kernel/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 /*
  29  *  Timer functions
  30  */
  31
  32 void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
  33 {
  34         unsigned long rate, mult, fsize, l, post;
  35         struct snd_pcm_runtime *runtime = substream->runtime;
  36
  37         mult = 1000000000;
  38         rate = runtime->rate;
  39         if (snd_BUG_ON(!rate))
  40                 return;
  41         l = gcd(mult, rate);
  42         mult /= l;
  43         rate /= l;
  44         fsize = runtime->period_size;
  45         if (snd_BUG_ON(!fsize))
  46                 return;
  47         l = gcd(rate, fsize);
  48         rate /= l;
  49         fsize /= l;
  50         post = 1;
  51         while ((mult * fsize) / fsize != mult) {
  52                 mult /= 2;
  53                 post *= 2;
  54         }
  55         if (rate == 0) {
  56                 pcm_err(substream->pcm,
  57                         "pcm timer resolution out of range (rate = %u, period_size = %lu)\n",
  58                         runtime->rate, runtime->period_size);
  59                 runtime->timer_resolution = -1;
  60                 return;
  61         }
  62         runtime->timer_resolution = (mult * fsize / rate) * post;
  63 }
  64
  65 static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
  66 {
  67         struct snd_pcm_substream *substream;
  68
  69         substream = timer->private_data;
  70         return substream->runtime ? substream->runtime->timer_resolution : 0;
  71 }
  72
  73 static int snd_pcm_timer_start(struct snd_timer * timer)
  74 {
  75         struct snd_pcm_substream *substream;
  76
  77         substream = snd_timer_chip(timer);
  78         substream->timer_running = 1;
  79         return 0;
  80 }
  81
  82 static int snd_pcm_timer_stop(struct snd_timer * timer)
  83 {
  84         struct snd_pcm_substream *substream;
  85
  86         substream = snd_timer_chip(timer);
  87         substream->timer_running = 0;
  88         return 0;
  89 }
  90
  91 static struct snd_timer_hardware snd_pcm_timer =
  92 {
  93         .flags =        SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
  94         .resolution =   0,
  95         .ticks =        1,
  96         .c_resolution = snd_pcm_timer_resolution,
  97         .start =        snd_pcm_timer_start,
  98         .stop =         snd_pcm_timer_stop,
  99 };
 100
 101 /*
 102  *  Init functions
 103  */
 104
 105 static void snd_pcm_timer_free(struct snd_timer *timer)
 106 {
 107         struct snd_pcm_substream *substream = timer->private_data;
 108         substream->timer = NULL;
 109 }
 110
 111 void snd_pcm_timer_init(struct snd_pcm_substream *substream)
 112 {
 113         struct snd_timer_id tid;
 114         struct snd_timer *timer;
 115
 116         tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
 117         tid.dev_class = SNDRV_TIMER_CLASS_PCM;
 118         tid.card = substream->pcm->card->number;
 119         tid.device = substream->pcm->device;
 120         tid.subdevice = (substream->number << 1) | (substream->stream & 1);
 121         if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
 122                 return;
 123         sprintf(timer->name, "PCM %s %i-%i-%i",
 124                         substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
 125                                 "capture" : "playback",
 126                         tid.card, tid.device, tid.subdevice);
 127         timer->hw = snd_pcm_timer;
 128         if (snd_device_register(timer->card, timer) < 0) {
 129                 snd_device_free(timer->card, timer);
 130                 return;
 131         }
 132         timer->private_data = substream;
 133         timer->private_free = snd_pcm_timer_free;
 134         substream->timer = timer;
 135 }
 136
 137 void snd_pcm_timer_done(struct snd_pcm_substream *substream)
 138 {
 139         if (substream->timer) {
 140                 snd_device_free(substream->pcm->card, substream->timer);
 141                 substream->timer = NULL;
 142         }
 143 }