linux/drivers/ptp/ptp_clock.c
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   1/*
   2 * PTP 1588 clock support
   3 *
   4 * Copyright (C) 2010 OMICRON electronics GmbH
   5 *
   6 *  This program is free software; you can redistribute it and/or modify
   7 *  it under the terms of the GNU General Public License as published by
   8 *  the Free Software Foundation; either version 2 of the License, or
   9 *  (at your option) any later version.
  10 *
  11 *  This program is distributed in the hope that it will be useful,
  12 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 *  GNU General Public License for more details.
  15 *
  16 *  You should have received a copy of the GNU General Public License
  17 *  along with this program; if not, write to the Free Software
  18 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20#include <linux/bitops.h>
  21#include <linux/device.h>
  22#include <linux/err.h>
  23#include <linux/init.h>
  24#include <linux/kernel.h>
  25#include <linux/module.h>
  26#include <linux/posix-clock.h>
  27#include <linux/pps_kernel.h>
  28#include <linux/slab.h>
  29#include <linux/syscalls.h>
  30#include <linux/uaccess.h>
  31
  32#include "ptp_private.h"
  33
  34#define PTP_MAX_ALARMS 4
  35#define PTP_MAX_CLOCKS 8
  36#define PTP_PPS_DEFAULTS (PPS_CAPTUREASSERT | PPS_OFFSETASSERT)
  37#define PTP_PPS_EVENT PPS_CAPTUREASSERT
  38#define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
  39
  40/* private globals */
  41
  42static dev_t ptp_devt;
  43static struct class *ptp_class;
  44
  45static DECLARE_BITMAP(ptp_clocks_map, PTP_MAX_CLOCKS);
  46static DEFINE_MUTEX(ptp_clocks_mutex); /* protects 'ptp_clocks_map' */
  47
  48/* time stamp event queue operations */
  49
  50static inline int queue_free(struct timestamp_event_queue *q)
  51{
  52        return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
  53}
  54
  55static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
  56                                       struct ptp_clock_event *src)
  57{
  58        struct ptp_extts_event *dst;
  59        unsigned long flags;
  60        s64 seconds;
  61        u32 remainder;
  62
  63        seconds = div_u64_rem(src->timestamp, 1000000000, &remainder);
  64
  65        spin_lock_irqsave(&queue->lock, flags);
  66
  67        dst = &queue->buf[queue->tail];
  68        dst->index = src->index;
  69        dst->t.sec = seconds;
  70        dst->t.nsec = remainder;
  71
  72        if (!queue_free(queue))
  73                queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
  74
  75        queue->tail = (queue->tail + 1) % PTP_MAX_TIMESTAMPS;
  76
  77        spin_unlock_irqrestore(&queue->lock, flags);
  78}
  79
  80static s32 scaled_ppm_to_ppb(long ppm)
  81{
  82        /*
  83         * The 'freq' field in the 'struct timex' is in parts per
  84         * million, but with a 16 bit binary fractional field.
  85         *
  86         * We want to calculate
  87         *
  88         *    ppb = scaled_ppm * 1000 / 2^16
  89         *
  90         * which simplifies to
  91         *
  92         *    ppb = scaled_ppm * 125 / 2^13
  93         */
  94        s64 ppb = 1 + ppm;
  95        ppb *= 125;
  96        ppb >>= 13;
  97        return (s32) ppb;
  98}
  99
 100/* posix clock implementation */
 101
 102static int ptp_clock_getres(struct posix_clock *pc, struct timespec *tp)
 103{
 104        tp->tv_sec = 0;
 105        tp->tv_nsec = 1;
 106        return 0;
 107}
 108
 109static int ptp_clock_settime(struct posix_clock *pc, const struct timespec *tp)
 110{
 111        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 112        return ptp->info->settime(ptp->info, tp);
 113}
 114
 115static int ptp_clock_gettime(struct posix_clock *pc, struct timespec *tp)
 116{
 117        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 118        return ptp->info->gettime(ptp->info, tp);
 119}
 120
 121static int ptp_clock_adjtime(struct posix_clock *pc, struct timex *tx)
 122{
 123        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 124        struct ptp_clock_info *ops;
 125        int err = -EOPNOTSUPP;
 126
 127        ops = ptp->info;
 128
 129        if (tx->modes & ADJ_SETOFFSET) {
 130                struct timespec ts;
 131                ktime_t kt;
 132                s64 delta;
 133
 134                ts.tv_sec  = tx->time.tv_sec;
 135                ts.tv_nsec = tx->time.tv_usec;
 136
 137                if (!(tx->modes & ADJ_NANO))
 138                        ts.tv_nsec *= 1000;
 139
 140                if ((unsigned long) ts.tv_nsec >= NSEC_PER_SEC)
 141                        return -EINVAL;
 142
 143                kt = timespec_to_ktime(ts);
 144                delta = ktime_to_ns(kt);
 145                err = ops->adjtime(ops, delta);
 146        } else if (tx->modes & ADJ_FREQUENCY) {
 147                err = ops->adjfreq(ops, scaled_ppm_to_ppb(tx->freq));
 148                ptp->dialed_frequency = tx->freq;
 149        } else if (tx->modes == 0) {
 150                tx->freq = ptp->dialed_frequency;
 151                err = 0;
 152        }
 153
 154        return err;
 155}
 156
 157static struct posix_clock_operations ptp_clock_ops = {
 158        .owner          = THIS_MODULE,
 159        .clock_adjtime  = ptp_clock_adjtime,
 160        .clock_gettime  = ptp_clock_gettime,
 161        .clock_getres   = ptp_clock_getres,
 162        .clock_settime  = ptp_clock_settime,
 163        .ioctl          = ptp_ioctl,
 164        .open           = ptp_open,
 165        .poll           = ptp_poll,
 166        .read           = ptp_read,
 167};
 168
 169static void delete_ptp_clock(struct posix_clock *pc)
 170{
 171        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 172
 173        mutex_destroy(&ptp->tsevq_mux);
 174
 175        /* Remove the clock from the bit map. */
 176        mutex_lock(&ptp_clocks_mutex);
 177        clear_bit(ptp->index, ptp_clocks_map);
 178        mutex_unlock(&ptp_clocks_mutex);
 179
 180        kfree(ptp);
 181}
 182
 183/* public interface */
 184
 185struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 186                                     struct device *parent)
 187{
 188        struct ptp_clock *ptp;
 189        int err = 0, index, major = MAJOR(ptp_devt);
 190
 191        if (info->n_alarm > PTP_MAX_ALARMS)
 192                return ERR_PTR(-EINVAL);
 193
 194        /* Find a free clock slot and reserve it. */
 195        err = -EBUSY;
 196        mutex_lock(&ptp_clocks_mutex);
 197        index = find_first_zero_bit(ptp_clocks_map, PTP_MAX_CLOCKS);
 198        if (index < PTP_MAX_CLOCKS)
 199                set_bit(index, ptp_clocks_map);
 200        else
 201                goto no_slot;
 202
 203        /* Initialize a clock structure. */
 204        err = -ENOMEM;
 205        ptp = kzalloc(sizeof(struct ptp_clock), GFP_KERNEL);
 206        if (ptp == NULL)
 207                goto no_memory;
 208
 209        ptp->clock.ops = ptp_clock_ops;
 210        ptp->clock.release = delete_ptp_clock;
 211        ptp->info = info;
 212        ptp->devid = MKDEV(major, index);
 213        ptp->index = index;
 214        spin_lock_init(&ptp->tsevq.lock);
 215        mutex_init(&ptp->tsevq_mux);
 216        init_waitqueue_head(&ptp->tsev_wq);
 217
 218        /* Create a new device in our class. */
 219        ptp->dev = device_create(ptp_class, parent, ptp->devid, ptp,
 220                                 "ptp%d", ptp->index);
 221        if (IS_ERR(ptp->dev))
 222                goto no_device;
 223
 224        dev_set_drvdata(ptp->dev, ptp);
 225
 226        err = ptp_populate_sysfs(ptp);
 227        if (err)
 228                goto no_sysfs;
 229
 230        /* Register a new PPS source. */
 231        if (info->pps) {
 232                struct pps_source_info pps;
 233                memset(&pps, 0, sizeof(pps));
 234                snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
 235                pps.mode = PTP_PPS_MODE;
 236                pps.owner = info->owner;
 237                ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
 238                if (!ptp->pps_source) {
 239                        pr_err("failed to register pps source\n");
 240                        goto no_pps;
 241                }
 242        }
 243
 244        /* Create a posix clock. */
 245        err = posix_clock_register(&ptp->clock, ptp->devid);
 246        if (err) {
 247                pr_err("failed to create posix clock\n");
 248                goto no_clock;
 249        }
 250
 251        mutex_unlock(&ptp_clocks_mutex);
 252        return ptp;
 253
 254no_clock:
 255        if (ptp->pps_source)
 256                pps_unregister_source(ptp->pps_source);
 257no_pps:
 258        ptp_cleanup_sysfs(ptp);
 259no_sysfs:
 260        device_destroy(ptp_class, ptp->devid);
 261no_device:
 262        mutex_destroy(&ptp->tsevq_mux);
 263        kfree(ptp);
 264no_memory:
 265        clear_bit(index, ptp_clocks_map);
 266no_slot:
 267        mutex_unlock(&ptp_clocks_mutex);
 268        return ERR_PTR(err);
 269}
 270EXPORT_SYMBOL(ptp_clock_register);
 271
 272int ptp_clock_unregister(struct ptp_clock *ptp)
 273{
 274        ptp->defunct = 1;
 275        wake_up_interruptible(&ptp->tsev_wq);
 276
 277        /* Release the clock's resources. */
 278        if (ptp->pps_source)
 279                pps_unregister_source(ptp->pps_source);
 280        ptp_cleanup_sysfs(ptp);
 281        device_destroy(ptp_class, ptp->devid);
 282
 283        posix_clock_unregister(&ptp->clock);
 284        return 0;
 285}
 286EXPORT_SYMBOL(ptp_clock_unregister);
 287
 288void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 289{
 290        struct pps_event_time evt;
 291
 292        switch (event->type) {
 293
 294        case PTP_CLOCK_ALARM:
 295                break;
 296
 297        case PTP_CLOCK_EXTTS:
 298                enqueue_external_timestamp(&ptp->tsevq, event);
 299                wake_up_interruptible(&ptp->tsev_wq);
 300                break;
 301
 302        case PTP_CLOCK_PPS:
 303                pps_get_ts(&evt);
 304                pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
 305                break;
 306
 307        case PTP_CLOCK_PPSUSR:
 308                pps_event(ptp->pps_source, &event->pps_times,
 309                          PTP_PPS_EVENT, NULL);
 310                break;
 311        }
 312}
 313EXPORT_SYMBOL(ptp_clock_event);
 314
 315int ptp_clock_index(struct ptp_clock *ptp)
 316{
 317        return ptp->index;
 318}
 319EXPORT_SYMBOL(ptp_clock_index);
 320
 321/* module operations */
 322
 323static void __exit ptp_exit(void)
 324{
 325        class_destroy(ptp_class);
 326        unregister_chrdev_region(ptp_devt, PTP_MAX_CLOCKS);
 327}
 328
 329static int __init ptp_init(void)
 330{
 331        int err;
 332
 333        ptp_class = class_create(THIS_MODULE, "ptp");
 334        if (IS_ERR(ptp_class)) {
 335                pr_err("ptp: failed to allocate class\n");
 336                return PTR_ERR(ptp_class);
 337        }
 338
 339        err = alloc_chrdev_region(&ptp_devt, 0, PTP_MAX_CLOCKS, "ptp");
 340        if (err < 0) {
 341                pr_err("ptp: failed to allocate device region\n");
 342                goto no_region;
 343        }
 344
 345        ptp_class->dev_attrs = ptp_dev_attrs;
 346        pr_info("PTP clock support registered\n");
 347        return 0;
 348
 349no_region:
 350        class_destroy(ptp_class);
 351        return err;
 352}
 353
 354subsys_initcall(ptp_init);
 355module_exit(ptp_exit);
 356
 357MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
 358MODULE_DESCRIPTION("PTP clocks support");
 359MODULE_LICENSE("GPL");
 360
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