thunderbolt: Setup control channel

Add struct tb which will contain our view of the thunderbolt bus.  For
now it just contains a pointer to the control channel and a workqueue
for hotplug events.

Add thunderbolt_alloc_and_start() and thunderbolt_shutdown_and_free()
which are responsible for setup and teardown of struct tb.

Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 134 insertions, 0 deletions

diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
new file mode 100644
index 000000000000..6920979c5b14
--- /dev/null
+++ b/drivers/thunderbolt/tb.c
@@ -0,0 +1,134 @@
+/*
+ * Thunderbolt Cactus Ridge driver - bus logic (NHI independent)
+ *
+ * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
+ */
+
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+
+#include "tb.h"
+
+/* hotplug handling */
+
+struct tb_hotplug_event {
+	struct work_struct work;
+	struct tb *tb;
+	u64 route;
+	u8 port;
+	bool unplug;
+};
+
+/**
+ * tb_handle_hotplug() - handle hotplug event
+ *
+ * Executes on tb->wq.
+ */
+static void tb_handle_hotplug(struct work_struct *work)
+{
+	struct tb_hotplug_event *ev = container_of(work, typeof(*ev), work);
+	struct tb *tb = ev->tb;
+	mutex_lock(&tb->lock);
+	if (!tb->hotplug_active)
+		goto out; /* during init, suspend or shutdown */
+
+	/* do nothing for now */
+out:
+	mutex_unlock(&tb->lock);
+	kfree(ev);
+}
+
+/**
+ * tb_schedule_hotplug_handler() - callback function for the control channel
+ *
+ * Delegates to tb_handle_hotplug.
+ */
+static void tb_schedule_hotplug_handler(void *data, u64 route, u8 port,
+					bool unplug)
+{
+	struct tb *tb = data;
+	struct tb_hotplug_event *ev = kmalloc(sizeof(*ev), GFP_KERNEL);
+	if (!ev)
+		return;
+	INIT_WORK(&ev->work, tb_handle_hotplug);
+	ev->tb = tb;
+	ev->route = route;
+	ev->port = port;
+	ev->unplug = unplug;
+	queue_work(tb->wq, &ev->work);
+}
+
+/**
+ * thunderbolt_shutdown_and_free() - shutdown everything
+ *
+ * Free all switches and the config channel.
+ *
+ * Used in the error path of thunderbolt_alloc_and_start.
+ */
+void thunderbolt_shutdown_and_free(struct tb *tb)
+{
+	mutex_lock(&tb->lock);
+
+	if (tb->ctl) {
+		tb_ctl_stop(tb->ctl);
+		tb_ctl_free(tb->ctl);
+	}
+	tb->ctl = NULL;
+	tb->hotplug_active = false; /* signal tb_handle_hotplug to quit */
+
+	/* allow tb_handle_hotplug to acquire the lock */
+	mutex_unlock(&tb->lock);
+	if (tb->wq) {
+		flush_workqueue(tb->wq);
+		destroy_workqueue(tb->wq);
+		tb->wq = NULL;
+	}
+	mutex_destroy(&tb->lock);
+	kfree(tb);
+}
+
+/**
+ * thunderbolt_alloc_and_start() - setup the thunderbolt bus
+ *
+ * Allocates a tb_cfg control channel, initializes the root switch, enables
+ * plug events and activates pci devices.
+ *
+ * Return: Returns NULL on error.
+ */
+struct tb *thunderbolt_alloc_and_start(struct tb_nhi *nhi)
+{
+	struct tb *tb;
+
+	tb = kzalloc(sizeof(*tb), GFP_KERNEL);
+	if (!tb)
+		return NULL;
+
+	tb->nhi = nhi;
+	mutex_init(&tb->lock);
+	mutex_lock(&tb->lock);
+
+	tb->wq = alloc_ordered_workqueue("thunderbolt", 0);
+	if (!tb->wq)
+		goto err_locked;
+
+	tb->ctl = tb_ctl_alloc(tb->nhi, tb_schedule_hotplug_handler, tb);
+	if (!tb->ctl)
+		goto err_locked;
+	/*
+	 * tb_schedule_hotplug_handler may be called as soon as the config
+	 * channel is started. Thats why we have to hold the lock here.
+	 */
+	tb_ctl_start(tb->ctl);
+
+	/* Allow tb_handle_hotplug to progress events */
+	tb->hotplug_active = true;
+	mutex_unlock(&tb->lock);
+	return tb;
+
+err_locked:
+	mutex_unlock(&tb->lock);
+	thunderbolt_shutdown_and_free(tb);
+	return NULL;
+}
+