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/*
* RTC based high-frequency timer
*
* Copyright (C) 2000 Takashi Iwai
* based on rtctimer.c by Steve Ratcliffe
*
* 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/interrupt.h>
#include <linux/module.h>
#include <linux/log2.h>
#include <sound/core.h>
#include <sound/timer.h>
#if IS_ENABLED(CONFIG_RTC)
#include <linux/mc146818rtc.h>
#define RTC_FREQ 1024 /* default frequency */
#define NANO_SEC 1000000000L /* 10^9 in sec */
/*
* prototypes
*/
static int rtctimer_open(struct snd_timer *t);
static int rtctimer_close(struct snd_timer *t);
static int rtctimer_start(struct snd_timer *t);
static int rtctimer_stop(struct snd_timer *t);
/*
* The hardware dependent description for this timer.
*/
static struct snd_timer_hardware rtc_hw = {
.flags = SNDRV_TIMER_HW_AUTO |
SNDRV_TIMER_HW_FIRST |
SNDRV_TIMER_HW_TASKLET,
.ticks = 100000000L, /* FIXME: XXX */
.open = rtctimer_open,
.close = rtctimer_close,
.start = rtctimer_start,
.stop = rtctimer_stop,
};
static int rtctimer_freq = RTC_FREQ; /* frequency */
static struct snd_timer *rtctimer;
static struct tasklet_struct rtc_tasklet;
static rtc_task_t rtc_task;
static int
rtctimer_open(struct snd_timer *t)
{
int err;
err = rtc_register(&rtc_task);
if (err < 0)
return err;
t->private_data = &rtc_task;
return 0;
}
static int
rtctimer_close(struct snd_timer *t)
{
rtc_task_t *rtc = t->private_data;
if (rtc) {
rtc_unregister(rtc);
tasklet_kill(&rtc_tasklet);
t->private_data = NULL;
}
return 0;
}
static int
rtctimer_start(struct snd_timer *timer)
{
rtc_task_t *rtc = timer->private_data;
if (snd_BUG_ON(!rtc))
return -EINVAL;
rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
rtc_control(rtc, RTC_PIE_ON, 0);
return 0;
}
static int
rtctimer_stop(struct snd_timer *timer)
{
rtc_task_t *rtc = timer->private_data;
if (snd_BUG_ON(!rtc))
return -EINVAL;
rtc_control(rtc, RTC_PIE_OFF, 0);
return 0;
}
static void rtctimer_tasklet(unsigned long data)
{
snd_timer_interrupt((struct snd_timer *)data, 1);
}
/*
* interrupt
*/
static void rtctimer_interrupt(void *private_data)
{
tasklet_schedule(private_data);
}
/*
* ENTRY functions
*/
static int __init rtctimer_init(void)
{
int err;
struct snd_timer *timer;
if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
!is_power_of_2(rtctimer_freq)) {
pr_err("ALSA: rtctimer: invalid frequency %d\n", rtctimer_freq);
return -EINVAL;
}
/* Create a new timer and set up the fields */
err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
if (err < 0)
return err;
timer->module = THIS_MODULE;
strcpy(timer->name, "RTC timer");
timer->hw = rtc_hw;
timer->hw.resolution = NANO_SEC / rtctimer_freq;
tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
/* set up RTC callback */
rtc_task.func = rtctimer_interrupt;
rtc_task.private_data = &rtc_tasklet;
err = snd_timer_global_register(timer);
if (err < 0) {
snd_timer_global_free(timer);
return err;
}
rtctimer = timer; /* remember this */
return 0;
}
static void __exit rtctimer_exit(void)
{
if (rtctimer) {
snd_timer_global_free(rtctimer);
rtctimer = NULL;
}
}
/*
* exported stuff
*/
module_init(rtctimer_init)
module_exit(rtctimer_exit)
module_param(rtctimer_freq, int, 0444);
MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
MODULE_LICENSE("GPL");
MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
#endif /* IS_ENABLED(CONFIG_RTC) */
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