Thomas Gleixner | 1a59d1b8 | 2019-05-27 08:55:05 +0200 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 2 | /* |
Takashi Iwai | 647808a | 2008-12-08 12:16:58 +0100 | [diff] [blame] | 3 | * ALSA timer back-end using hrtimer |
| 4 | * Copyright (C) 2008 Takashi Iwai |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 5 | */ |
| 6 | |
| 7 | #include <linux/init.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 8 | #include <linux/slab.h> |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 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 | |
| 15 | MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>"); |
| 16 | MODULE_DESCRIPTION("ALSA hrtimer backend"); |
| 17 | MODULE_LICENSE("GPL"); |
| 18 | |
| 19 | MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER)); |
| 20 | |
| 21 | #define NANO_SEC 1000000000UL /* 10^9 in sec */ |
| 22 | static unsigned int resolution; |
| 23 | |
| 24 | struct snd_hrtimer { |
| 25 | struct snd_timer *timer; |
| 26 | struct hrtimer hrt; |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 27 | bool in_callback; |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 28 | }; |
| 29 | |
| 30 | static 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; |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 34 | ktime_t delta; |
| 35 | unsigned long ticks; |
| 36 | enum hrtimer_restart ret = HRTIMER_NORESTART; |
Takashi Iwai | fcfdebe | 2009-12-11 12:51:05 +0100 | [diff] [blame] | 37 | |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 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); |
Takashi Iwai | fcfdebe | 2009-12-11 12:51:05 +0100 | [diff] [blame] | 44 | |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 45 | /* calculate the drift */ |
| 46 | delta = ktime_sub(hrt->base->get_time(), hrtimer_get_expires(hrt)); |
Thomas Gleixner | 2456e85 | 2016-12-25 11:38:40 +0100 | [diff] [blame] | 47 | if (delta > 0) |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 48 | ticks += ktime_divns(delta, ticks * resolution); |
Takashi Iwai | fcfdebe | 2009-12-11 12:51:05 +0100 | [diff] [blame] | 49 | |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 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; |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 62 | } |
| 63 | |
| 64 | static int snd_hrtimer_open(struct snd_timer *t) |
| 65 | { |
| 66 | struct snd_hrtimer *stime; |
| 67 | |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 68 | stime = kzalloc(sizeof(*stime), GFP_KERNEL); |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 69 | if (!stime) |
| 70 | return -ENOMEM; |
| 71 | hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| 72 | stime->timer = t; |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 73 | stime->hrt.function = snd_hrtimer_callback; |
| 74 | t->private_data = stime; |
| 75 | return 0; |
| 76 | } |
| 77 | |
| 78 | static int snd_hrtimer_close(struct snd_timer *t) |
| 79 | { |
| 80 | struct snd_hrtimer *stime = t->private_data; |
| 81 | |
| 82 | if (stime) { |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 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 | |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 88 | hrtimer_cancel(&stime->hrt); |
| 89 | kfree(stime); |
| 90 | t->private_data = NULL; |
| 91 | } |
| 92 | return 0; |
| 93 | } |
| 94 | |
| 95 | static int snd_hrtimer_start(struct snd_timer *t) |
| 96 | { |
| 97 | struct snd_hrtimer *stime = t->private_data; |
| 98 | |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 99 | if (stime->in_callback) |
| 100 | return 0; |
Takashi Iwai | 647808a | 2008-12-08 12:16:58 +0100 | [diff] [blame] | 101 | hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution), |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 102 | HRTIMER_MODE_REL); |
| 103 | return 0; |
| 104 | } |
| 105 | |
| 106 | static int snd_hrtimer_stop(struct snd_timer *t) |
| 107 | { |
| 108 | struct snd_hrtimer *stime = t->private_data; |
Takashi Iwai | d2c5cf8 | 2016-04-24 22:52:18 +0200 | [diff] [blame] | 109 | |
| 110 | if (stime->in_callback) |
| 111 | return 0; |
Takashi Iwai | 2ba1fe7 | 2016-01-18 13:52:47 +0100 | [diff] [blame] | 112 | hrtimer_try_to_cancel(&stime->hrt); |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 113 | return 0; |
| 114 | } |
| 115 | |
Bhumika Goyal | 3840583 | 2017-09-19 16:44:38 +0530 | [diff] [blame] | 116 | static const struct snd_timer_hardware hrtimer_hw __initconst = { |
Clemens Ladisch | 2243c4d | 2011-02-10 16:16:32 +0100 | [diff] [blame] | 117 | .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET, |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 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 | |
| 128 | static struct snd_timer *mytimer; |
| 129 | |
| 130 | static int __init snd_hrtimer_init(void) |
| 131 | { |
| 132 | struct snd_timer *timer; |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 133 | int err; |
| 134 | |
Thomas Gleixner | 447fbbd | 2015-04-14 21:08:30 +0000 | [diff] [blame] | 135 | resolution = hrtimer_resolution; |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 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; |
Takashi Iwai | 9b7d869 | 2017-11-05 10:07:43 +0100 | [diff] [blame] | 148 | timer->max_instances = 100; /* lower the limit */ |
Takashi Iwai | bbaf5e9 | 2008-10-24 18:16:50 +0200 | [diff] [blame] | 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 | |
| 160 | static void __exit snd_hrtimer_exit(void) |
| 161 | { |
| 162 | if (mytimer) { |
| 163 | snd_timer_global_free(mytimer); |
| 164 | mytimer = NULL; |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | module_init(snd_hrtimer_init); |
| 169 | module_exit(snd_hrtimer_exit); |