14d483d6b3b00746d619fcc3695a3005a6309aad
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / sound / core / hrtimer.c
1 /*
2 * 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 *
19 */
20
21 #include <linux/init.h>
22 #include <linux/slab.h>
23 #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
29 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
30 MODULE_DESCRIPTION("ALSA hrtimer backend");
31 MODULE_LICENSE("GPL");
32
33 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
34
35 #define NANO_SEC 1000000000UL /* 10^9 in sec */
36 static unsigned int resolution;
37
38 struct snd_hrtimer {
39 struct snd_timer *timer;
40 struct hrtimer hrt;
41 atomic_t running;
42 };
43
44 static 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;
48 unsigned long oruns;
49
50 if (!atomic_read(&stime->running))
51 return HRTIMER_NORESTART;
52
53 oruns = hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
54 snd_timer_interrupt(stime->timer, t->sticks * oruns);
55
56 if (!atomic_read(&stime->running))
57 return HRTIMER_NORESTART;
58 return HRTIMER_RESTART;
59 }
60
61 static 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;
70 stime->hrt.function = snd_hrtimer_callback;
71 atomic_set(&stime->running, 0);
72 t->private_data = stime;
73 return 0;
74 }
75
76 static 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
88 static int snd_hrtimer_start(struct snd_timer *t)
89 {
90 struct snd_hrtimer *stime = t->private_data;
91
92 atomic_set(&stime->running, 0);
93 hrtimer_try_to_cancel(&stime->hrt);
94 hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
95 HRTIMER_MODE_REL);
96 atomic_set(&stime->running, 1);
97 return 0;
98 }
99
100 static int snd_hrtimer_stop(struct snd_timer *t)
101 {
102 struct snd_hrtimer *stime = t->private_data;
103 atomic_set(&stime->running, 0);
104 hrtimer_try_to_cancel(&stime->hrt);
105 return 0;
106 }
107
108 static struct snd_timer_hardware hrtimer_hw = {
109 .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET,
110 .open = snd_hrtimer_open,
111 .close = snd_hrtimer_close,
112 .start = snd_hrtimer_start,
113 .stop = snd_hrtimer_stop,
114 };
115
116 /*
117 * entry functions
118 */
119
120 static struct snd_timer *mytimer;
121
122 static int __init snd_hrtimer_init(void)
123 {
124 struct snd_timer *timer;
125 struct timespec tp;
126 int err;
127
128 hrtimer_get_res(CLOCK_MONOTONIC, &tp);
129 if (tp.tv_sec > 0 || !tp.tv_nsec) {
130 snd_printk(KERN_ERR
131 "snd-hrtimer: Invalid resolution %u.%09u",
132 (unsigned)tp.tv_sec, (unsigned)tp.tv_nsec);
133 return -EINVAL;
134 }
135 resolution = tp.tv_nsec;
136
137 /* Create a new timer and set up the fields */
138 err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
139 &timer);
140 if (err < 0)
141 return err;
142
143 timer->module = THIS_MODULE;
144 strcpy(timer->name, "HR timer");
145 timer->hw = hrtimer_hw;
146 timer->hw.resolution = resolution;
147 timer->hw.ticks = NANO_SEC / resolution;
148
149 err = snd_timer_global_register(timer);
150 if (err < 0) {
151 snd_timer_global_free(timer);
152 return err;
153 }
154 mytimer = timer; /* remember this */
155
156 return 0;
157 }
158
159 static void __exit snd_hrtimer_exit(void)
160 {
161 if (mytimer) {
162 snd_timer_global_free(mytimer);
163 mytimer = NULL;
164 }
165 }
166
167 module_init(snd_hrtimer_init);
168 module_exit(snd_hrtimer_exit);