drivers/ptp/ptp_clock.c

   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
  42 static dev_t ptp_devt;
  43 static struct class *ptp_class;
  44
  45 static DECLARE_BITMAP(ptp_clocks_map, PTP_MAX_CLOCKS);
  46 static DEFINE_MUTEX(ptp_clocks_mutex); /* protects 'ptp_clocks_map' */
  47
  48 /* time stamp event queue operations */
  49
  50 static inline int queue_free(struct timestamp_event_queue *q)
  51 {
  52         return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
  53 }
  54
  55 static 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
  80 static 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
 102 static 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
 109 static 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
 115 static 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
 121 static 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
 147         } else if (tx->modes & ADJ_FREQUENCY) {
 148
 149                 err = ops->adjfreq(ops, scaled_ppm_to_ppb(tx->freq));
 150         }
 151
 152         return err;
 153 }
 154
 155 static 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
 167 static 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
 173         /* Remove the clock from the bit map. */
 174         mutex_lock(&ptp_clocks_mutex);
 175         clear_bit(ptp->index, ptp_clocks_map);
 176         mutex_unlock(&ptp_clocks_mutex);
 177
 178         kfree(ptp);
 179 }
 180
 181 /* public interface */
 182
 183 struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info)
 184 {
 185         struct ptp_clock *ptp;
 186         int err = 0, index, major = MAJOR(ptp_devt);
 187
 188         if (info->n_alarm > PTP_MAX_ALARMS)
 189                 return ERR_PTR(-EINVAL);
 190
 191         /* Find a free clock slot and reserve it. */
 192         err = -EBUSY;
 193         mutex_lock(&ptp_clocks_mutex);
 194         index = find_first_zero_bit(ptp_clocks_map, PTP_MAX_CLOCKS);
 195         if (index < PTP_MAX_CLOCKS)
 196                 set_bit(index, ptp_clocks_map);
 197         else
 198                 goto no_slot;
 199
 200         /* Initialize a clock structure. */
 201         err = -ENOMEM;
 202         ptp = kzalloc(sizeof(struct ptp_clock), GFP_KERNEL);
 203         if (ptp == NULL)
 204                 goto no_memory;
 205
 206         ptp->clock.ops = ptp_clock_ops;
 207         ptp->clock.release = delete_ptp_clock;
 208         ptp->info = info;
 209         ptp->devid = MKDEV(major, index);
 210         ptp->index = index;
 211         spin_lock_init(&ptp->tsevq.lock);
 212         mutex_init(&ptp->tsevq_mux);
 213         init_waitqueue_head(&ptp->tsev_wq);
 214
 215         /* Create a new device in our class. */
 216         ptp->dev = device_create(ptp_class, NULL, ptp->devid, ptp,
 217                                  "ptp%d", ptp->index);
 218         if (IS_ERR(ptp->dev))
 219                 goto no_device;
 220
 221         dev_set_drvdata(ptp->dev, ptp);
 222
 223         err = ptp_populate_sysfs(ptp);
 224         if (err)
 225                 goto no_sysfs;
 226
 227         /* Register a new PPS source. */
 228         if (info->pps) {
 229                 struct pps_source_info pps;
 230                 memset(&pps, 0, sizeof(pps));
 231                 snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
 232                 pps.mode = PTP_PPS_MODE;
 233                 pps.owner = info->owner;
 234                 ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
 235                 if (!ptp->pps_source) {
 236                         pr_err("failed to register pps source\n");
 237                         goto no_pps;
 238                 }
 239         }
 240
 241         /* Create a posix clock. */
 242         err = posix_clock_register(&ptp->clock, ptp->devid);
 243         if (err) {
 244                 pr_err("failed to create posix clock\n");
 245                 goto no_clock;
 246         }
 247
 248         mutex_unlock(&ptp_clocks_mutex);
 249         return ptp;
 250
 251 no_clock:
 252         if (ptp->pps_source)
 253                 pps_unregister_source(ptp->pps_source);
 254 no_pps:
 255         ptp_cleanup_sysfs(ptp);
 256 no_sysfs:
 257         device_destroy(ptp_class, ptp->devid);
 258 no_device:
 259         mutex_destroy(&ptp->tsevq_mux);
 260         kfree(ptp);
 261 no_memory:
 262         clear_bit(index, ptp_clocks_map);
 263 no_slot:
 264         mutex_unlock(&ptp_clocks_mutex);
 265         return ERR_PTR(err);
 266 }
 267 EXPORT_SYMBOL(ptp_clock_register);
 268
 269 int ptp_clock_unregister(struct ptp_clock *ptp)
 270 {
 271         ptp->defunct = 1;
 272         wake_up_interruptible(&ptp->tsev_wq);
 273
 274         /* Release the clock's resources. */
 275         if (ptp->pps_source)
 276                 pps_unregister_source(ptp->pps_source);
 277         ptp_cleanup_sysfs(ptp);
 278         device_destroy(ptp_class, ptp->devid);
 279
 280         posix_clock_unregister(&ptp->clock);
 281         return 0;
 282 }
 283 EXPORT_SYMBOL(ptp_clock_unregister);
 284
 285 void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
 286 {
 287         struct pps_event_time evt;
 288
 289         switch (event->type) {
 290
 291         case PTP_CLOCK_ALARM:
 292                 break;
 293
 294         case PTP_CLOCK_EXTTS:
 295                 enqueue_external_timestamp(&ptp->tsevq, event);
 296                 wake_up_interruptible(&ptp->tsev_wq);
 297                 break;
 298
 299         case PTP_CLOCK_PPS:
 300                 pps_get_ts(&evt);
 301                 pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
 302                 break;
 303         }
 304 }
 305 EXPORT_SYMBOL(ptp_clock_event);
 306
 307 /* module operations */
 308
 309 static void __exit ptp_exit(void)
 310 {
 311         class_destroy(ptp_class);
 312         unregister_chrdev_region(ptp_devt, PTP_MAX_CLOCKS);
 313 }
 314
 315 static int __init ptp_init(void)
 316 {
 317         int err;
 318
 319         ptp_class = class_create(THIS_MODULE, "ptp");
 320         if (IS_ERR(ptp_class)) {
 321                 pr_err("ptp: failed to allocate class\n");
 322                 return PTR_ERR(ptp_class);
 323         }
 324
 325         err = alloc_chrdev_region(&ptp_devt, 0, PTP_MAX_CLOCKS, "ptp");
 326         if (err < 0) {
 327                 pr_err("ptp: failed to allocate device region\n");
 328                 goto no_region;
 329         }
 330
 331         ptp_class->dev_attrs = ptp_dev_attrs;
 332         pr_info("PTP clock support registered\n");
 333         return 0;
 334
 335 no_region:
 336         class_destroy(ptp_class);
 337         return err;
 338 }
 339
 340 subsys_initcall(ptp_init);
 341 module_exit(ptp_exit);
 342
 343 MODULE_AUTHOR("Richard Cochran <richard.cochran@omicron.at>");
 344 MODULE_DESCRIPTION("PTP clocks support");
 345 MODULE_LICENSE("GPL");