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 */ 32 static 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 47 void 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 78 static 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 86 static 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 98 static 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 } 109 110 static 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 */ 123 124 static void snd_pcm_timer_free(struct snd_timer *timer) 125 { 126 struct snd_pcm_substream *substream = timer->private_data; 127 substream->timer = NULL; 128 } 129 130 void 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 } 155 156 void 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