1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  Digital Audio (PCM) abstract layer
4 *  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 functions
17 */
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 functions
90 */
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			substream->stream == SNDRV_PCM_STREAM_CAPTURE ?
112				"capture" : "playback",
113			tid.card, tid.device, tid.subdevice);
114	timer->hw = snd_pcm_timer;
115	if (snd_device_register(timer->card, timer) < 0) {
116		snd_device_free(timer->card, timer);
117		return;
118	}
119	timer->private_data = substream;
120	timer->private_free = snd_pcm_timer_free;
121	substream->timer = timer;
122}
123
124void snd_pcm_timer_done(struct snd_pcm_substream *substream)
125{
126	if (substream->timer) {
127		snd_device_free(substream->pcm->card, substream->timer);
128		substream->timer = NULL;
129	}
130}
131