linux/drivers/pps/kapi.c
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   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
  41static 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
  55static 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
  78struct 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
 132kfree_pps:
 133        kfree(pps);
 134
 135pps_register_source_exit:
 136        pr_err("%s: unable to register source\n", info->name);
 137
 138        return NULL;
 139}
 140EXPORT_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
 149void 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}
 157EXPORT_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 */
 172void 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}
 236EXPORT_SYMBOL(pps_event);
 237
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