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(snd_pcm_substream_t *substream)
49 {
50 unsigned long rate, mult, fsize, l, post;
51 snd_pcm_runtime_t *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(snd_timer_t * timer)
78 {
79 snd_pcm_substream_t * 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(snd_timer_t * timer)
86 {
87 unsigned long flags;
88 snd_pcm_substream_t * 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(snd_timer_t * timer)
98 {
99 unsigned long flags;
100 snd_pcm_substream_t * 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(snd_timer_t *timer)
124 {
125 snd_pcm_substream_t *substream = timer->private_data;
126 substream->timer = NULL;
127 }
128
129 void snd_pcm_timer_init(snd_pcm_substream_t *substream)
130 {
131 snd_timer_id_t tid;
132 snd_timer_t *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(snd_pcm_substream_t *substream)
156 {
157 if (substream->timer) {
158 snd_device_free(substream->pcm->card, substream->timer);
159 substream->timer = NULL;
160 }
161 }
162
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