diff options
Diffstat (limited to 'sound/core/rtctimer.c')
| -rw-r--r-- | sound/core/rtctimer.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/sound/core/rtctimer.c b/sound/core/rtctimer.c new file mode 100644 index 000000000000..bd5d584d284d --- /dev/null +++ b/sound/core/rtctimer.c @@ -0,0 +1,188 @@ +/* + * 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 */ |