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/idr.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_PPS_DEFAULTS (PPS_CAPTUREASSERT | PPS_OFFSETASSERT)
  36#define PTP_PPS_EVENT PPS_CAPTUREASSERT
  37#define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
  38
  39/* private globals */
  40
  41static dev_t ptp_devt;
  42static struct class *ptp_class;
  43
  44static DEFINE_IDA(ptp_clocks_map);
  45
  46/* time stamp event queue operations */
  47
  48static inline int queue_free(struct timestamp_event_queue *q)
  49{
  50        return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
  51}
  52
  53static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
  54                                       struct ptp_clock_event *src)
  55{
  56        struct ptp_extts_event *dst;
  57        unsigned long flags;
  58        s64 seconds;
  59        u32 remainder;
  60
  61        seconds = div_u64_rem(src->timestamp, 1000000000, &remainder);
  62
  63        spin_lock_irqsave(&queue->lock, flags);
  64
  65        dst = &queue->buf[queue->tail];
  66        dst->index = src->index;
  67        dst->t.sec = seconds;
  68        dst->t.nsec = remainder;
  69
  70        if (!queue_free(queue))
  71                queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
  72
  73        queue->tail = (queue->tail + 1) % PTP_MAX_TIMESTAMPS;
  74
  75        spin_unlock_irqrestore(&queue->lock, flags);
  76}
  77
  78static s32 scaled_ppm_to_ppb(long ppm)
  79{
  80        /*
  81         * The 'freq' field in the 'struct timex' is in parts per
  82         * million, but with a 16 bit binary fractional field.
  83         *
  84         * We want to calculate
  85         *
  86         *    ppb = scaled_ppm * 1000 / 2^16
  87         *
  88         * which simplifies to
  89         *
  90         *    ppb = scaled_ppm * 125 / 2^13
  91         */
  92        s64 ppb = 1 + ppm;
  93        ppb *= 125;
  94        ppb >>= 13;
  95        return (s32) ppb;
  96}
  97
  98/* posix clock implementation */
  99
 100static int ptp_clock_getres(struct posix_clock *pc, struct timespec *tp)
 101{
 102        tp->tv_sec = 0;
 103        tp->tv_nsec = 1;
 104        return 0;
 105}
 106
 107static int ptp_clock_settime(struct posix_clock *pc, const struct timespec *tp)
 108{
 109        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 110        return ptp->info->settime(ptp->info, tp);
 111}
 112
 113static int ptp_clock_gettime(struct posix_clock *pc, struct timespec *tp)
 114{
 115        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 116        return ptp->info->gettime(ptp->info, tp);
 117}
 118
 119static int ptp_clock_adjtime(struct posix_clock *pc, struct timex *tx)
 120{
 121        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 122        struct ptp_clock_info *ops;
 123        int err = -EOPNOTSUPP;
 124
 125        ops = ptp->info;
 126
 127        if (tx->modes & ADJ_SETOFFSET) {
 128                struct timespec ts;
 129                ktime_t kt;
 130                s64 delta;
 131
 132                ts.tv_sec  = tx->time.tv_sec;
 133                ts.tv_nsec = tx->time.tv_usec;
 134
 135                if (!(tx->modes & ADJ_NANO))
 136                        ts.tv_nsec *= 1000;
 137
 138                if ((unsigned long) ts.tv_nsec >= NSEC_PER_SEC)
 139                        return -EINVAL;
 140
 141                kt = timespec_to_ktime(ts);
 142                delta = ktime_to_ns(kt);
 143                err = ops->adjtime(ops, delta);
 144        } else if (tx->modes & ADJ_FREQUENCY) {
 145                err = ops->adjfreq(ops, scaled_ppm_to_ppb(tx->freq));
 146                ptp->dialed_frequency = tx->freq;
 147        } else if (tx->modes == 0) {
 148                tx->freq = ptp->dialed_frequency;
 149                err = 0;
 150        }
 151
 152        return err;
 153}
 154
 155static struct posix_clock_operations ptp_clock_ops = {
 156        .owner          = THIS_MODULE,
 157        .clock_adjtime  = ptp_clock_adjtime,
 158        .clock_gettime  = ptp_clock_gettime,
 159        .clock_getres   = ptp_clock_getres,
 160        .clock_settime  = ptp_clock_settime,
 161        .ioctl          = ptp_ioctl,
 162        .open           = ptp_open,
 163        .poll           = ptp_poll,
 164        .read           = ptp_read,
 165};
 166
 167static void delete_ptp_clock(struct posix_clock *pc)
 168{
 169        struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
 170
 171        mutex_destroy(&ptp->tsevq_mux);
 172        ida_simple_remove(&ptp_clocks_map, ptp->index);
 173        kfree(ptp);
 174}
 175
 176/* public interface */
 177
 178struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
 179                                     struct device *parent)
 180{
 181        struct ptp_clock *ptp;
 182        int err = 0, index, major = MAJOR(ptp_devt);
 183
 184        if (info->n_alarm > PTP_MAX_ALARMS)
 185                return ERR_PTR(-EINVAL);
 186
 187        /* Initialize a clock structure. */
 188        err = -ENOMEM;
 189        ptp = kzalloc(sizeof(struct ptp_clock), GFP_KERNEL);
 190        if (ptp == NULL)
 191                goto no_memory;
 192
 193        index = ida_simple_get(&ptp_clocks_map, 0, MINORMASK + 1, GFP_KERNEL);
 194        if (index < 0) {
 195                err = index;
 196                goto no_slot;
 197        }
 198
 199        ptp->clock.ops = ptp_clock_ops;
 200        ptp->clock.release = delete_ptp_clock;
 201        ptp->info = info;
 202        ptp->devid = MKDEV(major, index);
 203        ptp->index = index;
 204        spin_lock_init(&ptp->tsevq.lock);
 205        mutex_init(&ptp->tsevq_mux);
 206        init_waitqueue_head(&ptp->tsev_wq);
 207
 208        /* Create a new device in our class. */
 209        ptp->dev = device_create(ptp_class, parent, ptp->devid, ptp,
 210                                 "ptp%d", ptp->index);
 211        if (IS_ERR(ptp->dev))
 212                goto no_device;
 213
 214        dev_set_drvdata(ptp->dev, ptp);
 215
 216        err = ptp_populate_sysfs(ptp);
 217        if (err)
 218                goto no_sysfs;
 219
 220        /* Register a new PPS source. */
 221        if (info->pps) {
 222                struct pps_source_info pps;
 223                memset(&pps, 0, sizeof(pps));
 224                snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
 225                pps.mode = PTP_PPS_MODE;
 226                pps.owner = info->owner;
 227                ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
 228                if (!ptp->pps_source) {
 229                        pr_err("failed to register pps source\n");
 230                        goto no_pps;
 231                }
 232        }
 233
 234        /* Create a posix clock. */
 235        err = posix_clock_register(&ptp->clock, ptp->devid);
 236        if (err) {
 237                pr_err("failed to create posix clock\n");
 238                goto no_clock;
 239        }
 240
 241        return ptp;
 242
 243no_clock:
 244        if (ptp->pps_source)
 245                pps_unregister_source(ptp->pps_source);
 246no_pps:
 247        ptp_cleanup_sysfs(ptp);
 248no_sysfs:
 249        device_destroy(ptp_class, ptp->devid);
 250no_device:
 251        mutex_destroy(&ptp->tsevq_mux);
 252no_slot:
 253        kfree(ptp);
 254no_memory:
 255        return ERR_PTR(err);
 256}
 257EXPORT_SYMBOL(ptp_clock_register);
 258
 259int ptp_clock_unregister(struct ptp_clock *ptp)
 260{
 261        ptp->defunct = 1;
 262        wake_up_interruptible(&ptp->tsev_wq);
 263
 264        /* Release the clock's resources. */
 265        if (ptp->pps_source)
 266                pps_unregister_source(ptp->pps_source);
 267        ptp_cleanup_sysfs(ptp);
 268        device_destroy(ptp_class, ptp->devid);
 269
 270        posix_clock_unregister(&ptp->clock);
 271        return 0;
 272}
 273EXPORT_SYMBOL(ptp_clock_unregister);
 274
 275void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 276{
 277        struct pps_event_time evt;
 278
 279        switch (event->type) {
 280
 281        case PTP_CLOCK_ALARM:
 282                break;
 283
 284        case PTP_CLOCK_EXTTS:
 285                enqueue_external_timestamp(&ptp->tsevq, event);
 286                wake_up_interruptible(&ptp->tsev_wq);
 287                break;
 288
 289        case PTP_CLOCK_PPS:
 290                pps_get_ts(&evt);
 291                pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
 292                break;
 293
 294        case PTP_CLOCK_PPSUSR:
 295                pps_event(ptp->pps_source, &event->pps_times,
 296                          PTP_PPS_EVENT, NULL);
 297                break;
 298        }
 299}
 300EXPORT_SYMBOL(ptp_clock_event);
 301
 302int ptp_clock_index(struct ptp_clock *ptp)
 303{
 304        return ptp->index;
 305}
 306EXPORT_SYMBOL(ptp_clock_index);
 307
 308/* module operations */
 309
 310static void __exit ptp_exit(void)
 311{
 312        class_destroy(ptp_class);
 313        unregister_chrdev_region(ptp_devt, MINORMASK + 1);
 314        ida_destroy(&ptp_clocks_map);
 315}
 316
 317static int __init ptp_init(void)
 318{
 319        int err;
 320
 321        ptp_class = class_create(THIS_MODULE, "ptp");
 322        if (IS_ERR(ptp_class)) {
 323                pr_err("ptp: failed to allocate class\n");
 324                return PTR_ERR(ptp_class);
 325        }
 326
 327        err = alloc_chrdev_region(&ptp_devt, 0, MINORMASK + 1, "ptp");
 328        if (err < 0) {
 329                pr_err("ptp: failed to allocate device region\n");
 330                goto no_region;
 331        }
 332
 333        ptp_class->dev_attrs = ptp_dev_attrs;
 334        pr_info("PTP clock support registered\n");
 335        return 0;
 336
 337no_region:
 338        class_destroy(ptp_class);
 339        return err;
 340}
 341
 342subsys_initcall(ptp_init);
 343module_exit(ptp_exit);
 344
 345MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
 346MODULE_DESCRIPTION("PTP clocks support");
 347MODULE_LICENSE("GPL");
 348
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