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