130 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Digital Audio (PCM) abstract layer4 * Copyright (c) by Jaroslav Kysela <perex@perex.cz>5 */6 7#include <linux/time.h>8#include <linux/gcd.h>9#include <sound/core.h>10#include <sound/pcm.h>11#include <sound/timer.h>12 13#include "pcm_local.h"14 15/*16 * Timer functions17 */18 19void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)20{21 unsigned long rate, mult, fsize, l, post;22 struct snd_pcm_runtime *runtime = substream->runtime;23 24 mult = 1000000000;25 rate = runtime->rate;26 if (snd_BUG_ON(!rate))27 return;28 l = gcd(mult, rate);29 mult /= l;30 rate /= l;31 fsize = runtime->period_size;32 if (snd_BUG_ON(!fsize))33 return;34 l = gcd(rate, fsize);35 rate /= l;36 fsize /= l;37 post = 1;38 while ((mult * fsize) / fsize != mult) {39 mult /= 2;40 post *= 2;41 }42 if (rate == 0) {43 pcm_err(substream->pcm,44 "pcm timer resolution out of range (rate = %u, period_size = %lu)\n",45 runtime->rate, runtime->period_size);46 runtime->timer_resolution = -1;47 return;48 }49 runtime->timer_resolution = (mult * fsize / rate) * post;50}51 52static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)53{54 struct snd_pcm_substream *substream;55 56 substream = timer->private_data;57 return substream->runtime ? substream->runtime->timer_resolution : 0;58}59 60static int snd_pcm_timer_start(struct snd_timer * timer)61{62 struct snd_pcm_substream *substream;63 64 substream = snd_timer_chip(timer);65 substream->timer_running = 1;66 return 0;67}68 69static int snd_pcm_timer_stop(struct snd_timer * timer)70{71 struct snd_pcm_substream *substream;72 73 substream = snd_timer_chip(timer);74 substream->timer_running = 0;75 return 0;76}77 78static const struct snd_timer_hardware snd_pcm_timer =79{80 .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,81 .resolution = 0,82 .ticks = 1,83 .c_resolution = snd_pcm_timer_resolution,84 .start = snd_pcm_timer_start,85 .stop = snd_pcm_timer_stop,86};87 88/*89 * Init functions90 */91 92static void snd_pcm_timer_free(struct snd_timer *timer)93{94 struct snd_pcm_substream *substream = timer->private_data;95 substream->timer = NULL;96}97 98void snd_pcm_timer_init(struct snd_pcm_substream *substream)99{100 struct snd_timer_id tid;101 struct snd_timer *timer;102 103 tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;104 tid.dev_class = SNDRV_TIMER_CLASS_PCM;105 tid.card = substream->pcm->card->number;106 tid.device = substream->pcm->device;107 tid.subdevice = (substream->number << 1) | (substream->stream & 1);108 if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)109 return;110 sprintf(timer->name, "PCM %s %i-%i-%i",111 snd_pcm_direction_name(substream->stream),112 tid.card, tid.device, tid.subdevice);113 timer->hw = snd_pcm_timer;114 if (snd_device_register(timer->card, timer) < 0) {115 snd_device_free(timer->card, timer);116 return;117 }118 timer->private_data = substream;119 timer->private_free = snd_pcm_timer_free;120 substream->timer = timer;121}122 123void snd_pcm_timer_done(struct snd_pcm_substream *substream)124{125 if (substream->timer) {126 snd_device_free(substream->pcm->card, substream->timer);127 substream->timer = NULL;128 }129}130