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 <linux/init.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/log2.h>
  27 #include <sound/core.h>
  28 #include <sound/timer.h>
  29
  30 #if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
  31
  32 #include <linux/mc146818rtc.h>
  33
  34 #define RTC_FREQ        1024            /* default frequency */
  35 #define NANO_SEC        1000000000L     /* 10^9 in sec */
  36
  37 /*
  38  * prototypes
  39  */
  40 static int rtctimer_open(struct snd_timer *t);
  41 static int rtctimer_close(struct snd_timer *t);
  42 static int rtctimer_start(struct snd_timer *t);
  43 static int rtctimer_stop(struct snd_timer *t);
  44
  45
  46 /*
  47  * The hardware dependent description for this timer.
  48  */
  49 static struct snd_timer_hardware rtc_hw = {
  50         .flags =        SNDRV_TIMER_HW_AUTO |
  51                         SNDRV_TIMER_HW_FIRST |
  52                         SNDRV_TIMER_HW_TASKLET,
  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 struct snd_timer *rtctimer;
  62 static struct tasklet_struct rtc_tasklet;
  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                 tasklet_kill(&rtc_tasklet);
  85                 t->private_data = NULL;
  86         }
  87         return 0;
  88 }
  89
  90 static int
  91 rtctimer_start(struct snd_timer *timer)
  92 {
  93         rtc_task_t *rtc = timer->private_data;
  94         snd_assert(rtc != NULL, return -EINVAL);
  95         rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
  96         rtc_control(rtc, RTC_PIE_ON, 0);
  97         return 0;
  98 }
  99
 100 static int
 101 rtctimer_stop(struct snd_timer *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 static void rtctimer_tasklet(unsigned long data)
 110 {
 111         snd_timer_interrupt((struct snd_timer *)data, 1);
 112 }
 113
 114 /*
 115  * interrupt
 116  */
 117 static void rtctimer_interrupt(void *private_data)
 118 {
 119         tasklet_hi_schedule(private_data);
 120 }
 121
 122
 123 /*
 124  *  ENTRY functions
 125  */
 126 static int __init rtctimer_init(void)
 127 {
 128         int err;
 129         struct snd_timer *timer;
 130
 131         if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
 132             !is_power_of_2(rtctimer_freq)) {
 133                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
 134                            rtctimer_freq);
 135                 return -EINVAL;
 136         }
 137
 138         /* Create a new timer and set up the fields */
 139         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
 140         if (err < 0)
 141                 return err;
 142
 143         timer->module = THIS_MODULE;
 144         strcpy(timer->name, "RTC timer");
 145         timer->hw = rtc_hw;
 146         timer->hw.resolution = NANO_SEC / rtctimer_freq;
 147
 148         tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
 149
 150         /* set up RTC callback */
 151         rtc_task.func = rtctimer_interrupt;
 152         rtc_task.private_data = &rtc_tasklet;
 153
 154         err = snd_timer_global_register(timer);
 155         if (err < 0) {
 156                 snd_timer_global_free(timer);
 157                 return err;
 158         }
 159         rtctimer = timer; /* remember this */
 160
 161         return 0;
 162 }
 163
 164 static void __exit rtctimer_exit(void)
 165 {
 166         if (rtctimer) {
 167                 snd_timer_global_free(rtctimer);
 168                 rtctimer = NULL;
 169         }
 170 }
 171
 172
 173 /*
 174  * exported stuff
 175  */
 176 module_init(rtctimer_init)
 177 module_exit(rtctimer_exit)
 178
 179 module_param(rtctimer_freq, int, 0444);
 180 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
 181
 182 MODULE_LICENSE("GPL");
 183
 184 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
 185
 186 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */