sound/core/rtctimer.c

   1 /*
   2  *  RTC based high-frequency timer
   3  *
   4  *  Copyright (C) 2000 Takashi Iwai
   5  *      based on rtctimer.c by Steve Ratcliffe
   6  *
   7  *   This program is free software; you can redistribute it and/or modify
   8  *   it under the terms of the GNU General Public License as published by
   9  *   the Free Software Foundation; either version 2 of the License, or
  10  *   (at your option) any later version.
  11  *
  12  *   This program is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with this program; if not, write to the Free Software
  19  *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20  *
  21  */
  22
  23 #include <sound/driver.h>
  24 #include <linux/init.h>
  25 #include <linux/time.h>
  26 #include <linux/threads.h>
  27 #include <linux/interrupt.h>
  28 #include <linux/moduleparam.h>
  29 #include <sound/core.h>
  30 #include <sound/timer.h>
  31 #include <sound/info.h>
  32
  33 #if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
  34
  35 #include <linux/mc146818rtc.h>
  36
  37 #define RTC_FREQ        1024            /* default frequency */
  38 #define NANO_SEC        1000000000L     /* 10^9 in sec */
  39
  40 /*
  41  * prototypes
  42  */
  43 static int rtctimer_open(struct snd_timer *t);
  44 static int rtctimer_close(struct snd_timer *t);
  45 static int rtctimer_start(struct snd_timer *t);
  46 static int rtctimer_stop(struct snd_timer *t);
  47
  48
  49 /*
  50  * The hardware dependent description for this timer.
  51  */
  52 static struct snd_timer_hardware rtc_hw = {
  53         .flags =        SNDRV_TIMER_HW_FIRST|SNDRV_TIMER_HW_AUTO,
  54         .ticks =        100000000L,             /* FIXME: XXX */
  55         .open =         rtctimer_open,
  56         .close =        rtctimer_close,
  57         .start =        rtctimer_start,
  58         .stop =         rtctimer_stop,
  59 };
  60
  61 static int rtctimer_freq = RTC_FREQ;            /* frequency */
  62 static struct snd_timer *rtctimer;
  63 static rtc_task_t rtc_task;
  64
  65
  66 static int
  67 rtctimer_open(struct snd_timer *t)
  68 {
  69         int err;
  70
  71         err = rtc_register(&rtc_task);
  72         if (err < 0)
  73                 return err;
  74         t->private_data = &rtc_task;
  75         return 0;
  76 }
  77
  78 static int
  79 rtctimer_close(struct snd_timer *t)
  80 {
  81         rtc_task_t *rtc = t->private_data;
  82         if (rtc) {
  83                 rtc_unregister(rtc);
  84                 t->private_data = NULL;
  85         }
  86         return 0;
  87 }
  88
  89 static int
  90 rtctimer_start(struct snd_timer *timer)
  91 {
  92         rtc_task_t *rtc = timer->private_data;
  93         snd_assert(rtc != NULL, return -EINVAL);
  94         rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
  95         rtc_control(rtc, RTC_PIE_ON, 0);
  96         return 0;
  97 }
  98
  99 static int
 100 rtctimer_stop(struct snd_timer *timer)
 101 {
 102         rtc_task_t *rtc = timer->private_data;
 103         snd_assert(rtc != NULL, return -EINVAL);
 104         rtc_control(rtc, RTC_PIE_OFF, 0);
 105         return 0;
 106 }
 107
 108 /*
 109  * interrupt
 110  */
 111 static void rtctimer_interrupt(void *private_data)
 112 {
 113         snd_timer_interrupt(private_data, 1);
 114 }
 115
 116
 117 /*
 118  *  ENTRY functions
 119  */
 120 static int __init rtctimer_init(void)
 121 {
 122         int err;
 123         struct snd_timer *timer;
 124
 125         if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
 126             (rtctimer_freq & (rtctimer_freq - 1)) != 0) {
 127                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
 128                            rtctimer_freq);
 129                 return -EINVAL;
 130         }
 131
 132         /* Create a new timer and set up the fields */
 133         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
 134         if (err < 0)
 135                 return err;
 136
 137         timer->module = THIS_MODULE;
 138         strcpy(timer->name, "RTC timer");
 139         timer->hw = rtc_hw;
 140         timer->hw.resolution = NANO_SEC / rtctimer_freq;
 141
 142         /* set up RTC callback */
 143         rtc_task.func = rtctimer_interrupt;
 144         rtc_task.private_data = timer;
 145
 146         err = snd_timer_global_register(timer);
 147         if (err < 0) {
 148                 snd_timer_global_free(timer);
 149                 return err;
 150         }
 151         rtctimer = timer; /* remember this */
 152
 153         return 0;
 154 }
 155
 156 static void __exit rtctimer_exit(void)
 157 {
 158         if (rtctimer) {
 159                 snd_timer_global_unregister(rtctimer);
 160                 rtctimer = NULL;
 161         }
 162 }
 163
 164
 165 /*
 166  * exported stuff
 167  */
 168 module_init(rtctimer_init)
 169 module_exit(rtctimer_exit)
 170
 171 module_param(rtctimer_freq, int, 0444);
 172 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
 173
 174 MODULE_LICENSE("GPL");
 175
 176 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
 177
 178 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */