drivers/pps/kapi.c

   1 /*
   2  * kernel API
   3  *
   4  *
   5  * Copyright (C) 2005-2009   Rodolfo Giometti <giometti@linux.it>
   6  *
   7  *   This program is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation; either version 2 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  23
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/init.h>
  27 #include <linux/sched.h>
  28 #include <linux/time.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/idr.h>
  31 #include <linux/fs.h>
  32 #include <linux/pps_kernel.h>
  33 #include <linux/slab.h>
  34
  35 /*
  36  * Local variables
  37  */
  38
  39 static DEFINE_SPINLOCK(pps_idr_lock);
  40 static DEFINE_IDR(pps_idr);
  41
  42 /*
  43  * Local functions
  44  */
  45
  46 static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
  47 {
  48         ts->nsec += offset->nsec;
  49         while (ts->nsec >= NSEC_PER_SEC) {
  50                 ts->nsec -= NSEC_PER_SEC;
  51                 ts->sec++;
  52         }
  53         while (ts->nsec < 0) {
  54                 ts->nsec += NSEC_PER_SEC;
  55                 ts->sec--;
  56         }
  57         ts->sec += offset->sec;
  58 }
  59
  60 /*
  61  * Exported functions
  62  */
  63
  64 /* pps_register_source - add a PPS source in the system
  65  * @info: the PPS info struct
  66  * @default_params: the default PPS parameters of the new source
  67  *
  68  * This function is used to add a new PPS source in the system. The new
  69  * source is described by info's fields and it will have, as default PPS
  70  * parameters, the ones specified into default_params.
  71  *
  72  * The function returns, in case of success, the PPS device. Otherwise NULL.
  73  */
  74
  75 struct pps_device *pps_register_source(struct pps_source_info *info,
  76                 int default_params)
  77 {
  78         struct pps_device *pps;
  79         int id;
  80         int err;
  81
  82         /* Sanity checks */
  83         if ((info->mode & default_params) != default_params) {
  84                 pr_err("%s: unsupported default parameters\n",
  85                                         info->name);
  86                 err = -EINVAL;
  87                 goto pps_register_source_exit;
  88         }
  89         if ((info->mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) != 0 &&
  90                         info->echo == NULL) {
  91                 pr_err("%s: echo function is not defined\n",
  92                                         info->name);
  93                 err = -EINVAL;
  94                 goto pps_register_source_exit;
  95         }
  96         if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
  97                 pr_err("%s: unspecified time format\n",
  98                                         info->name);
  99                 err = -EINVAL;
 100                 goto pps_register_source_exit;
 101         }
 102
 103         /* Allocate memory for the new PPS source struct */
 104         pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
 105         if (pps == NULL) {
 106                 err = -ENOMEM;
 107                 goto pps_register_source_exit;
 108         }
 109
 110         /* These initializations must be done before calling idr_get_new()
 111          * in order to avoid reces into pps_event().
 112          */
 113         pps->params.api_version = PPS_API_VERS;
 114         pps->params.mode = default_params;
 115         pps->info = *info;
 116
 117         init_waitqueue_head(&pps->queue);
 118         spin_lock_init(&pps->lock);
 119
 120         /* Get new ID for the new PPS source */
 121         if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
 122                 err = -ENOMEM;
 123                 goto kfree_pps;
 124         }
 125
 126         spin_lock_irq(&pps_idr_lock);
 127
 128         /* Now really allocate the PPS source.
 129          * After idr_get_new() calling the new source will be freely available
 130          * into the kernel.
 131          */
 132         err = idr_get_new(&pps_idr, pps, &id);
 133         if (err < 0) {
 134                 spin_unlock_irq(&pps_idr_lock);
 135                 goto kfree_pps;
 136         }
 137
 138         id = id & MAX_ID_MASK;
 139         if (id >= PPS_MAX_SOURCES) {
 140                 spin_unlock_irq(&pps_idr_lock);
 141
 142                 pr_err("%s: too many PPS sources in the system\n",
 143                                         info->name);
 144                 err = -EBUSY;
 145                 goto free_idr;
 146         }
 147         pps->id = id;
 148
 149         spin_unlock_irq(&pps_idr_lock);
 150
 151         /* Create the char device */
 152         err = pps_register_cdev(pps);
 153         if (err < 0) {
 154                 pr_err("%s: unable to create char device\n",
 155                                         info->name);
 156                 goto free_idr;
 157         }
 158
 159         dev_info(pps->dev, "new PPS source %s\n", info->name);
 160
 161         return pps;
 162
 163 free_idr:
 164         spin_lock_irq(&pps_idr_lock);
 165         idr_remove(&pps_idr, id);
 166         spin_unlock_irq(&pps_idr_lock);
 167
 168 kfree_pps:
 169         kfree(pps);
 170
 171 pps_register_source_exit:
 172         pr_err("%s: unable to register source\n", info->name);
 173
 174         return NULL;
 175 }
 176 EXPORT_SYMBOL(pps_register_source);
 177
 178 /* pps_unregister_source - remove a PPS source from the system
 179  * @pps: the PPS source
 180  *
 181  * This function is used to remove a previously registered PPS source from
 182  * the system.
 183  */
 184
 185 void pps_unregister_source(struct pps_device *pps)
 186 {
 187         unsigned int id = pps->id;
 188
 189         pps_unregister_cdev(pps);
 190
 191         spin_lock_irq(&pps_idr_lock);
 192         idr_remove(&pps_idr, pps->id);
 193         spin_unlock_irq(&pps_idr_lock);
 194
 195         kfree(pps);
 196 }
 197 EXPORT_SYMBOL(pps_unregister_source);
 198
 199 /* pps_event - register a PPS event into the system
 200  * @pps: the PPS device
 201  * @ts: the event timestamp
 202  * @event: the event type
 203  * @data: userdef pointer
 204  *
 205  * This function is used by each PPS client in order to register a new
 206  * PPS event into the system (it's usually called inside an IRQ handler).
 207  *
 208  * If an echo function is associated with the PPS device it will be called
 209  * as:
 210  *      pps->info.echo(pps, event, data);
 211  */
 212 void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
 213                 void *data)
 214 {
 215         unsigned long flags;
 216         int captured = 0;
 217         struct pps_ktime ts_real;
 218
 219         if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) {
 220                 dev_err(pps->dev, "unknown event (%x)\n", event);
 221                 return;
 222         }
 223
 224         dev_dbg(pps->dev, "PPS event at %ld.%09ld\n",
 225                         ts->ts_real.tv_sec, ts->ts_real.tv_nsec);
 226
 227         timespec_to_pps_ktime(&ts_real, ts->ts_real);
 228
 229         spin_lock_irqsave(&pps->lock, flags);
 230
 231         /* Must call the echo function? */
 232         if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
 233                 pps->info.echo(pps, event, data);
 234
 235         /* Check the event */
 236         pps->current_mode = pps->params.mode;
 237         if ((event & PPS_CAPTUREASSERT) &
 238                         (pps->params.mode & PPS_CAPTUREASSERT)) {
 239                 /* We have to add an offset? */
 240                 if (pps->params.mode & PPS_OFFSETASSERT)
 241                         pps_add_offset(&ts_real,
 242                                         &pps->params.assert_off_tu);
 243
 244                 /* Save the time stamp */
 245                 pps->assert_tu = ts_real;
 246                 pps->assert_sequence++;
 247                 dev_dbg(pps->dev, "capture assert seq #%u\n",
 248                         pps->assert_sequence);
 249
 250                 captured = ~0;
 251         }
 252         if ((event & PPS_CAPTURECLEAR) &
 253                         (pps->params.mode & PPS_CAPTURECLEAR)) {
 254                 /* We have to add an offset? */
 255                 if (pps->params.mode & PPS_OFFSETCLEAR)
 256                         pps_add_offset(&ts_real,
 257                                         &pps->params.clear_off_tu);
 258
 259                 /* Save the time stamp */
 260                 pps->clear_tu = ts_real;
 261                 pps->clear_sequence++;
 262                 dev_dbg(pps->dev, "capture clear seq #%u\n",
 263                         pps->clear_sequence);
 264
 265                 captured = ~0;
 266         }
 267
 268         /* Wake up if captured something */
 269         if (captured) {
 270                 pps->last_ev++;
 271                 wake_up_interruptible_all(&pps->queue);
 272
 273                 kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
 274         }
 275
 276         spin_unlock_irqrestore(&pps->lock, flags);
 277 }
 278 EXPORT_SYMBOL(pps_event);