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(I'm so sorry!) Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168// SPDX-License-Identifier: GPL-2.0-or-later/* * ALSA timer back-end using hrtimer * Copyright (C) 2008 Takashi Iwai */
#include <linux/init.h>#include <linux/slab.h>#include <linux/string.h>#include <linux/module.h>#include <linux/moduleparam.h>#include <linux/hrtimer.h>#include <sound/core.h>#include <sound/timer.h>
MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");MODULE_DESCRIPTION("ALSA hrtimer backend");MODULE_LICENSE("GPL");
MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
#define NANO_SEC 1000000000UL /* 10^9 in sec */static unsigned int resolution __ro_after_init;
struct snd_hrtimer { struct snd_timer *timer; struct hrtimer hrt; bool in_callback;};
static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt){ struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt); struct snd_timer *t = stime->timer; ktime_t delta; unsigned long ticks; enum hrtimer_restart ret = HRTIMER_NORESTART;
scoped_guard(spinlock, &t->lock) { if (!t->running) return HRTIMER_NORESTART; /* fast path */ stime->in_callback = true; ticks = t->sticks; }
/* calculate the drift */ delta = ktime_sub(hrtimer_cb_get_time(hrt), hrtimer_get_expires(hrt)); if (delta > 0) ticks += ktime_divns(delta, ticks * resolution);
snd_timer_interrupt(stime->timer, ticks);
guard(spinlock)(&t->lock); if (t->running) { hrtimer_add_expires_ns(hrt, t->sticks * resolution); ret = HRTIMER_RESTART; }
stime->in_callback = false; return ret;}
static int snd_hrtimer_open(struct snd_timer *t){ struct snd_hrtimer *stime;
stime = kzalloc_obj(*stime); if (!stime) return -ENOMEM; stime->timer = t; hrtimer_setup(&stime->hrt, snd_hrtimer_callback, CLOCK_MONOTONIC, HRTIMER_MODE_REL); t->private_data = stime; return 0;}
static int snd_hrtimer_close(struct snd_timer *t){ struct snd_hrtimer *stime = t->private_data;
if (stime) { scoped_guard(spinlock_irq, &t->lock) { t->running = 0; /* just to be sure */ stime->in_callback = 1; /* skip start/stop */ }
hrtimer_cancel(&stime->hrt); kfree(stime); t->private_data = NULL; } return 0;}
static int snd_hrtimer_start(struct snd_timer *t){ struct snd_hrtimer *stime = t->private_data;
if (stime->in_callback) return 0; hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution), HRTIMER_MODE_REL); return 0;}
static int snd_hrtimer_stop(struct snd_timer *t){ struct snd_hrtimer *stime = t->private_data;
if (stime->in_callback) return 0; hrtimer_try_to_cancel(&stime->hrt); return 0;}
static const struct snd_timer_hardware hrtimer_hw __initconst = { .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_WORK, .open = snd_hrtimer_open, .close = snd_hrtimer_close, .start = snd_hrtimer_start, .stop = snd_hrtimer_stop,};
/* * entry functions */
static struct snd_timer *mytimer;
static int __init snd_hrtimer_init(void){ struct snd_timer *timer; int err;
resolution = hrtimer_resolution;
/* Create a new timer and set up the fields */ err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER, &timer); if (err < 0) return err;
timer->module = THIS_MODULE; strscpy(timer->name, "HR timer"); timer->hw = hrtimer_hw; timer->hw.resolution = resolution; timer->hw.ticks = NANO_SEC / resolution; timer->max_instances = 100; /* lower the limit */
err = snd_timer_global_register(timer); if (err < 0) { snd_timer_global_free(timer); return err; } mytimer = timer; /* remember this */
return 0;}
static void __exit snd_hrtimer_exit(void){ if (mytimer) { snd_timer_global_free(mytimer); mytimer = NULL; }}
module_init(snd_hrtimer_init);module_exit(snd_hrtimer_exit);