From d94ba80ebbea17f036cecb104398fbcd788aa742 Mon Sep 17 00:00:00 2001 From: Richard Cochran Date: Fri, 22 Apr 2011 12:03:08 +0200 Subject: 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 Acked-by: Arnd Bergmann Acked-by: David S. Miller Signed-off-by: John Stultz --- drivers/ptp/ptp_clock.c | 343 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 343 insertions(+) create mode 100644 drivers/ptp/ptp_clock.c (limited to 'drivers/ptp/ptp_clock.c') 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#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 "); +MODULE_DESCRIPTION("PTP clocks support"); +MODULE_LICENSE("GPL"); -- cgit v1.2.3