+		return;
+	}
+
+	/* This had better require an ack, otherwise complain */
+	if (!hvlpevent_need_ack(event)) {
+		printk(KERN_WARNING "hvc: viocharopen without ack bit!\n");
+		return;
+	}
+
+	spin_lock_irqsave(&consolelock, flags);
+
+	/* Make sure this is a good virtual tty */
+	if (port >= VTTY_PORTS) {
+		event->xRc = HvLpEvent_Rc_SubtypeError;
+		cevent->subtype_result_code = viorc_openRejected;
+		/*
+		 * Flag state here since we can't printk while holding
+		 * the consolelock spinlock.
+		 */
+		reject = 1;
+	} else {
+		pi = &port_info[port];
+		if ((pi->lp != HvLpIndexInvalid) &&
+				(pi->lp != event->xSourceLp)) {
+			/*
+			 * If this is tty is already connected to a different
+			 * partition, fail.
+			 */
+			event->xRc = HvLpEvent_Rc_SubtypeError;
+			cevent->subtype_result_code = viorc_openRejected;
+			reject = 2;
+		} else {
+			pi->lp = event->xSourceLp;
+			event->xRc = HvLpEvent_Rc_Good;
+			cevent->subtype_result_code = viorc_good;
+			pi->seq = pi->ack = 0;
+		}
+	}
+
+	spin_unlock_irqrestore(&consolelock, flags);
+
+	if (reject == 1)
+		printk(KERN_WARNING "hvc: open rejected: bad virtual tty.\n");
+	else if (reject == 2)
+		printk(KERN_WARNING "hvc: open rejected: console in exclusive "
+				"use by another partition.\n");
+
+	/* Return the acknowledgement */
+	HvCallEvent_ackLpEvent(event);
+}
+
+/*
+ * Handle a close charLpEvent.  This should ONLY be an Interrupt because the
+ * virtual console should never actually issue a close event to the hypervisor
+ * because the virtual console never goes away.  A close event coming from the
+ * hypervisor simply means that there are no client consoles connected to the
+ * virtual console.
+ */
+static void hvc_close_event(struct HvLpEvent *event)
+{
+	unsigned long flags;
+	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
+	u8 port = cevent->virtual_device;
+
+	if (!hvlpevent_is_int(event)) {
+		printk(KERN_WARNING
+			"hvc: got unexpected close acknowledgement\n");
+		return;
+	}
+
+	if (port >= VTTY_PORTS) {
+		printk(KERN_WARNING
+			"hvc: close message from invalid virtual device.\n");
+		return;
+	}
+
+	/* For closes, just mark the console partition invalid */
+	spin_lock_irqsave(&consolelock, flags);
+
+	if (port_info[port].lp == event->xSourceLp)
+		port_info[port].lp = HvLpIndexInvalid;
+
+	spin_unlock_irqrestore(&consolelock, flags);
+}
+
+static void hvc_data_event(struct HvLpEvent *event)
+{
+	unsigned long flags;
+	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
+	struct port_info *pi;
+	int n;
+	u8 port = cevent->virtual_device;
+
+	if (port >= VTTY_PORTS) {
+		printk(KERN_WARNING "hvc: data on invalid virtual device %d\n",
+				port);
+		return;
+	}
+	if (cevent->len == 0)
+		return;
+
+	/*
+	 * Change 05/01/2003 - Ryan Arnold: If a partition other than
+	 * the current exclusive partition tries to send us data
+	 * events then just drop them on the floor because we don't
+	 * want his stinking data.  He isn't authorized to receive
+	 * data because he wasn't the first one to get the console,
+	 * therefore he shouldn't be allowed to send data either.
+	 * This will work without an iSeries fix.
+	 */
+	pi = &port_info[port];
+	if (pi->lp != event->xSourceLp)
+		return;
+
+	spin_lock_irqsave(&consolelock, flags);
+
+	n = IN_BUF_SIZE - pi->in_end;
+	if (n > cevent->len)
+		n = cevent->len;
+	if (n > 0) {
+		memcpy(&pi->in_buf[pi->in_end], cevent->data, n);
+		pi->in_end += n;
+	}
+	spin_unlock_irqrestore(&consolelock, flags);
+	if (n == 0)
+		printk(KERN_WARNING "hvc: input buffer overflow\n");
+}
+
+static void hvc_ack_event(struct HvLpEvent *event)
+{
+	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
+	unsigned long flags;
+	u8 port = cevent->virtual_device;
+
+	if (port >= VTTY_PORTS) {
+		printk(KERN_WARNING "hvc: data on invalid virtual device\n");
+		return;
+	}
+
+	spin_lock_irqsave(&consolelock, flags);
+	port_info[port].ack = event->xCorrelationToken;
+	spin_unlock_irqrestore(&consolelock, flags);
+}
+
+static void hvc_config_event(struct HvLpEvent *event)
+{
+	struct viocharlpevent *cevent = (struct viocharlpevent *)event;
+
+	if (cevent->data[0] == 0x01)
+		printk(KERN_INFO "hvc: window resized to %d: %d: %d: %d\n",
+		       cevent->data[1], cevent->data[2],
+		       cevent->data[3], cevent->data[4]);
+	else
+		printk(KERN_WARNING "hvc: unknown config event\n");
+}
+
+static void hvc_handle_event(struct HvLpEvent *event)
+{
+	int charminor;
+
+	if (event == NULL)
+		return;
+
+	charminor = event->xSubtype & VIOMINOR_SUBTYPE_MASK;
+	switch (charminor) {
+	case viocharopen:
+		hvc_open_event(event);
+		break;
+	case viocharclose:
+		hvc_close_event(event);
+		break;
+	case viochardata:
+		hvc_data_event(event);
+		break;
+	case viocharack:
+		hvc_ack_event(event);
+		break;
+	case viocharconfig:
+		hvc_config_event(event);
+		break;
+	default:
+		if (hvlpevent_is_int(event) && hvlpevent_need_ack(event)) {
+			event->xRc = HvLpEvent_Rc_InvalidSubtype;
+			HvCallEvent_ackLpEvent(event);
+		}
+	}
+}
+
+static int __init send_open(HvLpIndex remoteLp, void *sem)
+{
+	return HvCallEvent_signalLpEventFast(remoteLp,
+			HvLpEvent_Type_VirtualIo,
+			viomajorsubtype_chario | viocharopen,
+			HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
+			viopath_sourceinst(remoteLp),
+			viopath_targetinst(remoteLp),
+			(u64)(unsigned long)sem, VIOVERSION << 16,
+			0, 0, 0, 0);
+}
+
+static int __init hvc_vio_init(void)
+{
+	atomic_t wait_flag;
+	int rc;
+
+	if (!firmware_has_feature(FW_FEATURE_ISERIES))
+		return -EIO;
+
+	/* +2 for fudge */
+	rc = viopath_open(HvLpConfig_getPrimaryLpIndex(),
+			viomajorsubtype_chario, VIOCHAR_WINDOW + 2);
+	if (rc)
+		printk(KERN_WARNING "hvc: error opening to primary %d\n", rc);
+
+	if (viopath_hostLp == HvLpIndexInvalid)
+		vio_set_hostlp();
+
+	/*
+	 * And if the primary is not the same as the hosting LP, open to the
+	 * hosting lp
+	 */
+	if ((viopath_hostLp != HvLpIndexInvalid) &&
+	    (viopath_hostLp != HvLpConfig_getPrimaryLpIndex())) {
+		printk(KERN_INFO "hvc: open path to hosting (%d)\n",
+				viopath_hostLp);
+		rc = viopath_open(viopath_hostLp, viomajorsubtype_chario,
+				VIOCHAR_WINDOW + 2);	/* +2 for fudge */
+		if (rc)
+			printk(KERN_WARNING
+				"error opening to partition %d: %d\n",
+				viopath_hostLp, rc);
+	}
+
+	if (vio_setHandler(viomajorsubtype_chario, hvc_handle_event) < 0)
+		printk(KERN_WARNING
+			"hvc: error seting handler for console events!\n");
+
+	/*
+	 * First, try to open the console to the hosting lp.
+	 * Wait on a semaphore for the response.
+	 */
+	atomic_set(&wait_flag, 0);
+	if ((viopath_isactive(viopath_hostLp)) &&
+	    (send_open(viopath_hostLp, &wait_flag) == 0)) {
+		printk(KERN_INFO "hvc: hosting partition %d\n", viopath_hostLp);
+		while (atomic_read(&wait_flag) == 0)
+			mb();
+		atomic_set(&wait_flag, 0);
+	}
+
+	/*
+	 * If we don't have an active console, try the primary
+	 */
+	if ((!viopath_isactive(port_info[0].lp)) &&
+	    (viopath_isactive(HvLpConfig_getPrimaryLpIndex())) &&
+	    (send_open(HvLpConfig_getPrimaryLpIndex(), &wait_flag) == 0)) {
+		printk(KERN_INFO "hvc: opening console to primary partition\n");
+		while (atomic_read(&wait_flag) == 0)
+			mb();
+	}
+
+	/* Register as a vio device to receive callbacks */
+	rc = vio_register_driver(&hvc_vio_driver);
+
+	return rc;
+}
+module_init(hvc_vio_init); /* after drivers/char/hvc_console.c */
+
+static void __exit hvc_vio_exit(void)
+{
+	vio_unregister_driver(&hvc_vio_driver);
+}
+module_exit(hvc_vio_exit);
+
+/* the device tree order defines our numbering */
+static int __init hvc_find_vtys(void)
+{
+	struct device_node *vty;
+	int num_found = 0;
+
+	for (vty = of_find_node_by_name(NULL, "vty"); vty != NULL;
+			vty = of_find_node_by_name(vty, "vty")) {
+		const uint32_t *vtermno;
+
+		/* We have statically defined space for only a certain number
+		 * of console adapters.
+		 */
+		if ((num_found >= MAX_NR_HVC_CONSOLES) ||
+				(num_found >= VTTY_PORTS)) {
+			of_node_put(vty);
+			break;
+		}
+
+		vtermno = of_get_property(vty, "reg", NULL);
+		if (!vtermno)
+			continue;
+
+		if (!of_device_is_compatible(vty, "IBM,iSeries-vty"))
+			continue;
+
+		if (num_found == 0)
+			add_preferred_console("hvc", 0, NULL);
+		hvc_instantiate(*vtermno, num_found, &hvc_get_put_ops);
+		++num_found;
+	}
+
+	return num_found;
+}
+console_initcall(hvc_find_vtys);
diff --git a/drivers/tty/hvc/hvc_iucv.c b/drivers/tty/hvc/hvc_iucv.c
new file mode 100644
index 000000000000..c3425bb3a1f6
--- /dev/null
+++ b/drivers/tty/hvc/hvc_iucv.c
@@ -0,0 +1,1337 @@
+/*
+ * hvc_iucv.c - z/VM IUCV hypervisor console (HVC) device driver
+ *
+ * This HVC device driver provides terminal access using
+ * z/VM IUCV communication paths.
+ *
+ * Copyright IBM Corp. 2008, 2009
+ *
+ * Author(s):	Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
+ */
+#define KMSG_COMPONENT		"hvc_iucv"
+#define pr_fmt(fmt)		KMSG_COMPONENT ": " fmt
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <asm/ebcdic.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/mempool.h>
+#include <linux/moduleparam.h>
+#include <linux/tty.h>
+#include <linux/wait.h>
+#include <net/iucv/iucv.h>
+
+#include "hvc_console.h"
+
+
+/* General device driver settings */
+#define HVC_IUCV_MAGIC		0xc9e4c3e5
+#define MAX_HVC_IUCV_LINES	HVC_ALLOC_TTY_ADAPTERS
+#define MEMPOOL_MIN_NR		(PAGE_SIZE / sizeof(struct iucv_tty_buffer)/4)
+
+/* IUCV TTY message  */
+#define MSG_VERSION		0x02	/* Message version */
+#define MSG_TYPE_ERROR		0x01	/* Error message */
+#define MSG_TYPE_TERMENV	0x02	/* Terminal environment variable */
+#define MSG_TYPE_TERMIOS	0x04	/* Terminal IO struct update */
+#define MSG_TYPE_WINSIZE	0x08	/* Terminal window size update */
+#define MSG_TYPE_DATA		0x10	/* Terminal data */
+
+struct iucv_tty_msg {
+	u8	version;		/* Message version */
+	u8	type;			/* Message type */
+#define MSG_MAX_DATALEN		((u16)(~0))
+	u16	datalen;		/* Payload length */
+	u8	data[];			/* Payload buffer */
+} __attribute__((packed));
+#define MSG_SIZE(s)		((s) + offsetof(struct iucv_tty_msg, data))
+
+enum iucv_state_t {
+	IUCV_DISCONN	= 0,
+	IUCV_CONNECTED	= 1,
+	IUCV_SEVERED	= 2,
+};
+
+enum tty_state_t {
+	TTY_CLOSED	= 0,
+	TTY_OPENED	= 1,
+};
+
+struct hvc_iucv_private {
+	struct hvc_struct	*hvc;		/* HVC struct reference */
+	u8			srv_name[8];	/* IUCV service name (ebcdic) */
+	unsigned char		is_console;	/* Linux console usage flag */
+	enum iucv_state_t	iucv_state;	/* IUCV connection status */
+	enum tty_state_t	tty_state;	/* TTY status */
+	struct iucv_path	*path;		/* IUCV path pointer */
+	spinlock_t		lock;		/* hvc_iucv_private lock */
+#define SNDBUF_SIZE		(PAGE_SIZE)	/* must be < MSG_MAX_DATALEN */
+	void			*sndbuf;	/* send buffer		  */
+	size_t			sndbuf_len;	/* length of send buffer  */
+#define QUEUE_SNDBUF_DELAY	(HZ / 25)
+	struct delayed_work	sndbuf_work;	/* work: send iucv msg(s) */
+	wait_queue_head_t	sndbuf_waitq;	/* wait for send completion */
+	struct list_head	tty_outqueue;	/* outgoing IUCV messages */
+	struct list_head	tty_inqueue;	/* incoming IUCV messages */
+	struct device		*dev;		/* device structure */
+};
+
+struct iucv_tty_buffer {
+	struct list_head	list;	/* list pointer */
+	struct iucv_message	msg;	/* store an IUCV message */
+	size_t			offset;	/* data buffer offset */
+	struct iucv_tty_msg	*mbuf;	/* buffer to store input/output data */
+};
+
+/* IUCV callback handler */
+static	int hvc_iucv_path_pending(struct iucv_path *, u8[8], u8[16]);
+static void hvc_iucv_path_severed(struct iucv_path *, u8[16]);
+static void hvc_iucv_msg_pending(struct iucv_path *, struct iucv_message *);
+static void hvc_iucv_msg_complete(struct iucv_path *, struct iucv_message *);
+
+
+/* Kernel module parameter: use one terminal device as default */
+static unsigned long hvc_iucv_devices = 1;
+
+/* Array of allocated hvc iucv tty lines... */
+static struct hvc_iucv_private *hvc_iucv_table[MAX_HVC_IUCV_LINES];
+#define IUCV_HVC_CON_IDX	(0)
+/* List of z/VM user ID filter entries (struct iucv_vmid_filter) */
+#define MAX_VMID_FILTER		(500)
+static size_t hvc_iucv_filter_size;
+static void *hvc_iucv_filter;
+static const char *hvc_iucv_filter_string;
+static DEFINE_RWLOCK(hvc_iucv_filter_lock);
+
+/* Kmem cache and mempool for iucv_tty_buffer elements */
+static struct kmem_cache *hvc_iucv_buffer_cache;
+static mempool_t *hvc_iucv_mempool;
+
+/* IUCV handler callback functions */
+static struct iucv_handler hvc_iucv_handler = {
+	.path_pending  = hvc_iucv_path_pending,
+	.path_severed  = hvc_iucv_path_severed,
+	.message_complete = hvc_iucv_msg_complete,
+	.message_pending  = hvc_iucv_msg_pending,
+};
+
+
+/**
+ * hvc_iucv_get_private() - Return a struct hvc_iucv_private instance.
+ * @num:	The HVC virtual terminal number (vtermno)
+ *
+ * This function returns the struct hvc_iucv_private instance that corresponds
+ * to the HVC virtual terminal number specified as parameter @num.
+ */
+struct hvc_iucv_private *hvc_iucv_get_private(uint32_t num)
+{
+	if ((num < HVC_IUCV_MAGIC) || (num - HVC_IUCV_MAGIC > hvc_iucv_devices))
+		return NULL;
+	return hvc_iucv_table[num - HVC_IUCV_MAGIC];
+}
+
+/**
+ * alloc_tty_buffer() - Return a new struct iucv_tty_buffer element.
+ * @size:	Size of the internal buffer used to store data.
+ * @flags:	Memory allocation flags passed to mempool.
+ *
+ * This function allocates a new struct iucv_tty_buffer element and, optionally,
+ * allocates an internal data buffer with the specified size @size.
+ * The internal data buffer is always allocated with GFP_DMA which is
+ * required for receiving and sending data with IUCV.
+ * Note: The total message size arises from the internal buffer size and the
+ *	 members of the iucv_tty_msg structure.
+ * The function returns NULL if memory allocation has failed.
+ */
+static struct iucv_tty_buffer *alloc_tty_buffer(size_t size, gfp_t flags)
+{
+	struct iucv_tty_buffer *bufp;
+
+	bufp = mempool_alloc(hvc_iucv_mempool, flags);
+	if (!bufp)
+		return NULL;
+	memset(bufp, 0, sizeof(*bufp));
+
+	if (size > 0) {
+		bufp->msg.length = MSG_SIZE(size);
+		bufp->mbuf = kmalloc(bufp->msg.length, flags | GFP_DMA);
+		if (!bufp->mbuf) {
+			mempool_free(bufp, hvc_iucv_mempool);
+			return NULL;
+		}
+		bufp->mbuf->version = MSG_VERSION;
+		bufp->mbuf->type    = MSG_TYPE_DATA;
+		bufp->mbuf->datalen = (u16) size;
+	}
+	return bufp;
+}
+
+/**
+ * destroy_tty_buffer() - destroy struct iucv_tty_buffer element.
+ * @bufp:	Pointer to a struct iucv_tty_buffer element, SHALL NOT be NULL.
+ */
+static void destroy_tty_buffer(struct iucv_tty_buffer *bufp)
+{
+	kfree(bufp->mbuf);
+	mempool_free(bufp, hvc_iucv_mempool);
+}
+
+/**
+ * destroy_tty_buffer_list() - call destroy_tty_buffer() for each list element.
+ * @list:	List containing struct iucv_tty_buffer elements.
+ */
+static void destroy_tty_buffer_list(struct list_head *list)
+{
+	struct iucv_tty_buffer *ent, *next;
+
+	list_for_each_entry_safe(ent, next, list, list) {
+		list_del(&ent->list);
+		destroy_tty_buffer(ent);
+	}
+}
+
+/**
+ * hvc_iucv_write() - Receive IUCV message & write data to HVC buffer.
+ * @priv:		Pointer to struct hvc_iucv_private
+ * @buf:		HVC buffer for writing received terminal data.
+ * @count:		HVC buffer size.
+ * @has_more_data:	Pointer to an int variable.
+ *
+ * The function picks up pending messages from the input queue and receives
+ * the message data that is then written to the specified buffer @buf.
+ * If the buffer size @count is less than the data message size, the
+ * message is kept on the input queue and @has_more_data is set to 1.
+ * If all message data has been written, the message is removed from
+ * the input queue.
+ *
+ * The function returns the number of bytes written to the terminal, zero if
+ * there are no pending data messages available or if there is no established
+ * IUCV path.
+ * If the IUCV path has been severed, then -EPIPE is returned to cause a
+ * hang up (that is issued by the HVC layer).
+ */
+static int hvc_iucv_write(struct hvc_iucv_private *priv,
+			  char *buf, int count, int *has_more_data)
+{
+	struct iucv_tty_buffer *rb;
+	int written;
+	int rc;
+
+	/* immediately return if there is no IUCV connection */
+	if (priv->iucv_state == IUCV_DISCONN)
+		return 0;
+
+	/* if the IUCV path has been severed, return -EPIPE to inform the
+	 * HVC layer to hang up the tty device. */
+	if (priv->iucv_state == IUCV_SEVERED)
+		return -EPIPE;
+
+	/* check if there are pending messages */
+	if (list_empty(&priv->tty_inqueue))
+		return 0;
+
+	/* receive an iucv message and flip data to the tty (ldisc) */
+	rb = list_first_entry(&priv->tty_inqueue, struct iucv_tty_buffer, list);
+
+	written = 0;
+	if (!rb->mbuf) { /* message not yet received ... */
+		/* allocate mem to store msg data; if no memory is available
+		 * then leave the buffer on the list and re-try later */
+		rb->mbuf = kmalloc(rb->msg.length, GFP_ATOMIC | GFP_DMA);
+		if (!rb->mbuf)
+			return -ENOMEM;
+
+		rc = __iucv_message_receive(priv->path, &rb->msg, 0,
+					    rb->mbuf, rb->msg.length, NULL);
+		switch (rc) {
+		case 0: /* Successful	    */
+			break;
+		case 2:	/* No message found */
+		case 9: /* Message purged   */
+			break;
+		default:
+			written = -EIO;
+		}
+		/* remove buffer if an error has occured or received data
+		 * is not correct */
+		if (rc || (rb->mbuf->version != MSG_VERSION) ||
+			  (rb->msg.length    != MSG_SIZE(rb->mbuf->datalen)))
+			goto out_remove_buffer;
+	}
+
+	switch (rb->mbuf->type) {
+	case MSG_TYPE_DATA:
+		written = min_t(int, rb->mbuf->datalen - rb->offset, count);
+		memcpy(buf, rb->mbuf->data + rb->offset, written);
+		if (written < (rb->mbuf->datalen - rb->offset)) {
+			rb->offset += written;
+			*has_more_data = 1;
+			goto out_written;
+		}
+		break;
+
+	case MSG_TYPE_WINSIZE:
+		if (rb->mbuf->datalen != sizeof(struct winsize))
+			break;
+		/* The caller must ensure that the hvc is locked, which
+		 * is the case when called from hvc_iucv_get_chars() */
+		__hvc_resize(priv->hvc, *((struct winsize *) rb->mbuf->data));
+		break;
+
+	case MSG_TYPE_ERROR:	/* ignored ... */
+	case MSG_TYPE_TERMENV:	/* ignored ... */
+	case MSG_TYPE_TERMIOS:	/* ignored ... */
+		break;
+	}
+
+out_remove_buffer:
+	list_del(&rb->list);
+	destroy_tty_buffer(rb);
+	*has_more_data = !list_empty(&priv->tty_inqueue);
+
+out_written:
+	return written;
+}
+
+/**
+ * hvc_iucv_get_chars() - HVC get_chars operation.
+ * @vtermno:	HVC virtual terminal number.
+ * @buf:	Pointer to a buffer to store data
+ * @count:	Size of buffer available for writing
+ *
+ * The HVC thread calls this method to read characters from the back-end.
+ * If an IUCV communication path has been established, pending IUCV messages
+ * are received and data is copied into buffer @buf up to @count bytes.
+ *
+ * Locking:	The routine gets called under an irqsave() spinlock; and
+ *		the routine locks the struct hvc_iucv_private->lock to call
+ *		helper functions.
+ */
+static int hvc_iucv_get_chars(uint32_t vtermno, char *buf, int count)
+{
+	struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno);
+	int written;
+	int has_more_data;
+
+	if (count <= 0)
+		return 0;
+
+	if (!priv)
+		return -ENODEV;
+
+	spin_lock(&priv->lock);
+	has_more_data = 0;
+	written = hvc_iucv_write(priv, buf, count, &has_more_data);
+	spin_unlock(&priv->lock);
+
+	/* if there are still messages on the queue... schedule another run */
+	if (has_more_data)
+		hvc_kick();
+
+	return written;
+}
+
+/**
+ * hvc_iucv_queue() - Buffer terminal data for sending.
+ * @priv:	Pointer to struct hvc_iucv_private instance.
+ * @buf:	Buffer containing data to send.
+ * @count:	Size of buffer and amount of data to send.
+ *
+ * The function queues data for sending. To actually send the buffered data,
+ * a work queue function is scheduled (with QUEUE_SNDBUF_DELAY).
+ * The function returns the number of data bytes that has been buffered.
+ *
+ * If the device is not connected, data is ignored and the function returns
+ * @count.
+ * If the buffer is full, the function returns 0.
+ * If an existing IUCV communicaton path has been severed, -EPIPE is returned
+ * (that can be passed to HVC layer to cause a tty hangup).
+ */
+static int hvc_iucv_queue(struct hvc_iucv_private *priv, const char *buf,
+			  int count)
+{
+	size_t len;
+
+	if (priv->iucv_state == IUCV_DISCONN)
+		return count;			/* ignore data */
+
+	if (priv->iucv_state == IUCV_SEVERED)
+		return -EPIPE;
+
+	len = min_t(size_t, count, SNDBUF_SIZE - priv->sndbuf_len);
+	if (!len)
+		return 0;
+
+	memcpy(priv->sndbuf + priv->sndbuf_len, buf, len);
+	priv->sndbuf_len += len;
+
+	if (priv->iucv_state == IUCV_CONNECTED)
+		schedule_delayed_work(&priv->sndbuf_work, QUEUE_SNDBUF_DELAY);
+
+	return len;
+}
+
+/**
+ * hvc_iucv_send() - Send an IUCV message containing terminal data.
+ * @priv:	Pointer to struct hvc_iucv_private instance.
+ *
+ * If an IUCV communication path has been established, the buffered output data
+ * is sent via an IUCV message and the number of bytes sent is returned.
+ * Returns 0 if there is no established IUCV communication path or
+ * -EPIPE if an existing IUCV communicaton path has been severed.
+ */
+static int hvc_iucv_send(struct hvc_iucv_private *priv)
+{
+	struct iucv_tty_buffer *sb;
+	int rc, len;
+
+	if (priv->iucv_state == IUCV_SEVERED)
+		return -EPIPE;
+
+	if (priv->iucv_state == IUCV_DISCONN)
+		return -EIO;
+
+	if (!priv->sndbuf_len)
+		return 0;
+
+	/* allocate internal buffer to store msg data and also compute total
+	 * message length */
+	sb = alloc_tty_buffer(priv->sndbuf_len, GFP_ATOMIC);
+	if (!sb)
+		return -ENOMEM;
+
+	memcpy(sb->mbuf->data, priv->sndbuf, priv->sndbuf_len);
+	sb->mbuf->datalen = (u16) priv->sndbuf_len;
+	sb->msg.length = MSG_SIZE(sb->mbuf->datalen);
+
+	list_add_tail(&sb->list, &priv->tty_outqueue);
+
+	rc = __iucv_message_send(priv->path, &sb->msg, 0, 0,
+				 (void *) sb->mbuf, sb->msg.length);
+	if (rc) {
+		/* drop the message here; however we might want to handle
+		 * 0x03 (msg limit reached) by trying again... */
+		list_del(&sb->list);
+		destroy_tty_buffer(sb);
+	}
+	len = priv->sndbuf_len;
+	priv->sndbuf_len = 0;
+
+	return len;
+}
+
+/**
+ * hvc_iucv_sndbuf_work() - Send buffered data over IUCV
+ * @work:	Work structure.
+ *
+ * This work queue function sends buffered output data over IUCV and,
+ * if not all buffered data could be sent, reschedules itself.
+ */
+static void hvc_iucv_sndbuf_work(struct work_struct *work)
+{
+	struct hvc_iucv_private *priv;
+
+	priv = container_of(work, struct hvc_iucv_private, sndbuf_work.work);
+	if (!priv)
+		return;
+
+	spin_lock_bh(&priv->lock);
+	hvc_iucv_send(priv);
+	spin_unlock_bh(&priv->lock);
+}
+
+/**
+ * hvc_iucv_put_chars() - HVC put_chars operation.
+ * @vtermno:	HVC virtual terminal number.
+ * @buf:	Pointer to an buffer to read data from
+ * @count:	Size of buffer available for reading
+ *
+ * The HVC thread calls this method to write characters to the back-end.
+ * The function calls hvc_iucv_queue() to queue terminal data for sending.
+ *
+ * Locking:	The method gets called under an irqsave() spinlock; and
+ *		locks struct hvc_iucv_private->lock.
+ */
+static int hvc_iucv_put_chars(uint32_t vtermno, const char *buf, int count)
+{
+	struct hvc_iucv_private *priv = hvc_iucv_get_private(vtermno);
+	int queued;
+
+	if (count <= 0)
+		return 0;
+
+	if (!priv)
+		return -ENODEV;
+
+	spin_lock(&priv->lock);
+	queued = hvc_iucv_queue(priv, buf, count);
+	spin_unlock(&priv->lock);
+
+	return queued;
+}
+
+/**
+ * hvc_iucv_notifier_add() - HVC notifier for opening a TTY for the first time.
+ * @hp:	Pointer to the HVC device (struct hvc_struct)
+ * @id:	Additional data (originally passed to hvc_alloc): the index of an struct
+ *	hvc_iucv_private instance.
+ *
+ * The function sets the tty state to TTY_OPENED for the struct hvc_iucv_private
+ * instance that is derived from @id. Always returns 0.
+ *
+ * Locking:	struct hvc_iucv_private->lock, spin_lock_bh
+ */
+static int hvc_iucv_notifier_add(struct hvc_struct *hp, int id)
+{
+	struct hvc_iucv_private *priv;
+
+	priv = hvc_iucv_get_private(id);
+	if (!priv)
+		return 0;
+
+	spin_lock_bh(&priv->lock);
+	priv->tty_state = TTY_OPENED;
+	spin_unlock_bh(&priv->lock);
+
+	return 0;
+}
+
+/**
+ * hvc_iucv_cleanup() - Clean up and reset a z/VM IUCV HVC instance.
+ * @priv:	Pointer to the struct hvc_iucv_private instance.
+ */
+static void hvc_iucv_cleanup(struct hvc_iucv_private *priv)
+{
+	destroy_tty_buffer_list(&priv->tty_outqueue);
+	destroy_tty_buffer_list(&priv->tty_inqueue);
+
+	priv->tty_state = TTY_CLOSED;
+	priv->iucv_state = IUCV_DISCONN;
+
+	priv->sndbuf_len = 0;
+}
+
+/**
+ * tty_outqueue_empty() - Test if the tty outq is empty
+ * @priv:	Pointer to struct hvc_iucv_private instance.
+ */
+static inline int tty_outqueue_empty(struct hvc_iucv_private *priv)
+{
+	int rc;
+
+	spin_lock_bh(&priv->lock);
+	rc = list_empty(&priv->tty_outqueue);
+	spin_unlock_bh(&priv->lock);
+
+	return rc;
+}
+
+/**
+ * flush_sndbuf_sync() - Flush send buffer and wait for completion
+ * @priv:	Pointer to struct hvc_iucv_private instance.
+ *
+ * The routine cancels a pending sndbuf work, calls hvc_iucv_send()
+ * to flush any buffered terminal output data and waits for completion.
+ */
+static void flush_sndbuf_sync(struct hvc_iucv_private *priv)
+{
+	int sync_wait;
+
+	cancel_delayed_work_sync(&priv->sndbuf_work);
+
+	spin_lock_bh(&priv->lock);
+	hvc_iucv_send(priv);		/* force sending buffered data */
+	sync_wait = !list_empty(&priv->tty_outqueue); /* anything queued ? */
+	spin_unlock_bh(&priv->lock);
+
+	if (sync_wait)
+		wait_event_timeout(priv->sndbuf_waitq,
+				   tty_outqueue_empty(priv), HZ/10);
+}
+
+/**
+ * hvc_iucv_hangup() - Sever IUCV path and schedule hvc tty hang up
+ * @priv:	Pointer to hvc_iucv_private structure
+ *
+ * This routine severs an existing IUCV communication path and hangs
+ * up the underlying HVC terminal device.
+ * The hang-up occurs only if an IUCV communication path is established;
+ * otherwise there is no need to hang up the terminal device.
+ *
+ * The IUCV HVC hang-up is separated into two steps:
+ * 1. After the IUCV path has been severed, the iucv_state is set to
+ *    IUCV_SEVERED.
+ * 2. Later, when the HVC thread calls hvc_iucv_get_chars(), the
+ *    IUCV_SEVERED state causes the tty hang-up in the HVC layer.
+ *
+ * If the tty has not yet been opened, clean up the hvc_iucv_private
+ * structure to allow re-connects.
+ * If the tty has been opened, let get_chars() return -EPIPE to signal
+ * the HVC layer to hang up the tty and, if so, wake up the HVC thread
+ * to call get_chars()...
+ *
+ * Special notes on hanging up a HVC terminal instantiated as console:
+ * Hang-up:	1. do_tty_hangup() replaces file ops (= hung_up_tty_fops)
+ *		2. do_tty_hangup() calls tty->ops->close() for console_filp
+ *			=> no hangup notifier is called by HVC (default)
+ *		2. hvc_close() returns because of tty_hung_up_p(filp)
+ *			=> no delete notifier is called!
+ * Finally, the back-end is not being notified, thus, the tty session is
+ * kept active (TTY_OPEN) to be ready for re-connects.
+ *
+ * Locking:	spin_lock(&priv->lock) w/o disabling bh
+ */
+static void hvc_iucv_hangup(struct hvc_iucv_private *priv)
+{
+	struct iucv_path *path;
+
+	path = NULL;
+	spin_lock(&priv->lock);
+	if (priv->iucv_state == IUCV_CONNECTED) {
+		path = priv->path;
+		priv->path = NULL;
+		priv->iucv_state = IUCV_SEVERED;
+		if (priv->tty_state == TTY_CLOSED)
+			hvc_iucv_cleanup(priv);
+		else
+			/* console is special (see above) */
+			if (priv->is_console) {
+				hvc_iucv_cleanup(priv);
+				priv->tty_state = TTY_OPENED;
+			} else
+				hvc_kick();
+	}
+	spin_unlock(&priv->lock);
+
+	/* finally sever path (outside of priv->lock due to lock ordering) */
+	if (path) {
+		iucv_path_sever(path, NULL);
+		iucv_path_free(path);
+	}
+}
+
+/**
+ * hvc_iucv_notifier_hangup() - HVC notifier for TTY hangups.
+ * @hp:		Pointer to the HVC device (struct hvc_struct)
+ * @id:		Additional data (originally passed to hvc_alloc):
+ *		the index of an struct hvc_iucv_private instance.
+ *
+ * This routine notifies the HVC back-end that a tty hangup (carrier loss,
+ * virtual or otherwise) has occured.
+ * The z/VM IUCV HVC device driver ignores virtual hangups (vhangup())
+ * to keep an existing IUCV communication path established.
+ * (Background: vhangup() is called from user space (by getty or login) to
+ *		disable writing to the tty by other applications).
+ * If the tty has been opened and an established IUCV path has been severed
+ * (we caused the tty hangup), the function calls hvc_iucv_cleanup().
+ *
+ * Locking:	struct hvc_iucv_private->lock
+ */
+static void hvc_iucv_notifier_hangup(struct hvc_struct *hp, int id)
+{
+	struct hvc_iucv_private *priv;
+
+	priv = hvc_iucv_get_private(id);
+	if (!priv)
+		return;
+
+	flush_sndbuf_sync(priv);
+
+	spin_lock_bh(&priv->lock);
+	/* NOTE: If the hangup was scheduled by ourself (from the iucv
+	 *	 path_servered callback [IUCV_SEVERED]), we have to clean up
+	 *	 our structure and to set state to TTY_CLOSED.
+	 *	 If the tty was hung up otherwise (e.g. vhangup()), then we
+	 *	 ignore this hangup and keep an established IUCV path open...
+	 *	 (...the reason is that we are not able to connect back to the
+	 *	 client if we disconnect on hang up) */
+	priv->tty_state = TTY_CLOSED;
+
+	if (priv->iucv_state == IUCV_SEVERED)
+		hvc_iucv_cleanup(priv);
+	spin_unlock_bh(&priv->lock);
+}
+
+/**
+ * hvc_iucv_notifier_del() - HVC notifier for closing a TTY for the last time.
+ * @hp:		Pointer to the HVC device (struct hvc_struct)
+ * @id:		Additional data (originally passed to hvc_alloc):
+ *		the index of an struct hvc_iucv_private instance.
+ *
+ * This routine notifies the HVC back-end that the last tty device fd has been
+ * closed.  The function calls hvc_iucv_cleanup() to clean up the struct
+ * hvc_iucv_private instance.
+ *
+ * Locking:	struct hvc_iucv_private->lock
+ */
+static void hvc_iucv_notifier_del(struct hvc_struct *hp, int id)
+{
+	struct hvc_iucv_private *priv;
+	struct iucv_path	*path;
+
+	priv = hvc_iucv_get_private(id);
+	if (!priv)
+		return;
+
+	flush_sndbuf_sync(priv);
+
+	spin_lock_bh(&priv->lock);
+	path = priv->path;		/* save reference to IUCV path */
+	priv->path = NULL;
+	hvc_iucv_cleanup(priv);
+	spin_unlock_bh(&priv->lock);
+
+	/* sever IUCV path outside of priv->lock due to lock ordering of:
+	 * priv->lock <--> iucv_table_lock */
+	if (path) {
+		iucv_path_sever(path, NULL);
+		iucv_path_free(path);
+	}
+}
+
+/**
+ * hvc_iucv_filter_connreq() - Filter connection request based on z/VM user ID
+ * @ipvmid:	Originating z/VM user ID (right padded with blanks)
+ *
+ * Returns 0 if the z/VM user ID @ipvmid is allowed to connection, otherwise
+ * non-zero.
+ */
+static int hvc_iucv_filter_connreq(u8 ipvmid[8])
+{
+	size_t i;
+
+	/* Note: default policy is ACCEPT if no filter is set */
+	if (!hvc_iucv_filter_size)
+		return 0;
+
+	for (i = 0; i < hvc_iucv_filter_size; i++)
+		if (0 == memcmp(ipvmid, hvc_iucv_filter + (8 * i), 8))
+			return 0;
+	return 1;
+}
+
+/**
+ * hvc_iucv_path_pending() - IUCV handler to process a connection request.
+ * @path:	Pending path (struct iucv_path)
+ * @ipvmid:	z/VM system identifier of originator
+ * @ipuser:	User specified data for this path
+ *		(AF_IUCV: port/service name and originator port)
+ *
+ * The function uses the @ipuser data to determine if the pending path belongs
+ * to a terminal managed by this device driver.
+ * If the path belongs to this driver, ensure that the terminal is not accessed
+ * multiple times (only one connection to a terminal is allowed).
+ * If the terminal is not yet connected, the pending path is accepted and is
+ * associated to the appropriate struct hvc_iucv_private instance.
+ *
+ * Returns 0 if @path belongs to a terminal managed by the this device driver;
+ * otherwise returns -ENODEV in order to dispatch this path to other handlers.
+ *
+ * Locking:	struct hvc_iucv_private->lock
+ */
+static	int hvc_iucv_path_pending(struct iucv_path *path,
+				  u8 ipvmid[8], u8 ipuser[16])
+{
+	struct hvc_iucv_private *priv;
+	u8 nuser_data[16];
+	u8 vm_user_id[9];
+	int i, rc;
+
+	priv = NULL;
+	for (i = 0; i < hvc_iucv_devices; i++)
+		if (hvc_iucv_table[i] &&
+		    (0 == memcmp(hvc_iucv_table[i]->srv_name, ipuser, 8))) {
+			priv = hvc_iucv_table[i];
+			break;
+		}
+	if (!priv)
+		return -ENODEV;
+
+	/* Enforce that ipvmid is allowed to connect to us */
+	read_lock(&hvc_iucv_filter_lock);
+	rc = hvc_iucv_filter_connreq(ipvmid);
+	read_unlock(&hvc_iucv_filter_lock);
+	if (rc) {
+		iucv_path_sever(path, ipuser);
+		iucv_path_free(path);
+		memcpy(vm_user_id, ipvmid, 8);
+		vm_user_id[8] = 0;
+		pr_info("A connection request from z/VM user ID %s "
+			"was refused\n", vm_user_id);
+		return 0;
+	}
+
+	spin_lock(&priv->lock);
+
+	/* If the terminal is already connected or being severed, then sever
+	 * this path to enforce that there is only ONE established communication
+	 * path per terminal. */
+	if (priv->iucv_state != IUCV_DISCONN) {
+		iucv_path_sever(path, ipuser);
+		iucv_path_free(path);
+		goto out_path_handled;
+	}
+
+	/* accept path */
+	memcpy(nuser_data, ipuser + 8, 8);  /* remote service (for af_iucv) */
+	memcpy(nuser_data + 8, ipuser, 8);  /* local service  (for af_iucv) */
+	path->msglim = 0xffff;		    /* IUCV MSGLIMIT */
+	path->flags &= ~IUCV_IPRMDATA;	    /* TODO: use IUCV_IPRMDATA */
+	rc = iucv_path_accept(path, &hvc_iucv_handler, nuser_data, priv);
+	if (rc) {
+		iucv_path_sever(path, ipuser);
+		iucv_path_free(path);
+		goto out_path_handled;
+	}
+	priv->path = path;
+	priv->iucv_state = IUCV_CONNECTED;
+
+	/* flush buffered output data... */
+	schedule_delayed_work(&priv->sndbuf_work, 5);
+
+out_path_handled:
+	spin_unlock(&priv->lock);
+	return 0;
+}
+
+/**
+ * hvc_iucv_path_severed() - IUCV handler to process a path sever.
+ * @path:	Pending path (struct iucv_path)
+ * @ipuser:	User specified data for this path
+ *		(AF_IUCV: port/service name and originator port)
+ *
+ * This function calls the hvc_iucv_hangup() function for the
+ * respective IUCV HVC terminal.
+ *
+ * Locking:	struct hvc_iucv_private->lock
+ */
+static void hvc_iucv_path_severed(struct iucv_path *path, u8 ipuser[16])
+{
+	struct hvc_iucv_private *priv = path->private;
+
+	hvc_iucv_hangup(priv);
+}
+
+/**
+ * hvc_iucv_msg_pending() - IUCV handler to process an incoming IUCV message.
+ * @path:	Pending path (struct iucv_path)
+ * @msg:	Pointer to the IUCV message
+ *
+ * The function puts an incoming message on the input queue for later
+ * processing (by hvc_iucv_get_chars() / hvc_iucv_write()).
+ * If the tty has not yet been opened, the message is rejected.
+ *
+ * Locking:	struct hvc_iucv_private->lock
+ */
+static void hvc_iucv_msg_pending(struct iucv_path *path,
+				 struct iucv_message *msg)
+{
+	struct hvc_iucv_private *priv = path->private;
+	struct iucv_tty_buffer *rb;
+
+	/* reject messages that exceed max size of iucv_tty_msg->datalen */
+	if (msg->length > MSG_SIZE(MSG_MAX_DATALEN)) {
+		iucv_message_reject(path, msg);
+		return;
+	}
+
+	spin_lock(&priv->lock);
+
+	/* reject messages if tty has not yet been opened */
+	if (priv->tty_state == TTY_CLOSED) {
+		iucv_message_reject(path, msg);
+		goto unlock_return;
+	}
+
+	/* allocate tty buffer to save iucv msg only */
+	rb = alloc_tty_buffer(0, GFP_ATOMIC);
+	if (!rb) {
+		iucv_message_reject(path, msg);
+		goto unlock_return;	/* -ENOMEM */
+	}
+	rb->msg = *msg;
+
+	list_add_tail(&rb->list, &priv->tty_inqueue);
+
+	hvc_kick();	/* wake up hvc thread */
+
+unlock_return:
+	spin_unlock(&priv->lock);
+}
+
+/**
+ * hvc_iucv_msg_complete() - IUCV handler to process message completion
+ * @path:	Pending path (struct iucv_path)
+ * @msg:	Pointer to the IUCV message
+ *
+ * The function is called upon completion of message delivery to remove the
+ * message from the outqueue. Additional delivery information can be found
+ * msg->audit: rejected messages (0x040000 (IPADRJCT)), and
+ *	       purged messages	 (0x010000 (IPADPGNR)).
+ *
+ * Locking:	struct hvc_iucv_private->lock
+ */
+static void hvc_iucv_msg_complete(struct iucv_path *path,
+				  struct iucv_message *msg)
+{
+	struct hvc_iucv_private *priv = path->private;
+	struct iucv_tty_buffer	*ent, *next;
+	LIST_HEAD(list_remove);
+
+	spin_lock(&priv->lock);
+	list_for_each_entry_safe(ent, next, &priv->tty_outqueue, list)
+		if (ent->msg.id == msg->id) {
+			list_move(&ent->list, &list_remove);
+			break;
+		}
+	wake_up(&priv->sndbuf_waitq);
+	spin_unlock(&priv->lock);
+	destroy_tty_buffer_list(&list_remove);
+}
+
+/**
+ * hvc_iucv_pm_freeze() - Freeze PM callback
+ * @dev:	IUVC HVC terminal device
+ *
+ * Sever an established IUCV communication path and
+ * trigger a hang-up of the underlying HVC terminal.
+ */
+static int hvc_iucv_pm_freeze(struct device *dev)
+{
+	struct hvc_iucv_private *priv = dev_get_drvdata(dev);
+
+	local_bh_disable();
+	hvc_iucv_hangup(priv);
+	local_bh_enable();
+
+	return 0;
+}
+
+/**
+ * hvc_iucv_pm_restore_thaw() - Thaw and restore PM callback
+ * @dev:	IUVC HVC terminal device
+ *
+ * Wake up the HVC thread to trigger hang-up and respective
+ * HVC back-end notifier invocations.
+ */
+static int hvc_iucv_pm_restore_thaw(struct device *dev)
+{
+	hvc_kick();
+	return 0;
+}
+
+
+/* HVC operations */
+static const struct hv_ops hvc_iucv_ops = {
+	.get_chars = hvc_iucv_get_chars,
+	.put_chars = hvc_iucv_put_chars,
+	.notifier_add = hvc_iucv_notifier_add,
+	.notifier_del = hvc_iucv_notifier_del,
+	.notifier_hangup = hvc_iucv_notifier_hangup,
+};
+
+/* Suspend / resume device operations */
+static const struct dev_pm_ops hvc_iucv_pm_ops = {
+	.freeze	  = hvc_iucv_pm_freeze,
+	.thaw	  = hvc_iucv_pm_restore_thaw,
+	.restore  = hvc_iucv_pm_restore_thaw,
+};
+
+/* IUCV HVC device driver */
+static struct device_driver hvc_iucv_driver = {
+	.name = KMSG_COMPONENT,
+	.bus  = &iucv_bus,
+	.pm   = &hvc_iucv_pm_ops,
+};
+
+/**
+ * hvc_iucv_alloc() - Allocates a new struct hvc_iucv_private instance
+ * @id:			hvc_iucv_table index
+ * @is_console:		Flag if the instance is used as Linux console
+ *
+ * This function allocates a new hvc_iucv_private structure and stores
+ * the instance in hvc_iucv_table at index @id.
+ * Returns 0 on success; otherwise non-zero.
+ */
+static int __init hvc_iucv_alloc(int id, unsigned int is_console)
+{
+	struct hvc_iucv_private *priv;
+	char name[9];
+	int rc;
+
+	priv = kzalloc(sizeof(struct hvc_iucv_private), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	spin_lock_init(&priv->lock);
+	INIT_LIST_HEAD(&priv->tty_outqueue);
+	INIT_LIST_HEAD(&priv->tty_inqueue);
+	INIT_DELAYED_WORK(&priv->sndbuf_work, hvc_iucv_sndbuf_work);
+	init_waitqueue_head(&priv->sndbuf_waitq);
+
+	priv->sndbuf = (void *) get_zeroed_page(GFP_KERNEL);
+	if (!priv->sndbuf) {
+		kfree(priv);
+		return -ENOMEM;
+	}
+
+	/* set console flag */
+	priv->is_console = is_console;
+
+	/* allocate hvc device */
+	priv->hvc = hvc_alloc(HVC_IUCV_MAGIC + id, /*		  PAGE_SIZE */
+			      HVC_IUCV_MAGIC + id, &hvc_iucv_ops, 256);
+	if (IS_ERR(priv->hvc)) {
+		rc = PTR_ERR(priv->hvc);
+		goto out_error_hvc;
+	}
+
+	/* notify HVC thread instead of using polling */
+	priv->hvc->irq_requested = 1;
+
+	/* setup iucv related information */
+	snprintf(name, 9, "lnxhvc%-2d", id);
+	memcpy(priv->srv_name, name, 8);
+	ASCEBC(priv->srv_name, 8);
+
+	/* create and setup device */
+	priv->dev = kzalloc(sizeof(*priv->dev), GFP_KERNEL);
+	if (!priv->dev) {
+		rc = -ENOMEM;
+		goto out_error_dev;
+	}
+	dev_set_name(priv->dev, "hvc_iucv%d", id);
+	dev_set_drvdata(priv->dev, priv);
+	priv->dev->bus = &iucv_bus;
+	priv->dev->parent = iucv_root;
+	priv->dev->driver = &hvc_iucv_driver;
+	priv->dev->release = (void (*)(struct device *)) kfree;
+	rc = device_register(priv->dev);
+	if (rc) {
+		put_device(priv->dev);
+		goto out_error_dev;
+	}
+
+	hvc_iucv_table[id] = priv;
+	return 0;
+
+out_error_dev:
+	hvc_remove(priv->hvc);
+out_error_hvc:
+	free_page((unsigned long) priv->sndbuf);
+	kfree(priv);
+
+	return rc;
+}
+
+/**
+ * hvc_iucv_destroy() - Destroy and free hvc_iucv_private instances
+ */
+static void __init hvc_iucv_destroy(struct hvc_iucv_private *priv)
+{
+	hvc_remove(priv->hvc);
+	device_unregister(priv->dev);
+	free_page((unsigned long) priv->sndbuf);
+	kfree(priv);
+}
+
+/**
+ * hvc_iucv_parse_filter() - Parse filter for a single z/VM user ID
+ * @filter:	String containing a comma-separated list of z/VM user IDs
+ */
+static const char *hvc_iucv_parse_filter(const char *filter, char *dest)
+{
+	const char *nextdelim, *residual;
+	size_t len;
+
+	nextdelim = strchr(filter, ',');
+	if (nextdelim) {
+		len = nextdelim - filter;
+		residual = nextdelim + 1;
+	} else {
+		len = strlen(filter);
+		residual = filter + len;
+	}
+
+	if (len == 0)
+		return ERR_PTR(-EINVAL);
+
+	/* check for '\n' (if called from sysfs) */
+	if (filter[len - 1] == '\n')
+		len--;
+
+	if (len > 8)
+		return ERR_PTR(-EINVAL);
+
+	/* pad with blanks and save upper case version of user ID */
+	memset(dest, ' ', 8);
+	while (len--)
+		dest[len] = toupper(filter[len]);
+	return residual;
+}
+
+/**
+ * hvc_iucv_setup_filter() - Set up z/VM user ID filter
+ * @filter:	String consisting of a comma-separated list of z/VM user IDs
+ *
+ * The function parses the @filter string and creates an array containing
+ * the list of z/VM user ID filter entries.
+ * Return code 0 means success, -EINVAL if the filter is syntactically
+ * incorrect, -ENOMEM if there was not enough memory to allocate the
+ * filter list array, or -ENOSPC if too many z/VM user IDs have been specified.
+ */
+static int hvc_iucv_setup_filter(const char *val)
+{
+	const char *residual;
+	int err;
+	size_t size, count;
+	void *array, *old_filter;
+
+	count = strlen(val);
+	if (count == 0 || (count == 1 && val[0] == '\n')) {
+		size  = 0;
+		array = NULL;
+		goto out_replace_filter;	/* clear filter */
+	}
+
+	/* count user IDs in order to allocate sufficient memory */
+	size = 1;
+	residual = val;
+	while ((residual = strchr(residual, ',')) != NULL) {
+		residual++;
+		size++;
+	}
+
+	/* check if the specified list exceeds the filter limit */
+	if (size > MAX_VMID_FILTER)
+		return -ENOSPC;
+
+	array = kzalloc(size * 8, GFP_KERNEL);
+	if (!array)
+		return -ENOMEM;
+
+	count = size;
+	residual = val;
+	while (*residual && count) {
+		residual = hvc_iucv_parse_filter(residual,
+						 array + ((size - count) * 8));
+		if (IS_ERR(residual)) {
+			err = PTR_ERR(residual);
+			kfree(array);
+			goto out_err;
+		}
+		count--;
+	}
+
+out_replace_filter:
+	write_lock_bh(&hvc_iucv_filter_lock);
+	old_filter = hvc_iucv_filter;
+	hvc_iucv_filter_size = size;
+	hvc_iucv_filter = array;
+	write_unlock_bh(&hvc_iucv_filter_lock);
+	kfree(old_filter);
+
+	err = 0;
+out_err:
+	return err;
+}
+
+/**
+ * param_set_vmidfilter() - Set z/VM user ID filter parameter
+ * @val:	String consisting of a comma-separated list of z/VM user IDs
+ * @kp:		Kernel parameter pointing to hvc_iucv_filter array
+ *
+ * The function sets up the z/VM user ID filter specified as comma-separated
+ * list of user IDs in @val.
+ * Note: If it is called early in the boot process, @val is stored and
+ *	 parsed later in hvc_iucv_init().
+ */
+static int param_set_vmidfilter(const char *val, const struct kernel_param *kp)
+{
+	int rc;
+
+	if (!MACHINE_IS_VM || !hvc_iucv_devices)
+		return -ENODEV;
+
+	if (!val)
+		return -EINVAL;
+
+	rc = 0;
+	if (slab_is_available())
+		rc = hvc_iucv_setup_filter(val);
+	else
+		hvc_iucv_filter_string = val;	/* defer... */
+	return rc;
+}
+
+/**
+ * param_get_vmidfilter() - Get z/VM user ID filter
+ * @buffer:	Buffer to store z/VM user ID filter,
+ *		(buffer size assumption PAGE_SIZE)
+ * @kp:		Kernel parameter pointing to the hvc_iucv_filter array
+ *
+ * The function stores the filter as a comma-separated list of z/VM user IDs
+ * in @buffer. Typically, sysfs routines call this function for attr show.
+ */
+static int param_get_vmidfilter(char *buffer, const struct kernel_param *kp)
+{
+	int rc;
+	size_t index, len;
+	void *start, *end;
+
+	if (!MACHINE_IS_VM || !hvc_iucv_devices)
+		return -ENODEV;
+
+	rc = 0;
+	read_lock_bh(&hvc_iucv_filter_lock);
+	for (index = 0; index < hvc_iucv_filter_size; index++) {
+		start = hvc_iucv_filter + (8 * index);
+		end   = memchr(start, ' ', 8);
+		len   = (end) ? end - start : 8;
+		memcpy(buffer + rc, start, len);
+		rc += len;
+		buffer[rc++] = ',';
+	}
+	read_unlock_bh(&hvc_iucv_filter_lock);
+	if (rc)
+		buffer[--rc] = '\0';	/* replace last comma and update rc */
+	return rc;
+}
+
+#define param_check_vmidfilter(name, p) __param_check(name, p, void)
+
+static struct kernel_param_ops param_ops_vmidfilter = {
+	.set = param_set_vmidfilter,
+	.get = param_get_vmidfilter,
+};
+
+/**
+ * hvc_iucv_init() - z/VM IUCV HVC device driver initialization
+ */
+static int __init hvc_iucv_init(void)
+{
+	int rc;
+	unsigned int i;
+
+	if (!hvc_iucv_devices)
+		return -ENODEV;
+
+	if (!MACHINE_IS_VM) {
+		pr_notice("The z/VM IUCV HVC device driver cannot "
+			   "be used without z/VM\n");
+		rc = -ENODEV;
+		goto out_error;
+	}
+
+	if (hvc_iucv_devices > MAX_HVC_IUCV_LINES) {
+		pr_err("%lu is not a valid value for the hvc_iucv= "
+			"kernel parameter\n", hvc_iucv_devices);
+		rc = -EINVAL;
+		goto out_error;
+	}
+
+	/* register IUCV HVC device driver */
+	rc = driver_register(&hvc_iucv_driver);
+	if (rc)
+		goto out_error;
+
+	/* parse hvc_iucv_allow string and create z/VM user ID filter list */
+	if (hvc_iucv_filter_string) {
+		rc = hvc_iucv_setup_filter(hvc_iucv_filter_string);
+		switch (rc) {
+		case 0:
+			break;
+		case -ENOMEM:
+			pr_err("Allocating memory failed with "
+				"reason code=%d\n", 3);
+			goto out_error;
+		case -EINVAL:
+			pr_err("hvc_iucv_allow= does not specify a valid "
+				"z/VM user ID list\n");
+			goto out_error;
+		case -ENOSPC:
+			pr_err("hvc_iucv_allow= specifies too many "
+				"z/VM user IDs\n");
+			goto out_error;
+		default:
+			goto out_error;
+		}
+	}
+
+	hvc_iucv_buffer_cache = kmem_cache_create(KMSG_COMPONENT,
+					   sizeof(struct iucv_tty_buffer),
+					   0, 0, NULL);
+	if (!hvc_iucv_buffer_cache) {
+		pr_err("Allocating memory failed with reason code=%d\n", 1);
+		rc = -ENOMEM;
+		goto out_error;
+	}
+
+	hvc_iucv_mempool = mempool_create_slab_pool(MEMPOOL_MIN_NR,
+						    hvc_iucv_buffer_cache);
+	if (!hvc_iucv_mempool) {
+		pr_err("Allocating memory failed with reason code=%d\n", 2);
+		kmem_cache_destroy(hvc_iucv_buffer_cache);
+		rc = -ENOMEM;
+		goto out_error;
+	}
+
+	/* register the first terminal device as console
+	 * (must be done before allocating hvc terminal devices) */
+	rc = hvc_instantiate(HVC_IUCV_MAGIC, IUCV_HVC_CON_IDX, &hvc_iucv_ops);
+	if (rc) {
+		pr_err("Registering HVC terminal device as "
+		       "Linux console failed\n");
+		goto out_error_memory;
+	}
+
+	/* allocate hvc_iucv_private structs */
+	for (i = 0; i < hvc_iucv_devices; i++) {
+		rc = hvc_iucv_alloc(i, (i == IUCV_HVC_CON_IDX) ? 1 : 0);
+		if (rc) {
+			pr_err("Creating a new HVC terminal device "
+				"failed with error code=%d\n", rc);
+			goto out_error_hvc;
+		}
+	}
+
+	/* register IUCV callback handler */
+	rc = iucv_register(&hvc_iucv_handler, 0);
+	if (rc) {
+		pr_err("Registering IUCV handlers failed with error code=%d\n",
+			rc);
+		goto out_error_hvc;
+	}
+
+	return 0;
+
+out_error_hvc:
+	for (i = 0; i < hvc_iucv_devices; i++)
+		if (hvc_iucv_table[i])
+			hvc_iucv_destroy(hvc_iucv_table[i]);
+out_error_memory:
+	mempool_destroy(hvc_iucv_mempool);
+	kmem_cache_destroy(hvc_iucv_buffer_cache);
+out_error:
+	if (hvc_iucv_filter)
+		kfree(hvc_iucv_filter);
+	hvc_iucv_devices = 0; /* ensure that we do not provide any device */
+	return rc;
+}
+
+/**
+ * hvc_iucv_config() - Parsing of hvc_iucv=  kernel command line parameter
+ * @val:	Parameter value (numeric)
+ */
+static	int __init hvc_iucv_config(char *val)
+{
+	 return strict_strtoul(val, 10, &hvc_iucv_devices);
+}
+
+
+device_initcall(hvc_iucv_init);
+__setup("hvc_iucv=", hvc_iucv_config);
+core_param(hvc_iucv_allow, hvc_iucv_filter, vmidfilter, 0640);
diff --git a/drivers/tty/hvc/hvc_rtas.c b/drivers/tty/hvc/hvc_rtas.c
new file mode 100644
index 000000000000..61c4a61558d9
--- /dev/null
+++ b/drivers/tty/hvc/hvc_rtas.c
@@ -0,0 +1,133 @@
+/*
+ * IBM RTAS driver interface to hvc_console.c
+ *
+ * (C) Copyright IBM Corporation 2001-2005
+ * (C) Copyright Red Hat, Inc. 2005
+ *
+ * Author(s): Maximino Augilar <IBM STI Design Center>
+ *	    : Ryan S. Arnold <rsa@us.ibm.com>
+ *	    : Utz Bacher <utz.bacher@de.ibm.com>
+ *	    : David Woodhouse <dwmw2@infradead.org>
+ *
+ *    inspired by drivers/char/hvc_console.c
+ *    written by Anton Blanchard and Paul Mackerras
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+
+#include <asm/irq.h>
+#include <asm/rtas.h>
+#include "hvc_console.h"
+
+#define hvc_rtas_cookie 0x67781e15
+struct hvc_struct *hvc_rtas_dev;
+
+static int rtascons_put_char_token = RTAS_UNKNOWN_SERVICE;
+static int rtascons_get_char_token = RTAS_UNKNOWN_SERVICE;
+
+static inline int hvc_rtas_write_console(uint32_t vtermno, const char *buf,
+		int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++) {
+		if (rtas_call(rtascons_put_char_token, 1, 1, NULL, buf[i]))
+			break;
+	}
+
+	return i;
+}
+
+static int hvc_rtas_read_console(uint32_t vtermno, char *buf, int count)
+{
+	int i, c;
+
+	for (i = 0; i < count; i++) {
+		if (rtas_call(rtascons_get_char_token, 0, 2, &c))
+			break;
+
+		buf[i] = c;
+	}
+
+	return i;
+}
+
+static const struct hv_ops hvc_rtas_get_put_ops = {
+	.get_chars = hvc_rtas_read_console,
+	.put_chars = hvc_rtas_write_console,
+};
+
+static int __init hvc_rtas_init(void)
+{
+	struct hvc_struct *hp;
+
+	if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
+		rtascons_put_char_token = rtas_token("put-term-char");
+	if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
+		return -EIO;
+
+	if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
+		rtascons_get_char_token = rtas_token("get-term-char");
+	if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
+		return -EIO;
+
+	BUG_ON(hvc_rtas_dev);
+
+	/* Allocate an hvc_struct for the console device we instantiated
+	 * earlier.  Save off hp so that we can return it on exit */
+	hp = hvc_alloc(hvc_rtas_cookie, NO_IRQ, &hvc_rtas_get_put_ops, 16);
+	if (IS_ERR(hp))
+		return PTR_ERR(hp);
+
+	hvc_rtas_dev = hp;
+
+	return 0;
+}
+module_init(hvc_rtas_init);
+
+/* This will tear down the tty portion of the driver */
+static void __exit hvc_rtas_exit(void)
+{
+	/* Really the fun isn't over until the worker thread breaks down and
+	 * the tty cleans up */
+	if (hvc_rtas_dev)
+		hvc_remove(hvc_rtas_dev);
+}
+module_exit(hvc_rtas_exit);
+
+/* This will happen prior to module init.  There is no tty at this time? */
+static int __init hvc_rtas_console_init(void)
+{
+	rtascons_put_char_token = rtas_token("put-term-char");
+	if (rtascons_put_char_token == RTAS_UNKNOWN_SERVICE)
+		return -EIO;
+
+	rtascons_get_char_token = rtas_token("get-term-char");
+	if (rtascons_get_char_token == RTAS_UNKNOWN_SERVICE)
+		return -EIO;
+
+	hvc_instantiate(hvc_rtas_cookie, 0, &hvc_rtas_get_put_ops);
+	add_preferred_console("hvc", 0, NULL);
+
+	return 0;
+}
+console_initcall(hvc_rtas_console_init);
diff --git a/drivers/tty/hvc/hvc_tile.c b/drivers/tty/hvc/hvc_tile.c
new file mode 100644
index 000000000000..7a84a0595477
--- /dev/null
+++ b/drivers/tty/hvc/hvc_tile.c
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2010 Tilera Corporation. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or
+ *   modify it under the terms of the GNU General Public License
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ *
+ * Tilera TILE Processor hypervisor console
+ */
+
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+
+#include <hv/hypervisor.h>
+
+#include "hvc_console.h"
+
+static int hvc_tile_put_chars(uint32_t vt, const char *buf, int count)
+{
+	return hv_console_write((HV_VirtAddr)buf, count);
+}
+
+static int hvc_tile_get_chars(uint32_t vt, char *buf, int count)
+{
+	int i, c;
+
+	for (i = 0; i < count; ++i) {
+		c = hv_console_read_if_ready();
+		if (c < 0)
+			break;
+		buf[i] = c;
+	}
+
+	return i;
+}
+
+static const struct hv_ops hvc_tile_get_put_ops = {
+	.get_chars = hvc_tile_get_chars,
+	.put_chars = hvc_tile_put_chars,
+};
+
+static int __init hvc_tile_console_init(void)
+{
+	extern void disable_early_printk(void);
+	hvc_instantiate(0, 0, &hvc_tile_get_put_ops);
+	add_preferred_console("hvc", 0, NULL);
+	disable_early_printk();
+	return 0;
+}
+console_initcall(hvc_tile_console_init);
+
+static int __init hvc_tile_init(void)
+{
+	struct hvc_struct *s;
+	s = hvc_alloc(0, 0, &hvc_tile_get_put_ops, 128);
+	return IS_ERR(s) ? PTR_ERR(s) : 0;
+}
+device_initcall(hvc_tile_init);
diff --git a/drivers/tty/hvc/hvc_udbg.c b/drivers/tty/hvc/hvc_udbg.c
new file mode 100644
index 000000000000..b0957e61a7be
--- /dev/null
+++ b/drivers/tty/hvc/hvc_udbg.c
@@ -0,0 +1,96 @@
+/*
+ * udbg interface to hvc_console.c
+ *
+ * (C) Copyright David Gibson, IBM Corporation 2008.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/irq.h>
+
+#include <asm/udbg.h>
+
+#include "hvc_console.h"
+
+struct hvc_struct *hvc_udbg_dev;
+
+static int hvc_udbg_put(uint32_t vtermno, const char *buf, int count)
+{
+	int i;
+
+	for (i = 0; i < count; i++)
+		udbg_putc(buf[i]);
+
+	return i;
+}
+
+static int hvc_udbg_get(uint32_t vtermno, char *buf, int count)
+{
+	int i, c;
+
+	if (!udbg_getc_poll)
+		return 0;
+
+	for (i = 0; i < count; i++) {
+		if ((c = udbg_getc_poll()) == -1)
+			break;
+		buf[i] = c;
+	}
+
+	return i;
+}
+
+static const struct hv_ops hvc_udbg_ops = {
+	.get_chars = hvc_udbg_get,
+	.put_chars = hvc_udbg_put,
+};
+
+static int __init hvc_udbg_init(void)
+{
+	struct hvc_struct *hp;
+
+	BUG_ON(hvc_udbg_dev);
+
+	hp = hvc_alloc(0, NO_IRQ, &hvc_udbg_ops, 16);
+	if (IS_ERR(hp))
+		return PTR_ERR(hp);
+
+	hvc_udbg_dev = hp;
+
+	return 0;
+}
+module_init(hvc_udbg_init);
+
+static void __exit hvc_udbg_exit(void)
+{
+	if (hvc_udbg_dev)
+		hvc_remove(hvc_udbg_dev);
+}
+module_exit(hvc_udbg_exit);
+
+static int __init hvc_udbg_console_init(void)
+{
+	hvc_instantiate(0, 0, &hvc_udbg_ops);
+	add_preferred_console("hvc", 0, NULL);
+
+	return 0;
+}
+console_initcall(hvc_udbg_console_init);
diff --git a/drivers/tty/hvc/hvc_vio.c b/drivers/tty/hvc/hvc_vio.c
new file mode 100644
index 000000000000..5e2f52b33327
--- /dev/null
+++ b/drivers/tty/hvc/hvc_vio.c
@@ -0,0 +1,173 @@
+/*
+ * vio driver interface to hvc_console.c
+ *
+ * This code was moved here to allow the remaing code to be reused as a
+ * generic polling mode with semi-reliable transport driver core to the
+ * console and tty subsystems.
+ *
+ *
+ * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Copyright (C) 2001 Paul Mackerras <paulus@au.ibm.com>, IBM
+ * Copyright (C) 2004 Benjamin Herrenschmidt <benh@kernel.crashing.org>, IBM Corp.
+ * Copyright (C) 2004 IBM Corporation
+ *
+ * Additional Author(s):
+ *  Ryan S. Arnold <rsa@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/types.h>
+#include <linux/init.h>
+
+#include <asm/hvconsole.h>
+#include <asm/vio.h>
+#include <asm/prom.h>
+#include <asm/firmware.h>
+
+#include "hvc_console.h"
+
+static const char hvc_driver_name[] = "hvc_console";
+
+static struct vio_device_id hvc_driver_table[] __devinitdata = {
+	{"serial", "hvterm1"},
+	{ "", "" }
+};
+MODULE_DEVICE_TABLE(vio, hvc_driver_table);
+
+static int filtered_get_chars(uint32_t vtermno, char *buf, int count)
+{
+	unsigned long got;
+	int i;
+
+	/*
+	 * Vio firmware will read up to SIZE_VIO_GET_CHARS at its own discretion
+	 * so we play safe and avoid the situation where got > count which could
+	 * overload the flip buffer.
+	 */
+	if (count < SIZE_VIO_GET_CHARS)
+		return -EAGAIN;
+
+	got = hvc_get_chars(vtermno, buf, count);
+
+	/*
+	 * Work around a HV bug where it gives us a null
+	 * after every \r.  -- paulus
+	 */
+	for (i = 1; i < got; ++i) {
+		if (buf[i] == 0 && buf[i-1] == '\r') {
+			--got;
+			if (i < got)
+				memmove(&buf[i], &buf[i+1],
+					got - i);
+		}
+	}
+	return got;
+}
+
+static const struct hv_ops hvc_get_put_ops = {
+	.get_chars = filtered_get_chars,
+	.put_chars = hvc_put_chars,
+	.notifier_add = notifier_add_irq,
+	.notifier_del = notifier_del_irq,
+	.notifier_hangup = notifier_hangup_irq,
+};
+
+static int __devinit hvc_vio_probe(struct vio_dev *vdev,
+				const struct vio_device_id *id)
+{
+	struct hvc_struct *hp;
+
+	/* probed with invalid parameters. */
+	if (!vdev || !id)
+		return -EPERM;
+
+	hp = hvc_alloc(vdev->unit_address, vdev->irq, &hvc_get_put_ops,
+			MAX_VIO_PUT_CHARS);
+	if (IS_ERR(hp))
+		return PTR_ERR(hp);
+	dev_set_drvdata(&vdev->dev, hp);
+
+	return 0;
+}
+
+static int __devexit hvc_vio_remove(struct vio_dev *vdev)
+{
+	struct hvc_struct *hp = dev_get_drvdata(&vdev->dev);
+
+	return hvc_remove(hp);
+}
+
+static struct vio_driver hvc_vio_driver = {
+	.id_table	= hvc_driver_table,
+	.probe		= hvc_vio_probe,
+	.remove		= __devexit_p(hvc_vio_remove),
+	.driver		= {
+		.name	= hvc_driver_name,
+		.owner	= THIS_MODULE,
+	}
+};
+
+static int __init hvc_vio_init(void)
+{
+	int rc;
+
+	if (firmware_has_feature(FW_FEATURE_ISERIES))
+		return -EIO;
+
+	/* Register as a vio device to receive callbacks */
+	rc = vio_register_driver(&hvc_vio_driver);
+
+	return rc;
+}
+module_init(hvc_vio_init); /* after drivers/char/hvc_console.c */
+
+static void __exit hvc_vio_exit(void)
+{
+	vio_unregister_driver(&hvc_vio_driver);
+}
+module_exit(hvc_vio_exit);
+
+/* the device tree order defines our numbering */
+static int hvc_find_vtys(void)
+{
+	struct device_node *vty;
+	int num_found = 0;
+
+	for (vty = of_find_node_by_name(NULL, "vty"); vty != NULL;
+			vty = of_find_node_by_name(vty, "vty")) {
+		const uint32_t *vtermno;
+
+		/* We have statically defined space for only a certain number
+		 * of console adapters.
+		 */
+		if (num_found >= MAX_NR_HVC_CONSOLES) {
+			of_node_put(vty);
+			break;
+		}
+
+		vtermno = of_get_property(vty, "reg", NULL);
+		if (!vtermno)
+			continue;
+
+		if (of_device_is_compatible(vty, "hvterm1")) {
+			hvc_instantiate(*vtermno, num_found, &hvc_get_put_ops);
+			++num_found;
+		}
+	}
+
+	return num_found;
+}
+console_initcall(hvc_find_vtys);
diff --git a/drivers/tty/hvc/hvc_xen.c b/drivers/tty/hvc/hvc_xen.c
new file mode 100644
index 000000000000..3740e327f180
--- /dev/null
+++ b/drivers/tty/hvc/hvc_xen.c
@@ -0,0 +1,271 @@
+/*
+ * xen console driver interface to hvc_console.c
+ *
+ * (c) 2007 Gerd Hoffmann <kraxel@suse.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/types.h>
+
+#include <asm/xen/hypervisor.h>
+
+#include <xen/xen.h>
+#include <xen/page.h>
+#include <xen/events.h>
+#include <xen/interface/io/console.h>
+#include <xen/hvc-console.h>
+
+#include "hvc_console.h"
+
+#define HVC_COOKIE   0x58656e /* "Xen" in hex */
+
+static struct hvc_struct *hvc;
+static int xencons_irq;
+
+/* ------------------------------------------------------------------ */
+
+static unsigned long console_pfn = ~0ul;
+
+static inline struct xencons_interface *xencons_interface(void)
+{
+	if (console_pfn == ~0ul)
+		return mfn_to_virt(xen_start_info->console.domU.mfn);
+	else
+		return __va(console_pfn << PAGE_SHIFT);
+}
+
+static inline void notify_daemon(void)
+{
+	/* Use evtchn: this is called early, before irq is set up. */
+	notify_remote_via_evtchn(xen_start_info->console.domU.evtchn);
+}
+
+static int __write_console(const char *data, int len)
+{
+	struct xencons_interface *intf = xencons_interface();
+	XENCONS_RING_IDX cons, prod;
+	int sent = 0;
+
+	cons = intf->out_cons;
+	prod = intf->out_prod;
+	mb();			/* update queue values before going on */
+	BUG_ON((prod - cons) > sizeof(intf->out));
+
+	while ((sent < len) && ((prod - cons) < sizeof(intf->out)))
+		intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++];
+
+	wmb();			/* write ring before updating pointer */
+	intf->out_prod = prod;
+
+	if (sent)
+		notify_daemon();
+	return sent;
+}
+
+static int domU_write_console(uint32_t vtermno, const char *data, int len)
+{
+	int ret = len;
+
+	/*
+	 * Make sure the whole buffer is emitted, polling if
+	 * necessary.  We don't ever want to rely on the hvc daemon
+	 * because the most interesting console output is when the
+	 * kernel is crippled.
+	 */
+	while (len) {
+		int sent = __write_console(data, len);
+		
+		data += sent;
+		len -= sent;
+
+		if (unlikely(len))
+			HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
+	}
+
+	return ret;
+}
+
+static int domU_read_console(uint32_t vtermno, char *buf, int len)
+{
+	struct xencons_interface *intf = xencons_interface();
+	XENCONS_RING_IDX cons, prod;
+	int recv = 0;
+
+	cons = intf->in_cons;
+	prod = intf->in_prod;
+	mb();			/* get pointers before reading ring */
+	BUG_ON((prod - cons) > sizeof(intf->in));
+
+	while (cons != prod && recv < len)
+		buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)];
+
+	mb();			/* read ring before consuming */
+	intf->in_cons = cons;
+
+	notify_daemon();
+	return recv;
+}
+
+static struct hv_ops domU_hvc_ops = {
+	.get_chars = domU_read_console,
+	.put_chars = domU_write_console,
+	.notifier_add = notifier_add_irq,
+	.notifier_del = notifier_del_irq,
+	.notifier_hangup = notifier_hangup_irq,
+};
+
+static int dom0_read_console(uint32_t vtermno, char *buf, int len)
+{
+	return HYPERVISOR_console_io(CONSOLEIO_read, len, buf);
+}
+
+/*
+ * Either for a dom0 to write to the system console, or a domU with a
+ * debug version of Xen
+ */
+static int dom0_write_console(uint32_t vtermno, const char *str, int len)
+{
+	int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str);
+	if (rc < 0)
+		return 0;
+
+	return len;
+}
+
+static struct hv_ops dom0_hvc_ops = {
+	.get_chars = dom0_read_console,
+	.put_chars = dom0_write_console,
+	.notifier_add = notifier_add_irq,
+	.notifier_del = notifier_del_irq,
+	.notifier_hangup = notifier_hangup_irq,
+};
+
+static int __init xen_hvc_init(void)
+{
+	struct hvc_struct *hp;
+	struct hv_ops *ops;
+
+	if (!xen_pv_domain())
+		return -ENODEV;
+
+	if (xen_initial_domain()) {
+		ops = &dom0_hvc_ops;
+		xencons_irq = bind_virq_to_irq(VIRQ_CONSOLE, 0);
+	} else {
+		if (!xen_start_info->console.domU.evtchn)
+			return -ENODEV;
+
+		ops = &domU_hvc_ops;
+		xencons_irq = bind_evtchn_to_irq(xen_start_info->console.domU.evtchn);
+	}
+	if (xencons_irq < 0)
+		xencons_irq = 0; /* NO_IRQ */
+
+	hp = hvc_alloc(HVC_COOKIE, xencons_irq, ops, 256);
+	if (IS_ERR(hp))
+		return PTR_ERR(hp);
+
+	hvc = hp;
+
+	console_pfn = mfn_to_pfn(xen_start_info->console.domU.mfn);
+
+	return 0;
+}
+
+void xen_console_resume(void)
+{
+	if (xencons_irq)
+		rebind_evtchn_irq(xen_start_info->console.domU.evtchn, xencons_irq);
+}
+
+static void __exit xen_hvc_fini(void)
+{
+	if (hvc)
+		hvc_remove(hvc);
+}
+
+static int xen_cons_init(void)
+{
+	struct hv_ops *ops;
+
+	if (!xen_pv_domain())
+		return 0;
+
+	if (xen_initial_domain())
+		ops = &dom0_hvc_ops;
+	else
+		ops = &domU_hvc_ops;
+
+	hvc_instantiate(HVC_COOKIE, 0, ops);
+	return 0;
+}
+
+module_init(xen_hvc_init);
+module_exit(xen_hvc_fini);
+console_initcall(xen_cons_init);
+
+#ifdef CONFIG_EARLY_PRINTK
+static void xenboot_write_console(struct console *console, const char *string,
+				  unsigned len)
+{
+	unsigned int linelen, off = 0;
+	const char *pos;
+
+	dom0_write_console(0, string, len);
+
+	if (xen_initial_domain())
+		return;
+
+	domU_write_console(0, "(early) ", 8);
+	while (off < len && NULL != (pos = strchr(string+off, '\n'))) {
+		linelen = pos-string+off;
+		if (off + linelen > len)
+			break;
+		domU_write_console(0, string+off, linelen);
+		domU_write_console(0, "\r\n", 2);
+		off += linelen + 1;
+	}
+	if (off < len)
+		domU_write_console(0, string+off, len-off);
+}
+
+struct console xenboot_console = {
+	.name		= "xenboot",
+	.write		= xenboot_write_console,
+	.flags		= CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME,
+};
+#endif	/* CONFIG_EARLY_PRINTK */
+
+void xen_raw_console_write(const char *str)
+{
+	dom0_write_console(0, str, strlen(str));
+}
+
+void xen_raw_printk(const char *fmt, ...)
+{
+	static char buf[512];
+	va_list ap;
+
+	va_start(ap, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, ap);
+	va_end(ap);
+
+	xen_raw_console_write(buf);
+}
diff --git a/drivers/tty/hvc/hvcs.c b/drivers/tty/hvc/hvcs.c
new file mode 100644
index 000000000000..bedc6c1b6fa5
--- /dev/null
+++ b/drivers/tty/hvc/hvcs.c
@@ -0,0 +1,1604 @@
+/*
+ * IBM eServer Hypervisor Virtual Console Server Device Driver
+ * Copyright (C) 2003, 2004 IBM Corp.
+ *  Ryan S. Arnold (rsa@us.ibm.com)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ *
+ * Author(s) :  Ryan S. Arnold <rsa@us.ibm.com>
+ *
+ * This is the device driver for the IBM Hypervisor Virtual Console Server,
+ * "hvcs".  The IBM hvcs provides a tty driver interface to allow Linux
+ * user space applications access to the system consoles of logically
+ * partitioned operating systems, e.g. Linux, running on the same partitioned
+ * Power5 ppc64 system.  Physical hardware consoles per partition are not
+ * practical on this hardware so system consoles are accessed by this driver
+ * using inter-partition firmware interfaces to virtual terminal devices.
+ *
+ * A vty is known to the HMC as a "virtual serial server adapter".  It is a
+ * virtual terminal device that is created by firmware upon partition creation
+ * to act as a partitioned OS's console device.
+ *
+ * Firmware dynamically (via hotplug) exposes vty-servers to a running ppc64
+ * Linux system upon their creation by the HMC or their exposure during boot.
+ * The non-user interactive backend of this driver is implemented as a vio
+ * device driver so that it can receive notification of vty-server lifetimes
+ * after it registers with the vio bus to handle vty-server probe and remove
+ * callbacks.
+ *
+ * Many vty-servers can be configured to connect to one vty, but a vty can
+ * only be actively connected to by a single vty-server, in any manner, at one
+ * time.  If the HMC is currently hosting the console for a target Linux
+ * partition; attempts to open the tty device to the partition's console using
+ * the hvcs on any partition will return -EBUSY with every open attempt until
+ * the HMC frees the connection between its vty-server and the desired
+ * partition's vty device.  Conversely, a vty-server may only be connected to
+ * a single vty at one time even though it may have several configured vty
+ * partner possibilities.
+ *
+ * Firmware does not provide notification of vty partner changes to this
+ * driver.  This means that an HMC Super Admin may add or remove partner vtys
+ * from a vty-server's partner list but the changes will not be signaled to
+ * the vty-server.  Firmware only notifies the driver when a vty-server is
+ * added or removed from the system.  To compensate for this deficiency, this
+ * driver implements a sysfs update attribute which provides a method for
+ * rescanning partner information upon a user's request.
+ *
+ * Each vty-server, prior to being exposed to this driver is reference counted
+ * using the 2.6 Linux kernel kref construct.
+ *
+ * For direction on installation and usage of this driver please reference
+ * Documentation/powerpc/hvcs.txt.
+ */
+
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/kref.h>
+#include <linux/kthread.h>
+#include <linux/list.h>
+#include <linux/major.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/stat.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <asm/hvconsole.h>
+#include <asm/hvcserver.h>
+#include <asm/uaccess.h>
+#include <asm/vio.h>
+
+/*
+ * 1.3.0 -> 1.3.1 In hvcs_open memset(..,0x00,..) instead of memset(..,0x3F,00).
+ * Removed braces around single statements following conditionals.  Removed '=
+ * 0' after static int declarations since these default to zero.  Removed
+ * list_for_each_safe() and replaced with list_for_each_entry() in
+ * hvcs_get_by_index().  The 'safe' version is un-needed now that the driver is
+ * using spinlocks.  Changed spin_lock_irqsave() to spin_lock() when locking
+ * hvcs_structs_lock and hvcs_pi_lock since these are not touched in an int
+ * handler.  Initialized hvcs_structs_lock and hvcs_pi_lock to
+ * SPIN_LOCK_UNLOCKED at declaration time rather than in hvcs_module_init().
+ * Added spin_lock around list_del() in destroy_hvcs_struct() to protect the
+ * list traversals from a deletion.  Removed '= NULL' from pointer declaration
+ * statements since they are initialized NULL by default.  Removed wmb()
+ * instances from hvcs_try_write().  They probably aren't needed with locking in
+ * place.  Added check and cleanup for hvcs_pi_buff = kmalloc() in
+ * hvcs_module_init().  Exposed hvcs_struct.index via a sysfs attribute so that
+ * the coupling between /dev/hvcs* and a vty-server can be automatically
+ * determined.  Moved kobject_put() in hvcs_open outside of the
+ * spin_unlock_irqrestore().
+ *
+ * 1.3.1 -> 1.3.2 Changed method for determining hvcs_struct->index and had it
+ * align with how the tty layer always assigns the lowest index available.  This
+ * change resulted in a list of ints that denotes which indexes are available.
+ * Device additions and removals use the new hvcs_get_index() and
+ * hvcs_return_index() helper functions.  The list is created with
+ * hvsc_alloc_index_list() and it is destroyed with hvcs_free_index_list().
+ * Without these fixes hotplug vty-server adapter support goes crazy with this
+ * driver if the user removes a vty-server adapter.  Moved free_irq() outside of
+ * the hvcs_final_close() function in order to get it out of the spinlock.
+ * Rearranged hvcs_close().  Cleaned up some printks and did some housekeeping
+ * on the changelog.  Removed local CLC_LENGTH and used HVCS_CLC_LENGTH from
+ * arch/powerepc/include/asm/hvcserver.h
+ *
+ * 1.3.2 -> 1.3.3 Replaced yield() in hvcs_close() with tty_wait_until_sent() to
+ * prevent possible lockup with realtime scheduling as similarily pointed out by
+ * akpm in hvc_console.  Changed resulted in the removal of hvcs_final_close()
+ * to reorder cleanup operations and prevent discarding of pending data during
+ * an hvcs_close().  Removed spinlock protection of hvcs_struct data members in
+ * hvcs_write_room() and hvcs_chars_in_buffer() because they aren't needed.
+ */
+
+#define HVCS_DRIVER_VERSION "1.3.3"
+
+MODULE_AUTHOR("Ryan S. Arnold <rsa@us.ibm.com>");
+MODULE_DESCRIPTION("IBM hvcs (Hypervisor Virtual Console Server) Driver");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(HVCS_DRIVER_VERSION);
+
+/*
+ * Wait this long per iteration while trying to push buffered data to the
+ * hypervisor before allowing the tty to complete a close operation.
+ */
+#define HVCS_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
+
+/*
+ * Since the Linux TTY code does not currently (2-04-2004) support dynamic
+ * addition of tty derived devices and we shouldn't allocate thousands of
+ * tty_device pointers when the number of vty-server & vty partner connections
+ * will most often be much lower than this, we'll arbitrarily allocate
+ * HVCS_DEFAULT_SERVER_ADAPTERS tty_structs and cdev's by default when we
+ * register the tty_driver. This can be overridden using an insmod parameter.
+ */
+#define HVCS_DEFAULT_SERVER_ADAPTERS	64
+
+/*
+ * The user can't insmod with more than HVCS_MAX_SERVER_ADAPTERS hvcs device
+ * nodes as a sanity check.  Theoretically there can be over 1 Billion
+ * vty-server & vty partner connections.
+ */
+#define HVCS_MAX_SERVER_ADAPTERS	1024
+
+/*
+ * We let Linux assign us a major number and we start the minors at zero.  There
+ * is no intuitive mapping between minor number and the target vty-server
+ * adapter except that each new vty-server adapter is always assigned to the
+ * smallest minor number available.
+ */
+#define HVCS_MINOR_START	0
+
+/*
+ * The hcall interface involves putting 8 chars into each of two registers.
+ * We load up those 2 registers (in arch/powerpc/platforms/pseries/hvconsole.c)
+ * by casting char[16] to long[2].  It would work without __ALIGNED__, but a 
+ * little (tiny) bit slower because an unaligned load is slower than aligned 
+ * load.
+ */
+#define __ALIGNED__	__attribute__((__aligned__(8)))
+
+/*
+ * How much data can firmware send with each hvc_put_chars()?  Maybe this
+ * should be moved into an architecture specific area.
+ */
+#define HVCS_BUFF_LEN	16
+
+/*
+ * This is the maximum amount of data we'll let the user send us (hvcs_write) at
+ * once in a chunk as a sanity check.
+ */
+#define HVCS_MAX_FROM_USER	4096
+
+/*
+ * Be careful when adding flags to this line discipline.  Don't add anything
+ * that will cause echoing or we'll go into recursive loop echoing chars back
+ * and forth with the console drivers.
+ */
+static struct ktermios hvcs_tty_termios = {
+	.c_iflag = IGNBRK | IGNPAR,
+	.c_oflag = OPOST,
+	.c_cflag = B38400 | CS8 | CREAD | HUPCL,
+	.c_cc = INIT_C_CC,
+	.c_ispeed = 38400,
+	.c_ospeed = 38400
+};
+
+/*
+ * This value is used to take the place of a command line parameter when the
+ * module is inserted.  It starts as -1 and stays as such if the user doesn't
+ * specify a module insmod parameter.  If they DO specify one then it is set to
+ * the value of the integer passed in.
+ */
+static int hvcs_parm_num_devs = -1;
+module_param(hvcs_parm_num_devs, int, 0);
+
+static const char hvcs_driver_name[] = "hvcs";
+static const char hvcs_device_node[] = "hvcs";
+static const char hvcs_driver_string[]
+	= "IBM hvcs (Hypervisor Virtual Console Server) Driver";
+
+/* Status of partner info rescan triggered via sysfs. */
+static int hvcs_rescan_status;
+
+static struct tty_driver *hvcs_tty_driver;
+
+/*
+ * In order to be somewhat sane this driver always associates the hvcs_struct
+ * index element with the numerically equal tty->index.  This means that a
+ * hotplugged vty-server adapter will always map to the lowest index valued
+ * device node.  If vty-servers were hotplug removed from the system and then
+ * new ones added the new vty-server may have the largest slot number of all
+ * the vty-server adapters in the partition but it may have the lowest dev node
+ * index of all the adapters due to the hole left by the hotplug removed
+ * adapter.  There are a set of functions provided to get the lowest index for
+ * a new device as well as return the index to the list.  This list is allocated
+ * with a number of elements equal to the number of device nodes requested when
+ * the module was inserted.
+ */
+static int *hvcs_index_list;
+
+/*
+ * How large is the list?  This is kept for traversal since the list is
+ * dynamically created.
+ */
+static int hvcs_index_count;
+
+/*
+ * Used by the khvcsd to pick up I/O operations when the kernel_thread is
+ * already awake but potentially shifted to TASK_INTERRUPTIBLE state.
+ */
+static int hvcs_kicked;
+
+/*
+ * Use by the kthread construct for task operations like waking the sleeping
+ * thread and stopping the kthread.
+ */
+static struct task_struct *hvcs_task;
+
+/*
+ * We allocate this for the use of all of the hvcs_structs when they fetch
+ * partner info.
+ */
+static unsigned long *hvcs_pi_buff;
+
+/* Only allow one hvcs_struct to use the hvcs_pi_buff at a time. */
+static DEFINE_SPINLOCK(hvcs_pi_lock);
+
+/* One vty-server per hvcs_struct */
+struct hvcs_struct {
+	spinlock_t lock;
+
+	/*
+	 * This index identifies this hvcs device as the complement to a
+	 * specific tty index.
+	 */
+	unsigned int index;
+
+	struct tty_struct *tty;
+	int open_count;
+
+	/*
+	 * Used to tell the driver kernel_thread what operations need to take
+	 * place upon this hvcs_struct instance.
+	 */
+	int todo_mask;
+
+	/*
+	 * This buffer is required so that when hvcs_write_room() reports that
+	 * it can send HVCS_BUFF_LEN characters that it will buffer the full
+	 * HVCS_BUFF_LEN characters if need be.  This is essential for opost
+	 * writes since they do not do high level buffering and expect to be
+	 * able to send what the driver commits to sending buffering
+	 * [e.g. tab to space conversions in n_tty.c opost()].
+	 */
+	char buffer[HVCS_BUFF_LEN];
+	int chars_in_buffer;
+
+	/*
+	 * Any variable below the kref is valid before a tty is connected and
+	 * stays valid after the tty is disconnected.  These shouldn't be
+	 * whacked until the koject refcount reaches zero though some entries
+	 * may be changed via sysfs initiatives.
+	 */
+	struct kref kref; /* ref count & hvcs_struct lifetime */
+	int connected; /* is the vty-server currently connected to a vty? */
+	uint32_t p_unit_address; /* partner unit address */
+	uint32_t p_partition_ID; /* partner partition ID */
+	char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
+	struct list_head next; /* list management */
+	struct vio_dev *vdev;
+};
+
+/* Required to back map a kref to its containing object */
+#define from_kref(k) container_of(k, struct hvcs_struct, kref)
+
+static LIST_HEAD(hvcs_structs);
+static DEFINE_SPINLOCK(hvcs_structs_lock);
+
+static void hvcs_unthrottle(struct tty_struct *tty);
+static void hvcs_throttle(struct tty_struct *tty);
+static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
+
+static int hvcs_write(struct tty_struct *tty,
+		const unsigned char *buf, int count);
+static int hvcs_write_room(struct tty_struct *tty);
+static int hvcs_chars_in_buffer(struct tty_struct *tty);
+
+static int hvcs_has_pi(struct hvcs_struct *hvcsd);
+static void hvcs_set_pi(struct hvcs_partner_info *pi,
+		struct hvcs_struct *hvcsd);
+static int hvcs_get_pi(struct hvcs_struct *hvcsd);
+static int hvcs_rescan_devices_list(void);
+
+static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
+static void hvcs_partner_free(struct hvcs_struct *hvcsd);
+
+static int hvcs_enable_device(struct hvcs_struct *hvcsd,
+		uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
+
+static int hvcs_open(struct tty_struct *tty, struct file *filp);
+static void hvcs_close(struct tty_struct *tty, struct file *filp);
+static void hvcs_hangup(struct tty_struct * tty);
+
+static int __devinit hvcs_probe(struct vio_dev *dev,
+		const struct vio_device_id *id);
+static int __devexit hvcs_remove(struct vio_dev *dev);
+static int __init hvcs_module_init(void);
+static void __exit hvcs_module_exit(void);
+
+#define HVCS_SCHED_READ	0x00000001
+#define HVCS_QUICK_READ	0x00000002
+#define HVCS_TRY_WRITE	0x00000004
+#define HVCS_READ_MASK	(HVCS_SCHED_READ | HVCS_QUICK_READ)
+
+static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
+{
+	return dev_get_drvdata(&viod->dev);
+}
+/* The sysfs interface for the driver and devices */
+
+static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct vio_dev *viod = to_vio_dev(dev);
+	struct hvcs_struct *hvcsd = from_vio_dev(viod);
+	unsigned long flags;
+	int retval;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	return retval;
+}
+static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
+
+static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct vio_dev *viod = to_vio_dev(dev);
+	struct hvcs_struct *hvcsd = from_vio_dev(viod);
+	unsigned long flags;
+	int retval;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	return retval;
+}
+static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
+
+static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
+		size_t count)
+{
+	/*
+	 * Don't need this feature at the present time because firmware doesn't
+	 * yet support multiple partners.
+	 */
+	printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
+	return -EPERM;
+}
+
+static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct vio_dev *viod = to_vio_dev(dev);
+	struct hvcs_struct *hvcsd = from_vio_dev(viod);
+	unsigned long flags;
+	int retval;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	return retval;
+}
+
+static DEVICE_ATTR(current_vty,
+	S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
+
+static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
+		size_t count)
+{
+	struct vio_dev *viod = to_vio_dev(dev);
+	struct hvcs_struct *hvcsd = from_vio_dev(viod);
+	unsigned long flags;
+
+	/* writing a '0' to this sysfs entry will result in the disconnect. */
+	if (simple_strtol(buf, NULL, 0) != 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+
+	if (hvcsd->open_count > 0) {
+		spin_unlock_irqrestore(&hvcsd->lock, flags);
+		printk(KERN_INFO "HVCS: vterm state unchanged.  "
+				"The hvcs device node is still in use.\n");
+		return -EPERM;
+	}
+
+	if (hvcsd->connected == 0) {
+		spin_unlock_irqrestore(&hvcsd->lock, flags);
+		printk(KERN_INFO "HVCS: vterm state unchanged. The"
+				" vty-server is not connected to a vty.\n");
+		return -EPERM;
+	}
+
+	hvcs_partner_free(hvcsd);
+	printk(KERN_INFO "HVCS: Closed vty-server@%X and"
+			" partner vty@%X:%d connection.\n",
+			hvcsd->vdev->unit_address,
+			hvcsd->p_unit_address,
+			(uint32_t)hvcsd->p_partition_ID);
+
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	return count;
+}
+
+static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct vio_dev *viod = to_vio_dev(dev);
+	struct hvcs_struct *hvcsd = from_vio_dev(viod);
+	unsigned long flags;
+	int retval;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	retval = sprintf(buf, "%d\n", hvcsd->connected);
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	return retval;
+}
+static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
+		hvcs_vterm_state_show, hvcs_vterm_state_store);
+
+static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct vio_dev *viod = to_vio_dev(dev);
+	struct hvcs_struct *hvcsd = from_vio_dev(viod);
+	unsigned long flags;
+	int retval;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	retval = sprintf(buf, "%d\n", hvcsd->index);
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	return retval;
+}
+
+static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
+
+static struct attribute *hvcs_attrs[] = {
+	&dev_attr_partner_vtys.attr,
+	&dev_attr_partner_clcs.attr,
+	&dev_attr_current_vty.attr,
+	&dev_attr_vterm_state.attr,
+	&dev_attr_index.attr,
+	NULL,
+};
+
+static struct attribute_group hvcs_attr_group = {
+	.attrs = hvcs_attrs,
+};
+
+static ssize_t hvcs_rescan_show(struct device_driver *ddp, char *buf)
+{
+	/* A 1 means it is updating, a 0 means it is done updating */
+	return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
+}
+
+static ssize_t hvcs_rescan_store(struct device_driver *ddp, const char * buf,
+		size_t count)
+{
+	if ((simple_strtol(buf, NULL, 0) != 1)
+		&& (hvcs_rescan_status != 0))
+		return -EINVAL;
+
+	hvcs_rescan_status = 1;
+	printk(KERN_INFO "HVCS: rescanning partner info for all"
+		" vty-servers.\n");
+	hvcs_rescan_devices_list();
+	hvcs_rescan_status = 0;
+	return count;
+}
+
+static DRIVER_ATTR(rescan,
+	S_IRUGO | S_IWUSR, hvcs_rescan_show, hvcs_rescan_store);
+
+static void hvcs_kick(void)
+{
+	hvcs_kicked = 1;
+	wmb();
+	wake_up_process(hvcs_task);
+}
+
+static void hvcs_unthrottle(struct tty_struct *tty)
+{
+	struct hvcs_struct *hvcsd = tty->driver_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	hvcsd->todo_mask |= HVCS_SCHED_READ;
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	hvcs_kick();
+}
+
+static void hvcs_throttle(struct tty_struct *tty)
+{
+	struct hvcs_struct *hvcsd = tty->driver_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	vio_disable_interrupts(hvcsd->vdev);
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+}
+
+/*
+ * If the device is being removed we don't have to worry about this interrupt
+ * handler taking any further interrupts because they are disabled which means
+ * the hvcs_struct will always be valid in this handler.
+ */
+static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
+{
+	struct hvcs_struct *hvcsd = dev_instance;
+
+	spin_lock(&hvcsd->lock);
+	vio_disable_interrupts(hvcsd->vdev);
+	hvcsd->todo_mask |= HVCS_SCHED_READ;
+	spin_unlock(&hvcsd->lock);
+	hvcs_kick();
+
+	return IRQ_HANDLED;
+}
+
+/* This function must be called with the hvcsd->lock held */
+static void hvcs_try_write(struct hvcs_struct *hvcsd)
+{
+	uint32_t unit_address = hvcsd->vdev->unit_address;
+	struct tty_struct *tty = hvcsd->tty;
+	int sent;
+
+	if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
+		/* won't send partial writes */
+		sent = hvc_put_chars(unit_address,
+				&hvcsd->buffer[0],
+				hvcsd->chars_in_buffer );
+		if (sent > 0) {
+			hvcsd->chars_in_buffer = 0;
+			/* wmb(); */
+			hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
+			/* wmb(); */
+
+			/*
+			 * We are still obligated to deliver the data to the
+			 * hypervisor even if the tty has been closed because
+			 * we commited to delivering it.  But don't try to wake
+			 * a non-existent tty.
+			 */
+			if (tty) {
+				tty_wakeup(tty);
+			}
+		}
+	}
+}
+
+static int hvcs_io(struct hvcs_struct *hvcsd)
+{
+	uint32_t unit_address;
+	struct tty_struct *tty;
+	char buf[HVCS_BUFF_LEN] __ALIGNED__;
+	unsigned long flags;
+	int got = 0;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+
+	unit_address = hvcsd->vdev->unit_address;
+	tty = hvcsd->tty;
+
+	hvcs_try_write(hvcsd);
+
+	if (!tty || test_bit(TTY_THROTTLED, &tty->flags)) {
+		hvcsd->todo_mask &= ~(HVCS_READ_MASK);
+		goto bail;
+	} else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
+		goto bail;
+
+	/* remove the read masks */
+	hvcsd->todo_mask &= ~(HVCS_READ_MASK);
+
+	if (tty_buffer_request_room(tty, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
+		got = hvc_get_chars(unit_address,
+				&buf[0],
+				HVCS_BUFF_LEN);
+		tty_insert_flip_string(tty, buf, got);
+	}
+
+	/* Give the TTY time to process the data we just sent. */
+	if (got)
+		hvcsd->todo_mask |= HVCS_QUICK_READ;
+
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	/* This is synch because tty->low_latency == 1 */
+	if(got)
+		tty_flip_buffer_push(tty);
+
+	if (!got) {
+		/* Do this _after_ the flip_buffer_push */
+		spin_lock_irqsave(&hvcsd->lock, flags);
+		vio_enable_interrupts(hvcsd->vdev);
+		spin_unlock_irqrestore(&hvcsd->lock, flags);
+	}
+
+	return hvcsd->todo_mask;
+
+ bail:
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	return hvcsd->todo_mask;
+}
+
+static int khvcsd(void *unused)
+{
+	struct hvcs_struct *hvcsd;
+	int hvcs_todo_mask;
+
+	__set_current_state(TASK_RUNNING);
+
+	do {
+		hvcs_todo_mask = 0;
+		hvcs_kicked = 0;
+		wmb();
+
+		spin_lock(&hvcs_structs_lock);
+		list_for_each_entry(hvcsd, &hvcs_structs, next) {
+			hvcs_todo_mask |= hvcs_io(hvcsd);
+		}
+		spin_unlock(&hvcs_structs_lock);
+
+		/*
+		 * If any of the hvcs adapters want to try a write or quick read
+		 * don't schedule(), yield a smidgen then execute the hvcs_io
+		 * thread again for those that want the write.
+		 */
+		 if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
+			yield();
+			continue;
+		}
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (!hvcs_kicked)
+			schedule();
+		__set_current_state(TASK_RUNNING);
+	} while (!kthread_should_stop());
+
+	return 0;
+}
+
+static struct vio_device_id hvcs_driver_table[] __devinitdata= {
+	{"serial-server", "hvterm2"},
+	{ "", "" }
+};
+MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
+
+static void hvcs_return_index(int index)
+{
+	/* Paranoia check */
+	if (!hvcs_index_list)
+		return;
+	if (index < 0 || index >= hvcs_index_count)
+		return;
+	if (hvcs_index_list[index] == -1)
+		return;
+	else
+		hvcs_index_list[index] = -1;
+}
+
+/* callback when the kref ref count reaches zero */
+static void destroy_hvcs_struct(struct kref *kref)
+{
+	struct hvcs_struct *hvcsd = from_kref(kref);
+	struct vio_dev *vdev;
+	unsigned long flags;
+
+	spin_lock(&hvcs_structs_lock);
+	spin_lock_irqsave(&hvcsd->lock, flags);
+
+	/* the list_del poisons the pointers */
+	list_del(&(hvcsd->next));
+
+	if (hvcsd->connected == 1) {
+		hvcs_partner_free(hvcsd);
+		printk(KERN_INFO "HVCS: Closed vty-server@%X and"
+				" partner vty@%X:%d connection.\n",
+				hvcsd->vdev->unit_address,
+				hvcsd->p_unit_address,
+				(uint32_t)hvcsd->p_partition_ID);
+	}
+	printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
+			hvcsd->vdev->unit_address);
+
+	vdev = hvcsd->vdev;
+	hvcsd->vdev = NULL;
+
+	hvcsd->p_unit_address = 0;
+	hvcsd->p_partition_ID = 0;
+	hvcs_return_index(hvcsd->index);
+	memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
+
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	spin_unlock(&hvcs_structs_lock);
+
+	sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
+
+	kfree(hvcsd);
+}
+
+static int hvcs_get_index(void)
+{
+	int i;
+	/* Paranoia check */
+	if (!hvcs_index_list) {
+		printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
+		return -EFAULT;
+	}
+	/* Find the numerically lowest first free index. */
+	for(i = 0; i < hvcs_index_count; i++) {
+		if (hvcs_index_list[i] == -1) {
+			hvcs_index_list[i] = 0;
+			return i;
+		}
+	}
+	return -1;
+}
+
+static int __devinit hvcs_probe(
+	struct vio_dev *dev,
+	const struct vio_device_id *id)
+{
+	struct hvcs_struct *hvcsd;
+	int index;
+	int retval;
+
+	if (!dev || !id) {
+		printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
+		return -EPERM;
+	}
+
+	/* early to avoid cleanup on failure */
+	index = hvcs_get_index();
+	if (index < 0) {
+		return -EFAULT;
+	}
+
+	hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
+	if (!hvcsd)
+		return -ENODEV;
+
+
+	spin_lock_init(&hvcsd->lock);
+	/* Automatically incs the refcount the first time */
+	kref_init(&hvcsd->kref);
+
+	hvcsd->vdev = dev;
+	dev_set_drvdata(&dev->dev, hvcsd);
+
+	hvcsd->index = index;
+
+	/* hvcsd->index = ++hvcs_struct_count; */
+	hvcsd->chars_in_buffer = 0;
+	hvcsd->todo_mask = 0;
+	hvcsd->connected = 0;
+
+	/*
+	 * This will populate the hvcs_struct's partner info fields for the
+	 * first time.
+	 */
+	if (hvcs_get_pi(hvcsd)) {
+		printk(KERN_ERR "HVCS: Failed to fetch partner"
+			" info for vty-server@%X on device probe.\n",
+			hvcsd->vdev->unit_address);
+	}
+
+	/*
+	 * If a user app opens a tty that corresponds to this vty-server before
+	 * the hvcs_struct has been added to the devices list then the user app
+	 * will get -ENODEV.
+	 */
+	spin_lock(&hvcs_structs_lock);
+	list_add_tail(&(hvcsd->next), &hvcs_structs);
+	spin_unlock(&hvcs_structs_lock);
+
+	retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
+	if (retval) {
+		printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
+		       hvcsd->vdev->unit_address);
+		return retval;
+	}
+
+	printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
+
+	/*
+	 * DON'T enable interrupts here because there is no user to receive the
+	 * data.
+	 */
+	return 0;
+}
+
+static int __devexit hvcs_remove(struct vio_dev *dev)
+{
+	struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
+	unsigned long flags;
+	struct tty_struct *tty;
+
+	if (!hvcsd)
+		return -ENODEV;
+
+	/* By this time the vty-server won't be getting any more interrupts */
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+
+	tty = hvcsd->tty;
+
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+
+	/*
+	 * Let the last holder of this object cause it to be removed, which
+	 * would probably be tty_hangup below.
+	 */
+	kref_put(&hvcsd->kref, destroy_hvcs_struct);
+
+	/*
+	 * The hangup is a scheduled function which will auto chain call
+	 * hvcs_hangup.  The tty should always be valid at this time unless a
+	 * simultaneous tty close already cleaned up the hvcs_struct.
+	 */
+	if (tty)
+		tty_hangup(tty);
+
+	printk(KERN_INFO "HVCS: vty-server@%X removed from the"
+			" vio bus.\n", dev->unit_address);
+	return 0;
+};
+
+static struct vio_driver hvcs_vio_driver = {
+	.id_table	= hvcs_driver_table,
+	.probe		= hvcs_probe,
+	.remove		= __devexit_p(hvcs_remove),
+	.driver		= {
+		.name	= hvcs_driver_name,
+		.owner	= THIS_MODULE,
+	}
+};
+
+/* Only called from hvcs_get_pi please */
+static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
+{
+	int clclength;
+
+	hvcsd->p_unit_address = pi->unit_address;
+	hvcsd->p_partition_ID  = pi->partition_ID;
+	clclength = strlen(&pi->location_code[0]);
+	if (clclength > HVCS_CLC_LENGTH)
+		clclength = HVCS_CLC_LENGTH;
+
+	/* copy the null-term char too */
+	strncpy(&hvcsd->p_location_code[0],
+			&pi->location_code[0], clclength + 1);
+}
+
+/*
+ * Traverse the list and add the partner info that is found to the hvcs_struct
+ * struct entry. NOTE: At this time I know that partner info will return a
+ * single entry but in the future there may be multiple partner info entries per
+ * vty-server and you'll want to zero out that list and reset it.  If for some
+ * reason you have an old version of this driver but there IS more than one
+ * partner info then hvcsd->p_* will hold the last partner info data from the
+ * firmware query.  A good way to update this code would be to replace the three
+ * partner info fields in hvcs_struct with a list of hvcs_partner_info
+ * instances.
+ *
+ * This function must be called with the hvcsd->lock held.
+ */
+static int hvcs_get_pi(struct hvcs_struct *hvcsd)
+{
+	struct hvcs_partner_info *pi;
+	uint32_t unit_address = hvcsd->vdev->unit_address;
+	struct list_head head;
+	int retval;
+
+	spin_lock(&hvcs_pi_lock);
+	if (!hvcs_pi_buff) {
+		spin_unlock(&hvcs_pi_lock);
+		return -EFAULT;
+	}
+	retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
+	spin_unlock(&hvcs_pi_lock);
+	if (retval) {
+		printk(KERN_ERR "HVCS: Failed to fetch partner"
+			" info for vty-server@%x.\n", unit_address);
+		return retval;
+	}
+
+	/* nixes the values if the partner vty went away */
+	hvcsd->p_unit_address = 0;
+	hvcsd->p_partition_ID = 0;
+
+	list_for_each_entry(pi, &head, node)
+		hvcs_set_pi(pi, hvcsd);
+
+	hvcs_free_partner_info(&head);
+	return 0;
+}
+
+/*
+ * This function is executed by the driver "rescan" sysfs entry.  It shouldn't
+ * be executed elsewhere, in order to prevent deadlock issues.
+ */
+static int hvcs_rescan_devices_list(void)
+{
+	struct hvcs_struct *hvcsd;
+	unsigned long flags;
+
+	spin_lock(&hvcs_structs_lock);
+
+	list_for_each_entry(hvcsd, &hvcs_structs, next) {
+		spin_lock_irqsave(&hvcsd->lock, flags);
+		hvcs_get_pi(hvcsd);
+		spin_unlock_irqrestore(&hvcsd->lock, flags);
+	}
+
+	spin_unlock(&hvcs_structs_lock);
+
+	return 0;
+}
+
+/*
+ * Farm this off into its own function because it could be more complex once
+ * multiple partners support is added. This function should be called with
+ * the hvcsd->lock held.
+ */
+static int hvcs_has_pi(struct hvcs_struct *hvcsd)
+{
+	if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
+		return 0;
+	return 1;
+}
+
+/*
+ * NOTE: It is possible that the super admin removed a partner vty and then
+ * added a different vty as the new partner.
+ *
+ * This function must be called with the hvcsd->lock held.
+ */
+static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
+{
+	int retval;
+	unsigned int unit_address = hvcsd->vdev->unit_address;
+
+	/*
+	 * If there wasn't any pi when the device was added it doesn't meant
+	 * there isn't any now.  This driver isn't notified when a new partner
+	 * vty is added to a vty-server so we discover changes on our own.
+	 * Please see comments in hvcs_register_connection() for justification
+	 * of this bizarre code.
+	 */
+	retval = hvcs_register_connection(unit_address,
+			hvcsd->p_partition_ID,
+			hvcsd->p_unit_address);
+	if (!retval) {
+		hvcsd->connected = 1;
+		return 0;
+	} else if (retval != -EINVAL)
+		return retval;
+
+	/*
+	 * As per the spec re-get the pi and try again if -EINVAL after the
+	 * first connection attempt.
+	 */
+	if (hvcs_get_pi(hvcsd))
+		return -ENOMEM;
+
+	if (!hvcs_has_pi(hvcsd))
+		return -ENODEV;
+
+	retval = hvcs_register_connection(unit_address,
+			hvcsd->p_partition_ID,
+			hvcsd->p_unit_address);
+	if (retval != -EINVAL) {
+		hvcsd->connected = 1;
+		return retval;
+	}
+
+	/*
+	 * EBUSY is the most likely scenario though the vty could have been
+	 * removed or there really could be an hcall error due to the parameter
+	 * data but thanks to ambiguous firmware return codes we can't really
+	 * tell.
+	 */
+	printk(KERN_INFO "HVCS: vty-server or partner"
+			" vty is busy.  Try again later.\n");
+	return -EBUSY;
+}
+
+/* This function must be called with the hvcsd->lock held */
+static void hvcs_partner_free(struct hvcs_struct *hvcsd)
+{
+	int retval;
+	do {
+		retval = hvcs_free_connection(hvcsd->vdev->unit_address);
+	} while (retval == -EBUSY);
+	hvcsd->connected = 0;
+}
+
+/* This helper function must be called WITHOUT the hvcsd->lock held */
+static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
+		unsigned int irq, struct vio_dev *vdev)
+{
+	unsigned long flags;
+	int rc;
+
+	/*
+	 * It is possible that the vty-server was removed between the time that
+	 * the conn was registered and now.
+	 */
+	if (!(rc = request_irq(irq, &hvcs_handle_interrupt,
+				IRQF_DISABLED, "ibmhvcs", hvcsd))) {
+		/*
+		 * It is possible the vty-server was removed after the irq was
+		 * requested but before we have time to enable interrupts.
+		 */
+		if (vio_enable_interrupts(vdev) == H_SUCCESS)
+			return 0;
+		else {
+			printk(KERN_ERR "HVCS: int enable failed for"
+					" vty-server@%X.\n", unit_address);
+			free_irq(irq, hvcsd);
+		}
+	} else
+		printk(KERN_ERR "HVCS: irq req failed for"
+				" vty-server@%X.\n", unit_address);
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	hvcs_partner_free(hvcsd);
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+
+	return rc;
+
+}
+
+/*
+ * This always increments the kref ref count if the call is successful.
+ * Please remember to dec when you are done with the instance.
+ *
+ * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
+ * calling this function or you will get deadlock.
+ */
+static struct hvcs_struct *hvcs_get_by_index(int index)
+{
+	struct hvcs_struct *hvcsd = NULL;
+	unsigned long flags;
+
+	spin_lock(&hvcs_structs_lock);
+	/* We can immediately discard OOB requests */
+	if (index >= 0 && index < HVCS_MAX_SERVER_ADAPTERS) {
+		list_for_each_entry(hvcsd, &hvcs_structs, next) {
+			spin_lock_irqsave(&hvcsd->lock, flags);
+			if (hvcsd->index == index) {
+				kref_get(&hvcsd->kref);
+				spin_unlock_irqrestore(&hvcsd->lock, flags);
+				spin_unlock(&hvcs_structs_lock);
+				return hvcsd;
+			}
+			spin_unlock_irqrestore(&hvcsd->lock, flags);
+		}
+		hvcsd = NULL;
+	}
+
+	spin_unlock(&hvcs_structs_lock);
+	return hvcsd;
+}
+
+/*
+ * This is invoked via the tty_open interface when a user app connects to the
+ * /dev node.
+ */
+static int hvcs_open(struct tty_struct *tty, struct file *filp)
+{
+	struct hvcs_struct *hvcsd;
+	int rc, retval = 0;
+	unsigned long flags;
+	unsigned int irq;
+	struct vio_dev *vdev;
+	unsigned long unit_address;
+
+	if (tty->driver_data)
+		goto fast_open;
+
+	/*
+	 * Is there a vty-server that shares the same index?
+	 * This function increments the kref index.
+	 */
+	if (!(hvcsd = hvcs_get_by_index(tty->index))) {
+		printk(KERN_WARNING "HVCS: open failed, no device associated"
+				" with tty->index %d.\n", tty->index);
+		return -ENODEV;
+	}
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+
+	if (hvcsd->connected == 0)
+		if ((retval = hvcs_partner_connect(hvcsd)))
+			goto error_release;
+
+	hvcsd->open_count = 1;
+	hvcsd->tty = tty;
+	tty->driver_data = hvcsd;
+
+	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
+
+	/*
+	 * Save these in the spinlock for the enable operations that need them
+	 * outside of the spinlock.
+	 */
+	irq = hvcsd->vdev->irq;
+	vdev = hvcsd->vdev;
+	unit_address = hvcsd->vdev->unit_address;
+
+	hvcsd->todo_mask |= HVCS_SCHED_READ;
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+
+	/*
+	 * This must be done outside of the spinlock because it requests irqs
+	 * and will grab the spinlock and free the connection if it fails.
+	 */
+	if (((rc = hvcs_enable_device(hvcsd, unit_address, irq, vdev)))) {
+		kref_put(&hvcsd->kref, destroy_hvcs_struct);
+		printk(KERN_WARNING "HVCS: enable device failed.\n");
+		return rc;
+	}
+
+	goto open_success;
+
+fast_open:
+	hvcsd = tty->driver_data;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	kref_get(&hvcsd->kref);
+	hvcsd->open_count++;
+	hvcsd->todo_mask |= HVCS_SCHED_READ;
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+
+open_success:
+	hvcs_kick();
+
+	printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
+		hvcsd->vdev->unit_address );
+
+	return 0;
+
+error_release:
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	kref_put(&hvcsd->kref, destroy_hvcs_struct);
+
+	printk(KERN_WARNING "HVCS: partner connect failed.\n");
+	return retval;
+}
+
+static void hvcs_close(struct tty_struct *tty, struct file *filp)
+{
+	struct hvcs_struct *hvcsd;
+	unsigned long flags;
+	int irq = NO_IRQ;
+
+	/*
+	 * Is someone trying to close the file associated with this device after
+	 * we have hung up?  If so tty->driver_data wouldn't be valid.
+	 */
+	if (tty_hung_up_p(filp))
+		return;
+
+	/*
+	 * No driver_data means that this close was probably issued after a
+	 * failed hvcs_open by the tty layer's release_dev() api and we can just
+	 * exit cleanly.
+	 */
+	if (!tty->driver_data)
+		return;
+
+	hvcsd = tty->driver_data;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	if (--hvcsd->open_count == 0) {
+
+		vio_disable_interrupts(hvcsd->vdev);
+
+		/*
+		 * NULL this early so that the kernel_thread doesn't try to
+		 * execute any operations on the TTY even though it is obligated
+		 * to deliver any pending I/O to the hypervisor.
+		 */
+		hvcsd->tty = NULL;
+
+		irq = hvcsd->vdev->irq;
+		spin_unlock_irqrestore(&hvcsd->lock, flags);
+
+		tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
+
+		/*
+		 * This line is important because it tells hvcs_open that this
+		 * device needs to be re-configured the next time hvcs_open is
+		 * called.
+		 */
+		tty->driver_data = NULL;
+
+		free_irq(irq, hvcsd);
+		kref_put(&hvcsd->kref, destroy_hvcs_struct);
+		return;
+	} else if (hvcsd->open_count < 0) {
+		printk(KERN_ERR "HVCS: vty-server@%X open_count: %d"
+				" is missmanaged.\n",
+		hvcsd->vdev->unit_address, hvcsd->open_count);
+	}
+
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+	kref_put(&hvcsd->kref, destroy_hvcs_struct);
+}
+
+static void hvcs_hangup(struct tty_struct * tty)
+{
+	struct hvcs_struct *hvcsd = tty->driver_data;
+	unsigned long flags;
+	int temp_open_count;
+	int irq = NO_IRQ;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+	/* Preserve this so that we know how many kref refs to put */
+	temp_open_count = hvcsd->open_count;
+
+	/*
+	 * Don't kref put inside the spinlock because the destruction
+	 * callback may use the spinlock and it may get called before the
+	 * spinlock has been released.
+	 */
+	vio_disable_interrupts(hvcsd->vdev);
+
+	hvcsd->todo_mask = 0;
+
+	/* I don't think the tty needs the hvcs_struct pointer after a hangup */
+	hvcsd->tty->driver_data = NULL;
+	hvcsd->tty = NULL;
+
+	hvcsd->open_count = 0;
+
+	/* This will drop any buffered data on the floor which is OK in a hangup
+	 * scenario. */
+	memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
+	hvcsd->chars_in_buffer = 0;
+
+	irq = hvcsd->vdev->irq;
+
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+
+	free_irq(irq, hvcsd);
+
+	/*
+	 * We need to kref_put() for every open_count we have since the
+	 * tty_hangup() function doesn't invoke a close per open connection on a
+	 * non-console device.
+	 */
+	while(temp_open_count) {
+		--temp_open_count;
+		/*
+		 * The final put will trigger destruction of the hvcs_struct.
+		 * NOTE:  If this hangup was signaled from user space then the
+		 * final put will never happen.
+		 */
+		kref_put(&hvcsd->kref, destroy_hvcs_struct);
+	}
+}
+
+/*
+ * NOTE: This is almost always from_user since user level apps interact with the
+ * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
+ * hvcs_remove (which removes the target device and executes tty_hangup()) that
+ * tty_hangup will allow hvcs_write time to complete execution before it
+ * terminates our device.
+ */
+static int hvcs_write(struct tty_struct *tty,
+		const unsigned char *buf, int count)
+{
+	struct hvcs_struct *hvcsd = tty->driver_data;
+	unsigned int unit_address;
+	const unsigned char *charbuf;
+	unsigned long flags;
+	int total_sent = 0;
+	int tosend = 0;
+	int result = 0;
+
+	/*
+	 * If they don't check the return code off of their open they may
+	 * attempt this even if there is no connected device.
+	 */
+	if (!hvcsd)
+		return -ENODEV;
+
+	/* Reasonable size to prevent user level flooding */
+	if (count > HVCS_MAX_FROM_USER) {
+		printk(KERN_WARNING "HVCS write: count being truncated to"
+				" HVCS_MAX_FROM_USER.\n");
+		count = HVCS_MAX_FROM_USER;
+	}
+
+	charbuf = buf;
+
+	spin_lock_irqsave(&hvcsd->lock, flags);
+
+	/*
+	 * Somehow an open succedded but the device was removed or the
+	 * connection terminated between the vty-server and partner vty during
+	 * the middle of a write operation?  This is a crummy place to do this
+	 * but we want to keep it all in the spinlock.
+	 */
+	if (hvcsd->open_count <= 0) {
+		spin_unlock_irqrestore(&hvcsd->lock, flags);
+		return -ENODEV;
+	}
+
+	unit_address = hvcsd->vdev->unit_address;
+
+	while (count > 0) {
+		tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
+		/*
+		 * No more space, this probably means that the last call to
+		 * hvcs_write() didn't succeed and the buffer was filled up.
+		 */
+		if (!tosend)
+			break;
+
+		memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
+				&charbuf[total_sent],
+				tosend);
+
+		hvcsd->chars_in_buffer += tosend;
+
+		result = 0;
+
+		/*
+		 * If this is true then we don't want to try writing to the
+		 * hypervisor because that is the kernel_threads job now.  We'll
+		 * just add to the buffer.
+		 */
+		if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
+			/* won't send partial writes */
+			result = hvc_put_chars(unit_address,
+					&hvcsd->buffer[0],
+					hvcsd->chars_in_buffer);
+
+		/*
+		 * Since we know we have enough room in hvcsd->buffer for
+		 * tosend we record that it was sent regardless of whether the
+		 * hypervisor actually took it because we have it buffered.
+		 */
+		total_sent+=tosend;
+		count-=tosend;
+		if (result == 0) {
+			hvcsd->todo_mask |= HVCS_TRY_WRITE;
+			hvcs_kick();
+			break;
+		}
+
+		hvcsd->chars_in_buffer = 0;
+		/*
+		 * Test after the chars_in_buffer reset otherwise this could
+		 * deadlock our writes if hvc_put_chars fails.
+		 */
+		if (result < 0)
+			break;
+	}
+
+	spin_unlock_irqrestore(&hvcsd->lock, flags);
+
+	if (result == -1)
+		return -EIO;
+	else
+		return total_sent;
+}
+
+/*
+ * This is really asking how much can we guarentee that we can send or that we
+ * absolutely WILL BUFFER if we can't send it.  This driver MUST honor the
+ * return value, hence the reason for hvcs_struct buffering.
+ */
+static int hvcs_write_room(struct tty_struct *tty)
+{
+	struct hvcs_struct *hvcsd = tty->driver_data;
+
+	if (!hvcsd || hvcsd->open_count <= 0)
+		return 0;
+
+	return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
+}
+
+static int hvcs_chars_in_buffer(struct tty_struct *tty)
+{
+	struct hvcs_struct *hvcsd = tty->driver_data;
+
+	return hvcsd->chars_in_buffer;
+}
+
+static const struct tty_operations hvcs_ops = {
+	.open = hvcs_open,
+	.close = hvcs_close,
+	.hangup = hvcs_hangup,
+	.write = hvcs_write,
+	.write_room = hvcs_write_room,
+	.chars_in_buffer = hvcs_chars_in_buffer,
+	.unthrottle = hvcs_unthrottle,
+	.throttle = hvcs_throttle,
+};
+
+static int hvcs_alloc_index_list(int n)
+{
+	int i;
+
+	hvcs_index_list = kmalloc(n * sizeof(hvcs_index_count),GFP_KERNEL);
+	if (!hvcs_index_list)
+		return -ENOMEM;
+	hvcs_index_count = n;
+	for (i = 0; i < hvcs_index_count; i++)
+		hvcs_index_list[i] = -1;
+	return 0;
+}
+
+static void hvcs_free_index_list(void)
+{
+	/* Paranoia check to be thorough. */
+	kfree(hvcs_index_list);
+	hvcs_index_list = NULL;
+	hvcs_index_count = 0;
+}
+
+static int __init hvcs_module_init(void)
+{
+	int rc;
+	int num_ttys_to_alloc;
+
+	printk(KERN_INFO "Initializing %s\n", hvcs_driver_string);
+
+	/* Has the user specified an overload with an insmod param? */
+	if (hvcs_parm_num_devs <= 0 ||
+		(hvcs_parm_num_devs > HVCS_MAX_SERVER_ADAPTERS)) {
+		num_ttys_to_alloc = HVCS_DEFAULT_SERVER_ADAPTERS;
+	} else
+		num_ttys_to_alloc = hvcs_parm_num_devs;
+
+	hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
+	if (!hvcs_tty_driver)
+		return -ENOMEM;
+
+	if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
+		rc = -ENOMEM;
+		goto index_fail;
+	}
+
+	hvcs_tty_driver->owner = THIS_MODULE;
+
+	hvcs_tty_driver->driver_name = hvcs_driver_name;
+	hvcs_tty_driver->name = hvcs_device_node;
+
+	/*
+	 * We'll let the system assign us a major number, indicated by leaving
+	 * it blank.
+	 */
+
+	hvcs_tty_driver->minor_start = HVCS_MINOR_START;
+	hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
+
+	/*
+	 * We role our own so that we DONT ECHO.  We can't echo because the
+	 * device we are connecting to already echoes by default and this would
+	 * throw us into a horrible recursive echo-echo-echo loop.
+	 */
+	hvcs_tty_driver->init_termios = hvcs_tty_termios;
+	hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
+
+	tty_set_operations(hvcs_tty_driver, &hvcs_ops);
+
+	/*
+	 * The following call will result in sysfs entries that denote the
+	 * dynamically assigned major and minor numbers for our devices.
+	 */
+	if (tty_register_driver(hvcs_tty_driver)) {
+		printk(KERN_ERR "HVCS: registration as a tty driver failed.\n");
+		rc = -EIO;
+		goto register_fail;
+	}
+
+	hvcs_pi_buff = kmalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!hvcs_pi_buff) {
+		rc = -ENOMEM;
+		goto buff_alloc_fail;
+	}
+
+	hvcs_task = kthread_run(khvcsd, NULL, "khvcsd");
+	if (IS_ERR(hvcs_task)) {
+		printk(KERN_ERR "HVCS: khvcsd creation failed.  Driver not loaded.\n");
+		rc = -EIO;
+		goto kthread_fail;
+	}
+
+	rc = vio_register_driver(&hvcs_vio_driver);
+	if (rc) {
+		printk(KERN_ERR "HVCS: can't register vio driver\n");
+		goto vio_fail;
+	}
+
+	/*
+	 * This needs to be done AFTER the vio_register_driver() call or else
+	 * the kobjects won't be initialized properly.
+	 */
+	rc = driver_create_file(&(hvcs_vio_driver.driver), &driver_attr_rescan);
+	if (rc) {
+		printk(KERN_ERR "HVCS: sysfs attr create failed\n");
+		goto attr_fail;
+	}
+
+	printk(KERN_INFO "HVCS: driver module inserted.\n");
+
+	return 0;
+
+attr_fail:
+	vio_unregister_driver(&hvcs_vio_driver);
+vio_fail:
+	kthread_stop(hvcs_task);
+kthread_fail:
+	kfree(hvcs_pi_buff);
+buff_alloc_fail:
+	tty_unregister_driver(hvcs_tty_driver);
+register_fail:
+	hvcs_free_index_list();
+index_fail:
+	put_tty_driver(hvcs_tty_driver);
+	hvcs_tty_driver = NULL;
+	return rc;
+}
+
+static void __exit hvcs_module_exit(void)
+{
+	/*
+	 * This driver receives hvcs_remove callbacks for each device upon
+	 * module removal.
+	 */
+
+	/*
+	 * This synchronous operation  will wake the khvcsd kthread if it is
+	 * asleep and will return when khvcsd has terminated.
+	 */
+	kthread_stop(hvcs_task);
+
+	spin_lock(&hvcs_pi_lock);
+	kfree(hvcs_pi_buff);
+	hvcs_pi_buff = NULL;
+	spin_unlock(&hvcs_pi_lock);
+
+	driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
+
+	vio_unregister_driver(&hvcs_vio_driver);
+
+	tty_unregister_driver(hvcs_tty_driver);
+
+	hvcs_free_index_list();
+
+	put_tty_driver(hvcs_tty_driver);
+
+	printk(KERN_INFO "HVCS: driver module removed.\n");
+}
+
+module_init(hvcs_module_init);
+module_exit(hvcs_module_exit);
diff --git a/drivers/tty/hvc/hvsi.c b/drivers/tty/hvc/hvsi.c
new file mode 100644
index 000000000000..67a75a502c01
--- /dev/null
+++ b/drivers/tty/hvc/hvsi.c
@@ -0,0 +1,1314 @@
+/*
+ * Copyright (C) 2004 Hollis Blanchard <hollisb@us.ibm.com>, IBM
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+/* Host Virtual Serial Interface (HVSI) is a protocol between the hosted OS
+ * and the service processor on IBM pSeries servers. On these servers, there
+ * are no serial ports under the OS's control, and sometimes there is no other
+ * console available either. However, the service processor has two standard
+ * serial ports, so this over-complicated protocol allows the OS to control
+ * those ports by proxy.
+ *
+ * Besides data, the procotol supports the reading/writing of the serial
+ * port's DTR line, and the reading of the CD line. This is to allow the OS to
+ * control a modem attached to the service processor's serial port. Note that
+ * the OS cannot change the speed of the port through this protocol.
+ */
+
+#undef DEBUG
+
+#include <linux/console.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/major.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/sysrq.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <asm/hvcall.h>
+#include <asm/hvconsole.h>
+#include <asm/prom.h>
+#include <asm/uaccess.h>
+#include <asm/vio.h>
+#include <asm/param.h>
+
+#define HVSI_MAJOR	229
+#define HVSI_MINOR	128
+#define MAX_NR_HVSI_CONSOLES 4
+
+#define HVSI_TIMEOUT (5*HZ)
+#define HVSI_VERSION 1
+#define HVSI_MAX_PACKET 256
+#define HVSI_MAX_READ 16
+#define HVSI_MAX_OUTGOING_DATA 12
+#define N_OUTBUF 12
+
+/*
+ * we pass data via two 8-byte registers, so we would like our char arrays
+ * properly aligned for those loads.
+ */
+#define __ALIGNED__	__attribute__((__aligned__(sizeof(long))))
+
+struct hvsi_struct {
+	struct delayed_work writer;
+	struct work_struct handshaker;
+	wait_queue_head_t emptyq; /* woken when outbuf is emptied */
+	wait_queue_head_t stateq; /* woken when HVSI state changes */
+	spinlock_t lock;
+	int index;
+	struct tty_struct *tty;
+	int count;
+	uint8_t throttle_buf[128];
+	uint8_t outbuf[N_OUTBUF]; /* to implement write_room and chars_in_buffer */
+	/* inbuf is for packet reassembly. leave a little room for leftovers. */
+	uint8_t inbuf[HVSI_MAX_PACKET + HVSI_MAX_READ];
+	uint8_t *inbuf_end;
+	int n_throttle;
+	int n_outbuf;
+	uint32_t vtermno;
+	uint32_t virq;
+	atomic_t seqno; /* HVSI packet sequence number */
+	uint16_t mctrl;
+	uint8_t state;  /* HVSI protocol state */
+	uint8_t flags;
+#ifdef CONFIG_MAGIC_SYSRQ
+	uint8_t sysrq;
+#endif /* CONFIG_MAGIC_SYSRQ */
+};
+static struct hvsi_struct hvsi_ports[MAX_NR_HVSI_CONSOLES];
+
+static struct tty_driver *hvsi_driver;
+static int hvsi_count;
+static int (*hvsi_wait)(struct hvsi_struct *hp, int state);
+
+enum HVSI_PROTOCOL_STATE {
+	HVSI_CLOSED,
+	HVSI_WAIT_FOR_VER_RESPONSE,
+	HVSI_WAIT_FOR_VER_QUERY,
+	HVSI_OPEN,
+	HVSI_WAIT_FOR_MCTRL_RESPONSE,
+	HVSI_FSP_DIED,
+};
+#define HVSI_CONSOLE 0x1
+
+#define VS_DATA_PACKET_HEADER           0xff
+#define VS_CONTROL_PACKET_HEADER        0xfe
+#define VS_QUERY_PACKET_HEADER          0xfd
+#define VS_QUERY_RESPONSE_PACKET_HEADER 0xfc
+
+/* control verbs */
+#define VSV_SET_MODEM_CTL    1 /* to service processor only */
+#define VSV_MODEM_CTL_UPDATE 2 /* from service processor only */
+#define VSV_CLOSE_PROTOCOL   3
+
+/* query verbs */
+#define VSV_SEND_VERSION_NUMBER 1
+#define VSV_SEND_MODEM_CTL_STATUS 2
+
+/* yes, these masks are not consecutive. */
+#define HVSI_TSDTR 0x01
+#define HVSI_TSCD  0x20
+
+struct hvsi_header {
+	uint8_t  type;
+	uint8_t  len;
+	uint16_t seqno;
+} __attribute__((packed));
+
+struct hvsi_data {
+	uint8_t  type;
+	uint8_t  len;
+	uint16_t seqno;
+	uint8_t  data[HVSI_MAX_OUTGOING_DATA];
+} __attribute__((packed));
+
+struct hvsi_control {
+	uint8_t  type;
+	uint8_t  len;
+	uint16_t seqno;
+	uint16_t verb;
+	/* optional depending on verb: */
+	uint32_t word;
+	uint32_t mask;
+} __attribute__((packed));
+
+struct hvsi_query {
+	uint8_t  type;
+	uint8_t  len;
+	uint16_t seqno;
+	uint16_t verb;
+} __attribute__((packed));
+
+struct hvsi_query_response {
+	uint8_t  type;
+	uint8_t  len;
+	uint16_t seqno;
+	uint16_t verb;
+	uint16_t query_seqno;
+	union {
+		uint8_t  version;
+		uint32_t mctrl_word;
+	} u;
+} __attribute__((packed));
+
+
+
+static inline int is_console(struct hvsi_struct *hp)
+{
+	return hp->flags & HVSI_CONSOLE;
+}
+
+static inline int is_open(struct hvsi_struct *hp)
+{
+	/* if we're waiting for an mctrl then we're already open */
+	return (hp->state == HVSI_OPEN)
+			|| (hp->state == HVSI_WAIT_FOR_MCTRL_RESPONSE);
+}
+
+static inline void print_state(struct hvsi_struct *hp)
+{
+#ifdef DEBUG
+	static const char *state_names[] = {
+		"HVSI_CLOSED",
+		"HVSI_WAIT_FOR_VER_RESPONSE",
+		"HVSI_WAIT_FOR_VER_QUERY",
+		"HVSI_OPEN",
+		"HVSI_WAIT_FOR_MCTRL_RESPONSE",
+		"HVSI_FSP_DIED",
+	};
+	const char *name = (hp->state < ARRAY_SIZE(state_names))
+		? state_names[hp->state] : "UNKNOWN";
+
+	pr_debug("hvsi%i: state = %s\n", hp->index, name);
+#endif /* DEBUG */
+}
+
+static inline void __set_state(struct hvsi_struct *hp, int state)
+{
+	hp->state = state;
+	print_state(hp);
+	wake_up_all(&hp->stateq);
+}
+
+static inline void set_state(struct hvsi_struct *hp, int state)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&hp->lock, flags);
+	__set_state(hp, state);
+	spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+static inline int len_packet(const uint8_t *packet)
+{
+	return (int)((struct hvsi_header *)packet)->len;
+}
+
+static inline int is_header(const uint8_t *packet)
+{
+	struct hvsi_header *header = (struct hvsi_header *)packet;
+	return header->type >= VS_QUERY_RESPONSE_PACKET_HEADER;
+}
+
+static inline int got_packet(const struct hvsi_struct *hp, uint8_t *packet)
+{
+	if (hp->inbuf_end < packet + sizeof(struct hvsi_header))
+		return 0; /* don't even have the packet header */
+
+	if (hp->inbuf_end < (packet + len_packet(packet)))
+		return 0; /* don't have the rest of the packet */
+
+	return 1;
+}
+
+/* shift remaining bytes in packetbuf down */
+static void compact_inbuf(struct hvsi_struct *hp, uint8_t *read_to)
+{
+	int remaining = (int)(hp->inbuf_end - read_to);
+
+	pr_debug("%s: %i chars remain\n", __func__, remaining);
+
+	if (read_to != hp->inbuf)
+		memmove(hp->inbuf, read_to, remaining);
+
+	hp->inbuf_end = hp->inbuf + remaining;
+}
+
+#ifdef DEBUG
+#define dbg_dump_packet(packet) dump_packet(packet)
+#define dbg_dump_hex(data, len) dump_hex(data, len)
+#else
+#define dbg_dump_packet(packet) do { } while (0)
+#define dbg_dump_hex(data, len) do { } while (0)
+#endif
+
+static void dump_hex(const uint8_t *data, int len)
+{
+	int i;
+
+	printk("    ");
+	for (i=0; i < len; i++)
+		printk("%.2x", data[i]);
+
+	printk("\n    ");
+	for (i=0; i < len; i++) {
+		if (isprint(data[i]))
+			printk("%c", data[i]);
+		else
+			printk(".");
+	}
+	printk("\n");
+}
+
+static void dump_packet(uint8_t *packet)
+{
+	struct hvsi_header *header = (struct hvsi_header *)packet;
+
+	printk("type 0x%x, len %i, seqno %i:\n", header->type, header->len,
+			header->seqno);
+
+	dump_hex(packet, header->len);
+}
+
+static int hvsi_read(struct hvsi_struct *hp, char *buf, int count)
+{
+	unsigned long got;
+
+	got = hvc_get_chars(hp->vtermno, buf, count);
+
+	return got;
+}
+
+static void hvsi_recv_control(struct hvsi_struct *hp, uint8_t *packet,
+	struct tty_struct **to_hangup, struct hvsi_struct **to_handshake)
+{
+	struct hvsi_control *header = (struct hvsi_control *)packet;
+
+	switch (header->verb) {
+		case VSV_MODEM_CTL_UPDATE:
+			if ((header->word & HVSI_TSCD) == 0) {
+				/* CD went away; no more connection */
+				pr_debug("hvsi%i: CD dropped\n", hp->index);
+				hp->mctrl &= TIOCM_CD;
+				/* If userland hasn't done an open(2) yet, hp->tty is NULL. */
+				if (hp->tty && !(hp->tty->flags & CLOCAL))
+					*to_hangup = hp->tty;
+			}
+			break;
+		case VSV_CLOSE_PROTOCOL:
+			pr_debug("hvsi%i: service processor came back\n", hp->index);
+			if (hp->state != HVSI_CLOSED) {
+				*to_handshake = hp;
+			}
+			break;
+		default:
+			printk(KERN_WARNING "hvsi%i: unknown HVSI control packet: ",
+				hp->index);
+			dump_packet(packet);
+			break;
+	}
+}
+
+static void hvsi_recv_response(struct hvsi_struct *hp, uint8_t *packet)
+{
+	struct hvsi_query_response *resp = (struct hvsi_query_response *)packet;
+
+	switch (hp->state) {
+		case HVSI_WAIT_FOR_VER_RESPONSE:
+			__set_state(hp, HVSI_WAIT_FOR_VER_QUERY);
+			break;
+		case HVSI_WAIT_FOR_MCTRL_RESPONSE:
+			hp->mctrl = 0;
+			if (resp->u.mctrl_word & HVSI_TSDTR)
+				hp->mctrl |= TIOCM_DTR;
+			if (resp->u.mctrl_word & HVSI_TSCD)
+				hp->mctrl |= TIOCM_CD;
+			__set_state(hp, HVSI_OPEN);
+			break;
+		default:
+			printk(KERN_ERR "hvsi%i: unexpected query response: ", hp->index);
+			dump_packet(packet);
+			break;
+	}
+}
+
+/* respond to service processor's version query */
+static int hvsi_version_respond(struct hvsi_struct *hp, uint16_t query_seqno)
+{
+	struct hvsi_query_response packet __ALIGNED__;
+	int wrote;
+
+	packet.type = VS_QUERY_RESPONSE_PACKET_HEADER;
+	packet.len = sizeof(struct hvsi_query_response);
+	packet.seqno = atomic_inc_return(&hp->seqno);
+	packet.verb = VSV_SEND_VERSION_NUMBER;
+	packet.u.version = HVSI_VERSION;
+	packet.query_seqno = query_seqno+1;
+
+	pr_debug("%s: sending %i bytes\n", __func__, packet.len);
+	dbg_dump_hex((uint8_t*)&packet, packet.len);
+
+	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
+	if (wrote != packet.len) {
+		printk(KERN_ERR "hvsi%i: couldn't send query response!\n",
+			hp->index);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void hvsi_recv_query(struct hvsi_struct *hp, uint8_t *packet)
+{
+	struct hvsi_query *query = (struct hvsi_query *)packet;
+
+	switch (hp->state) {
+		case HVSI_WAIT_FOR_VER_QUERY:
+			hvsi_version_respond(hp, query->seqno);
+			__set_state(hp, HVSI_OPEN);
+			break;
+		default:
+			printk(KERN_ERR "hvsi%i: unexpected query: ", hp->index);
+			dump_packet(packet);
+			break;
+	}
+}
+
+static void hvsi_insert_chars(struct hvsi_struct *hp, const char *buf, int len)
+{
+	int i;
+
+	for (i=0; i < len; i++) {
+		char c = buf[i];
+#ifdef CONFIG_MAGIC_SYSRQ
+		if (c == '\0') {
+			hp->sysrq = 1;
+			continue;
+		} else if (hp->sysrq) {
+			handle_sysrq(c);
+			hp->sysrq = 0;
+			continue;
+		}
+#endif /* CONFIG_MAGIC_SYSRQ */
+		tty_insert_flip_char(hp->tty, c, 0);
+	}
+}
+
+/*
+ * We could get 252 bytes of data at once here. But the tty layer only
+ * throttles us at TTY_THRESHOLD_THROTTLE (128) bytes, so we could overflow
+ * it. Accordingly we won't send more than 128 bytes at a time to the flip
+ * buffer, which will give the tty buffer a chance to throttle us. Should the
+ * value of TTY_THRESHOLD_THROTTLE change in n_tty.c, this code should be
+ * revisited.
+ */
+#define TTY_THRESHOLD_THROTTLE 128
+static struct tty_struct *hvsi_recv_data(struct hvsi_struct *hp,
+		const uint8_t *packet)
+{
+	const struct hvsi_header *header = (const struct hvsi_header *)packet;
+	const uint8_t *data = packet + sizeof(struct hvsi_header);
+	int datalen = header->len - sizeof(struct hvsi_header);
+	int overflow = datalen - TTY_THRESHOLD_THROTTLE;
+
+	pr_debug("queueing %i chars '%.*s'\n", datalen, datalen, data);
+
+	if (datalen == 0)
+		return NULL;
+
+	if (overflow > 0) {
+		pr_debug("%s: got >TTY_THRESHOLD_THROTTLE bytes\n", __func__);
+		datalen = TTY_THRESHOLD_THROTTLE;
+	}
+
+	hvsi_insert_chars(hp, data, datalen);
+
+	if (overflow > 0) {
+		/*
+		 * we still have more data to deliver, so we need to save off the
+		 * overflow and send it later
+		 */
+		pr_debug("%s: deferring overflow\n", __func__);
+		memcpy(hp->throttle_buf, data + TTY_THRESHOLD_THROTTLE, overflow);
+		hp->n_throttle = overflow;
+	}
+
+	return hp->tty;
+}
+
+/*
+ * Returns true/false indicating data successfully read from hypervisor.
+ * Used both to get packets for tty connections and to advance the state
+ * machine during console handshaking (in which case tty = NULL and we ignore
+ * incoming data).
+ */
+static int hvsi_load_chunk(struct hvsi_struct *hp, struct tty_struct **flip,
+		struct tty_struct **hangup, struct hvsi_struct **handshake)
+{
+	uint8_t *packet = hp->inbuf;
+	int chunklen;
+
+	*flip = NULL;
+	*hangup = NULL;
+	*handshake = NULL;
+
+	chunklen = hvsi_read(hp, hp->inbuf_end, HVSI_MAX_READ);
+	if (chunklen == 0) {
+		pr_debug("%s: 0-length read\n", __func__);
+		return 0;
+	}
+
+	pr_debug("%s: got %i bytes\n", __func__, chunklen);
+	dbg_dump_hex(hp->inbuf_end, chunklen);
+
+	hp->inbuf_end += chunklen;
+
+	/* handle all completed packets */
+	while ((packet < hp->inbuf_end) && got_packet(hp, packet)) {
+		struct hvsi_header *header = (struct hvsi_header *)packet;
+
+		if (!is_header(packet)) {
+			printk(KERN_ERR "hvsi%i: got malformed packet\n", hp->index);
+			/* skip bytes until we find a header or run out of data */
+			while ((packet < hp->inbuf_end) && (!is_header(packet)))
+				packet++;
+			continue;
+		}
+
+		pr_debug("%s: handling %i-byte packet\n", __func__,
+				len_packet(packet));
+		dbg_dump_packet(packet);
+
+		switch (header->type) {
+			case VS_DATA_PACKET_HEADER:
+				if (!is_open(hp))
+					break;
+				if (hp->tty == NULL)
+					break; /* no tty buffer to put data in */
+				*flip = hvsi_recv_data(hp, packet);
+				break;
+			case VS_CONTROL_PACKET_HEADER:
+				hvsi_recv_control(hp, packet, hangup, handshake);
+				break;
+			case VS_QUERY_RESPONSE_PACKET_HEADER:
+				hvsi_recv_response(hp, packet);
+				break;
+			case VS_QUERY_PACKET_HEADER:
+				hvsi_recv_query(hp, packet);
+				break;
+			default:
+				printk(KERN_ERR "hvsi%i: unknown HVSI packet type 0x%x\n",
+						hp->index, header->type);
+				dump_packet(packet);
+				break;
+		}
+
+		packet += len_packet(packet);
+
+		if (*hangup || *handshake) {
+			pr_debug("%s: hangup or handshake\n", __func__);
+			/*
+			 * we need to send the hangup now before receiving any more data.
+			 * If we get "data, hangup, data", we can't deliver the second
+			 * data before the hangup.
+			 */
+			break;
+		}
+	}
+
+	compact_inbuf(hp, packet);
+
+	return 1;
+}
+
+static void hvsi_send_overflow(struct hvsi_struct *hp)
+{
+	pr_debug("%s: delivering %i bytes overflow\n", __func__,
+			hp->n_throttle);
+
+	hvsi_insert_chars(hp, hp->throttle_buf, hp->n_throttle);
+	hp->n_throttle = 0;
+}
+
+/*
+ * must get all pending data because we only get an irq on empty->non-empty
+ * transition
+ */
+static irqreturn_t hvsi_interrupt(int irq, void *arg)
+{
+	struct hvsi_struct *hp = (struct hvsi_struct *)arg;
+	struct tty_struct *flip;
+	struct tty_struct *hangup;
+	struct hvsi_struct *handshake;
+	unsigned long flags;
+	int again = 1;
+
+	pr_debug("%s\n", __func__);
+
+	while (again) {
+		spin_lock_irqsave(&hp->lock, flags);
+		again = hvsi_load_chunk(hp, &flip, &hangup, &handshake);
+		spin_unlock_irqrestore(&hp->lock, flags);
+
+		/*
+		 * we have to call tty_flip_buffer_push() and tty_hangup() outside our
+		 * spinlock. But we also have to keep going until we've read all the
+		 * available data.
+		 */
+
+		if (flip) {
+			/* there was data put in the tty flip buffer */
+			tty_flip_buffer_push(flip);
+			flip = NULL;
+		}
+
+		if (hangup) {
+			tty_hangup(hangup);
+		}
+
+		if (handshake) {
+			pr_debug("hvsi%i: attempting re-handshake\n", handshake->index);
+			schedule_work(&handshake->handshaker);
+		}
+	}
+
+	spin_lock_irqsave(&hp->lock, flags);
+	if (hp->tty && hp->n_throttle
+			&& (!test_bit(TTY_THROTTLED, &hp->tty->flags))) {
+		/* we weren't hung up and we weren't throttled, so we can deliver the
+		 * rest now */
+		flip = hp->tty;
+		hvsi_send_overflow(hp);
+	}
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	if (flip) {
+		tty_flip_buffer_push(flip);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/* for boot console, before the irq handler is running */
+static int __init poll_for_state(struct hvsi_struct *hp, int state)
+{
+	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
+
+	for (;;) {
+		hvsi_interrupt(hp->virq, (void *)hp); /* get pending data */
+
+		if (hp->state == state)
+			return 0;
+
+		mdelay(5);
+		if (time_after(jiffies, end_jiffies))
+			return -EIO;
+	}
+}
+
+/* wait for irq handler to change our state */
+static int wait_for_state(struct hvsi_struct *hp, int state)
+{
+	int ret = 0;
+
+	if (!wait_event_timeout(hp->stateq, (hp->state == state), HVSI_TIMEOUT))
+		ret = -EIO;
+
+	return ret;
+}
+
+static int hvsi_query(struct hvsi_struct *hp, uint16_t verb)
+{
+	struct hvsi_query packet __ALIGNED__;
+	int wrote;
+
+	packet.type = VS_QUERY_PACKET_HEADER;
+	packet.len = sizeof(struct hvsi_query);
+	packet.seqno = atomic_inc_return(&hp->seqno);
+	packet.verb = verb;
+
+	pr_debug("%s: sending %i bytes\n", __func__, packet.len);
+	dbg_dump_hex((uint8_t*)&packet, packet.len);
+
+	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
+	if (wrote != packet.len) {
+		printk(KERN_ERR "hvsi%i: couldn't send query (%i)!\n", hp->index,
+			wrote);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int hvsi_get_mctrl(struct hvsi_struct *hp)
+{
+	int ret;
+
+	set_state(hp, HVSI_WAIT_FOR_MCTRL_RESPONSE);
+	hvsi_query(hp, VSV_SEND_MODEM_CTL_STATUS);
+
+	ret = hvsi_wait(hp, HVSI_OPEN);
+	if (ret < 0) {
+		printk(KERN_ERR "hvsi%i: didn't get modem flags\n", hp->index);
+		set_state(hp, HVSI_OPEN);
+		return ret;
+	}
+
+	pr_debug("%s: mctrl 0x%x\n", __func__, hp->mctrl);
+
+	return 0;
+}
+
+/* note that we can only set DTR */
+static int hvsi_set_mctrl(struct hvsi_struct *hp, uint16_t mctrl)
+{
+	struct hvsi_control packet __ALIGNED__;
+	int wrote;
+
+	packet.type = VS_CONTROL_PACKET_HEADER,
+	packet.seqno = atomic_inc_return(&hp->seqno);
+	packet.len = sizeof(struct hvsi_control);
+	packet.verb = VSV_SET_MODEM_CTL;
+	packet.mask = HVSI_TSDTR;
+
+	if (mctrl & TIOCM_DTR)
+		packet.word = HVSI_TSDTR;
+
+	pr_debug("%s: sending %i bytes\n", __func__, packet.len);
+	dbg_dump_hex((uint8_t*)&packet, packet.len);
+
+	wrote = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
+	if (wrote != packet.len) {
+		printk(KERN_ERR "hvsi%i: couldn't set DTR!\n", hp->index);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static void hvsi_drain_input(struct hvsi_struct *hp)
+{
+	uint8_t buf[HVSI_MAX_READ] __ALIGNED__;
+	unsigned long end_jiffies = jiffies + HVSI_TIMEOUT;
+
+	while (time_before(end_jiffies, jiffies))
+		if (0 == hvsi_read(hp, buf, HVSI_MAX_READ))
+			break;
+}
+
+static int hvsi_handshake(struct hvsi_struct *hp)
+{
+	int ret;
+
+	/*
+	 * We could have a CLOSE or other data waiting for us before we even try
+	 * to open; try to throw it all away so we don't get confused. (CLOSE
+	 * is the first message sent up the pipe when the FSP comes online. We
+	 * need to distinguish between "it came up a while ago and we're the first
+	 * user" and "it was just reset before it saw our handshake packet".)
+	 */
+	hvsi_drain_input(hp);
+
+	set_state(hp, HVSI_WAIT_FOR_VER_RESPONSE);
+	ret = hvsi_query(hp, VSV_SEND_VERSION_NUMBER);
+	if (ret < 0) {
+		printk(KERN_ERR "hvsi%i: couldn't send version query\n", hp->index);
+		return ret;
+	}
+
+	ret = hvsi_wait(hp, HVSI_OPEN);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+static void hvsi_handshaker(struct work_struct *work)
+{
+	struct hvsi_struct *hp =
+		container_of(work, struct hvsi_struct, handshaker);
+
+	if (hvsi_handshake(hp) >= 0)
+		return;
+
+	printk(KERN_ERR "hvsi%i: re-handshaking failed\n", hp->index);
+	if (is_console(hp)) {
+		/*
+		 * ttys will re-attempt the handshake via hvsi_open, but
+		 * the console will not.
+		 */
+		printk(KERN_ERR "hvsi%i: lost console!\n", hp->index);
+	}
+}
+
+static int hvsi_put_chars(struct hvsi_struct *hp, const char *buf, int count)
+{
+	struct hvsi_data packet __ALIGNED__;
+	int ret;
+
+	BUG_ON(count > HVSI_MAX_OUTGOING_DATA);
+
+	packet.type = VS_DATA_PACKET_HEADER;
+	packet.seqno = atomic_inc_return(&hp->seqno);
+	packet.len = count + sizeof(struct hvsi_header);
+	memcpy(&packet.data, buf, count);
+
+	ret = hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
+	if (ret == packet.len) {
+		/* return the number of chars written, not the packet length */
+		return count;
+	}
+	return ret; /* return any errors */
+}
+
+static void hvsi_close_protocol(struct hvsi_struct *hp)
+{
+	struct hvsi_control packet __ALIGNED__;
+
+	packet.type = VS_CONTROL_PACKET_HEADER;
+	packet.seqno = atomic_inc_return(&hp->seqno);
+	packet.len = 6;
+	packet.verb = VSV_CLOSE_PROTOCOL;
+
+	pr_debug("%s: sending %i bytes\n", __func__, packet.len);
+	dbg_dump_hex((uint8_t*)&packet, packet.len);
+
+	hvc_put_chars(hp->vtermno, (char *)&packet, packet.len);
+}
+
+static int hvsi_open(struct tty_struct *tty, struct file *filp)
+{
+	struct hvsi_struct *hp;
+	unsigned long flags;
+	int line = tty->index;
+	int ret;
+
+	pr_debug("%s\n", __func__);
+
+	if (line < 0 || line >= hvsi_count)
+		return -ENODEV;
+	hp = &hvsi_ports[line];
+
+	tty->driver_data = hp;
+
+	mb();
+	if (hp->state == HVSI_FSP_DIED)
+		return -EIO;
+
+	spin_lock_irqsave(&hp->lock, flags);
+	hp->tty = tty;
+	hp->count++;
+	atomic_set(&hp->seqno, 0);
+	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	if (is_console(hp))
+		return 0; /* this has already been handshaked as the console */
+
+	ret = hvsi_handshake(hp);
+	if (ret < 0) {
+		printk(KERN_ERR "%s: HVSI handshaking failed\n", tty->name);
+		return ret;
+	}
+
+	ret = hvsi_get_mctrl(hp);
+	if (ret < 0) {
+		printk(KERN_ERR "%s: couldn't get initial modem flags\n", tty->name);
+		return ret;
+	}
+
+	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
+	if (ret < 0) {
+		printk(KERN_ERR "%s: couldn't set DTR\n", tty->name);
+		return ret;
+	}
+
+	return 0;
+}
+
+/* wait for hvsi_write_worker to empty hp->outbuf */
+static void hvsi_flush_output(struct hvsi_struct *hp)
+{
+	wait_event_timeout(hp->emptyq, (hp->n_outbuf <= 0), HVSI_TIMEOUT);
+
+	/* 'writer' could still be pending if it didn't see n_outbuf = 0 yet */
+	cancel_delayed_work_sync(&hp->writer);
+	flush_work_sync(&hp->handshaker);
+
+	/*
+	 * it's also possible that our timeout expired and hvsi_write_worker
+	 * didn't manage to push outbuf. poof.
+	 */
+	hp->n_outbuf = 0;
+}
+
+static void hvsi_close(struct tty_struct *tty, struct file *filp)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+	unsigned long flags;
+
+	pr_debug("%s\n", __func__);
+
+	if (tty_hung_up_p(filp))
+		return;
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	if (--hp->count == 0) {
+		hp->tty = NULL;
+		hp->inbuf_end = hp->inbuf; /* discard remaining partial packets */
+
+		/* only close down connection if it is not the console */
+		if (!is_console(hp)) {
+			h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE); /* no more irqs */
+			__set_state(hp, HVSI_CLOSED);
+			/*
+			 * any data delivered to the tty layer after this will be
+			 * discarded (except for XON/XOFF)
+			 */
+			tty->closing = 1;
+
+			spin_unlock_irqrestore(&hp->lock, flags);
+
+			/* let any existing irq handlers finish. no more will start. */
+			synchronize_irq(hp->virq);
+
+			/* hvsi_write_worker will re-schedule until outbuf is empty. */
+			hvsi_flush_output(hp);
+
+			/* tell FSP to stop sending data */
+			hvsi_close_protocol(hp);
+
+			/*
+			 * drain anything FSP is still in the middle of sending, and let
+			 * hvsi_handshake drain the rest on the next open.
+			 */
+			hvsi_drain_input(hp);
+
+			spin_lock_irqsave(&hp->lock, flags);
+		}
+	} else if (hp->count < 0)
+		printk(KERN_ERR "hvsi_close %lu: oops, count is %d\n",
+		       hp - hvsi_ports, hp->count);
+
+	spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+static void hvsi_hangup(struct tty_struct *tty)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+	unsigned long flags;
+
+	pr_debug("%s\n", __func__);
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	hp->count = 0;
+	hp->n_outbuf = 0;
+	hp->tty = NULL;
+
+	spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+/* called with hp->lock held */
+static void hvsi_push(struct hvsi_struct *hp)
+{
+	int n;
+
+	if (hp->n_outbuf <= 0)
+		return;
+
+	n = hvsi_put_chars(hp, hp->outbuf, hp->n_outbuf);
+	if (n > 0) {
+		/* success */
+		pr_debug("%s: wrote %i chars\n", __func__, n);
+		hp->n_outbuf = 0;
+	} else if (n == -EIO) {
+		__set_state(hp, HVSI_FSP_DIED);
+		printk(KERN_ERR "hvsi%i: service processor died\n", hp->index);
+	}
+}
+
+/* hvsi_write_worker will keep rescheduling itself until outbuf is empty */
+static void hvsi_write_worker(struct work_struct *work)
+{
+	struct hvsi_struct *hp =
+		container_of(work, struct hvsi_struct, writer.work);
+	unsigned long flags;
+#ifdef DEBUG
+	static long start_j = 0;
+
+	if (start_j == 0)
+		start_j = jiffies;
+#endif /* DEBUG */
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
+
+	if (!is_open(hp)) {
+		/*
+		 * We could have a non-open connection if the service processor died
+		 * while we were busily scheduling ourselves. In that case, it could
+		 * be minutes before the service processor comes back, so only try
+		 * again once a second.
+		 */
+		schedule_delayed_work(&hp->writer, HZ);
+		goto out;
+	}
+
+	hvsi_push(hp);
+	if (hp->n_outbuf > 0)
+		schedule_delayed_work(&hp->writer, 10);
+	else {
+#ifdef DEBUG
+		pr_debug("%s: outbuf emptied after %li jiffies\n", __func__,
+				jiffies - start_j);
+		start_j = 0;
+#endif /* DEBUG */
+		wake_up_all(&hp->emptyq);
+		tty_wakeup(hp->tty);
+	}
+
+out:
+	spin_unlock_irqrestore(&hp->lock, flags);
+}
+
+static int hvsi_write_room(struct tty_struct *tty)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+
+	return N_OUTBUF - hp->n_outbuf;
+}
+
+static int hvsi_chars_in_buffer(struct tty_struct *tty)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+
+	return hp->n_outbuf;
+}
+
+static int hvsi_write(struct tty_struct *tty,
+		     const unsigned char *buf, int count)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+	const char *source = buf;
+	unsigned long flags;
+	int total = 0;
+	int origcount = count;
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	pr_debug("%s: %i chars in buffer\n", __func__, hp->n_outbuf);
+
+	if (!is_open(hp)) {
+		/* we're either closing or not yet open; don't accept data */
+		pr_debug("%s: not open\n", __func__);
+		goto out;
+	}
+
+	/*
+	 * when the hypervisor buffer (16K) fills, data will stay in hp->outbuf
+	 * and hvsi_write_worker will be scheduled. subsequent hvsi_write() calls
+	 * will see there is no room in outbuf and return.
+	 */
+	while ((count > 0) && (hvsi_write_room(hp->tty) > 0)) {
+		int chunksize = min(count, hvsi_write_room(hp->tty));
+
+		BUG_ON(hp->n_outbuf < 0);
+		memcpy(hp->outbuf + hp->n_outbuf, source, chunksize);
+		hp->n_outbuf += chunksize;
+
+		total += chunksize;
+		source += chunksize;
+		count -= chunksize;
+		hvsi_push(hp);
+	}
+
+	if (hp->n_outbuf > 0) {
+		/*
+		 * we weren't able to write it all to the hypervisor.
+		 * schedule another push attempt.
+		 */
+		schedule_delayed_work(&hp->writer, 10);
+	}
+
+out:
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	if (total != origcount)
+		pr_debug("%s: wanted %i, only wrote %i\n", __func__, origcount,
+			total);
+
+	return total;
+}
+
+/*
+ * I have never seen throttle or unthrottle called, so this little throttle
+ * buffering scheme may or may not work.
+ */
+static void hvsi_throttle(struct tty_struct *tty)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+
+	pr_debug("%s\n", __func__);
+
+	h_vio_signal(hp->vtermno, VIO_IRQ_DISABLE);
+}
+
+static void hvsi_unthrottle(struct tty_struct *tty)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+	unsigned long flags;
+	int shouldflip = 0;
+
+	pr_debug("%s\n", __func__);
+
+	spin_lock_irqsave(&hp->lock, flags);
+	if (hp->n_throttle) {
+		hvsi_send_overflow(hp);
+		shouldflip = 1;
+	}
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	if (shouldflip)
+		tty_flip_buffer_push(hp->tty);
+
+	h_vio_signal(hp->vtermno, VIO_IRQ_ENABLE);
+}
+
+static int hvsi_tiocmget(struct tty_struct *tty, struct file *file)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+
+	hvsi_get_mctrl(hp);
+	return hp->mctrl;
+}
+
+static int hvsi_tiocmset(struct tty_struct *tty, struct file *file,
+		unsigned int set, unsigned int clear)
+{
+	struct hvsi_struct *hp = tty->driver_data;
+	unsigned long flags;
+	uint16_t new_mctrl;
+
+	/* we can only alter DTR */
+	clear &= TIOCM_DTR;
+	set &= TIOCM_DTR;
+
+	spin_lock_irqsave(&hp->lock, flags);
+
+	new_mctrl = (hp->mctrl & ~clear) | set;
+
+	if (hp->mctrl != new_mctrl) {
+		hvsi_set_mctrl(hp, new_mctrl);
+		hp->mctrl = new_mctrl;
+	}
+	spin_unlock_irqrestore(&hp->lock, flags);
+
+	return 0;
+}
+
+
+static const struct tty_operations hvsi_ops = {
+	.open = hvsi_open,
+	.close = hvsi_close,
+	.write = hvsi_write,
+	.hangup = hvsi_hangup,
+	.write_room = hvsi_write_room,
+	.chars_in_buffer = hvsi_chars_in_buffer,
+	.throttle = hvsi_throttle,
+	.unthrottle = hvsi_unthrottle,
+	.tiocmget = hvsi_tiocmget,
+	.tiocmset = hvsi_tiocmset,
+};
+
+static int __init hvsi_init(void)
+{
+	int i;
+
+	hvsi_driver = alloc_tty_driver(hvsi_count);
+	if (!hvsi_driver)
+		return -ENOMEM;
+
+	hvsi_driver->owner = THIS_MODULE;
+	hvsi_driver->driver_name = "hvsi";
+	hvsi_driver->name = "hvsi";
+	hvsi_driver->major = HVSI_MAJOR;
+	hvsi_driver->minor_start = HVSI_MINOR;
+	hvsi_driver->type = TTY_DRIVER_TYPE_SYSTEM;
+	hvsi_driver->init_termios = tty_std_termios;
+	hvsi_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL;
+	hvsi_driver->init_termios.c_ispeed = 9600;
+	hvsi_driver->init_termios.c_ospeed = 9600;
+	hvsi_driver->flags = TTY_DRIVER_REAL_RAW;
+	tty_set_operations(hvsi_driver, &hvsi_ops);
+
+	for (i=0; i < hvsi_count; i++) {
+		struct hvsi_struct *hp = &hvsi_ports[i];
+		int ret = 1;
+
+		ret = request_irq(hp->virq, hvsi_interrupt, IRQF_DISABLED, "hvsi", hp);
+		if (ret)
+			printk(KERN_ERR "HVSI: couldn't reserve irq 0x%x (error %i)\n",
+				hp->virq, ret);
+	}
+	hvsi_wait = wait_for_state; /* irqs active now */
+
+	if (tty_register_driver(hvsi_driver))
+		panic("Couldn't register hvsi console driver\n");
+
+	printk(KERN_DEBUG "HVSI: registered %i devices\n", hvsi_count);
+
+	return 0;
+}
+device_initcall(hvsi_init);
+
+/***** console (not tty) code: *****/
+
+static void hvsi_console_print(struct console *console, const char *buf,
+		unsigned int count)
+{
+	struct hvsi_struct *hp = &hvsi_ports[console->index];
+	char c[HVSI_MAX_OUTGOING_DATA] __ALIGNED__;
+	unsigned int i = 0, n = 0;
+	int ret, donecr = 0;
+
+	mb();
+	if (!is_open(hp))
+		return;
+
+	/*
+	 * ugh, we have to translate LF -> CRLF ourselves, in place.
+	 * copied from hvc_console.c:
+	 */
+	while (count > 0 || i > 0) {
+		if (count > 0 && i < sizeof(c)) {
+			if (buf[n] == '\n' && !donecr) {
+				c[i++] = '\r';
+				donecr = 1;
+			} else {
+				c[i++] = buf[n++];
+				donecr = 0;
+				--count;
+			}
+		} else {
+			ret = hvsi_put_chars(hp, c, i);
+			if (ret < 0)
+				i = 0;
+			i -= ret;
+		}
+	}
+}
+
+static struct tty_driver *hvsi_console_device(struct console *console,
+	int *index)
+{
+	*index = console->index;
+	return hvsi_driver;
+}
+
+static int __init hvsi_console_setup(struct console *console, char *options)
+{
+	struct hvsi_struct *hp;
+	int ret;
+
+	if (console->index < 0 || console->index >= hvsi_count)
+		return -1;
+	hp = &hvsi_ports[console->index];
+
+	/* give the FSP a chance to change the baud rate when we re-open */
+	hvsi_close_protocol(hp);
+
+	ret = hvsi_handshake(hp);
+	if (ret < 0)
+		return ret;
+
+	ret = hvsi_get_mctrl(hp);
+	if (ret < 0)
+		return ret;
+
+	ret = hvsi_set_mctrl(hp, hp->mctrl | TIOCM_DTR);
+	if (ret < 0)
+		return ret;
+
+	hp->flags |= HVSI_CONSOLE;
+
+	return 0;
+}
+
+static struct console hvsi_console = {
+	.name		= "hvsi",
+	.write		= hvsi_console_print,
+	.device		= hvsi_console_device,
+	.setup		= hvsi_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+};
+
+static int __init hvsi_console_init(void)
+{
+	struct device_node *vty;
+
+	hvsi_wait = poll_for_state; /* no irqs yet; must poll */
+
+	/* search device tree for vty nodes */
+	for (vty = of_find_compatible_node(NULL, "serial", "hvterm-protocol");
+			vty != NULL;
+			vty = of_find_compatible_node(vty, "serial", "hvterm-protocol")) {
+		struct hvsi_struct *hp;
+		const uint32_t *vtermno, *irq;
+
+		vtermno = of_get_property(vty, "reg", NULL);
+		irq = of_get_property(vty, "interrupts", NULL);
+		if (!vtermno || !irq)
+			continue;
+
+		if (hvsi_count >= MAX_NR_HVSI_CONSOLES) {
+			of_node_put(vty);
+			break;
+		}
+
+		hp = &hvsi_ports[hvsi_count];
+		INIT_DELAYED_WORK(&hp->writer, hvsi_write_worker);
+		INIT_WORK(&hp->handshaker, hvsi_handshaker);
+		init_waitqueue_head(&hp->emptyq);
+		init_waitqueue_head(&hp->stateq);
+		spin_lock_init(&hp->lock);
+		hp->index = hvsi_count;
+		hp->inbuf_end = hp->inbuf;
+		hp->state = HVSI_CLOSED;
+		hp->vtermno = *vtermno;
+		hp->virq = irq_create_mapping(NULL, irq[0]);
+		if (hp->virq == NO_IRQ) {
+			printk(KERN_ERR "%s: couldn't create irq mapping for 0x%x\n",
+				__func__, irq[0]);
+			continue;
+		}
+
+		hvsi_count++;
+	}
+
+	if (hvsi_count)
+		register_console(&hvsi_console);
+	return 0;
+}
+console_initcall(hvsi_console_init);
diff --git a/drivers/tty/hvc/virtio_console.c b/drivers/tty/hvc/virtio_console.c
new file mode 100644
index 000000000000..896a2ced1d27
--- /dev/null
+++ b/drivers/tty/hvc/virtio_console.c
@@ -0,0 +1,1838 @@
+/*
+ * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
+ * Copyright (C) 2009, 2010 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#include <linux/cdev.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/list.h>
+#include <linux/poll.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/virtio.h>
+#include <linux/virtio_console.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include "hvc_console.h"
+
+/*
+ * This is a global struct for storing common data for all the devices
+ * this driver handles.
+ *
+ * Mainly, it has a linked list for all the consoles in one place so
+ * that callbacks from hvc for get_chars(), put_chars() work properly
+ * across multiple devices and multiple ports per device.
+ */
+struct ports_driver_data {
+	/* Used for registering chardevs */
+	struct class *class;
+
+	/* Used for exporting per-port information to debugfs */
+	struct dentry *debugfs_dir;
+
+	/* List of all the devices we're handling */
+	struct list_head portdevs;
+
+	/* Number of devices this driver is handling */
+	unsigned int index;
+
+	/*
+	 * This is used to keep track of the number of hvc consoles
+	 * spawned by this driver.  This number is given as the first
+	 * argument to hvc_alloc().  To correctly map an initial
+	 * console spawned via hvc_instantiate to the console being
+	 * hooked up via hvc_alloc, we need to pass the same vtermno.
+	 *
+	 * We also just assume the first console being initialised was
+	 * the first one that got used as the initial console.
+	 */
+	unsigned int next_vtermno;
+
+	/* All the console devices handled by this driver */
+	struct list_head consoles;
+};
+static struct ports_driver_data pdrvdata;
+
+DEFINE_SPINLOCK(pdrvdata_lock);
+
+/* This struct holds information that's relevant only for console ports */
+struct console {
+	/* We'll place all consoles in a list in the pdrvdata struct */
+	struct list_head list;
+
+	/* The hvc device associated with this console port */
+	struct hvc_struct *hvc;
+
+	/* The size of the console */
+	struct winsize ws;
+
+	/*
+	 * This number identifies the number that we used to register
+	 * with hvc in hvc_instantiate() and hvc_alloc(); this is the
+	 * number passed on by the hvc callbacks to us to
+	 * differentiate between the other console ports handled by
+	 * this driver
+	 */
+	u32 vtermno;
+};
+
+struct port_buffer {
+	char *buf;
+
+	/* size of the buffer in *buf above */
+	size_t size;
+
+	/* used length of the buffer */
+	size_t len;
+	/* offset in the buf from which to consume data */
+	size_t offset;
+};
+
+/*
+ * This is a per-device struct that stores data common to all the
+ * ports for that device (vdev->priv).
+ */
+struct ports_device {
+	/* Next portdev in the list, head is in the pdrvdata struct */
+	struct list_head list;
+
+	/*
+	 * Workqueue handlers where we process deferred work after
+	 * notification
+	 */
+	struct work_struct control_work;
+
+	struct list_head ports;
+
+	/* To protect the list of ports */
+	spinlock_t ports_lock;
+
+	/* To protect the vq operations for the control channel */
+	spinlock_t cvq_lock;
+
+	/* The current config space is stored here */
+	struct virtio_console_config config;
+
+	/* The virtio device we're associated with */
+	struct virtio_device *vdev;
+
+	/*
+	 * A couple of virtqueues for the control channel: one for
+	 * guest->host transfers, one for host->guest transfers
+	 */
+	struct virtqueue *c_ivq, *c_ovq;
+
+	/* Array of per-port IO virtqueues */
+	struct virtqueue **in_vqs, **out_vqs;
+
+	/* Used for numbering devices for sysfs and debugfs */
+	unsigned int drv_index;
+
+	/* Major number for this device.  Ports will be created as minors. */
+	int chr_major;
+};
+
+/* This struct holds the per-port data */
+struct port {
+	/* Next port in the list, head is in the ports_device */
+	struct list_head list;
+
+	/* Pointer to the parent virtio_console device */
+	struct ports_device *portdev;
+
+	/* The current buffer from which data has to be fed to readers */
+	struct port_buffer *inbuf;
+
+	/*
+	 * To protect the operations on the in_vq associated with this
+	 * port.  Has to be a spinlock because it can be called from
+	 * interrupt context (get_char()).
+	 */
+	spinlock_t inbuf_lock;
+
+	/* Protect the operations on the out_vq. */
+	spinlock_t outvq_lock;
+
+	/* The IO vqs for this port */
+	struct virtqueue *in_vq, *out_vq;
+
+	/* File in the debugfs directory that exposes this port's information */
+	struct dentry *debugfs_file;
+
+	/*
+	 * The entries in this struct will be valid if this port is
+	 * hooked up to an hvc console
+	 */
+	struct console cons;
+
+	/* Each port associates with a separate char device */
+	struct cdev *cdev;
+	struct device *dev;
+
+	/* Reference-counting to handle port hot-unplugs and file operations */
+	struct kref kref;
+
+	/* A waitqueue for poll() or blocking read operations */
+	wait_queue_head_t waitqueue;
+
+	/* The 'name' of the port that we expose via sysfs properties */
+	char *name;
+
+	/* We can notify apps of host connect / disconnect events via SIGIO */
+	struct fasync_struct *async_queue;
+
+	/* The 'id' to identify the port with the Host */
+	u32 id;
+
+	bool outvq_full;
+
+	/* Is the host device open */
+	bool host_connected;
+
+	/* We should allow only one process to open a port */
+	bool guest_connected;
+};
+
+/* This is the very early arch-specified put chars function. */
+static int (*early_put_chars)(u32, const char *, int);
+
+static struct port *find_port_by_vtermno(u32 vtermno)
+{
+	struct port *port;
+	struct console *cons;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pdrvdata_lock, flags);
+	list_for_each_entry(cons, &pdrvdata.consoles, list) {
+		if (cons->vtermno == vtermno) {
+			port = container_of(cons, struct port, cons);
+			goto out;
+		}
+	}
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&pdrvdata_lock, flags);
+	return port;
+}
+
+static struct port *find_port_by_devt_in_portdev(struct ports_device *portdev,
+						 dev_t dev)
+{
+	struct port *port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&portdev->ports_lock, flags);
+	list_for_each_entry(port, &portdev->ports, list)
+		if (port->cdev->dev == dev)
+			goto out;
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&portdev->ports_lock, flags);
+
+	return port;
+}
+
+static struct port *find_port_by_devt(dev_t dev)
+{
+	struct ports_device *portdev;
+	struct port *port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pdrvdata_lock, flags);
+	list_for_each_entry(portdev, &pdrvdata.portdevs, list) {
+		port = find_port_by_devt_in_portdev(portdev, dev);
+		if (port)
+			goto out;
+	}
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&pdrvdata_lock, flags);
+	return port;
+}
+
+static struct port *find_port_by_id(struct ports_device *portdev, u32 id)
+{
+	struct port *port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&portdev->ports_lock, flags);
+	list_for_each_entry(port, &portdev->ports, list)
+		if (port->id == id)
+			goto out;
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&portdev->ports_lock, flags);
+
+	return port;
+}
+
+static struct port *find_port_by_vq(struct ports_device *portdev,
+				    struct virtqueue *vq)
+{
+	struct port *port;
+	unsigned long flags;
+
+	spin_lock_irqsave(&portdev->ports_lock, flags);
+	list_for_each_entry(port, &portdev->ports, list)
+		if (port->in_vq == vq || port->out_vq == vq)
+			goto out;
+	port = NULL;
+out:
+	spin_unlock_irqrestore(&portdev->ports_lock, flags);
+	return port;
+}
+
+static bool is_console_port(struct port *port)
+{
+	if (port->cons.hvc)
+		return true;
+	return false;
+}
+
+static inline bool use_multiport(struct ports_device *portdev)
+{
+	/*
+	 * This condition can be true when put_chars is called from
+	 * early_init
+	 */
+	if (!portdev->vdev)
+		return 0;
+	return portdev->vdev->features[0] & (1 << VIRTIO_CONSOLE_F_MULTIPORT);
+}
+
+static void free_buf(struct port_buffer *buf)
+{
+	kfree(buf->buf);
+	kfree(buf);
+}
+
+static struct port_buffer *alloc_buf(size_t buf_size)
+{
+	struct port_buffer *buf;
+
+	buf = kmalloc(sizeof(*buf), GFP_KERNEL);
+	if (!buf)
+		goto fail;
+	buf->buf = kzalloc(buf_size, GFP_KERNEL);
+	if (!buf->buf)
+		goto free_buf;
+	buf->len = 0;
+	buf->offset = 0;
+	buf->size = buf_size;
+	return buf;
+
+free_buf:
+	kfree(buf);
+fail:
+	return NULL;
+}
+
+/* Callers should take appropriate locks */
+static void *get_inbuf(struct port *port)
+{
+	struct port_buffer *buf;
+	struct virtqueue *vq;
+	unsigned int len;
+
+	vq = port->in_vq;
+	buf = virtqueue_get_buf(vq, &len);
+	if (buf) {
+		buf->len = len;
+		buf->offset = 0;
+	}
+	return buf;
+}
+
+/*
+ * Create a scatter-gather list representing our input buffer and put
+ * it in the queue.
+ *
+ * Callers should take appropriate locks.
+ */
+static int add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
+{
+	struct scatterlist sg[1];
+	int ret;
+
+	sg_init_one(sg, buf->buf, buf->size);
+
+	ret = virtqueue_add_buf(vq, sg, 0, 1, buf);
+	virtqueue_kick(vq);
+	return ret;
+}
+
+/* Discard any unread data this port has. Callers lockers. */
+static void discard_port_data(struct port *port)
+{
+	struct port_buffer *buf;
+	struct virtqueue *vq;
+	unsigned int len;
+	int ret;
+
+	vq = port->in_vq;
+	if (port->inbuf)
+		buf = port->inbuf;
+	else
+		buf = virtqueue_get_buf(vq, &len);
+
+	ret = 0;
+	while (buf) {
+		if (add_inbuf(vq, buf) < 0) {
+			ret++;
+			free_buf(buf);
+		}
+		buf = virtqueue_get_buf(vq, &len);
+	}
+	port->inbuf = NULL;
+	if (ret)
+		dev_warn(port->dev, "Errors adding %d buffers back to vq\n",
+			 ret);
+}
+
+static bool port_has_data(struct port *port)
+{
+	unsigned long flags;
+	bool ret;
+
+	spin_lock_irqsave(&port->inbuf_lock, flags);
+	if (port->inbuf) {
+		ret = true;
+		goto out;
+	}
+	port->inbuf = get_inbuf(port);
+	if (port->inbuf) {
+		ret = true;
+		goto out;
+	}
+	ret = false;
+out:
+	spin_unlock_irqrestore(&port->inbuf_lock, flags);
+	return ret;
+}
+
+static ssize_t __send_control_msg(struct ports_device *portdev, u32 port_id,
+				  unsigned int event, unsigned int value)
+{
+	struct scatterlist sg[1];
+	struct virtio_console_control cpkt;
+	struct virtqueue *vq;
+	unsigned int len;
+
+	if (!use_multiport(portdev))
+		return 0;
+
+	cpkt.id = port_id;
+	cpkt.event = event;
+	cpkt.value = value;
+
+	vq = portdev->c_ovq;
+
+	sg_init_one(sg, &cpkt, sizeof(cpkt));
+	if (virtqueue_add_buf(vq, sg, 1, 0, &cpkt) >= 0) {
+		virtqueue_kick(vq);
+		while (!virtqueue_get_buf(vq, &len))
+			cpu_relax();
+	}
+	return 0;
+}
+
+static ssize_t send_control_msg(struct port *port, unsigned int event,
+				unsigned int value)
+{
+	/* Did the port get unplugged before userspace closed it? */
+	if (port->portdev)
+		return __send_control_msg(port->portdev, port->id, event, value);
+	return 0;
+}
+
+/* Callers must take the port->outvq_lock */
+static void reclaim_consumed_buffers(struct port *port)
+{
+	void *buf;
+	unsigned int len;
+
+	while ((buf = virtqueue_get_buf(port->out_vq, &len))) {
+		kfree(buf);
+		port->outvq_full = false;
+	}
+}
+
+static ssize_t send_buf(struct port *port, void *in_buf, size_t in_count,
+			bool nonblock)
+{
+	struct scatterlist sg[1];
+	struct virtqueue *out_vq;
+	ssize_t ret;
+	unsigned long flags;
+	unsigned int len;
+
+	out_vq = port->out_vq;
+
+	spin_lock_irqsave(&port->outvq_lock, flags);
+
+	reclaim_consumed_buffers(port);
+
+	sg_init_one(sg, in_buf, in_count);
+	ret = virtqueue_add_buf(out_vq, sg, 1, 0, in_buf);
+
+	/* Tell Host to go! */
+	virtqueue_kick(out_vq);
+
+	if (ret < 0) {
+		in_count = 0;
+		goto done;
+	}
+
+	if (ret == 0)
+		port->outvq_full = true;
+
+	if (nonblock)
+		goto done;
+
+	/*
+	 * Wait till the host acknowledges it pushed out the data we
+	 * sent.  This is done for data from the hvc_console; the tty
+	 * operations are performed with spinlocks held so we can't
+	 * sleep here.  An alternative would be to copy the data to a
+	 * buffer and relax the spinning requirement.  The downside is
+	 * we need to kmalloc a GFP_ATOMIC buffer each time the
+	 * console driver writes something out.
+	 */
+	while (!virtqueue_get_buf(out_vq, &len))
+		cpu_relax();
+done:
+	spin_unlock_irqrestore(&port->outvq_lock, flags);
+	/*
+	 * We're expected to return the amount of data we wrote -- all
+	 * of it
+	 */
+	return in_count;
+}
+
+/*
+ * Give out the data that's requested from the buffer that we have
+ * queued up.
+ */
+static ssize_t fill_readbuf(struct port *port, char *out_buf, size_t out_count,
+			    bool to_user)
+{
+	struct port_buffer *buf;
+	unsigned long flags;
+
+	if (!out_count || !port_has_data(port))
+		return 0;
+
+	buf = port->inbuf;
+	out_count = min(out_count, buf->len - buf->offset);
+
+	if (to_user) {
+		ssize_t ret;
+
+		ret = copy_to_user(out_buf, buf->buf + buf->offset, out_count);
+		if (ret)
+			return -EFAULT;
+	} else {
+		memcpy(out_buf, buf->buf + buf->offset, out_count);
+	}
+
+	buf->offset += out_count;
+
+	if (buf->offset == buf->len) {
+		/*
+		 * We're done using all the data in this buffer.
+		 * Re-queue so that the Host can send us more data.
+		 */
+		spin_lock_irqsave(&port->inbuf_lock, flags);
+		port->inbuf = NULL;
+
+		if (add_inbuf(port->in_vq, buf) < 0)
+			dev_warn(port->dev, "failed add_buf\n");
+
+		spin_unlock_irqrestore(&port->inbuf_lock, flags);
+	}
+	/* Return the number of bytes actually copied */
+	return out_count;
+}
+
+/* The condition that must be true for polling to end */
+static bool will_read_block(struct port *port)
+{
+	if (!port->guest_connected) {
+		/* Port got hot-unplugged. Let's exit. */
+		return false;
+	}
+	return !port_has_data(port) && port->host_connected;
+}
+
+static bool will_write_block(struct port *port)
+{
+	bool ret;
+
+	if (!port->guest_connected) {
+		/* Port got hot-unplugged. Let's exit. */
+		return false;
+	}
+	if (!port->host_connected)
+		return true;
+
+	spin_lock_irq(&port->outvq_lock);
+	/*
+	 * Check if the Host has consumed any buffers since we last
+	 * sent data (this is only applicable for nonblocking ports).
+	 */
+	reclaim_consumed_buffers(port);
+	ret = port->outvq_full;
+	spin_unlock_irq(&port->outvq_lock);
+
+	return ret;
+}
+
+static ssize_t port_fops_read(struct file *filp, char __user *ubuf,
+			      size_t count, loff_t *offp)
+{
+	struct port *port;
+	ssize_t ret;
+
+	port = filp->private_data;
+
+	if (!port_has_data(port)) {
+		/*
+		 * If nothing's connected on the host just return 0 in
+		 * case of list_empty; this tells the userspace app
+		 * that there's no connection
+		 */
+		if (!port->host_connected)
+			return 0;
+		if (filp->f_flags & O_NONBLOCK)
+			return -EAGAIN;
+
+		ret = wait_event_interruptible(port->waitqueue,
+					       !will_read_block(port));
+		if (ret < 0)
+			return ret;
+	}
+	/* Port got hot-unplugged. */
+	if (!port->guest_connected)
+		return -ENODEV;
+	/*
+	 * We could've received a disconnection message while we were
+	 * waiting for more data.
+	 *
+	 * This check is not clubbed in the if() statement above as we
+	 * might receive some data as well as the host could get
+	 * disconnected after we got woken up from our wait.  So we
+	 * really want to give off whatever data we have and only then
+	 * check for host_connected.
+	 */
+	if (!port_has_data(port) && !port->host_connected)
+		return 0;
+
+	return fill_readbuf(port, ubuf, count, true);
+}
+
+static ssize_t port_fops_write(struct file *filp, const char __user *ubuf,
+			       size_t count, loff_t *offp)
+{
+	struct port *port;
+	char *buf;
+	ssize_t ret;
+	bool nonblock;
+
+	/* Userspace could be out to fool us */
+	if (!count)
+		return 0;
+
+	port = filp->private_data;
+
+	nonblock = filp->f_flags & O_NONBLOCK;
+
+	if (will_write_block(port)) {
+		if (nonblock)
+			return -EAGAIN;
+
+		ret = wait_event_interruptible(port->waitqueue,
+					       !will_write_block(port));
+		if (ret < 0)
+			return ret;
+	}
+	/* Port got hot-unplugged. */
+	if (!port->guest_connected)
+		return -ENODEV;
+
+	count = min((size_t)(32 * 1024), count);
+
+	buf = kmalloc(count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = copy_from_user(buf, ubuf, count);
+	if (ret) {
+		ret = -EFAULT;
+		goto free_buf;
+	}
+
+	/*
+	 * We now ask send_buf() to not spin for generic ports -- we
+	 * can re-use the same code path that non-blocking file
+	 * descriptors take for blocking file descriptors since the
+	 * wait is already done and we're certain the write will go
+	 * through to the host.
+	 */
+	nonblock = true;
+	ret = send_buf(port, buf, count, nonblock);
+
+	if (nonblock && ret > 0)
+		goto out;
+
+free_buf:
+	kfree(buf);
+out:
+	return ret;
+}
+
+static unsigned int port_fops_poll(struct file *filp, poll_table *wait)
+{
+	struct port *port;
+	unsigned int ret;
+
+	port = filp->private_data;
+	poll_wait(filp, &port->waitqueue, wait);
+
+	if (!port->guest_connected) {
+		/* Port got unplugged */
+		return POLLHUP;
+	}
+	ret = 0;
+	if (!will_read_block(port))
+		ret |= POLLIN | POLLRDNORM;
+	if (!will_write_block(port))
+		ret |= POLLOUT;
+	if (!port->host_connected)
+		ret |= POLLHUP;
+
+	return ret;
+}
+
+static void remove_port(struct kref *kref);
+
+static int port_fops_release(struct inode *inode, struct file *filp)
+{
+	struct port *port;
+
+	port = filp->private_data;
+
+	/* Notify host of port being closed */
+	send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 0);
+
+	spin_lock_irq(&port->inbuf_lock);
+	port->guest_connected = false;
+
+	discard_port_data(port);
+
+	spin_unlock_irq(&port->inbuf_lock);
+
+	spin_lock_irq(&port->outvq_lock);
+	reclaim_consumed_buffers(port);
+	spin_unlock_irq(&port->outvq_lock);
+
+	/*
+	 * Locks aren't necessary here as a port can't be opened after
+	 * unplug, and if a port isn't unplugged, a kref would already
+	 * exist for the port.  Plus, taking ports_lock here would
+	 * create a dependency on other locks taken by functions
+	 * inside remove_port if we're the last holder of the port,
+	 * creating many problems.
+	 */
+	kref_put(&port->kref, remove_port);
+
+	return 0;
+}
+
+static int port_fops_open(struct inode *inode, struct file *filp)
+{
+	struct cdev *cdev = inode->i_cdev;
+	struct port *port;
+	int ret;
+
+	port = find_port_by_devt(cdev->dev);
+	filp->private_data = port;
+
+	/* Prevent against a port getting hot-unplugged at the same time */
+	spin_lock_irq(&port->portdev->ports_lock);
+	kref_get(&port->kref);
+	spin_unlock_irq(&port->portdev->ports_lock);
+
+	/*
+	 * Don't allow opening of console port devices -- that's done
+	 * via /dev/hvc
+	 */
+	if (is_console_port(port)) {
+		ret = -ENXIO;
+		goto out;
+	}
+
+	/* Allow only one process to open a particular port at a time */
+	spin_lock_irq(&port->inbuf_lock);
+	if (port->guest_connected) {
+		spin_unlock_irq(&port->inbuf_lock);
+		ret = -EMFILE;
+		goto out;
+	}
+
+	port->guest_connected = true;
+	spin_unlock_irq(&port->inbuf_lock);
+
+	spin_lock_irq(&port->outvq_lock);
+	/*
+	 * There might be a chance that we missed reclaiming a few
+	 * buffers in the window of the port getting previously closed
+	 * and opening now.
+	 */
+	reclaim_consumed_buffers(port);
+	spin_unlock_irq(&port->outvq_lock);
+
+	nonseekable_open(inode, filp);
+
+	/* Notify host of port being opened */
+	send_control_msg(filp->private_data, VIRTIO_CONSOLE_PORT_OPEN, 1);
+
+	return 0;
+out:
+	kref_put(&port->kref, remove_port);
+	return ret;
+}
+
+static int port_fops_fasync(int fd, struct file *filp, int mode)
+{
+	struct port *port;
+
+	port = filp->private_data;
+	return fasync_helper(fd, filp, mode, &port->async_queue);
+}
+
+/*
+ * The file operations that we support: programs in the guest can open
+ * a console device, read from it, write to it, poll for data and
+ * close it.  The devices are at
+ *   /dev/vport<device number>p<port number>
+ */
+static const struct file_operations port_fops = {
+	.owner = THIS_MODULE,
+	.open  = port_fops_open,
+	.read  = port_fops_read,
+	.write = port_fops_write,
+	.poll  = port_fops_poll,
+	.release = port_fops_release,
+	.fasync = port_fops_fasync,
+	.llseek = no_llseek,
+};
+
+/*
+ * The put_chars() callback is pretty straightforward.
+ *
+ * We turn the characters into a scatter-gather list, add it to the
+ * output queue and then kick the Host.  Then we sit here waiting for
+ * it to finish: inefficient in theory, but in practice
+ * implementations will do it immediately (lguest's Launcher does).
+ */
+static int put_chars(u32 vtermno, const char *buf, int count)
+{
+	struct port *port;
+
+	if (unlikely(early_put_chars))
+		return early_put_chars(vtermno, buf, count);
+
+	port = find_port_by_vtermno(vtermno);
+	if (!port)
+		return -EPIPE;
+
+	return send_buf(port, (void *)buf, count, false);
+}
+
+/*
+ * get_chars() is the callback from the hvc_console infrastructure
+ * when an interrupt is received.
+ *
+ * We call out to fill_readbuf that gets us the required data from the
+ * buffers that are queued up.
+ */
+static int get_chars(u32 vtermno, char *buf, int count)
+{
+	struct port *port;
+
+	/* If we've not set up the port yet, we have no input to give. */
+	if (unlikely(early_put_chars))
+		return 0;
+
+	port = find_port_by_vtermno(vtermno);
+	if (!port)
+		return -EPIPE;
+
+	/* If we don't have an input queue yet, we can't get input. */
+	BUG_ON(!port->in_vq);
+
+	return fill_readbuf(port, buf, count, false);
+}
+
+static void resize_console(struct port *port)
+{
+	struct virtio_device *vdev;
+
+	/* The port could have been hot-unplugged */
+	if (!port || !is_console_port(port))
+		return;
+
+	vdev = port->portdev->vdev;
+	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_SIZE))
+		hvc_resize(port->cons.hvc, port->cons.ws);
+}
+
+/* We set the configuration at this point, since we now have a tty */
+static int notifier_add_vio(struct hvc_struct *hp, int data)
+{
+	struct port *port;
+
+	port = find_port_by_vtermno(hp->vtermno);
+	if (!port)
+		return -EINVAL;
+
+	hp->irq_requested = 1;
+	resize_console(port);
+
+	return 0;
+}
+
+static void notifier_del_vio(struct hvc_struct *hp, int data)
+{
+	hp->irq_requested = 0;
+}
+
+/* The operations for console ports. */
+static const struct hv_ops hv_ops = {
+	.get_chars = get_chars,
+	.put_chars = put_chars,
+	.notifier_add = notifier_add_vio,
+	.notifier_del = notifier_del_vio,
+	.notifier_hangup = notifier_del_vio,
+};
+
+/*
+ * Console drivers are initialized very early so boot messages can go
+ * out, so we do things slightly differently from the generic virtio
+ * initialization of the net and block drivers.
+ *
+ * At this stage, the console is output-only.  It's too early to set
+ * up a virtqueue, so we let the drivers do some boutique early-output
+ * thing.
+ */
+int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
+{
+	early_put_chars = put_chars;
+	return hvc_instantiate(0, 0, &hv_ops);
+}
+
+int init_port_console(struct port *port)
+{
+	int ret;
+
+	/*
+	 * The Host's telling us this port is a console port.  Hook it
+	 * up with an hvc console.
+	 *
+	 * To set up and manage our virtual console, we call
+	 * hvc_alloc().
+	 *
+	 * The first argument of hvc_alloc() is the virtual console
+	 * number.  The second argument is the parameter for the
+	 * notification mechanism (like irq number).  We currently
+	 * leave this as zero, virtqueues have implicit notifications.
+	 *
+	 * The third argument is a "struct hv_ops" containing the
+	 * put_chars() get_chars(), notifier_add() and notifier_del()
+	 * pointers.  The final argument is the output buffer size: we
+	 * can do any size, so we put PAGE_SIZE here.
+	 */
+	port->cons.vtermno = pdrvdata.next_vtermno;
+
+	port->cons.hvc = hvc_alloc(port->cons.vtermno, 0, &hv_ops, PAGE_SIZE);
+	if (IS_ERR(port->cons.hvc)) {
+		ret = PTR_ERR(port->cons.hvc);
+		dev_err(port->dev,
+			"error %d allocating hvc for port\n", ret);
+		port->cons.hvc = NULL;
+		return ret;
+	}
+	spin_lock_irq(&pdrvdata_lock);
+	pdrvdata.next_vtermno++;
+	list_add_tail(&port->cons.list, &pdrvdata.consoles);
+	spin_unlock_irq(&pdrvdata_lock);
+	port->guest_connected = true;
+
+	/*
+	 * Start using the new console output if this is the first
+	 * console to come up.
+	 */
+	if (early_put_chars)
+		early_put_chars = NULL;
+
+	/* Notify host of port being opened */
+	send_control_msg(port, VIRTIO_CONSOLE_PORT_OPEN, 1);
+
+	return 0;
+}
+
+static ssize_t show_port_name(struct device *dev,
+			      struct device_attribute *attr, char *buffer)
+{
+	struct port *port;
+
+	port = dev_get_drvdata(dev);
+
+	return sprintf(buffer, "%s\n", port->name);
+}
+
+static DEVICE_ATTR(name, S_IRUGO, show_port_name, NULL);
+
+static struct attribute *port_sysfs_entries[] = {
+	&dev_attr_name.attr,
+	NULL
+};
+
+static struct attribute_group port_attribute_group = {
+	.name = NULL,		/* put in device directory */
+	.attrs = port_sysfs_entries,
+};
+
+static int debugfs_open(struct inode *inode, struct file *filp)
+{
+	filp->private_data = inode->i_private;
+	return 0;
+}
+
+static ssize_t debugfs_read(struct file *filp, char __user *ubuf,
+			    size_t count, loff_t *offp)
+{
+	struct port *port;
+	char *buf;
+	ssize_t ret, out_offset, out_count;
+
+	out_count = 1024;
+	buf = kmalloc(out_count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	port = filp->private_data;
+	out_offset = 0;
+	out_offset += snprintf(buf + out_offset, out_count,
+			       "name: %s\n", port->name ? port->name : "");
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "guest_connected: %d\n", port->guest_connected);
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "host_connected: %d\n", port->host_connected);
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "outvq_full: %d\n", port->outvq_full);
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "is_console: %s\n",
+			       is_console_port(port) ? "yes" : "no");
+	out_offset += snprintf(buf + out_offset, out_count - out_offset,
+			       "console_vtermno: %u\n", port->cons.vtermno);
+
+	ret = simple_read_from_buffer(ubuf, count, offp, buf, out_offset);
+	kfree(buf);
+	return ret;
+}
+
+static const struct file_operations port_debugfs_ops = {
+	.owner = THIS_MODULE,
+	.open  = debugfs_open,
+	.read  = debugfs_read,
+};
+
+static void set_console_size(struct port *port, u16 rows, u16 cols)
+{
+	if (!port || !is_console_port(port))
+		return;
+
+	port->cons.ws.ws_row = rows;
+	port->cons.ws.ws_col = cols;
+}
+
+static unsigned int fill_queue(struct virtqueue *vq, spinlock_t *lock)
+{
+	struct port_buffer *buf;
+	unsigned int nr_added_bufs;
+	int ret;
+
+	nr_added_bufs = 0;
+	do {
+		buf = alloc_buf(PAGE_SIZE);
+		if (!buf)
+			break;
+
+		spin_lock_irq(lock);
+		ret = add_inbuf(vq, buf);
+		if (ret < 0) {
+			spin_unlock_irq(lock);
+			free_buf(buf);
+			break;
+		}
+		nr_added_bufs++;
+		spin_unlock_irq(lock);
+	} while (ret > 0);
+
+	return nr_added_bufs;
+}
+
+static void send_sigio_to_port(struct port *port)
+{
+	if (port->async_queue && port->guest_connected)
+		kill_fasync(&port->async_queue, SIGIO, POLL_OUT);
+}
+
+static int add_port(struct ports_device *portdev, u32 id)
+{
+	char debugfs_name[16];
+	struct port *port;
+	struct port_buffer *buf;
+	dev_t devt;
+	unsigned int nr_added_bufs;
+	int err;
+
+	port = kmalloc(sizeof(*port), GFP_KERNEL);
+	if (!port) {
+		err = -ENOMEM;
+		goto fail;
+	}
+	kref_init(&port->kref);
+
+	port->portdev = portdev;
+	port->id = id;
+
+	port->name = NULL;
+	port->inbuf = NULL;
+	port->cons.hvc = NULL;
+	port->async_queue = NULL;
+
+	port->cons.ws.ws_row = port->cons.ws.ws_col = 0;
+
+	port->host_connected = port->guest_connected = false;
+
+	port->outvq_full = false;
+
+	port->in_vq = portdev->in_vqs[port->id];
+	port->out_vq = portdev->out_vqs[port->id];
+
+	port->cdev = cdev_alloc();
+	if (!port->cdev) {
+		dev_err(&port->portdev->vdev->dev, "Error allocating cdev\n");
+		err = -ENOMEM;
+		goto free_port;
+	}
+	port->cdev->ops = &port_fops;
+
+	devt = MKDEV(portdev->chr_major, id);
+	err = cdev_add(port->cdev, devt, 1);
+	if (err < 0) {
+		dev_err(&port->portdev->vdev->dev,
+			"Error %d adding cdev for port %u\n", err, id);
+		goto free_cdev;
+	}
+	port->dev = device_create(pdrvdata.class, &port->portdev->vdev->dev,
+				  devt, port, "vport%up%u",
+				  port->portdev->drv_index, id);
+	if (IS_ERR(port->dev)) {
+		err = PTR_ERR(port->dev);
+		dev_err(&port->portdev->vdev->dev,
+			"Error %d creating device for port %u\n",
+			err, id);
+		goto free_cdev;
+	}
+
+	spin_lock_init(&port->inbuf_lock);
+	spin_lock_init(&port->outvq_lock);
+	init_waitqueue_head(&port->waitqueue);
+
+	/* Fill the in_vq with buffers so the host can send us data. */
+	nr_added_bufs = fill_queue(port->in_vq, &port->inbuf_lock);
+	if (!nr_added_bufs) {
+		dev_err(port->dev, "Error allocating inbufs\n");
+		err = -ENOMEM;
+		goto free_device;
+	}
+
+	/*
+	 * If we're not using multiport support, this has to be a console port
+	 */
+	if (!use_multiport(port->portdev)) {
+		err = init_port_console(port);
+		if (err)
+			goto free_inbufs;
+	}
+
+	spin_lock_irq(&portdev->ports_lock);
+	list_add_tail(&port->list, &port->portdev->ports);
+	spin_unlock_irq(&portdev->ports_lock);
+
+	/*
+	 * Tell the Host we're set so that it can send us various
+	 * configuration parameters for this port (eg, port name,
+	 * caching, whether this is a console port, etc.)
+	 */
+	send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+
+	if (pdrvdata.debugfs_dir) {
+		/*
+		 * Finally, create the debugfs file that we can use to
+		 * inspect a port's state at any time
+		 */
+		sprintf(debugfs_name, "vport%up%u",
+			port->portdev->drv_index, id);
+		port->debugfs_file = debugfs_create_file(debugfs_name, 0444,
+							 pdrvdata.debugfs_dir,
+							 port,
+							 &port_debugfs_ops);
+	}
+	return 0;
+
+free_inbufs:
+	while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
+		free_buf(buf);
+free_device:
+	device_destroy(pdrvdata.class, port->dev->devt);
+free_cdev:
+	cdev_del(port->cdev);
+free_port:
+	kfree(port);
+fail:
+	/* The host might want to notify management sw about port add failure */
+	__send_control_msg(portdev, id, VIRTIO_CONSOLE_PORT_READY, 0);
+	return err;
+}
+
+/* No users remain, remove all port-specific data. */
+static void remove_port(struct kref *kref)
+{
+	struct port *port;
+
+	port = container_of(kref, struct port, kref);
+
+	sysfs_remove_group(&port->dev->kobj, &port_attribute_group);
+	device_destroy(pdrvdata.class, port->dev->devt);
+	cdev_del(port->cdev);
+
+	kfree(port->name);
+
+	debugfs_remove(port->debugfs_file);
+
+	kfree(port);
+}
+
+/*
+ * Port got unplugged.  Remove port from portdev's list and drop the
+ * kref reference.  If no userspace has this port opened, it will
+ * result in immediate removal the port.
+ */
+static void unplug_port(struct port *port)
+{
+	struct port_buffer *buf;
+
+	spin_lock_irq(&port->portdev->ports_lock);
+	list_del(&port->list);
+	spin_unlock_irq(&port->portdev->ports_lock);
+
+	if (port->guest_connected) {
+		port->guest_connected = false;
+		port->host_connected = false;
+		wake_up_interruptible(&port->waitqueue);
+
+		/* Let the app know the port is going down. */
+		send_sigio_to_port(port);
+	}
+
+	if (is_console_port(port)) {
+		spin_lock_irq(&pdrvdata_lock);
+		list_del(&port->cons.list);
+		spin_unlock_irq(&pdrvdata_lock);
+#if 0
+		/*
+		 * hvc_remove() not called as removing one hvc port
+		 * results in other hvc ports getting frozen.
+		 *
+		 * Once this is resolved in hvc, this functionality
+		 * will be enabled.  Till that is done, the -EPIPE
+		 * return from get_chars() above will help
+		 * hvc_console.c to clean up on ports we remove here.
+		 */
+		hvc_remove(port->cons.hvc);
+#endif
+	}
+
+	/* Remove unused data this port might have received. */
+	discard_port_data(port);
+
+	reclaim_consumed_buffers(port);
+
+	/* Remove buffers we queued up for the Host to send us data in. */
+	while ((buf = virtqueue_detach_unused_buf(port->in_vq)))
+		free_buf(buf);
+
+	/*
+	 * We should just assume the device itself has gone off --
+	 * else a close on an open port later will try to send out a
+	 * control message.
+	 */
+	port->portdev = NULL;
+
+	/*
+	 * Locks around here are not necessary - a port can't be
+	 * opened after we removed the port struct from ports_list
+	 * above.
+	 */
+	kref_put(&port->kref, remove_port);
+}
+
+/* Any private messages that the Host and Guest want to share */
+static void handle_control_message(struct ports_device *portdev,
+				   struct port_buffer *buf)
+{
+	struct virtio_console_control *cpkt;
+	struct port *port;
+	size_t name_size;
+	int err;
+
+	cpkt = (struct virtio_console_control *)(buf->buf + buf->offset);
+
+	port = find_port_by_id(portdev, cpkt->id);
+	if (!port && cpkt->event != VIRTIO_CONSOLE_PORT_ADD) {
+		/* No valid header at start of buffer.  Drop it. */
+		dev_dbg(&portdev->vdev->dev,
+			"Invalid index %u in control packet\n", cpkt->id);
+		return;
+	}
+
+	switch (cpkt->event) {
+	case VIRTIO_CONSOLE_PORT_ADD:
+		if (port) {
+			dev_dbg(&portdev->vdev->dev,
+				"Port %u already added\n", port->id);
+			send_control_msg(port, VIRTIO_CONSOLE_PORT_READY, 1);
+			break;
+		}
+		if (cpkt->id >= portdev->config.max_nr_ports) {
+			dev_warn(&portdev->vdev->dev,
+				"Request for adding port with out-of-bound id %u, max. supported id: %u\n",
+				cpkt->id, portdev->config.max_nr_ports - 1);
+			break;
+		}
+		add_port(portdev, cpkt->id);
+		break;
+	case VIRTIO_CONSOLE_PORT_REMOVE:
+		unplug_port(port);
+		break;
+	case VIRTIO_CONSOLE_CONSOLE_PORT:
+		if (!cpkt->value)
+			break;
+		if (is_console_port(port))
+			break;
+
+		init_port_console(port);
+		/*
+		 * Could remove the port here in case init fails - but
+		 * have to notify the host first.
+		 */
+		break;
+	case VIRTIO_CONSOLE_RESIZE: {
+		struct {
+			__u16 rows;
+			__u16 cols;
+		} size;
+
+		if (!is_console_port(port))
+			break;
+
+		memcpy(&size, buf->buf + buf->offset + sizeof(*cpkt),
+		       sizeof(size));
+		set_console_size(port, size.rows, size.cols);
+
+		port->cons.hvc->irq_requested = 1;
+		resize_console(port);
+		break;
+	}
+	case VIRTIO_CONSOLE_PORT_OPEN:
+		port->host_connected = cpkt->value;
+		wake_up_interruptible(&port->waitqueue);
+		/*
+		 * If the host port got closed and the host had any
+		 * unconsumed buffers, we'll be able to reclaim them
+		 * now.
+		 */
+		spin_lock_irq(&port->outvq_lock);
+		reclaim_consumed_buffers(port);
+		spin_unlock_irq(&port->outvq_lock);
+
+		/*
+		 * If the guest is connected, it'll be interested in
+		 * knowing the host connection state changed.
+		 */
+		send_sigio_to_port(port);
+		break;
+	case VIRTIO_CONSOLE_PORT_NAME:
+		/*
+		 * Skip the size of the header and the cpkt to get the size
+		 * of the name that was sent
+		 */
+		name_size = buf->len - buf->offset - sizeof(*cpkt) + 1;
+
+		port->name = kmalloc(name_size, GFP_KERNEL);
+		if (!port->name) {
+			dev_err(port->dev,
+				"Not enough space to store port name\n");
+			break;
+		}
+		strncpy(port->name, buf->buf + buf->offset + sizeof(*cpkt),
+			name_size - 1);
+		port->name[name_size - 1] = 0;
+
+		/*
+		 * Since we only have one sysfs attribute, 'name',
+		 * create it only if we have a name for the port.
+		 */
+		err = sysfs_create_group(&port->dev->kobj,
+					 &port_attribute_group);
+		if (err) {
+			dev_err(port->dev,
+				"Error %d creating sysfs device attributes\n",
+				err);
+		} else {
+			/*
+			 * Generate a udev event so that appropriate
+			 * symlinks can be created based on udev
+			 * rules.
+			 */
+			kobject_uevent(&port->dev->kobj, KOBJ_CHANGE);
+		}
+		break;
+	}
+}
+
+static void control_work_handler(struct work_struct *work)
+{
+	struct ports_device *portdev;
+	struct virtqueue *vq;
+	struct port_buffer *buf;
+	unsigned int len;
+
+	portdev = container_of(work, struct ports_device, control_work);
+	vq = portdev->c_ivq;
+
+	spin_lock(&portdev->cvq_lock);
+	while ((buf = virtqueue_get_buf(vq, &len))) {
+		spin_unlock(&portdev->cvq_lock);
+
+		buf->len = len;
+		buf->offset = 0;
+
+		handle_control_message(portdev, buf);
+
+		spin_lock(&portdev->cvq_lock);
+		if (add_inbuf(portdev->c_ivq, buf) < 0) {
+			dev_warn(&portdev->vdev->dev,
+				 "Error adding buffer to queue\n");
+			free_buf(buf);
+		}
+	}
+	spin_unlock(&portdev->cvq_lock);
+}
+
+static void in_intr(struct virtqueue *vq)
+{
+	struct port *port;
+	unsigned long flags;
+
+	port = find_port_by_vq(vq->vdev->priv, vq);
+	if (!port)
+		return;
+
+	spin_lock_irqsave(&port->inbuf_lock, flags);
+	if (!port->inbuf)
+		port->inbuf = get_inbuf(port);
+
+	/*
+	 * Don't queue up data when port is closed.  This condition
+	 * can be reached when a console port is not yet connected (no
+	 * tty is spawned) and the host sends out data to console
+	 * ports.  For generic serial ports, the host won't
+	 * (shouldn't) send data till the guest is connected.
+	 */
+	if (!port->guest_connected)
+		discard_port_data(port);
+
+	spin_unlock_irqrestore(&port->inbuf_lock, flags);
+
+	wake_up_interruptible(&port->waitqueue);
+
+	/* Send a SIGIO indicating new data in case the process asked for it */
+	send_sigio_to_port(port);
+
+	if (is_console_port(port) && hvc_poll(port->cons.hvc))
+		hvc_kick();
+}
+
+static void control_intr(struct virtqueue *vq)
+{
+	struct ports_device *portdev;
+
+	portdev = vq->vdev->priv;
+	schedule_work(&portdev->control_work);
+}
+
+static void config_intr(struct virtio_device *vdev)
+{
+	struct ports_device *portdev;
+
+	portdev = vdev->priv;
+
+	if (!use_multiport(portdev)) {
+		struct port *port;
+		u16 rows, cols;
+
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config, cols),
+				  &cols, sizeof(u16));
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_console_config, rows),
+				  &rows, sizeof(u16));
+
+		port = find_port_by_id(portdev, 0);
+		set_console_size(port, rows, cols);
+
+		/*
+		 * We'll use this way of resizing only for legacy
+		 * support.  For newer userspace
+		 * (VIRTIO_CONSOLE_F_MULTPORT+), use control messages
+		 * to indicate console size changes so that it can be
+		 * done per-port.
+		 */
+		resize_console(port);
+	}
+}
+
+static int init_vqs(struct ports_device *portdev)
+{
+	vq_callback_t **io_callbacks;
+	char **io_names;
+	struct virtqueue **vqs;
+	u32 i, j, nr_ports, nr_queues;
+	int err;
+
+	nr_ports = portdev->config.max_nr_ports;
+	nr_queues = use_multiport(portdev) ? (nr_ports + 1) * 2 : 2;
+
+	vqs = kmalloc(nr_queues * sizeof(struct virtqueue *), GFP_KERNEL);
+	io_callbacks = kmalloc(nr_queues * sizeof(vq_callback_t *), GFP_KERNEL);
+	io_names = kmalloc(nr_queues * sizeof(char *), GFP_KERNEL);
+	portdev->in_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *),
+				  GFP_KERNEL);
+	portdev->out_vqs = kmalloc(nr_ports * sizeof(struct virtqueue *),
+				   GFP_KERNEL);
+	if (!vqs || !io_callbacks || !io_names || !portdev->in_vqs ||
+			!portdev->out_vqs) {
+		err = -ENOMEM;
+		goto free;
+	}
+
+	/*
+	 * For backward compat (newer host but older guest), the host
+	 * spawns a console port first and also inits the vqs for port
+	 * 0 before others.
+	 */
+	j = 0;
+	io_callbacks[j] = in_intr;
+	io_callbacks[j + 1] = NULL;
+	io_names[j] = "input";
+	io_names[j + 1] = "output";
+	j += 2;
+
+	if (use_multiport(portdev)) {
+		io_callbacks[j] = control_intr;
+		io_callbacks[j + 1] = NULL;
+		io_names[j] = "control-i";
+		io_names[j + 1] = "control-o";
+
+		for (i = 1; i < nr_ports; i++) {
+			j += 2;
+			io_callbacks[j] = in_intr;
+			io_callbacks[j + 1] = NULL;
+			io_names[j] = "input";
+			io_names[j + 1] = "output";
+		}
+	}
+	/* Find the queues. */
+	err = portdev->vdev->config->find_vqs(portdev->vdev, nr_queues, vqs,
+					      io_callbacks,
+					      (const char **)io_names);
+	if (err)
+		goto free;
+
+	j = 0;
+	portdev->in_vqs[0] = vqs[0];
+	portdev->out_vqs[0] = vqs[1];
+	j += 2;
+	if (use_multiport(portdev)) {
+		portdev->c_ivq = vqs[j];
+		portdev->c_ovq = vqs[j + 1];
+
+		for (i = 1; i < nr_ports; i++) {
+			j += 2;
+			portdev->in_vqs[i] = vqs[j];
+			portdev->out_vqs[i] = vqs[j + 1];
+		}
+	}
+	kfree(io_names);
+	kfree(io_callbacks);
+	kfree(vqs);
+
+	return 0;
+
+free:
+	kfree(portdev->out_vqs);
+	kfree(portdev->in_vqs);
+	kfree(io_names);
+	kfree(io_callbacks);
+	kfree(vqs);
+
+	return err;
+}
+
+static const struct file_operations portdev_fops = {
+	.owner = THIS_MODULE,
+};
+
+/*
+ * Once we're further in boot, we get probed like any other virtio
+ * device.
+ *
+ * If the host also supports multiple console ports, we check the
+ * config space to see how many ports the host has spawned.  We
+ * initialize each port found.
+ */
+static int __devinit virtcons_probe(struct virtio_device *vdev)
+{
+	struct ports_device *portdev;
+	int err;
+	bool multiport;
+
+	portdev = kmalloc(sizeof(*portdev), GFP_KERNEL);
+	if (!portdev) {
+		err = -ENOMEM;
+		goto fail;
+	}
+
+	/* Attach this portdev to this virtio_device, and vice-versa. */
+	portdev->vdev = vdev;
+	vdev->priv = portdev;
+
+	spin_lock_irq(&pdrvdata_lock);
+	portdev->drv_index = pdrvdata.index++;
+	spin_unlock_irq(&pdrvdata_lock);
+
+	portdev->chr_major = register_chrdev(0, "virtio-portsdev",
+					     &portdev_fops);
+	if (portdev->chr_major < 0) {
+		dev_err(&vdev->dev,
+			"Error %d registering chrdev for device %u\n",
+			portdev->chr_major, portdev->drv_index);
+		err = portdev->chr_major;
+		goto free;
+	}
+
+	multiport = false;
+	portdev->config.max_nr_ports = 1;
+	if (virtio_has_feature(vdev, VIRTIO_CONSOLE_F_MULTIPORT)) {
+		multiport = true;
+		vdev->features[0] |= 1 << VIRTIO_CONSOLE_F_MULTIPORT;
+
+		vdev->config->get(vdev, offsetof(struct virtio_console_config,
+						 max_nr_ports),
+				  &portdev->config.max_nr_ports,
+				  sizeof(portdev->config.max_nr_ports));
+	}
+
+	/* Let the Host know we support multiple ports.*/
+	vdev->config->finalize_features(vdev);
+
+	err = init_vqs(portdev);
+	if (err < 0) {
+		dev_err(&vdev->dev, "Error %d initializing vqs\n", err);
+		goto free_chrdev;
+	}
+
+	spin_lock_init(&portdev->ports_lock);
+	INIT_LIST_HEAD(&portdev->ports);
+
+	if (multiport) {
+		unsigned int nr_added_bufs;
+
+		spin_lock_init(&portdev->cvq_lock);
+		INIT_WORK(&portdev->control_work, &control_work_handler);
+
+		nr_added_bufs = fill_queue(portdev->c_ivq, &portdev->cvq_lock);
+		if (!nr_added_bufs) {
+			dev_err(&vdev->dev,
+				"Error allocating buffers for control queue\n");
+			err = -ENOMEM;
+			goto free_vqs;
+		}
+	} else {
+		/*
+		 * For backward compatibility: Create a console port
+		 * if we're running on older host.
+		 */
+		add_port(portdev, 0);
+	}
+
+	spin_lock_irq(&pdrvdata_lock);
+	list_add_tail(&portdev->list, &pdrvdata.portdevs);
+	spin_unlock_irq(&pdrvdata_lock);
+
+	__send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID,
+			   VIRTIO_CONSOLE_DEVICE_READY, 1);
+	return 0;
+
+free_vqs:
+	/* The host might want to notify mgmt sw about device add failure */
+	__send_control_msg(portdev, VIRTIO_CONSOLE_BAD_ID,
+			   VIRTIO_CONSOLE_DEVICE_READY, 0);
+	vdev->config->del_vqs(vdev);
+	kfree(portdev->in_vqs);
+	kfree(portdev->out_vqs);
+free_chrdev:
+	unregister_chrdev(portdev->chr_major, "virtio-portsdev");
+free:
+	kfree(portdev);
+fail:
+	return err;
+}
+
+static void virtcons_remove(struct virtio_device *vdev)
+{
+	struct ports_device *portdev;
+	struct port *port, *port2;
+
+	portdev = vdev->priv;
+
+	spin_lock_irq(&pdrvdata_lock);
+	list_del(&portdev->list);
+	spin_unlock_irq(&pdrvdata_lock);
+
+	/* Disable interrupts for vqs */
+	vdev->config->reset(vdev);
+	/* Finish up work that's lined up */
+	cancel_work_sync(&portdev->control_work);
+
+	list_for_each_entry_safe(port, port2, &portdev->ports, list)
+		unplug_port(port);
+
+	unregister_chrdev(portdev->chr_major, "virtio-portsdev");
+
+	/*
+	 * When yanking out a device, we immediately lose the
+	 * (device-side) queues.  So there's no point in keeping the
+	 * guest side around till we drop our final reference.  This
+	 * also means that any ports which are in an open state will
+	 * have to just stop using the port, as the vqs are going
+	 * away.
+	 */
+	if (use_multiport(portdev)) {
+		struct port_buffer *buf;
+		unsigned int len;
+
+		while ((buf = virtqueue_get_buf(portdev->c_ivq, &len)))
+			free_buf(buf);
+
+		while ((buf = virtqueue_detach_unused_buf(portdev->c_ivq)))
+			free_buf(buf);
+	}
+
+	vdev->config->del_vqs(vdev);
+	kfree(portdev->in_vqs);
+	kfree(portdev->out_vqs);
+
+	kfree(portdev);
+}
+
+static struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static unsigned int features[] = {
+	VIRTIO_CONSOLE_F_SIZE,
+	VIRTIO_CONSOLE_F_MULTIPORT,
+};
+
+static struct virtio_driver virtio_console = {
+	.feature_table = features,
+	.feature_table_size = ARRAY_SIZE(features),
+	.driver.name =	KBUILD_MODNAME,
+	.driver.owner =	THIS_MODULE,
+	.id_table =	id_table,
+	.probe =	virtcons_probe,
+	.remove =	virtcons_remove,
+	.config_changed = config_intr,
+};
+
+static int __init init(void)
+{
+	int err;
+
+	pdrvdata.class = class_create(THIS_MODULE, "virtio-ports");
+	if (IS_ERR(pdrvdata.class)) {
+		err = PTR_ERR(pdrvdata.class);
+		pr_err("Error %d creating virtio-ports class\n", err);
+		return err;
+	}
+
+	pdrvdata.debugfs_dir = debugfs_create_dir("virtio-ports", NULL);
+	if (!pdrvdata.debugfs_dir) {
+		pr_warning("Error %ld creating debugfs dir for virtio-ports\n",
+			   PTR_ERR(pdrvdata.debugfs_dir));
+	}
+	INIT_LIST_HEAD(&pdrvdata.consoles);
+	INIT_LIST_HEAD(&pdrvdata.portdevs);
+
+	return register_virtio_driver(&virtio_console);
+}
+
+static void __exit fini(void)
+{
+	unregister_virtio_driver(&virtio_console);
+
+	class_destroy(pdrvdata.class);
+	if (pdrvdata.debugfs_dir)
+		debugfs_remove_recursive(pdrvdata.debugfs_dir);
+}
+module_init(init);
+module_exit(fini);
+
+MODULE_DEVICE_TABLE(virtio, id_table);
+MODULE_DESCRIPTION("Virtio console driver");
+MODULE_LICENSE("GPL");