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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;
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010048
49 if (!atomic_read(&stime->running))
50 return HRTIMER_NORESTART;
51
Takashi Iwai647808a2008-12-08 12:16:58 +010052 hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020053 snd_timer_interrupt(stime->timer, t->sticks);
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010054
55 if (!atomic_read(&stime->running))
56 return HRTIMER_NORESTART;
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020057 return HRTIMER_RESTART;
58}
59
60static int snd_hrtimer_open(struct snd_timer *t)
61{
62 struct snd_hrtimer *stime;
63
64 stime = kmalloc(sizeof(*stime), GFP_KERNEL);
65 if (!stime)
66 return -ENOMEM;
67 hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
68 stime->timer = t;
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020069 stime->hrt.function = snd_hrtimer_callback;
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010070 atomic_set(&stime->running, 0);
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020071 t->private_data = stime;
72 return 0;
73}
74
75static int snd_hrtimer_close(struct snd_timer *t)
76{
77 struct snd_hrtimer *stime = t->private_data;
78
79 if (stime) {
80 hrtimer_cancel(&stime->hrt);
81 kfree(stime);
82 t->private_data = NULL;
83 }
84 return 0;
85}
86
87static int snd_hrtimer_start(struct snd_timer *t)
88{
89 struct snd_hrtimer *stime = t->private_data;
90
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010091 atomic_set(&stime->running, 0);
92 hrtimer_cancel(&stime->hrt);
Takashi Iwai647808a2008-12-08 12:16:58 +010093 hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020094 HRTIMER_MODE_REL);
Takashi Iwaifcfdebe2009-12-11 12:51:05 +010095 atomic_set(&stime->running, 1);
Takashi Iwaibbaf5e92008-10-24 18:16:50 +020096 return 0;
97}
98
99static int snd_hrtimer_stop(struct snd_timer *t)
100{
101 struct snd_hrtimer *stime = t->private_data;
Takashi Iwaifcfdebe2009-12-11 12:51:05 +0100102 atomic_set(&stime->running, 0);
Takashi Iwaibbaf5e92008-10-24 18:16:50 +0200103 return 0;
104}
105
106static struct snd_timer_hardware hrtimer_hw = {
Takashi Iwai5e03c542008-12-08 12:40:56 +0100107 .flags = SNDRV_TIMER_HW_AUTO,
Takashi Iwaibbaf5e92008-10-24 18:16:50 +0200108 .open = snd_hrtimer_open,
109 .close = snd_hrtimer_close,
110 .start = snd_hrtimer_start,
111 .stop = snd_hrtimer_stop,
112};
113
114/*
115 * entry functions
116 */
117
118static struct snd_timer *mytimer;
119
120static int __init snd_hrtimer_init(void)
121{
122 struct snd_timer *timer;
123 struct timespec tp;
124 int err;
125
126 hrtimer_get_res(CLOCK_MONOTONIC, &tp);
127 if (tp.tv_sec > 0 || !tp.tv_nsec) {
128 snd_printk(KERN_ERR
129 "snd-hrtimer: Invalid resolution %u.%09u",
130 (unsigned)tp.tv_sec, (unsigned)tp.tv_nsec);
131 return -EINVAL;
132 }
133 resolution = tp.tv_nsec;
134
135 /* Create a new timer and set up the fields */
136 err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
137 &timer);
138 if (err < 0)
139 return err;
140
141 timer->module = THIS_MODULE;
142 strcpy(timer->name, "HR timer");
143 timer->hw = hrtimer_hw;
144 timer->hw.resolution = resolution;
145 timer->hw.ticks = NANO_SEC / resolution;
146
147 err = snd_timer_global_register(timer);
148 if (err < 0) {
149 snd_timer_global_free(timer);
150 return err;
151 }
152 mytimer = timer; /* remember this */
153
154 return 0;
155}
156
157static void __exit snd_hrtimer_exit(void)
158{
159 if (mytimer) {
160 snd_timer_global_free(mytimer);
161 mytimer = NULL;
162 }
163}
164
165module_init(snd_hrtimer_init);
166module_exit(snd_hrtimer_exit);