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authorRichard Cochran <richardcochran@gmail.com>2011-04-22 12:03:08 +0200
committerJohn Stultz <john.stultz@linaro.org>2011-05-23 13:01:00 -0700
commitd94ba80ebbea17f036cecb104398fbcd788aa742 (patch)
tree7fe40228c5ea2bb77f2892b722d27155df8c1157 /drivers/ptp/ptp_clock.c
parentcaebc160ce3f76761cc62ad96ef6d6f30f54e3dd (diff)
downloadlinux-linaro-stable-d94ba80ebbea17f036cecb104398fbcd788aa742.tar.gz
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>
Diffstat (limited to 'drivers/ptp/ptp_clock.c')
-rw-r--r--drivers/ptp/ptp_clock.c343
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 000000000000..cf3f9997546d
--- /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");