linux/sound/core/pcm_timer.c
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   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 <sound/core.h>
  24#include <sound/pcm.h>
  25#include <sound/timer.h>
  26
  27/*
  28 *  Timer functions
  29 */
  30
  31/* Greatest common divisor */
  32static unsigned long gcd(unsigned long a, unsigned long b)
  33{
  34        unsigned long r;
  35        if (a < b) {
  36                r = a;
  37                a = b;
  38                b = r;
  39        }
  40        while ((r = a % b) != 0) {
  41                a = b;
  42                b = r;
  43        }
  44        return b;
  45}
  46
  47void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
  48{
  49        unsigned long rate, mult, fsize, l, post;
  50        struct snd_pcm_runtime *runtime = substream->runtime;
  51        
  52        mult = 1000000000;
  53        rate = runtime->rate;
  54        if (snd_BUG_ON(!rate))
  55                return;
  56        l = gcd(mult, rate);
  57        mult /= l;
  58        rate /= l;
  59        fsize = runtime->period_size;
  60        if (snd_BUG_ON(!fsize))
  61                return;
  62        l = gcd(rate, fsize);
  63        rate /= l;
  64        fsize /= l;
  65        post = 1;
  66        while ((mult * fsize) / fsize != mult) {
  67                mult /= 2;
  68                post *= 2;
  69        }
  70        if (rate == 0) {
  71                snd_printk(KERN_ERR "pcm timer resolution out of range (rate = %u, period_size = %lu)\n", runtime->rate, runtime->period_size);
  72                runtime->timer_resolution = -1;
  73                return;
  74        }
  75        runtime->timer_resolution = (mult * fsize / rate) * post;
  76}
  77
  78static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
  79{
  80        struct snd_pcm_substream *substream;
  81        
  82        substream = timer->private_data;
  83        return substream->runtime ? substream->runtime->timer_resolution : 0;
  84}
  85
  86static int snd_pcm_timer_start(struct snd_timer * timer)
  87{
  88        unsigned long flags;
  89        struct snd_pcm_substream *substream;
  90        
  91        substream = snd_timer_chip(timer);
  92        spin_lock_irqsave(&substream->timer_lock, flags);
  93        substream->timer_running = 1;
  94        spin_unlock_irqrestore(&substream->timer_lock, flags);
  95        return 0;
  96}
  97
  98static int snd_pcm_timer_stop(struct snd_timer * timer)
  99{
 100        unsigned long flags;
 101        struct snd_pcm_substream *substream;
 102        
 103        substream = snd_timer_chip(timer);
 104        spin_lock_irqsave(&substream->timer_lock, flags);
 105        substream->timer_running = 0;
 106        spin_unlock_irqrestore(&substream->timer_lock, flags);
 107        return 0;
 108}
 109
 110static struct snd_timer_hardware snd_pcm_timer =
 111{
 112        .flags =        SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
 113        .resolution =   0,
 114        .ticks =        1,
 115        .c_resolution = snd_pcm_timer_resolution,
 116        .start =        snd_pcm_timer_start,
 117        .stop =         snd_pcm_timer_stop,
 118};
 119
 120/*
 121 *  Init functions
 122 */
 123
 124static void snd_pcm_timer_free(struct snd_timer *timer)
 125{
 126        struct snd_pcm_substream *substream = timer->private_data;
 127        substream->timer = NULL;
 128}
 129
 130void snd_pcm_timer_init(struct snd_pcm_substream *substream)
 131{
 132        struct snd_timer_id tid;
 133        struct snd_timer *timer;
 134        
 135        tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
 136        tid.dev_class = SNDRV_TIMER_CLASS_PCM;
 137        tid.card = substream->pcm->card->number;
 138        tid.device = substream->pcm->device;
 139        tid.subdevice = (substream->number << 1) | (substream->stream & 1);
 140        if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
 141                return;
 142        sprintf(timer->name, "PCM %s %i-%i-%i",
 143                        substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
 144                                "capture" : "playback",
 145                        tid.card, tid.device, tid.subdevice);
 146        timer->hw = snd_pcm_timer;
 147        if (snd_device_register(timer->card, timer) < 0) {
 148                snd_device_free(timer->card, timer);
 149                return;
 150        }
 151        timer->private_data = substream;
 152        timer->private_free = snd_pcm_timer_free;
 153        substream->timer = timer;
 154}
 155
 156void snd_pcm_timer_done(struct snd_pcm_substream *substream)
 157{
 158        if (substream->timer) {
 159                snd_device_free(substream->pcm->card, substream->timer);
 160                substream->timer = NULL;
 161        }
 162}
 163