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