sound/core/pcm_timer.c

   1 /*
   2  *  Digital Audio (PCM) abstract layer
   3  *  Copyright (c) by Jaroslav Kysela <perex@perex.cz>
   4  *
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation; either version 2 of the License, or
   9  *   (at your option) any later version.
  10  *
  11  *   This program is distributed in the hope that it will be useful,
  12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *   GNU General Public License for more details.
  15  *
  16  *   You should have received a copy of the GNU General Public License
  17  *   along with this program; if not, write to the Free Software
  18  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  19  *
  20  */
  21
  22 #include <linux/time.h>
  23 #include <linux/gcd.h>
  24 #include <sound/core.h>
  25 #include <sound/pcm.h>
  26 #include <sound/timer.h>
  27
  28 #include "pcm_local.h"
  29
  30 /*
  31  *  Timer functions
  32  */
  33
  34 void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
  35 {
  36         unsigned long rate, mult, fsize, l, post;
  37         struct snd_pcm_runtime *runtime = substream->runtime;
  38
  39         mult = 1000000000;
  40         rate = runtime->rate;
  41         if (snd_BUG_ON(!rate))
  42                 return;
  43         l = gcd(mult, rate);
  44         mult /= l;
  45         rate /= l;
  46         fsize = runtime->period_size;
  47         if (snd_BUG_ON(!fsize))
  48                 return;
  49         l = gcd(rate, fsize);
  50         rate /= l;
  51         fsize /= l;
  52         post = 1;
  53         while ((mult * fsize) / fsize != mult) {
  54                 mult /= 2;
  55                 post *= 2;
  56         }
  57         if (rate == 0) {
  58                 pcm_err(substream->pcm,
  59                         "pcm timer resolution out of range (rate = %u, period_size = %lu)\n",
  60                         runtime->rate, runtime->period_size);
  61                 runtime->timer_resolution = -1;
  62                 return;
  63         }
  64         runtime->timer_resolution = (mult * fsize / rate) * post;
  65 }
  66
  67 static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
  68 {
  69         struct snd_pcm_substream *substream;
  70
  71         substream = timer->private_data;
  72         return substream->runtime ? substream->runtime->timer_resolution : 0;
  73 }
  74
  75 static int snd_pcm_timer_start(struct snd_timer * timer)
  76 {
  77         struct snd_pcm_substream *substream;
  78
  79         substream = snd_timer_chip(timer);
  80         substream->timer_running = 1;
  81         return 0;
  82 }
  83
  84 static int snd_pcm_timer_stop(struct snd_timer * timer)
  85 {
  86         struct snd_pcm_substream *substream;
  87
  88         substream = snd_timer_chip(timer);
  89         substream->timer_running = 0;
  90         return 0;
  91 }
  92
  93 static struct snd_timer_hardware snd_pcm_timer =
  94 {
  95         .flags =        SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
  96         .resolution =   0,
  97         .ticks =        1,
  98         .c_resolution = snd_pcm_timer_resolution,
  99         .start =        snd_pcm_timer_start,
 100         .stop =         snd_pcm_timer_stop,
 101 };
 102
 103 /*
 104  *  Init functions
 105  */
 106
 107 static void snd_pcm_timer_free(struct snd_timer *timer)
 108 {
 109         struct snd_pcm_substream *substream = timer->private_data;
 110         substream->timer = NULL;
 111 }
 112
 113 void snd_pcm_timer_init(struct snd_pcm_substream *substream)
 114 {
 115         struct snd_timer_id tid;
 116         struct snd_timer *timer;
 117
 118         tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
 119         tid.dev_class = SNDRV_TIMER_CLASS_PCM;
 120         tid.card = substream->pcm->card->number;
 121         tid.device = substream->pcm->device;
 122         tid.subdevice = (substream->number << 1) | (substream->stream & 1);
 123         if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
 124                 return;
 125         sprintf(timer->name, "PCM %s %i-%i-%i",
 126                         substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
 127                                 "capture" : "playback",
 128                         tid.card, tid.device, tid.subdevice);
 129         timer->hw = snd_pcm_timer;
 130         if (snd_device_register(timer->card, timer) < 0) {
 131                 snd_device_free(timer->card, timer);
 132                 return;
 133         }
 134         timer->private_data = substream;
 135         timer->private_free = snd_pcm_timer_free;
 136         substream->timer = timer;
 137 }
 138
 139 void snd_pcm_timer_done(struct snd_pcm_substream *substream)
 140 {
 141         if (substream->timer) {
 142                 snd_device_free(substream->pcm->card, substream->timer);
 143                 substream->timer = NULL;
 144         }
 145 }