ptp: Added a brand new class driver for ptp clocks.

This patch adds an infrastructure for hardware clocks that implement
IEEE 1588, the Precision Time Protocol (PTP). A class driver offers a
registration method to particular hardware clock drivers. Each clock is
presented as a standard POSIX clock.

The ancillary clock features are exposed in two different ways, via
the sysfs and by a character device.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: John Stultz <john.stultz@linaro.org>

1 files changed, 343 insertions, 0 deletions

diff --git a/drivers/ptp/ptp_clock.c b/drivers/ptp/ptp_clock.c
new file mode 100644
index 00000000000..cf3f9997546
--- /dev/null
+++ b/drivers/ptp/ptp_clock.c
@@ -0,0 +1,343 @@
+/*
+ * PTP 1588 clock support
+ *
+ * Copyright (C) 2010 OMICRON electronics GmbH
+ *
+ *  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., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/posix-clock.h>
+#include <linux/pps_kernel.h>
+#include <linux/slab.h>
+#include <linux/syscalls.h>
+#include <linux/uaccess.h>
+
+#include "ptp_private.h"
+
+#define PTP_MAX_ALARMS 4
+#define PTP_MAX_CLOCKS 8
+#define PTP_PPS_DEFAULTS (PPS_CAPTUREASSERT | PPS_OFFSETASSERT)
+#define PTP_PPS_EVENT PPS_CAPTUREASSERT
+#define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
+
+/* private globals */
+
+static dev_t ptp_devt;
+static struct class *ptp_class;
+
+static DECLARE_BITMAP(ptp_clocks_map, PTP_MAX_CLOCKS);
+static DEFINE_MUTEX(ptp_clocks_mutex); /* protects 'ptp_clocks_map' */
+
+/* time stamp event queue operations */
+
+static inline int queue_free(struct timestamp_event_queue *q)
+{
+	return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
+}
+
+static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
+				       struct ptp_clock_event *src)
+{
+	struct ptp_extts_event *dst;
+	unsigned long flags;
+	s64 seconds;
+	u32 remainder;
+
+	seconds = div_u64_rem(src->timestamp, 1000000000, &remainder);
+
+	spin_lock_irqsave(&queue->lock, flags);
+
+	dst = &queue->buf[queue->tail];
+	dst->index = src->index;
+	dst->t.sec = seconds;
+	dst->t.nsec = remainder;
+
+	if (!queue_free(queue))
+		queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
+
+	queue->tail = (queue->tail + 1) % PTP_MAX_TIMESTAMPS;
+
+	spin_unlock_irqrestore(&queue->lock, flags);
+}
+
+static s32 scaled_ppm_to_ppb(long ppm)
+{
+	/*
+	 * The 'freq' field in the 'struct timex' is in parts per
+	 * million, but with a 16 bit binary fractional field.
+	 *
+	 * We want to calculate
+	 *
+	 *    ppb = scaled_ppm * 1000 / 2^16
+	 *
+	 * which simplifies to
+	 *
+	 *    ppb = scaled_ppm * 125 / 2^13
+	 */
+	s64 ppb = 1 + ppm;
+	ppb *= 125;
+	ppb >>= 13;
+	return (s32) ppb;
+}
+
+/* posix clock implementation */
+
+static int ptp_clock_getres(struct posix_clock *pc, struct timespec *tp)
+{
+	return 1; /* always round timer functions to one nanosecond */
+}
+
+static int ptp_clock_settime(struct posix_clock *pc, const struct timespec *tp)
+{
+	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+	return ptp->info->settime(ptp->info, tp);
+}
+
+static int ptp_clock_gettime(struct posix_clock *pc, struct timespec *tp)
+{
+	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+	return ptp->info->gettime(ptp->info, tp);
+}
+
+static int ptp_clock_adjtime(struct posix_clock *pc, struct timex *tx)
+{
+	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+	struct ptp_clock_info *ops;
+	int err = -EOPNOTSUPP;
+
+	ops = ptp->info;
+
+	if (tx->modes & ADJ_SETOFFSET) {
+		struct timespec ts;
+		ktime_t kt;
+		s64 delta;
+
+		ts.tv_sec  = tx->time.tv_sec;
+		ts.tv_nsec = tx->time.tv_usec;
+
+		if (!(tx->modes & ADJ_NANO))
+			ts.tv_nsec *= 1000;
+
+		if ((unsigned long) ts.tv_nsec >= NSEC_PER_SEC)
+			return -EINVAL;
+
+		kt = timespec_to_ktime(ts);
+		delta = ktime_to_ns(kt);
+		err = ops->adjtime(ops, delta);
+
+	} else if (tx->modes & ADJ_FREQUENCY) {
+
+		err = ops->adjfreq(ops, scaled_ppm_to_ppb(tx->freq));
+	}
+
+	return err;
+}
+
+static struct posix_clock_operations ptp_clock_ops = {
+	.owner		= THIS_MODULE,
+	.clock_adjtime	= ptp_clock_adjtime,
+	.clock_gettime	= ptp_clock_gettime,
+	.clock_getres	= ptp_clock_getres,
+	.clock_settime	= ptp_clock_settime,
+	.ioctl		= ptp_ioctl,
+	.open		= ptp_open,
+	.poll		= ptp_poll,
+	.read		= ptp_read,
+};
+
+static void delete_ptp_clock(struct posix_clock *pc)
+{
+	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
+
+	mutex_destroy(&ptp->tsevq_mux);
+
+	/* Remove the clock from the bit map. */
+	mutex_lock(&ptp_clocks_mutex);
+	clear_bit(ptp->index, ptp_clocks_map);
+	mutex_unlock(&ptp_clocks_mutex);
+
+	kfree(ptp);
+}
+
+/* public interface */
+
+struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info)
+{
+	struct ptp_clock *ptp;
+	int err = 0, index, major = MAJOR(ptp_devt);
+
+	if (info->n_alarm > PTP_MAX_ALARMS)
+		return ERR_PTR(-EINVAL);
+
+	/* Find a free clock slot and reserve it. */
+	err = -EBUSY;
+	mutex_lock(&ptp_clocks_mutex);
+	index = find_first_zero_bit(ptp_clocks_map, PTP_MAX_CLOCKS);
+	if (index < PTP_MAX_CLOCKS)
+		set_bit(index, ptp_clocks_map);
+	else
+		goto no_slot;
+
+	/* Initialize a clock structure. */
+	err = -ENOMEM;
+	ptp = kzalloc(sizeof(struct ptp_clock), GFP_KERNEL);
+	if (ptp == NULL)
+		goto no_memory;
+
+	ptp->clock.ops = ptp_clock_ops;
+	ptp->clock.release = delete_ptp_clock;
+	ptp->info = info;
+	ptp->devid = MKDEV(major, index);
+	ptp->index = index;
+	spin_lock_init(&ptp->tsevq.lock);
+	mutex_init(&ptp->tsevq_mux);
+	init_waitqueue_head(&ptp->tsev_wq);
+
+	/* Create a new device in our class. */
+	ptp->dev = device_create(ptp_class, NULL, ptp->devid, ptp,
+				 "ptp%d", ptp->index);
+	if (IS_ERR(ptp->dev))
+		goto no_device;
+
+	dev_set_drvdata(ptp->dev, ptp);
+
+	err = ptp_populate_sysfs(ptp);
+	if (err)
+		goto no_sysfs;
+
+	/* Register a new PPS source. */
+	if (info->pps) {
+		struct pps_source_info pps;
+		memset(&pps, 0, sizeof(pps));
+		snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
+		pps.mode = PTP_PPS_MODE;
+		pps.owner = info->owner;
+		ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
+		if (!ptp->pps_source) {
+			pr_err("failed to register pps source\n");
+			goto no_pps;
+		}
+	}
+
+	/* Create a posix clock. */
+	err = posix_clock_register(&ptp->clock, ptp->devid);
+	if (err) {
+		pr_err("failed to create posix clock\n");
+		goto no_clock;
+	}
+
+	mutex_unlock(&ptp_clocks_mutex);
+	return ptp;
+
+no_clock:
+	if (ptp->pps_source)
+		pps_unregister_source(ptp->pps_source);
+no_pps:
+	ptp_cleanup_sysfs(ptp);
+no_sysfs:
+	device_destroy(ptp_class, ptp->devid);
+no_device:
+	mutex_destroy(&ptp->tsevq_mux);
+	kfree(ptp);
+no_memory:
+	clear_bit(index, ptp_clocks_map);
+no_slot:
+	mutex_unlock(&ptp_clocks_mutex);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL(ptp_clock_register);
+
+int ptp_clock_unregister(struct ptp_clock *ptp)
+{
+	ptp->defunct = 1;
+	wake_up_interruptible(&ptp->tsev_wq);
+
+	/* Release the clock's resources. */
+	if (ptp->pps_source)
+		pps_unregister_source(ptp->pps_source);
+	ptp_cleanup_sysfs(ptp);
+	device_destroy(ptp_class, ptp->devid);
+
+	posix_clock_unregister(&ptp->clock);
+	return 0;
+}
+EXPORT_SYMBOL(ptp_clock_unregister);
+
+void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
+{
+	struct pps_event_time evt;
+
+	switch (event->type) {
+
+	case PTP_CLOCK_ALARM:
+		break;
+
+	case PTP_CLOCK_EXTTS:
+		enqueue_external_timestamp(&ptp->tsevq, event);
+		wake_up_interruptible(&ptp->tsev_wq);
+		break;
+
+	case PTP_CLOCK_PPS:
+		pps_get_ts(&evt);
+		pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
+		break;
+	}
+}
+EXPORT_SYMBOL(ptp_clock_event);
+
+/* module operations */
+
+static void __exit ptp_exit(void)
+{
+	class_destroy(ptp_class);
+	unregister_chrdev_region(ptp_devt, PTP_MAX_CLOCKS);
+}
+
+static int __init ptp_init(void)
+{
+	int err;
+
+	ptp_class = class_create(THIS_MODULE, "ptp");
+	if (IS_ERR(ptp_class)) {
+		pr_err("ptp: failed to allocate class\n");
+		return PTR_ERR(ptp_class);
+	}
+
+	err = alloc_chrdev_region(&ptp_devt, 0, PTP_MAX_CLOCKS, "ptp");
+	if (err < 0) {
+		pr_err("ptp: failed to allocate device region\n");
+		goto no_region;
+	}
+
+	ptp_class->dev_attrs = ptp_dev_attrs;
+	pr_info("PTP clock support registered\n");
+	return 0;
+
+no_region:
+	class_destroy(ptp_class);
+	return err;
+}
+
+subsys_initcall(ptp_init);
+module_exit(ptp_exit);
+
+MODULE_AUTHOR("Richard Cochran <richard.cochran@omicron.at>");
+MODULE_DESCRIPTION("PTP clocks support");
+MODULE_LICENSE("GPL");