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Takashi Iwaibbaf5e92008-10-24 18:16:50 +02001/*
Takashi Iwai647808a2008-12-08 12:16:58 +01002 * ALSA timer back-end using hrtimer
3 * Copyright (C) 2008 Takashi Iwai
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 *
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020019 */
20
21#include <linux/init.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090022#include <linux/slab.h>
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020023#include <linux/module.h>
24#include <linux/moduleparam.h>
25#include <linux/hrtimer.h>
26#include <sound/core.h>
27#include <sound/timer.h>
28
29MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
30MODULE_DESCRIPTION("ALSA hrtimer backend");
31MODULE_LICENSE("GPL");
32
33MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
34
35#define NANO_SEC 1000000000UL /* 10^9 in sec */
36static unsigned int resolution;
37
38struct snd_hrtimer {
39 struct snd_timer *timer;
40 struct hrtimer hrt;
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010041 atomic_t running;
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020042};
43
44static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
45{
46 struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
47 struct snd_timer *t = stime->timer;
Clemens Ladischb1d4f7f2011-02-10 16:15:44 +010048 unsigned long oruns;
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010049
50 if (!atomic_read(&stime->running))
51 return HRTIMER_NORESTART;
52
Clemens Ladischb1d4f7f2011-02-10 16:15:44 +010053 oruns = hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
54 snd_timer_interrupt(stime->timer, t->sticks * oruns);
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010055
56 if (!atomic_read(&stime->running))
57 return HRTIMER_NORESTART;
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020058 return HRTIMER_RESTART;
59}
60
61static int snd_hrtimer_open(struct snd_timer *t)
62{
63 struct snd_hrtimer *stime;
64
65 stime = kmalloc(sizeof(*stime), GFP_KERNEL);
66 if (!stime)
67 return -ENOMEM;
68 hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
69 stime->timer = t;
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020070 stime->hrt.function = snd_hrtimer_callback;
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010071 atomic_set(&stime->running, 0);
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020072 t->private_data = stime;
73 return 0;
74}
75
76static int snd_hrtimer_close(struct snd_timer *t)
77{
78 struct snd_hrtimer *stime = t->private_data;
79
80 if (stime) {
81 hrtimer_cancel(&stime->hrt);
82 kfree(stime);
83 t->private_data = NULL;
84 }
85 return 0;
86}
87
88static int snd_hrtimer_start(struct snd_timer *t)
89{
90 struct snd_hrtimer *stime = t->private_data;
91
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010092 atomic_set(&stime->running, 0);
93 hrtimer_cancel(&stime->hrt);
Takashi Iwai647808a2008-12-08 12:16:58 +010094 hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020095 HRTIMER_MODE_REL);
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010096 atomic_set(&stime->running, 1);
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020097 return 0;
98}
99
100static int snd_hrtimer_stop(struct snd_timer *t)
101{
102 struct snd_hrtimer *stime = t->private_data;
Takashi Iwaifcfdebe2009-12-11 12:51:05 +0100103 atomic_set(&stime->running, 0);
Takashi Iwaibbaf5e92008-10-24 18:16:50 +0200104 return 0;
105}
106
107static struct snd_timer_hardware hrtimer_hw = {
Clemens Ladisch2243c4d2011-02-10 16:16:32 +0100108 .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET,
Takashi Iwaibbaf5e92008-10-24 18:16:50 +0200109 .open = snd_hrtimer_open,
110 .close = snd_hrtimer_close,
111 .start = snd_hrtimer_start,
112 .stop = snd_hrtimer_stop,
113};
114
115/*
116 * entry functions
117 */
118
119static struct snd_timer *mytimer;
120
121static int __init snd_hrtimer_init(void)
122{
123 struct snd_timer *timer;
124 struct timespec tp;
125 int err;
126
127 hrtimer_get_res(CLOCK_MONOTONIC, &tp);
128 if (tp.tv_sec > 0 || !tp.tv_nsec) {
129 snd_printk(KERN_ERR
130 "snd-hrtimer: Invalid resolution %u.%09u",
131 (unsigned)tp.tv_sec, (unsigned)tp.tv_nsec);
132 return -EINVAL;
133 }
134 resolution = tp.tv_nsec;
135
136 /* Create a new timer and set up the fields */
137 err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
138 &timer);
139 if (err < 0)
140 return err;
141
142 timer->module = THIS_MODULE;
143 strcpy(timer->name, "HR timer");
144 timer->hw = hrtimer_hw;
145 timer->hw.resolution = resolution;
146 timer->hw.ticks = NANO_SEC / resolution;
147
148 err = snd_timer_global_register(timer);
149 if (err < 0) {
150 snd_timer_global_free(timer);
151 return err;
152 }
153 mytimer = timer; /* remember this */
154
155 return 0;
156}
157
158static void __exit snd_hrtimer_exit(void)
159{
160 if (mytimer) {
161 snd_timer_global_free(mytimer);
162 mytimer = NULL;
163 }
164}
165
166module_init(snd_hrtimer_init);
167module_exit(snd_hrtimer_exit);