xref: /openbmc/linux/sound/core/pcm_timer.c (revision df76996a)
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 
snd_pcm_timer_resolution_change(struct snd_pcm_substream * substream)19 void 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 
snd_pcm_timer_resolution(struct snd_timer * timer)52 static 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 
snd_pcm_timer_start(struct snd_timer * timer)60 static 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 
snd_pcm_timer_stop(struct snd_timer * timer)69 static 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 
78 static 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 
snd_pcm_timer_free(struct snd_timer * timer)92 static 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 
snd_pcm_timer_init(struct snd_pcm_substream * substream)98 void 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 
snd_pcm_timer_done(struct snd_pcm_substream * substream)124 void 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