sound/core/pcm_timer.c

   1 /*
   2  *  Digital Audio (PCM) abstract layer
   3  *  Copyright (c) by Jaroslav Kysela <perex@suse.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 <sound/driver.h>
  23 #include <linux/time.h>
  24 #include <sound/core.h>
  25 #include <sound/pcm.h>
  26 #include <sound/timer.h>
  27
  28 /*
  29  *  Timer functions
  30  */
  31
  32 /* Greatest common divisor */
  33 static unsigned long gcd(unsigned long a, unsigned long b)
  34 {
  35         unsigned long r;
  36         if (a < b) {
  37                 r = a;
  38                 a = b;
  39                 b = r;
  40         }
  41         while ((r = a % b) != 0) {
  42                 a = b;
  43                 b = r;
  44         }
  45         return b;
  46 }
  47
  48 void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
  49 {
  50         unsigned long rate, mult, fsize, l, post;
  51         struct snd_pcm_runtime *runtime = substream->runtime;
  52
  53         mult = 1000000000;
  54         rate = runtime->rate;
  55         snd_assert(rate != 0, return);
  56         l = gcd(mult, rate);
  57         mult /= l;
  58         rate /= l;
  59         fsize = runtime->period_size;
  60         snd_assert(fsize != 0, return);
  61         l = gcd(rate, fsize);
  62         rate /= l;
  63         fsize /= l;
  64         post = 1;
  65         while ((mult * fsize) / fsize != mult) {
  66                 mult /= 2;
  67                 post *= 2;
  68         }
  69         if (rate == 0) {
  70                 snd_printk(KERN_ERR "pcm timer resolution out of range (rate = %u, period_size = %lu)\n", runtime->rate, runtime->period_size);
  71                 runtime->timer_resolution = -1;
  72                 return;
  73         }
  74         runtime->timer_resolution = (mult * fsize / rate) * post;
  75 }
  76
  77 static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
  78 {
  79         struct snd_pcm_substream *substream;
  80
  81         substream = timer->private_data;
  82         return substream->runtime ? substream->runtime->timer_resolution : 0;
  83 }
  84
  85 static int snd_pcm_timer_start(struct snd_timer * timer)
  86 {
  87         unsigned long flags;
  88         struct snd_pcm_substream *substream;
  89
  90         substream = snd_timer_chip(timer);
  91         spin_lock_irqsave(&substream->timer_lock, flags);
  92         substream->timer_running = 1;
  93         spin_unlock_irqrestore(&substream->timer_lock, flags);
  94         return 0;
  95 }
  96
  97 static int snd_pcm_timer_stop(struct snd_timer * timer)
  98 {
  99         unsigned long flags;
 100         struct snd_pcm_substream *substream;
 101
 102         substream = snd_timer_chip(timer);
 103         spin_lock_irqsave(&substream->timer_lock, flags);
 104         substream->timer_running = 0;
 105         spin_unlock_irqrestore(&substream->timer_lock, flags);
 106         return 0;
 107 }
 108
 109 static struct snd_timer_hardware snd_pcm_timer =
 110 {
 111         .flags =        SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
 112         .resolution =   0,
 113         .ticks =        1,
 114         .c_resolution = snd_pcm_timer_resolution,
 115         .start =        snd_pcm_timer_start,
 116         .stop =         snd_pcm_timer_stop,
 117 };
 118
 119 /*
 120  *  Init functions
 121  */
 122
 123 static void snd_pcm_timer_free(struct snd_timer *timer)
 124 {
 125         struct snd_pcm_substream *substream = timer->private_data;
 126         substream->timer = NULL;
 127 }
 128
 129 void snd_pcm_timer_init(struct snd_pcm_substream *substream)
 130 {
 131         struct snd_timer_id tid;
 132         struct snd_timer *timer;
 133
 134         tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
 135         tid.dev_class = SNDRV_TIMER_CLASS_PCM;
 136         tid.card = substream->pcm->card->number;
 137         tid.device = substream->pcm->device;
 138         tid.subdevice = (substream->number << 1) | (substream->stream & 1);
 139         if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
 140                 return;
 141         sprintf(timer->name, "PCM %s %i-%i-%i",
 142                         substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
 143                                 "capture" : "playback",
 144                         tid.card, tid.device, tid.subdevice);
 145         timer->hw = snd_pcm_timer;
 146         if (snd_device_register(timer->card, timer) < 0) {
 147                 snd_device_free(timer->card, timer);
 148                 return;
 149         }
 150         timer->private_data = substream;
 151         timer->private_free = snd_pcm_timer_free;
 152         substream->timer = timer;
 153 }
 154
 155 void snd_pcm_timer_done(struct snd_pcm_substream *substream)
 156 {
 157         if (substream->timer) {
 158                 snd_device_free(substream->pcm->card, substream->timer);
 159                 substream->timer = NULL;
 160         }
 161 }