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![Thomas Gleixner](/assets/img/avatar_default.png)
ktime is a union because the initial implementation stored the time in scalar nanoseconds on 64 bit machine and in a endianess optimized timespec variant for 32bit machines. The Y2038 cleanup removed the timespec variant and switched everything to scalar nanoseconds. The union remained, but become completely pointless. Get rid of the union and just keep ktime_t as simple typedef of type s64. The conversion was done with coccinelle and some manual mopping up. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org>
182 lines
4.2 KiB
C
182 lines
4.2 KiB
C
/*
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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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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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 struct snd_timer_hardware hrtimer_hw = {
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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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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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