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 } 162