Loading...
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// 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 scoped_guard(spinlock, &t->lock) {
39 if (!t->running)
40 return HRTIMER_NORESTART; /* fast path */
41 stime->in_callback = true;
42 ticks = t->sticks;
43 }
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 guard(spinlock)(&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 return ret;
60}
61
62static int snd_hrtimer_open(struct snd_timer *t)
63{
64 struct snd_hrtimer *stime;
65
66 stime = kzalloc(sizeof(*stime), GFP_KERNEL);
67 if (!stime)
68 return -ENOMEM;
69 hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
70 stime->timer = t;
71 stime->hrt.function = snd_hrtimer_callback;
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 scoped_guard(spinlock_irq, &t->lock) {
82 t->running = 0; /* just to be sure */
83 stime->in_callback = 1; /* skip start/stop */
84 }
85
86 hrtimer_cancel(&stime->hrt);
87 kfree(stime);
88 t->private_data = NULL;
89 }
90 return 0;
91}
92
93static int snd_hrtimer_start(struct snd_timer *t)
94{
95 struct snd_hrtimer *stime = t->private_data;
96
97 if (stime->in_callback)
98 return 0;
99 hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
100 HRTIMER_MODE_REL);
101 return 0;
102}
103
104static int snd_hrtimer_stop(struct snd_timer *t)
105{
106 struct snd_hrtimer *stime = t->private_data;
107
108 if (stime->in_callback)
109 return 0;
110 hrtimer_try_to_cancel(&stime->hrt);
111 return 0;
112}
113
114static const struct snd_timer_hardware hrtimer_hw __initconst = {
115 .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_WORK,
116 .open = snd_hrtimer_open,
117 .close = snd_hrtimer_close,
118 .start = snd_hrtimer_start,
119 .stop = snd_hrtimer_stop,
120};
121
122/*
123 * entry functions
124 */
125
126static struct snd_timer *mytimer;
127
128static int __init snd_hrtimer_init(void)
129{
130 struct snd_timer *timer;
131 int err;
132
133 resolution = hrtimer_resolution;
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 timer->max_instances = 100; /* lower the limit */
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
158static void __exit snd_hrtimer_exit(void)
159{
160 if (mytimer) {
161 snd_timer_global_free(mytimer);
162 mytimer = NULL;
163 }
164}
165
166module_init(snd_hrtimer_init);
167module_exit(snd_hrtimer_exit);