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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * Digital Audio (PCM) abstract layer
- * Copyright (c) by Jaroslav Kysela <perex@perex.cz>
- */
- #include <linux/time.h>
- #include <linux/gcd.h>
- #include <sound/core.h>
- #include <sound/pcm.h>
- #include <sound/timer.h>
- #include "pcm_local.h"
- /*
- * Timer functions
- */
- void snd_pcm_timer_resolution_change(struct snd_pcm_substream *substream)
- {
- unsigned long rate, mult, fsize, l, post;
- struct snd_pcm_runtime *runtime = substream->runtime;
- mult = 1000000000;
- rate = runtime->rate;
- if (snd_BUG_ON(!rate))
- return;
- l = gcd(mult, rate);
- mult /= l;
- rate /= l;
- fsize = runtime->period_size;
- if (snd_BUG_ON(!fsize))
- return;
- l = gcd(rate, fsize);
- rate /= l;
- fsize /= l;
- post = 1;
- while ((mult * fsize) / fsize != mult) {
- mult /= 2;
- post *= 2;
- }
- if (rate == 0) {
- pcm_err(substream->pcm,
- "pcm timer resolution out of range (rate = %u, period_size = %lu)\n",
- runtime->rate, runtime->period_size);
- runtime->timer_resolution = -1;
- return;
- }
- runtime->timer_resolution = (mult * fsize / rate) * post;
- }
- static unsigned long snd_pcm_timer_resolution(struct snd_timer * timer)
- {
- struct snd_pcm_substream *substream;
- substream = timer->private_data;
- return substream->runtime ? substream->runtime->timer_resolution : 0;
- }
- static int snd_pcm_timer_start(struct snd_timer * timer)
- {
- struct snd_pcm_substream *substream;
- substream = snd_timer_chip(timer);
- substream->timer_running = 1;
- return 0;
- }
- static int snd_pcm_timer_stop(struct snd_timer * timer)
- {
- struct snd_pcm_substream *substream;
- substream = snd_timer_chip(timer);
- substream->timer_running = 0;
- return 0;
- }
- static const struct snd_timer_hardware snd_pcm_timer =
- {
- .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_SLAVE,
- .resolution = 0,
- .ticks = 1,
- .c_resolution = snd_pcm_timer_resolution,
- .start = snd_pcm_timer_start,
- .stop = snd_pcm_timer_stop,
- };
- /*
- * Init functions
- */
- static void snd_pcm_timer_free(struct snd_timer *timer)
- {
- struct snd_pcm_substream *substream = timer->private_data;
- substream->timer = NULL;
- }
- void snd_pcm_timer_init(struct snd_pcm_substream *substream)
- {
- struct snd_timer_id tid;
- struct snd_timer *timer;
- tid.dev_sclass = SNDRV_TIMER_SCLASS_NONE;
- tid.dev_class = SNDRV_TIMER_CLASS_PCM;
- tid.card = substream->pcm->card->number;
- tid.device = substream->pcm->device;
- tid.subdevice = (substream->number << 1) | (substream->stream & 1);
- if (snd_timer_new(substream->pcm->card, "PCM", &tid, &timer) < 0)
- return;
- sprintf(timer->name, "PCM %s %i-%i-%i",
- substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
- "capture" : "playback",
- tid.card, tid.device, tid.subdevice);
- timer->hw = snd_pcm_timer;
- if (snd_device_register(timer->card, timer) < 0) {
- snd_device_free(timer->card, timer);
- return;
- }
- timer->private_data = substream;
- timer->private_free = snd_pcm_timer_free;
- substream->timer = timer;
- }
- void snd_pcm_timer_done(struct snd_pcm_substream *substream)
- {
- if (substream->timer) {
- snd_device_free(substream->pcm->card, substream->timer);
- substream->timer = NULL;
- }
- }
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