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/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
  41 static dev_t ptp_devt;
  42 static struct class *ptp_class;
  43
  44 static DEFINE_IDA(ptp_clocks_map);
  45
  46 /* time stamp event queue operations */
  47
  48 static inline int queue_free(struct timestamp_event_queue *q)
  49 {
  50         return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
  51 }
  52
  53 static 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
  78 static 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
 100 static 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
 107 static 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
 113 static 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
 119 static 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
 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         ida_simple_remove(&ptp_clocks_map, ptp->index);
 173         kfree(ptp);
 174 }
 175
 176 /* public interface */
 177
 178 struct 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
 243 no_clock:
 244         if (ptp->pps_source)
 245                 pps_unregister_source(ptp->pps_source);
 246 no_pps:
 247         ptp_cleanup_sysfs(ptp);
 248 no_sysfs:
 249         device_destroy(ptp_class, ptp->devid);
 250 no_device:
 251         mutex_destroy(&ptp->tsevq_mux);
 252 no_slot:
 253         kfree(ptp);
 254 no_memory:
 255         return ERR_PTR(err);
 256 }
 257 EXPORT_SYMBOL(ptp_clock_register);
 258
 259 int 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 }
 273 EXPORT_SYMBOL(ptp_clock_unregister);
 274
 275 void 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 }
 300 EXPORT_SYMBOL(ptp_clock_event);
 301
 302 int ptp_clock_index(struct ptp_clock *ptp)
 303 {
 304         return ptp->index;
 305 }
 306 EXPORT_SYMBOL(ptp_clock_index);
 307
 308 /* module operations */
 309
 310 static 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
 317 static 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
 337 no_region:
 338         class_destroy(ptp_class);
 339         return err;
 340 }
 341
 342 subsys_initcall(ptp_init);
 343 module_exit(ptp_exit);
 344
 345 MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
 346 MODULE_DESCRIPTION("PTP clocks support");
 347 MODULE_LICENSE("GPL");