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 <sound/core.h>
  29 #include <sound/timer.h>
  30 #include <sound/info.h>
  31
  32 #if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
  33
  34 #include <linux/mc146818rtc.h>
  35
  36 #define RTC_FREQ        1024            /* default frequency */
  37 #define NANO_SEC        1000000000L     /* 10^9 in sec */
  38
  39 /*
  40  * prototypes
  41  */
  42 static int rtctimer_open(snd_timer_t *t);
  43 static int rtctimer_close(snd_timer_t *t);
  44 static int rtctimer_start(snd_timer_t *t);
  45 static int rtctimer_stop(snd_timer_t *t);
  46
  47
  48 /*
  49  * The hardware dependent description for this timer.
  50  */
  51 static struct _snd_timer_hardware rtc_hw = {
  52         .flags =        SNDRV_TIMER_HW_FIRST|SNDRV_TIMER_HW_AUTO,
  53         .ticks =        100000000L,             /* FIXME: XXX */
  54         .open =         rtctimer_open,
  55         .close =        rtctimer_close,
  56         .start =        rtctimer_start,
  57         .stop =         rtctimer_stop,
  58 };
  59
  60 static int rtctimer_freq = RTC_FREQ;            /* frequency */
  61 static snd_timer_t *rtctimer;
  62 static atomic_t rtc_inc = ATOMIC_INIT(0);
  63 static rtc_task_t rtc_task;
  64
  65
  66 static int
  67 rtctimer_open(snd_timer_t *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(snd_timer_t *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(snd_timer_t *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         atomic_set(&rtc_inc, 0);
  97         return 0;
  98 }
  99
 100 static int
 101 rtctimer_stop(snd_timer_t *timer)
 102 {
 103         rtc_task_t *rtc = timer->private_data;
 104         snd_assert(rtc != NULL, return -EINVAL);
 105         rtc_control(rtc, RTC_PIE_OFF, 0);
 106         return 0;
 107 }
 108
 109 /*
 110  * interrupt
 111  */
 112 static void rtctimer_interrupt(void *private_data)
 113 {
 114         int ticks;
 115
 116         atomic_inc(&rtc_inc);
 117         ticks = atomic_read(&rtc_inc);
 118         snd_timer_interrupt((snd_timer_t*)private_data, ticks);
 119         atomic_sub(ticks, &rtc_inc);
 120 }
 121
 122
 123 /*
 124  *  ENTRY functions
 125  */
 126 static int __init rtctimer_init(void)
 127 {
 128         int order, err;
 129         snd_timer_t *timer;
 130
 131         if (rtctimer_freq < 2 || rtctimer_freq > 8192) {
 132                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n", rtctimer_freq);
 133                 return -EINVAL;
 134         }
 135         for (order = 1; rtctimer_freq > order; order <<= 1)
 136                 ;
 137         if (rtctimer_freq != order) {
 138                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n", rtctimer_freq);
 139                 return -EINVAL;
 140         }
 141
 142         /* Create a new timer and set up the fields */
 143         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
 144         if (err < 0)
 145                 return err;
 146
 147         strcpy(timer->name, "RTC timer");
 148         timer->hw = rtc_hw;
 149         timer->hw.resolution = NANO_SEC / rtctimer_freq;
 150
 151         /* set up RTC callback */
 152         rtc_task.func = rtctimer_interrupt;
 153         rtc_task.private_data = timer;
 154
 155         err = snd_timer_global_register(timer);
 156         if (err < 0) {
 157                 snd_timer_global_free(timer);
 158                 return err;
 159         }
 160         rtctimer = timer; /* remember this */
 161
 162         return 0;
 163 }
 164
 165 static void __exit rtctimer_exit(void)
 166 {
 167         if (rtctimer) {
 168                 snd_timer_global_unregister(rtctimer);
 169                 rtctimer = NULL;
 170         }
 171 }
 172
 173
 174 /*
 175  * exported stuff
 176  */
 177 module_init(rtctimer_init)
 178 module_exit(rtctimer_exit)
 179
 180 MODULE_PARM(rtctimer_freq, "i");
 181 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
 182
 183 MODULE_LICENSE("GPL");
 184
 185 #ifndef MODULE
 186 /* format is: snd-rtctimer=freq */
 187
 188 static int __init rtctimer_setup(char *str)
 189 {
 190         (void)(get_option(&str,&rtctimer_freq) == 2);
 191         return 1;
 192 }
 193
 194 __setup("snd-rtctimer=", rtctimer_setup);
 195 #endif /* ifndef MODULE */
 196
 197 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */