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