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bbaf5e97 | 1 | /* |
647808a6 TI |
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 | * | |
bbaf5e97 TI |
19 | */ |
20 | ||
21 | #include <linux/init.h> | |
5a0e3ad6 | 22 | #include <linux/slab.h> |
bbaf5e97 TI |
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; | |
fcfdebe7 | 41 | atomic_t running; |
bbaf5e97 TI |
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; | |
fcfdebe7 TI |
48 | |
49 | if (!atomic_read(&stime->running)) | |
50 | return HRTIMER_NORESTART; | |
51 | ||
647808a6 | 52 | hrtimer_forward_now(hrt, ns_to_ktime(t->sticks * resolution)); |
bbaf5e97 | 53 | snd_timer_interrupt(stime->timer, t->sticks); |
fcfdebe7 TI |
54 | |
55 | if (!atomic_read(&stime->running)) | |
56 | return HRTIMER_NORESTART; | |
bbaf5e97 TI |
57 | return HRTIMER_RESTART; |
58 | } | |
59 | ||
60 | static 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; | |
bbaf5e97 | 69 | stime->hrt.function = snd_hrtimer_callback; |
fcfdebe7 | 70 | atomic_set(&stime->running, 0); |
bbaf5e97 TI |
71 | t->private_data = stime; |
72 | return 0; | |
73 | } | |
74 | ||
75 | static 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 | ||
87 | static int snd_hrtimer_start(struct snd_timer *t) | |
88 | { | |
89 | struct snd_hrtimer *stime = t->private_data; | |
90 | ||
fcfdebe7 TI |
91 | atomic_set(&stime->running, 0); |
92 | hrtimer_cancel(&stime->hrt); | |
647808a6 | 93 | hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution), |
bbaf5e97 | 94 | HRTIMER_MODE_REL); |
fcfdebe7 | 95 | atomic_set(&stime->running, 1); |
bbaf5e97 TI |
96 | return 0; |
97 | } | |
98 | ||
99 | static int snd_hrtimer_stop(struct snd_timer *t) | |
100 | { | |
101 | struct snd_hrtimer *stime = t->private_data; | |
fcfdebe7 | 102 | atomic_set(&stime->running, 0); |
bbaf5e97 TI |
103 | return 0; |
104 | } | |
105 | ||
106 | static struct snd_timer_hardware hrtimer_hw = { | |
5e03c54e | 107 | .flags = SNDRV_TIMER_HW_AUTO, |
bbaf5e97 TI |
108 | .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 | ||
118 | static struct snd_timer *mytimer; | |
119 | ||
120 | static 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 | ||
157 | static void __exit snd_hrtimer_exit(void) | |
158 | { | |
159 | if (mytimer) { | |
160 | snd_timer_global_free(mytimer); | |
161 | mytimer = NULL; | |
162 | } | |
163 | } | |
164 | ||
165 | module_init(snd_hrtimer_init); | |
166 | module_exit(snd_hrtimer_exit); |