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_AUTO |
  54                         SNDRV_TIMER_HW_FIRST |
  55                         SNDRV_TIMER_HW_TASKLET,
  56         .ticks =        100000000L,             /* FIXME: XXX */
  57         .open =         rtctimer_open,
  58         .close =        rtctimer_close,
  59         .start =        rtctimer_start,
  60         .stop =         rtctimer_stop,
  61 };
  62
  63 static int rtctimer_freq = RTC_FREQ;            /* frequency */
  64 static struct snd_timer *rtctimer;
  65 static struct tasklet_struct rtc_tasklet;
  66 static rtc_task_t rtc_task;
  67
  68
  69 static int
  70 rtctimer_open(struct snd_timer *t)
  71 {
  72         int err;
  73
  74         err = rtc_register(&rtc_task);
  75         if (err < 0)
  76                 return err;
  77         t->private_data = &rtc_task;
  78         return 0;
  79 }
  80
  81 static int
  82 rtctimer_close(struct snd_timer *t)
  83 {
  84         rtc_task_t *rtc = t->private_data;
  85         if (rtc) {
  86                 rtc_unregister(rtc);
  87                 tasklet_kill(&rtc_tasklet);
  88                 t->private_data = NULL;
  89         }
  90         return 0;
  91 }
  92
  93 static int
  94 rtctimer_start(struct snd_timer *timer)
  95 {
  96         rtc_task_t *rtc = timer->private_data;
  97         snd_assert(rtc != NULL, return -EINVAL);
  98         rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
  99         rtc_control(rtc, RTC_PIE_ON, 0);
 100         return 0;
 101 }
 102
 103 static int
 104 rtctimer_stop(struct snd_timer *timer)
 105 {
 106         rtc_task_t *rtc = timer->private_data;
 107         snd_assert(rtc != NULL, return -EINVAL);
 108         rtc_control(rtc, RTC_PIE_OFF, 0);
 109         return 0;
 110 }
 111
 112 static void rtctimer_tasklet(unsigned long data)
 113 {
 114         snd_timer_interrupt((struct snd_timer *)data, 1);
 115 }
 116
 117 /*
 118  * interrupt
 119  */
 120 static void rtctimer_interrupt(void *private_data)
 121 {
 122         tasklet_hi_schedule(private_data);
 123 }
 124
 125
 126 /*
 127  *  ENTRY functions
 128  */
 129 static int __init rtctimer_init(void)
 130 {
 131         int err;
 132         struct snd_timer *timer;
 133
 134         if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
 135             (rtctimer_freq & (rtctimer_freq - 1)) != 0) {
 136                 snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
 137                            rtctimer_freq);
 138                 return -EINVAL;
 139         }
 140
 141         /* Create a new timer and set up the fields */
 142         err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
 143         if (err < 0)
 144                 return err;
 145
 146         timer->module = THIS_MODULE;
 147         strcpy(timer->name, "RTC timer");
 148         timer->hw = rtc_hw;
 149         timer->hw.resolution = NANO_SEC / rtctimer_freq;
 150
 151         tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
 152
 153         /* set up RTC callback */
 154         rtc_task.func = rtctimer_interrupt;
 155         rtc_task.private_data = &rtc_tasklet;
 156
 157         err = snd_timer_global_register(timer);
 158         if (err < 0) {
 159                 snd_timer_global_free(timer);
 160                 return err;
 161         }
 162         rtctimer = timer; /* remember this */
 163
 164         return 0;
 165 }
 166
 167 static void __exit rtctimer_exit(void)
 168 {
 169         if (rtctimer) {
 170                 snd_timer_global_unregister(rtctimer);
 171                 rtctimer = NULL;
 172         }
 173 }
 174
 175
 176 /*
 177  * exported stuff
 178  */
 179 module_init(rtctimer_init)
 180 module_exit(rtctimer_exit)
 181
 182 module_param(rtctimer_freq, int, 0444);
 183 MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
 184
 185 MODULE_LICENSE("GPL");
 186
 187 MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
 188
 189 #endif /* CONFIG_RTC || CONFIG_RTC_MODULE */