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Release 4.14 sound/core/hrtimer.c

Directory: sound/core
/*
 * ALSA timer back-end using hrtimer
 * Copyright (C) 2008 Takashi Iwai
 *
 *   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
 *
 */

#include <linux/init.h>
#include <linux/slab.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;


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; spin_lock(&t->lock); if (!t->running) goto out; /* fast path */ stime->in_callback = true; ticks = t->sticks; spin_unlock(&t->lock); /* calculate the drift */ delta = ktime_sub(hrt->base->get_time(), hrtimer_get_expires(hrt)); if (delta > 0) ticks += ktime_divns(delta, ticks * resolution); snd_timer_interrupt(stime->timer, ticks); spin_lock(&t->lock); if (t->running) { hrtimer_add_expires_ns(hrt, t->sticks * resolution); ret = HRTIMER_RESTART; } stime->in_callback = false; out: spin_unlock(&t->lock); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai17897.80%375.00%
Clemens Ladisch42.20%125.00%
Total182100.00%4100.00%


static int snd_hrtimer_open(struct snd_timer *t) { struct snd_hrtimer *stime; stime = kzalloc(sizeof(*stime), GFP_KERNEL); if (!stime) return -ENOMEM; hrtimer_init(&stime->hrt, CLOCK_MONOTONIC, HRTIMER_MODE_REL); stime->timer = t; stime->hrt.function = snd_hrtimer_callback; t->private_data = stime; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai73100.00%2100.00%
Total73100.00%2100.00%


static int snd_hrtimer_close(struct snd_timer *t) { struct snd_hrtimer *stime = t->private_data; if (stime) { spin_lock_irq(&t->lock); t->running = 0; /* just to be sure */ stime->in_callback = 1; /* skip start/stop */ spin_unlock_irq(&t->lock); hrtimer_cancel(&stime->hrt); kfree(stime); t->private_data = NULL; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai78100.00%2100.00%
Total78100.00%2100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai51100.00%4100.00%
Total51100.00%4100.00%


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; }

Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai40100.00%4100.00%
Total40100.00%4100.00%

static struct snd_timer_hardware hrtimer_hw = { .flags = SNDRV_TIMER_HW_AUTO | SNDRV_TIMER_HW_TASKLET, .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; strcpy(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; }

Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai11999.17%266.67%
Thomas Gleixner10.83%133.33%
Total120100.00%3100.00%


static void __exit snd_hrtimer_exit(void) { if (mytimer) { snd_timer_global_free(mytimer); mytimer = NULL; } }

Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai24100.00%1100.00%
Total24100.00%1100.00%

module_init(snd_hrtimer_init); module_exit(snd_hrtimer_exit);

Overall Contributors

PersonTokensPropCommitsCommitProp
Takashi Iwai68298.55%660.00%
Clemens Ladisch60.87%220.00%
Tejun Heo30.43%110.00%
Thomas Gleixner10.14%110.00%
Total692100.00%10100.00%
Directory: sound/core
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