cpts: introduce time stamping code and a PTP hardware clock.

This patch adds a driver for the CPTS that offers time
stamping and a PTP hardware clock. Because some of the
CPTS hardware variants (like the am335x) do not support
frequency adjustment, we have implemented this in software
by changing the multiplication factor of the timecounter.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 427 insertions, 0 deletions

diff --git a/drivers/net/ethernet/ti/cpts.c b/drivers/net/ethernet/ti/cpts.c
new file mode 100644
index 000000000000..337766738eca
--- /dev/null
+++ b/drivers/net/ethernet/ti/cpts.c
@@ -0,0 +1,427 @@
+/*
+ * TI Common Platform Time Sync
+ *
+ * Copyright (C) 2012 Richard Cochran <richardcochran@gmail.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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+#include <linux/err.h>
+#include <linux/if.h>
+#include <linux/hrtimer.h>
+#include <linux/module.h>
+#include <linux/net_tstamp.h>
+#include <linux/ptp_classify.h>
+#include <linux/time.h>
+#include <linux/uaccess.h>
+#include <linux/workqueue.h>
+
+#include <plat/clock.h>
+
+#include "cpts.h"
+
+#ifdef CONFIG_TI_CPTS
+
+static struct sock_filter ptp_filter[] = {
+	PTP_FILTER
+};
+
+#define cpts_read32(c, r)	__raw_readl(&c->reg->r)
+#define cpts_write32(c, v, r)	__raw_writel(v, &c->reg->r)
+
+static int event_expired(struct cpts_event *event)
+{
+	return time_after(jiffies, event->tmo);
+}
+
+static int event_type(struct cpts_event *event)
+{
+	return (event->high >> EVENT_TYPE_SHIFT) & EVENT_TYPE_MASK;
+}
+
+static int cpts_fifo_pop(struct cpts *cpts, u32 *high, u32 *low)
+{
+	u32 r = cpts_read32(cpts, intstat_raw);
+
+	if (r & TS_PEND_RAW) {
+		*high = cpts_read32(cpts, event_high);
+		*low  = cpts_read32(cpts, event_low);
+		cpts_write32(cpts, EVENT_POP, event_pop);
+		return 0;
+	}
+	return -1;
+}
+
+/*
+ * Returns zero if matching event type was found.
+ */
+static int cpts_fifo_read(struct cpts *cpts, int match)
+{
+	int i, type = -1;
+	u32 hi, lo;
+	struct cpts_event *event;
+
+	for (i = 0; i < CPTS_FIFO_DEPTH; i++) {
+		if (cpts_fifo_pop(cpts, &hi, &lo))
+			break;
+		if (list_empty(&cpts->pool)) {
+			pr_err("cpts: event pool is empty\n");
+			return -1;
+		}
+		event = list_first_entry(&cpts->pool, struct cpts_event, list);
+		event->tmo = jiffies + 2;
+		event->high = hi;
+		event->low = lo;
+		type = event_type(event);
+		switch (type) {
+		case CPTS_EV_PUSH:
+		case CPTS_EV_RX:
+		case CPTS_EV_TX:
+			list_del_init(&event->list);
+			list_add_tail(&event->list, &cpts->events);
+			break;
+		case CPTS_EV_ROLL:
+		case CPTS_EV_HALF:
+		case CPTS_EV_HW:
+			break;
+		default:
+			pr_err("cpts: unkown event type\n");
+			break;
+		}
+		if (type == match)
+			break;
+	}
+	return type == match ? 0 : -1;
+}
+
+static cycle_t cpts_systim_read(const struct cyclecounter *cc)
+{
+	u64 val = 0;
+	struct cpts_event *event;
+	struct list_head *this, *next;
+	struct cpts *cpts = container_of(cc, struct cpts, cc);
+
+	cpts_write32(cpts, TS_PUSH, ts_push);
+	if (cpts_fifo_read(cpts, CPTS_EV_PUSH))
+		pr_err("cpts: unable to obtain a time stamp\n");
+
+	list_for_each_safe(this, next, &cpts->events) {
+		event = list_entry(this, struct cpts_event, list);
+		if (event_type(event) == CPTS_EV_PUSH) {
+			list_del_init(&event->list);
+			list_add(&event->list, &cpts->pool);
+			val = event->low;
+			break;
+		}
+	}
+
+	return val;
+}
+
+/* PTP clock operations */
+
+static int cpts_ptp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
+{
+	u64 adj;
+	u32 diff, mult;
+	int neg_adj = 0;
+	unsigned long flags;
+	struct cpts *cpts = container_of(ptp, struct cpts, info);
+
+	if (ppb < 0) {
+		neg_adj = 1;
+		ppb = -ppb;
+	}
+	mult = cpts->cc_mult;
+	adj = mult;
+	adj *= ppb;
+	diff = div_u64(adj, 1000000000ULL);
+
+	spin_lock_irqsave(&cpts->lock, flags);
+
+	timecounter_read(&cpts->tc);
+
+	cpts->cc.mult = neg_adj ? mult - diff : mult + diff;
+
+	spin_unlock_irqrestore(&cpts->lock, flags);
+
+	return 0;
+}
+
+static int cpts_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+	s64 now;
+	unsigned long flags;
+	struct cpts *cpts = container_of(ptp, struct cpts, info);
+
+	spin_lock_irqsave(&cpts->lock, flags);
+	now = timecounter_read(&cpts->tc);
+	now += delta;
+	timecounter_init(&cpts->tc, &cpts->cc, now);
+	spin_unlock_irqrestore(&cpts->lock, flags);
+
+	return 0;
+}
+
+static int cpts_ptp_gettime(struct ptp_clock_info *ptp, struct timespec *ts)
+{
+	u64 ns;
+	u32 remainder;
+	unsigned long flags;
+	struct cpts *cpts = container_of(ptp, struct cpts, info);
+
+	spin_lock_irqsave(&cpts->lock, flags);
+	ns = timecounter_read(&cpts->tc);
+	spin_unlock_irqrestore(&cpts->lock, flags);
+
+	ts->tv_sec = div_u64_rem(ns, 1000000000, &remainder);
+	ts->tv_nsec = remainder;
+
+	return 0;
+}
+
+static int cpts_ptp_settime(struct ptp_clock_info *ptp,
+			    const struct timespec *ts)
+{
+	u64 ns;
+	unsigned long flags;
+	struct cpts *cpts = container_of(ptp, struct cpts, info);
+
+	ns = ts->tv_sec * 1000000000ULL;
+	ns += ts->tv_nsec;
+
+	spin_lock_irqsave(&cpts->lock, flags);
+	timecounter_init(&cpts->tc, &cpts->cc, ns);
+	spin_unlock_irqrestore(&cpts->lock, flags);
+
+	return 0;
+}
+
+static int cpts_ptp_enable(struct ptp_clock_info *ptp,
+			   struct ptp_clock_request *rq, int on)
+{
+	return -EOPNOTSUPP;
+}
+
+static struct ptp_clock_info cpts_info = {
+	.owner		= THIS_MODULE,
+	.name		= "CTPS timer",
+	.max_adj	= 1000000,
+	.n_ext_ts	= 0,
+	.pps		= 0,
+	.adjfreq	= cpts_ptp_adjfreq,
+	.adjtime	= cpts_ptp_adjtime,
+	.gettime	= cpts_ptp_gettime,
+	.settime	= cpts_ptp_settime,
+	.enable		= cpts_ptp_enable,
+};
+
+static void cpts_overflow_check(struct work_struct *work)
+{
+	struct timespec ts;
+	struct cpts *cpts = container_of(work, struct cpts, overflow_work.work);
+
+	cpts_write32(cpts, CPTS_EN, control);
+	cpts_write32(cpts, TS_PEND_EN, int_enable);
+	cpts_ptp_gettime(&cpts->info, &ts);
+	pr_debug("cpts overflow check at %ld.%09lu\n", ts.tv_sec, ts.tv_nsec);
+	schedule_delayed_work(&cpts->overflow_work, CPTS_OVERFLOW_PERIOD);
+}
+
+#define CPTS_REF_CLOCK_NAME "cpsw_cpts_rft_clk"
+
+static void cpts_clk_init(struct cpts *cpts)
+{
+	cpts->refclk = clk_get(NULL, CPTS_REF_CLOCK_NAME);
+	if (IS_ERR(cpts->refclk)) {
+		pr_err("Failed to clk_get %s\n", CPTS_REF_CLOCK_NAME);
+		cpts->refclk = NULL;
+		return;
+	}
+	clk_enable(cpts->refclk);
+	cpts->freq = cpts->refclk->recalc(cpts->refclk);
+}
+
+static void cpts_clk_release(struct cpts *cpts)
+{
+	clk_disable(cpts->refclk);
+	clk_put(cpts->refclk);
+}
+
+static int cpts_match(struct sk_buff *skb, unsigned int ptp_class,
+		      u16 ts_seqid, u8 ts_msgtype)
+{
+	u16 *seqid;
+	unsigned int offset;
+	u8 *msgtype, *data = skb->data;
+
+	switch (ptp_class) {
+	case PTP_CLASS_V1_IPV4:
+	case PTP_CLASS_V2_IPV4:
+		offset = ETH_HLEN + IPV4_HLEN(data) + UDP_HLEN;
+		break;
+	case PTP_CLASS_V1_IPV6:
+	case PTP_CLASS_V2_IPV6:
+		offset = OFF_PTP6;
+		break;
+	case PTP_CLASS_V2_L2:
+		offset = ETH_HLEN;
+		break;
+	case PTP_CLASS_V2_VLAN:
+		offset = ETH_HLEN + VLAN_HLEN;
+		break;
+	default:
+		return 0;
+	}
+
+	if (skb->len + ETH_HLEN < offset + OFF_PTP_SEQUENCE_ID + sizeof(*seqid))
+		return 0;
+
+	if (unlikely(ptp_class & PTP_CLASS_V1))
+		msgtype = data + offset + OFF_PTP_CONTROL;
+	else
+		msgtype = data + offset;
+
+	seqid = (u16 *)(data + offset + OFF_PTP_SEQUENCE_ID);
+
+	return (ts_msgtype == (*msgtype & 0xf) && ts_seqid == ntohs(*seqid));
+}
+
+static u64 cpts_find_ts(struct cpts *cpts, struct sk_buff *skb, int ev_type)
+{
+	u64 ns = 0;
+	struct cpts_event *event;
+	struct list_head *this, *next;
+	unsigned int class = sk_run_filter(skb, ptp_filter);
+	unsigned long flags;
+	u16 seqid;
+	u8 mtype;
+
+	if (class == PTP_CLASS_NONE)
+		return 0;
+
+	spin_lock_irqsave(&cpts->lock, flags);
+	cpts_fifo_read(cpts, CPTS_EV_PUSH);
+	list_for_each_safe(this, next, &cpts->events) {
+		event = list_entry(this, struct cpts_event, list);
+		if (event_expired(event)) {
+			list_del_init(&event->list);
+			list_add(&event->list, &cpts->pool);
+			continue;
+		}
+		mtype = (event->high >> MESSAGE_TYPE_SHIFT) & MESSAGE_TYPE_MASK;
+		seqid = (event->high >> SEQUENCE_ID_SHIFT) & SEQUENCE_ID_MASK;
+		if (ev_type == event_type(event) &&
+		    cpts_match(skb, class, seqid, mtype)) {
+			ns = timecounter_cyc2time(&cpts->tc, event->low);
+			list_del_init(&event->list);
+			list_add(&event->list, &cpts->pool);
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&cpts->lock, flags);
+
+	return ns;
+}
+
+void cpts_rx_timestamp(struct cpts *cpts, struct sk_buff *skb)
+{
+	u64 ns;
+	struct skb_shared_hwtstamps *ssh;
+
+	if (!cpts->rx_enable)
+		return;
+	ns = cpts_find_ts(cpts, skb, CPTS_EV_RX);
+	if (!ns)
+		return;
+	ssh = skb_hwtstamps(skb);
+	memset(ssh, 0, sizeof(*ssh));
+	ssh->hwtstamp = ns_to_ktime(ns);
+}
+
+void cpts_tx_timestamp(struct cpts *cpts, struct sk_buff *skb)
+{
+	u64 ns;
+	struct skb_shared_hwtstamps ssh;
+
+	if (!(skb_shinfo(skb)->tx_flags & SKBTX_IN_PROGRESS))
+		return;
+	ns = cpts_find_ts(cpts, skb, CPTS_EV_TX);
+	if (!ns)
+		return;
+	memset(&ssh, 0, sizeof(ssh));
+	ssh.hwtstamp = ns_to_ktime(ns);
+	skb_tstamp_tx(skb, &ssh);
+}
+
+#endif /*CONFIG_TI_CPTS*/
+
+int cpts_register(struct device *dev, struct cpts *cpts,
+		  u32 mult, u32 shift)
+{
+#ifdef CONFIG_TI_CPTS
+	int err, i;
+	unsigned long flags;
+
+	if (ptp_filter_init(ptp_filter, ARRAY_SIZE(ptp_filter))) {
+		pr_err("cpts: bad ptp filter\n");
+		return -EINVAL;
+	}
+	cpts->info = cpts_info;
+	cpts->clock = ptp_clock_register(&cpts->info, dev);
+	if (IS_ERR(cpts->clock)) {
+		err = PTR_ERR(cpts->clock);
+		cpts->clock = NULL;
+		return err;
+	}
+	spin_lock_init(&cpts->lock);
+
+	cpts->cc.read = cpts_systim_read;
+	cpts->cc.mask = CLOCKSOURCE_MASK(32);
+	cpts->cc_mult = mult;
+	cpts->cc.mult = mult;
+	cpts->cc.shift = shift;
+
+	INIT_LIST_HEAD(&cpts->events);
+	INIT_LIST_HEAD(&cpts->pool);
+	for (i = 0; i < CPTS_MAX_EVENTS; i++)
+		list_add(&cpts->pool_data[i].list, &cpts->pool);
+
+	cpts_clk_init(cpts);
+	cpts_write32(cpts, CPTS_EN, control);
+	cpts_write32(cpts, TS_PEND_EN, int_enable);
+
+	spin_lock_irqsave(&cpts->lock, flags);
+	timecounter_init(&cpts->tc, &cpts->cc, ktime_to_ns(ktime_get_real()));
+	spin_unlock_irqrestore(&cpts->lock, flags);
+
+	INIT_DELAYED_WORK(&cpts->overflow_work, cpts_overflow_check);
+	schedule_delayed_work(&cpts->overflow_work, CPTS_OVERFLOW_PERIOD);
+
+	cpts->phc_index = ptp_clock_index(cpts->clock);
+#endif
+	return 0;
+}
+
+void cpts_unregister(struct cpts *cpts)
+{
+#ifdef CONFIG_TI_CPTS
+	if (cpts->clock) {
+		ptp_clock_unregister(cpts->clock);
+		cancel_delayed_work_sync(&cpts->overflow_work);
+	}
+	if (cpts->refclk)
+		cpts_clk_release(cpts);
+#endif
+}