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![Thomas Gleixner](/assets/img/avatar_default.png)
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Richard Fontana <rfontana@redhat.com> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
169 lines
3.6 KiB
C
169 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* ALSA timer back-end using hrtimer
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* Copyright (C) 2008 Takashi Iwai
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*/
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/hrtimer.h>
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#include <sound/core.h>
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#include <sound/timer.h>
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MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
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MODULE_DESCRIPTION("ALSA hrtimer backend");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_HRTIMER));
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#define NANO_SEC 1000000000UL /* 10^9 in sec */
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static unsigned int resolution;
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struct snd_hrtimer {
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struct snd_timer *timer;
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struct hrtimer hrt;
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bool in_callback;
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};
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static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
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{
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struct snd_hrtimer *stime = container_of(hrt, struct snd_hrtimer, hrt);
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struct snd_timer *t = stime->timer;
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ktime_t delta;
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unsigned long ticks;
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enum hrtimer_restart ret = HRTIMER_NORESTART;
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spin_lock(&t->lock);
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if (!t->running)
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goto out; /* fast path */
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stime->in_callback = true;
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ticks = t->sticks;
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spin_unlock(&t->lock);
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/* calculate the drift */
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delta = ktime_sub(hrt->base->get_time(), hrtimer_get_expires(hrt));
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if (delta > 0)
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ticks += ktime_divns(delta, ticks * resolution);
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snd_timer_interrupt(stime->timer, ticks);
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spin_lock(&t->lock);
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if (t->running) {
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hrtimer_add_expires_ns(hrt, t->sticks * resolution);
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ret = HRTIMER_RESTART;
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}
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stime->in_callback = false;
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out:
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spin_unlock(&t->lock);
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return ret;
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}
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static int snd_hrtimer_open(struct snd_timer *t)
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{
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struct snd_hrtimer *stime;
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stime = kzalloc(sizeof(*stime), GFP_KERNEL);
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if (!stime)
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return -ENOMEM;
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hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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stime->timer = t;
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stime->hrt.function = snd_hrtimer_callback;
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t->private_data = stime;
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return 0;
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}
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static int snd_hrtimer_close(struct snd_timer *t)
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{
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struct snd_hrtimer *stime = t->private_data;
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if (stime) {
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spin_lock_irq(&t->lock);
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t->running = 0; /* just to be sure */
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stime->in_callback = 1; /* skip start/stop */
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spin_unlock_irq(&t->lock);
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hrtimer_cancel(&stime->hrt);
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kfree(stime);
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t->private_data = NULL;
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}
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return 0;
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}
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static int snd_hrtimer_start(struct snd_timer *t)
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{
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struct snd_hrtimer *stime = t->private_data;
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if (stime->in_callback)
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return 0;
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hrtimer_start(&stime->hrt, ns_to_ktime(t->sticks * resolution),
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HRTIMER_MODE_REL);
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return 0;
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}
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static int snd_hrtimer_stop(struct snd_timer *t)
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{
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struct snd_hrtimer *stime = t->private_data;
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if (stime->in_callback)
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return 0;
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hrtimer_try_to_cancel(&stime->hrt);
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return 0;
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}
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static const struct snd_timer_hardware hrtimer_hw __initconst = {
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.flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET,
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.open = snd_hrtimer_open,
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.close = snd_hrtimer_close,
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.start = snd_hrtimer_start,
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.stop = snd_hrtimer_stop,
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};
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/*
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* entry functions
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*/
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static struct snd_timer *mytimer;
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static int __init snd_hrtimer_init(void)
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{
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struct snd_timer *timer;
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int err;
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resolution = hrtimer_resolution;
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/* Create a new timer and set up the fields */
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err = snd_timer_global_new("hrtimer", SNDRV_TIMER_GLOBAL_HRTIMER,
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&timer);
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if (err < 0)
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return err;
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timer->module = THIS_MODULE;
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strcpy(timer->name, "HR timer");
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timer->hw = hrtimer_hw;
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timer->hw.resolution = resolution;
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timer->hw.ticks = NANO_SEC / resolution;
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timer->max_instances = 100; /* lower the limit */
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err = snd_timer_global_register(timer);
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if (err < 0) {
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snd_timer_global_free(timer);
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return err;
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}
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mytimer = timer; /* remember this */
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return 0;
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}
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static void __exit snd_hrtimer_exit(void)
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{
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if (mytimer) {
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snd_timer_global_free(mytimer);
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mytimer = NULL;
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}
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}
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module_init(snd_hrtimer_init);
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module_exit(snd_hrtimer_exit);
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