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