Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6.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/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/hrtimer.h>
25 #include <sound/core.h>
26 #include <sound/timer.h>
27
28 MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
29 MODULE_DESCRIPTION("ALSA hrtimer backend");
30 MODULE_LICENSE("GPL");
31
32 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
33
34 #define NANO_SEC        1000000000UL    /* 10^9 in sec */
35 static unsigned int resolution;
36
37 struct snd_hrtimer {
38         struct snd_timer *timer;
39         struct hrtimer hrt;
40 };
41
42 static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
43 {
44         struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
45         struct snd_timer *t = stime->timer;
46         hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution));
47         snd_timer_interrupt(stime->timer, t->sticks);
48         return HRTIMER_RESTART;
49 }
50
51 static int snd_hrtimer_open(struct snd_timer *t)
52 {
53         struct snd_hrtimer *stime;
54
55         stime = kmalloc(sizeof(*stime), GFP_KERNEL);
56         if (!stime)
57                 return -ENOMEM;
58         hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
59         stime->timer = t;
60         stime->hrt.function = snd_hrtimer_callback;
61         t->private_data = stime;
62         return 0;
63 }
64
65 static int snd_hrtimer_close(struct snd_timer *t)
66 {
67         struct snd_hrtimer *stime = t->private_data;
68
69         if (stime) {
70                 hrtimer_cancel(&stime->hrt);
71                 kfree(stime);
72                 t->private_data = NULL;
73         }
74         return 0;
75 }
76
77 static int snd_hrtimer_start(struct snd_timer *t)
78 {
79         struct snd_hrtimer *stime = t->private_data;
80
81         hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
82                       HRTIMER_MODE_REL);
83         return 0;
84 }
85
86 static int snd_hrtimer_stop(struct snd_timer *t)
87 {
88         struct snd_hrtimer *stime = t->private_data;
89
90         hrtimer_cancel(&stime->hrt);
91         return 0;
92 }
93
94 static struct snd_timer_hardware hrtimer_hw = {
95         .flags =        SNDRV_TIMER_HW_AUTO,
96         .open =         snd_hrtimer_open,
97         .close =        snd_hrtimer_close,
98         .start =        snd_hrtimer_start,
99         .stop =         snd_hrtimer_stop,
100 };
101
102 /*
103  * entry functions
104  */
105
106 static struct snd_timer *mytimer;
107
108 static int __init snd_hrtimer_init(void)
109 {
110         struct snd_timer *timer;
111         struct timespec tp;
112         int err;
113
114         hrtimer_get_res(CLOCK_MONOTONIC, &tp);
115         if (tp.tv_sec > 0 || !tp.tv_nsec) {
116                 snd_printk(KERN_ERR
117                            "snd-hrtimer: Invalid resolution %u.%09u",
118                            (unsigned)tp.tv_sec, (unsigned)tp.tv_nsec);
119                 return -EINVAL;
120         }
121         resolution = tp.tv_nsec;
122
123         /* Create a new timer and set up the fields */
124         err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
125                                    &timer);
126         if (err < 0)
127                 return err;
128
129         timer->module = THIS_MODULE;
130         strcpy(timer->name, "HR timer");
131         timer->hw = hrtimer_hw;
132         timer->hw.resolution = resolution;
133         timer->hw.ticks = NANO_SEC / resolution;
134
135         err = snd_timer_global_register(timer);
136         if (err < 0) {
137                 snd_timer_global_free(timer);
138                 return err;
139         }
140         mytimer = timer; /* remember this */
141
142         return 0;
143 }
144
145 static void __exit snd_hrtimer_exit(void)
146 {
147         if (mytimer) {
148                 snd_timer_global_free(mytimer);
149                 mytimer = NULL;
150         }
151 }
152
153 module_init(snd_hrtimer_init);
154 module_exit(snd_hrtimer_exit);