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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
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;
41 atomic_t running;
42};
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;
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
61static 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
76static 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
88static 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
100static 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
107static 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
119static struct snd_timer *mytimer;
120
121static 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 pr_err("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);
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
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;
41 bool in_callback;
42};
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;
48 ktime_t delta;
49 unsigned long ticks;
50 enum hrtimer_restart ret = HRTIMER_NORESTART;
51
52 spin_lock(&t->lock);
53 if (!t->running)
54 goto out; /* fast path */
55 stime->in_callback = true;
56 ticks = t->sticks;
57 spin_unlock(&t->lock);
58
59 /* calculate the drift */
60 delta = ktime_sub(hrt->base->get_time(), hrtimer_get_expires(hrt));
61 if (delta > 0)
62 ticks += ktime_divns(delta, ticks * resolution);
63
64 snd_timer_interrupt(stime->timer, ticks);
65
66 spin_lock(&t->lock);
67 if (t->running) {
68 hrtimer_add_expires_ns(hrt, t->sticks * resolution);
69 ret = HRTIMER_RESTART;
70 }
71
72 stime->in_callback = false;
73 out:
74 spin_unlock(&t->lock);
75 return ret;
76}
77
78static int snd_hrtimer_open(struct snd_timer *t)
79{
80 struct snd_hrtimer *stime;
81
82 stime = kzalloc(sizeof(*stime), GFP_KERNEL);
83 if (!stime)
84 return -ENOMEM;
85 hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
86 stime->timer = t;
87 stime->hrt.function = snd_hrtimer_callback;
88 t->private_data = stime;
89 return 0;
90}
91
92static int snd_hrtimer_close(struct snd_timer *t)
93{
94 struct snd_hrtimer *stime = t->private_data;
95
96 if (stime) {
97 spin_lock_irq(&t->lock);
98 t->running = 0; /* just to be sure */
99 stime->in_callback = 1; /* skip start/stop */
100 spin_unlock_irq(&t->lock);
101
102 hrtimer_cancel(&stime->hrt);
103 kfree(stime);
104 t->private_data = NULL;
105 }
106 return 0;
107}
108
109static int snd_hrtimer_start(struct snd_timer *t)
110{
111 struct snd_hrtimer *stime = t->private_data;
112
113 if (stime->in_callback)
114 return 0;
115 hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
116 HRTIMER_MODE_REL);
117 return 0;
118}
119
120static int snd_hrtimer_stop(struct snd_timer *t)
121{
122 struct snd_hrtimer *stime = t->private_data;
123
124 if (stime->in_callback)
125 return 0;
126 hrtimer_try_to_cancel(&stime->hrt);
127 return 0;
128}
129
130static const struct snd_timer_hardware hrtimer_hw __initconst = {
131 .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET,
132 .open = snd_hrtimer_open,
133 .close = snd_hrtimer_close,
134 .start = snd_hrtimer_start,
135 .stop = snd_hrtimer_stop,
136};
137
138/*
139 * entry functions
140 */
141
142static struct snd_timer *mytimer;
143
144static int __init snd_hrtimer_init(void)
145{
146 struct snd_timer *timer;
147 int err;
148
149 resolution = hrtimer_resolution;
150
151 /* Create a new timer and set up the fields */
152 err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
153 &timer);
154 if (err < 0)
155 return err;
156
157 timer->module = THIS_MODULE;
158 strcpy(timer->name, "HR timer");
159 timer->hw = hrtimer_hw;
160 timer->hw.resolution = resolution;
161 timer->hw.ticks = NANO_SEC / resolution;
162 timer->max_instances = 100; /* lower the limit */
163
164 err = snd_timer_global_register(timer);
165 if (err < 0) {
166 snd_timer_global_free(timer);
167 return err;
168 }
169 mytimer = timer; /* remember this */
170
171 return 0;
172}
173
174static void __exit snd_hrtimer_exit(void)
175{
176 if (mytimer) {
177 snd_timer_global_free(mytimer);
178 mytimer = NULL;
179 }
180}
181
182module_init(snd_hrtimer_init);
183module_exit(snd_hrtimer_exit);