/* * 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 */