/*
* 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 <sound/driver.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/threads.h>
#include <linux/interrupt.h>
#include <linux/moduleparam.h>
#include <sound/core.h>
#include <sound/timer.h>
#include <sound/info.h>
#if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
#include <linux/mc146818rtc.h>
#define RTC_FREQ 1024 /* default frequency */
#define NANO_SEC 1000000000L /* 10^9 in sec */
/*
* prototypes
*/
static int rtctimer_open(snd_timer_t *t);
static int rtctimer_close(snd_timer_t *t);
static int rtctimer_start(snd_timer_t *t);
static int rtctimer_stop(snd_timer_t *t);
/*
* The hardware dependent description for this timer.
*/
static struct _snd_timer_hardware rtc_hw = {
.flags = SNDRV_TIMER_HW_FIRST|SNDRV_TIMER_HW_AUTO,
.ticks = 100000000L, /* FIXME: XXX */
.open = rtctimer_open,
.close = rtctimer_close,
.start = rtctimer_start,
.stop = rtctimer_stop,
};
static int rtctimer_freq = RTC_FREQ; /* frequency */
static snd_timer_t *rtctimer;
static atomic_t rtc_inc = ATOMIC_INIT(0);
static rtc_task_t rtc_task;
static int
rtctimer_open(snd_timer_t *t)
{
int err;
err = rtc_register(&rtc_task);
if (err < 0)
return err;
t->private_data = &rtc_task;
return 0;
}
static int
rtctimer_close(snd_timer_t *t)
{
rtc_task_t *rtc = t->private_data;
if (rtc) {
rtc_unregister(rtc);
t->private_data = NULL;
}
return 0;
}
static int
rtctimer_start(snd_timer_t *timer)
{
rtc_task_t *rtc = timer->private_data;
snd_assert(rtc != NULL, return -EINVAL);
rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
rtc_control(rtc, RTC_PIE_ON, 0);
atomic_set(&rtc_inc, 0);
return 0;
}
static int
rtctimer_stop(snd_timer_t *timer)
{
rtc_task_t *rtc = timer->private_data;
snd_assert(rtc != NULL, return -EINVAL);
rtc_control(rtc, RTC_PIE_OFF, 0);
return 0;
}
/*
* interrupt
*/
static void rtctimer_interrupt(void *private_data)
{
int ticks;
atomic_inc(&rtc_inc);
ticks = atomic_read(&rtc_inc);
snd_timer_interrupt((snd_timer_t*)private_data, ticks);
atomic_sub(ticks, &rtc_inc);
}
/*
* ENTRY functions
*/
static int __init rtctimer_init(void)
{
int order, err;
snd_timer_t *timer;
if (rtctimer_freq < 2 || rtctimer_freq > 8192) {
snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n", rtctimer_freq);
return -EINVAL;
}
for (order = 1; rtctimer_freq > order; order <<= 1)
;
if (rtctimer_freq != order) {
snd_printk(KERN_ERR "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;
strcpy(timer->name, "RTC timer");
timer->hw = rtc_hw;
timer->hw.resolution = NANO_SEC / rtctimer_freq;
/* set up RTC callback */
rtc_task.func = rtctimer_interrupt;
rtc_task.private_data = timer;
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_unregister(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 /* CONFIG_RTC || CONFIG_RTC_MODULE */
