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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * ALSA timer back-end using hrtimer
4 * Copyright (C) 2008 Takashi Iwai
5 */
6
7#include <linux/init.h>
8#include <linux/slab.h>
9#include <linux/module.h>
10#include <linux/moduleparam.h>
11#include <linux/hrtimer.h>
12#include <sound/core.h>
13#include <sound/timer.h>
14
15MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
16MODULE_DESCRIPTION("ALSA hrtimer backend");
17MODULE_LICENSE("GPL");
18
19MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
20
21#define NANO_SEC 1000000000UL /* 10^9 in sec */
22static unsigned int resolution;
23
24struct snd_hrtimer {
25 struct snd_timer *timer;
26 struct hrtimer hrt;
27 bool in_callback;
28};
29
30static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
31{
32 struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
33 struct snd_timer *t = stime->timer;
34 ktime_t delta;
35 unsigned long ticks;
36 enum hrtimer_restart ret = HRTIMER_NORESTART;
37
38 spin_lock(&t->lock);
39 if (!t->running)
40 goto out; /* fast path */
41 stime->in_callback = true;
42 ticks = t->sticks;
43 spin_unlock(&t->lock);
44
45 /* calculate the drift */
46 delta = ktime_sub(hrt->base->get_time(), hrtimer_get_expires(hrt));
47 if (delta > 0)
48 ticks += ktime_divns(delta, ticks * resolution);
49
50 snd_timer_interrupt(stime->timer, ticks);
51
52 spin_lock(&t->lock);
53 if (t->running) {
54 hrtimer_add_expires_ns(hrt, t->sticks * resolution);
55 ret = HRTIMER_RESTART;
56 }
57
58 stime->in_callback = false;
59 out:
60 spin_unlock(&t->lock);
61 return ret;
62}
63
64static int snd_hrtimer_open(struct snd_timer *t)
65{
66 struct snd_hrtimer *stime;
67
68 stime = kzalloc(sizeof(*stime), GFP_KERNEL);
69 if (!stime)
70 return -ENOMEM;
71 hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
72 stime->timer = t;
73 stime->hrt.function = snd_hrtimer_callback;
74 t->private_data = stime;
75 return 0;
76}
77
78static int snd_hrtimer_close(struct snd_timer *t)
79{
80 struct snd_hrtimer *stime = t->private_data;
81
82 if (stime) {
83 spin_lock_irq(&t->lock);
84 t->running = 0; /* just to be sure */
85 stime->in_callback = 1; /* skip start/stop */
86 spin_unlock_irq(&t->lock);
87
88 hrtimer_cancel(&stime->hrt);
89 kfree(stime);
90 t->private_data = NULL;
91 }
92 return 0;
93}
94
95static int snd_hrtimer_start(struct snd_timer *t)
96{
97 struct snd_hrtimer *stime = t->private_data;
98
99 if (stime->in_callback)
100 return 0;
101 hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
102 HRTIMER_MODE_REL);
103 return 0;
104}
105
106static int snd_hrtimer_stop(struct snd_timer *t)
107{
108 struct snd_hrtimer *stime = t->private_data;
109
110 if (stime->in_callback)
111 return 0;
112 hrtimer_try_to_cancel(&stime->hrt);
113 return 0;
114}
115
116static const struct snd_timer_hardware hrtimer_hw __initconst = {
117 .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET,
118 .open = snd_hrtimer_open,
119 .close = snd_hrtimer_close,
120 .start = snd_hrtimer_start,
121 .stop = snd_hrtimer_stop,
122};
123
124/*
125 * entry functions
126 */
127
128static struct snd_timer *mytimer;
129
130static int __init snd_hrtimer_init(void)
131{
132 struct snd_timer *timer;
133 int err;
134
135 resolution = hrtimer_resolution;
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 timer->max_instances = 100; /* lower the limit */
149
150 err = snd_timer_global_register(timer);
151 if (err < 0) {
152 snd_timer_global_free(timer);
153 return err;
154 }
155 mytimer = timer; /* remember this */
156
157 return 0;
158}
159
160static void __exit snd_hrtimer_exit(void)
161{
162 if (mytimer) {
163 snd_timer_global_free(mytimer);
164 mytimer = NULL;
165 }
166}
167
168module_init(snd_hrtimer_init);
169module_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 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_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
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 hrtimer_try_to_cancel(&stime->hrt);
105 return 0;
106}
107
108static 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
120static struct snd_timer *mytimer;
121
122static int __init snd_hrtimer_init(void)
123{
124 struct snd_timer *timer;
125 int err;
126
127 resolution = hrtimer_resolution;
128
129 /* Create a new timer and set up the fields */
130 err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
131 &timer);
132 if (err < 0)
133 return err;
134
135 timer->module = THIS_MODULE;
136 strcpy(timer->name, "HR timer");
137 timer->hw = hrtimer_hw;
138 timer->hw.resolution = resolution;
139 timer->hw.ticks = NANO_SEC / resolution;
140
141 err = snd_timer_global_register(timer);
142 if (err < 0) {
143 snd_timer_global_free(timer);
144 return err;
145 }
146 mytimer = timer; /* remember this */
147
148 return 0;
149}
150
151static void __exit snd_hrtimer_exit(void)
152{
153 if (mytimer) {
154 snd_timer_global_free(mytimer);
155 mytimer = NULL;
156 }
157}
158
159module_init(snd_hrtimer_init);
160module_exit(snd_hrtimer_exit);