Merge branch 'linux-3.4.57' into rel-17
[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/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_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         return 0;
105 }
106
107 static struct snd_timer_hardware hrtimer_hw = {
108         .flags =        SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET,
109         .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
119 static struct snd_timer *mytimer;
120
121 static 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
158 static void __exit snd_hrtimer_exit(void)
159 {
160         if (mytimer) {
161                 snd_timer_global_free(mytimer);
162                 mytimer = NULL;
163         }
164 }
165
166 module_init(snd_hrtimer_init);
167 module_exit(snd_hrtimer_exit);