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
  23 #include <linux/kernel.h>
  24 #include <linux/module.h>
  25 #include <linux/init.h>
  26 #include <linux/sched.h>
  27 #include <linux/time.h>
  28 #include <linux/spinlock.h>
  29 #include <linux/idr.h>
  30 #include <linux/fs.h>
  31 #include <linux/pps_kernel.h>
  32 #include <linux/slab.h>
  33
  34 /*
  35  * Local variables
  36  */
  37
  38 static DEFINE_SPINLOCK(pps_idr_lock);
  39 static DEFINE_IDR(pps_idr);
  40
  41 /*
  42  * Local functions
  43  */
  44
  45 static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
  46 {
  47         ts->nsec += offset->nsec;
  48         while (ts->nsec >= NSEC_PER_SEC) {
  49                 ts->nsec -= NSEC_PER_SEC;
  50                 ts->sec++;
  51         }
  52         while (ts->nsec < 0) {
  53                 ts->nsec += NSEC_PER_SEC;
  54                 ts->sec--;
  55         }
  56         ts->sec += offset->sec;
  57 }
  58
  59 /*
  60  * Exported functions
  61  */
  62
  63 /* pps_register_source - add a PPS source in the system
  64  * @info: the PPS info struct
  65  * @default_params: the default PPS parameters of the new source
  66  *
  67  * This function is used to add a new PPS source in the system. The new
  68  * source is described by info's fields and it will have, as default PPS
  69  * parameters, the ones specified into default_params.
  70  *
  71  * The function returns, in case of success, the PPS device. Otherwise NULL.
  72  */
  73
  74 struct pps_device *pps_register_source(struct pps_source_info *info,
  75                 int default_params)
  76 {
  77         struct pps_device *pps;
  78         int id;
  79         int err;
  80
  81         /* Sanity checks */
  82         if ((info->mode & default_params) != default_params) {
  83                 printk(KERN_ERR "pps: %s: unsupported default parameters\n",
  84                                         info->name);
  85                 err = -EINVAL;
  86                 goto pps_register_source_exit;
  87         }
  88         if ((info->mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) != 0 &&
  89                         info->echo == NULL) {
  90                 printk(KERN_ERR "pps: %s: echo function is not defined\n",
  91                                         info->name);
  92                 err = -EINVAL;
  93                 goto pps_register_source_exit;
  94         }
  95         if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
  96                 printk(KERN_ERR "pps: %s: unspecified time format\n",
  97                                         info->name);
  98                 err = -EINVAL;
  99                 goto pps_register_source_exit;
 100         }
 101
 102         /* Allocate memory for the new PPS source struct */
 103         pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
 104         if (pps == NULL) {
 105                 err = -ENOMEM;
 106                 goto pps_register_source_exit;
 107         }
 108
 109         /* These initializations must be done before calling idr_get_new()
 110          * in order to avoid reces into pps_event().
 111          */
 112         pps->params.api_version = PPS_API_VERS;
 113         pps->params.mode = default_params;
 114         pps->info = *info;
 115
 116         init_waitqueue_head(&pps->queue);
 117         spin_lock_init(&pps->lock);
 118
 119         /* Get new ID for the new PPS source */
 120         if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
 121                 err = -ENOMEM;
 122                 goto kfree_pps;
 123         }
 124
 125         spin_lock_irq(&pps_idr_lock);
 126
 127         /* Now really allocate the PPS source.
 128          * After idr_get_new() calling the new source will be freely available
 129          * into the kernel.
 130          */
 131         err = idr_get_new(&pps_idr, pps, &id);
 132         if (err < 0) {
 133                 spin_unlock_irq(&pps_idr_lock);
 134                 goto kfree_pps;
 135         }
 136
 137         id = id & MAX_ID_MASK;
 138         if (id >= PPS_MAX_SOURCES) {
 139                 spin_unlock_irq(&pps_idr_lock);
 140
 141                 printk(KERN_ERR "pps: %s: too many PPS sources in the system\n",
 142                                         info->name);
 143                 err = -EBUSY;
 144                 goto free_idr;
 145         }
 146         pps->id = id;
 147
 148         spin_unlock_irq(&pps_idr_lock);
 149
 150         /* Create the char device */
 151         err = pps_register_cdev(pps);
 152         if (err < 0) {
 153                 printk(KERN_ERR "pps: %s: unable to create char device\n",
 154                                         info->name);
 155                 goto free_idr;
 156         }
 157
 158         pr_info("new PPS source %s at ID %d\n", info->name, id);
 159
 160         return pps;
 161
 162 free_idr:
 163         spin_lock_irq(&pps_idr_lock);
 164         idr_remove(&pps_idr, id);
 165         spin_unlock_irq(&pps_idr_lock);
 166
 167 kfree_pps:
 168         kfree(pps);
 169
 170 pps_register_source_exit:
 171         printk(KERN_ERR "pps: %s: unable to register source\n", info->name);
 172
 173         return NULL;
 174 }
 175 EXPORT_SYMBOL(pps_register_source);
 176
 177 /* pps_unregister_source - remove a PPS source from the system
 178  * @pps: the PPS source
 179  *
 180  * This function is used to remove a previously registered PPS source from
 181  * the system.
 182  */
 183
 184 void pps_unregister_source(struct pps_device *pps)
 185 {
 186         unsigned int id = pps->id;
 187
 188         pps_unregister_cdev(pps);
 189
 190         spin_lock_irq(&pps_idr_lock);
 191         idr_remove(&pps_idr, pps->id);
 192         spin_unlock_irq(&pps_idr_lock);
 193
 194         kfree(pps);
 195 }
 196 EXPORT_SYMBOL(pps_unregister_source);
 197
 198 /* pps_event - register a PPS event into the system
 199  * @pps: the PPS device
 200  * @ts: the event timestamp
 201  * @event: the event type
 202  * @data: userdef pointer
 203  *
 204  * This function is used by each PPS client in order to register a new
 205  * PPS event into the system (it's usually called inside an IRQ handler).
 206  *
 207  * If an echo function is associated with the PPS device it will be called
 208  * as:
 209  *      pps->info.echo(pps, event, data);
 210  */
 211 void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
 212                 void *data)
 213 {
 214         unsigned long flags;
 215         int captured = 0;
 216         struct pps_ktime ts_real;
 217
 218         if ((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0) {
 219                 dev_err(pps->dev, "unknown event (%x)\n", event);
 220                 return;
 221         }
 222
 223         dev_dbg(pps->dev, "PPS event at %ld.%09ld\n",
 224                         ts->ts_real.tv_sec, ts->ts_real.tv_nsec);
 225
 226         timespec_to_pps_ktime(&ts_real, ts->ts_real);
 227
 228         spin_lock_irqsave(&pps->lock, flags);
 229
 230         /* Must call the echo function? */
 231         if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
 232                 pps->info.echo(pps, event, data);
 233
 234         /* Check the event */
 235         pps->current_mode = pps->params.mode;
 236         if ((event & PPS_CAPTUREASSERT) &
 237                         (pps->params.mode & PPS_CAPTUREASSERT)) {
 238                 /* We have to add an offset? */
 239                 if (pps->params.mode & PPS_OFFSETASSERT)
 240                         pps_add_offset(&ts_real,
 241                                         &pps->params.assert_off_tu);
 242
 243                 /* Save the time stamp */
 244                 pps->assert_tu = ts_real;
 245                 pps->assert_sequence++;
 246                 dev_dbg(pps->dev, "capture assert seq #%u\n",
 247                         pps->assert_sequence);
 248
 249                 captured = ~0;
 250         }
 251         if ((event & PPS_CAPTURECLEAR) &
 252                         (pps->params.mode & PPS_CAPTURECLEAR)) {
 253                 /* We have to add an offset? */
 254                 if (pps->params.mode & PPS_OFFSETCLEAR)
 255                         pps_add_offset(&ts_real,
 256                                         &pps->params.clear_off_tu);
 257
 258                 /* Save the time stamp */
 259                 pps->clear_tu = ts_real;
 260                 pps->clear_sequence++;
 261                 dev_dbg(pps->dev, "capture clear seq #%u\n",
 262                         pps->clear_sequence);
 263
 264                 captured = ~0;
 265         }
 266
 267         /* Wake up if captured something */
 268         if (captured) {
 269                 pps->last_ev++;
 270                 wake_up_interruptible_all(&pps->queue);
 271
 272                 kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
 273         }
 274
 275         spin_unlock_irqrestore(&pps->lock, flags);
 276 }
 277 EXPORT_SYMBOL(pps_event);