linux/sound/core/rtctimer.c
<<
>>
Prefs
   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/interrupt.h>
  26#include <linux/moduleparam.h>
  27#include <linux/log2.h>
  28#include <sound/core.h>
  29#include <sound/timer.h>
  30
  31#if defined(CONFIG_RTC) || defined(CONFIG_RTC_MODULE)
  32
  33#include <linux/mc146818rtc.h>
  34
  35#define RTC_FREQ        1024            /* default frequency */
  36#define NANO_SEC        1000000000L     /* 10^9 in sec */
  37
  38/*
  39 * prototypes
  40 */
  41static int rtctimer_open(struct snd_timer *t);
  42static int rtctimer_close(struct snd_timer *t);
  43static int rtctimer_start(struct snd_timer *t);
  44static int rtctimer_stop(struct snd_timer *t);
  45
  46
  47/*
  48 * The hardware dependent description for this timer.
  49 */
  50static struct snd_timer_hardware rtc_hw = {
  51        .flags =        SNDRV_TIMER_HW_AUTO |
  52                        SNDRV_TIMER_HW_FIRST |
  53                        SNDRV_TIMER_HW_TASKLET,
  54        .ticks =        100000000L,             /* FIXME: XXX */
  55        .open =         rtctimer_open,
  56        .close =        rtctimer_close,
  57        .start =        rtctimer_start,
  58        .stop =         rtctimer_stop,
  59};
  60
  61static int rtctimer_freq = RTC_FREQ;            /* frequency */
  62static struct snd_timer *rtctimer;
  63static struct tasklet_struct rtc_tasklet;
  64static rtc_task_t rtc_task;
  65
  66
  67static int
  68rtctimer_open(struct snd_timer *t)
  69{
  70        int err;
  71
  72        err = rtc_register(&rtc_task);
  73        if (err < 0)
  74                return err;
  75        t->private_data = &rtc_task;
  76        return 0;
  77}
  78
  79static int
  80rtctimer_close(struct snd_timer *t)
  81{
  82        rtc_task_t *rtc = t->private_data;
  83        if (rtc) {
  84                rtc_unregister(rtc);
  85                tasklet_kill(&rtc_tasklet);
  86                t->private_data = NULL;
  87        }
  88        return 0;
  89}
  90
  91static int
  92rtctimer_start(struct snd_timer *timer)
  93{
  94        rtc_task_t *rtc = timer->private_data;
  95        snd_assert(rtc != NULL, return -EINVAL);
  96        rtc_control(rtc, RTC_IRQP_SET, rtctimer_freq);
  97        rtc_control(rtc, RTC_PIE_ON, 0);
  98        return 0;
  99}
 100
 101static int
 102rtctimer_stop(struct snd_timer *timer)
 103{
 104        rtc_task_t *rtc = timer->private_data;
 105        snd_assert(rtc != NULL, return -EINVAL);
 106        rtc_control(rtc, RTC_PIE_OFF, 0);
 107        return 0;
 108}
 109
 110static void rtctimer_tasklet(unsigned long data)
 111{
 112        snd_timer_interrupt((struct snd_timer *)data, 1);
 113}
 114
 115/*
 116 * interrupt
 117 */
 118static void rtctimer_interrupt(void *private_data)
 119{
 120        tasklet_hi_schedule(private_data);
 121}
 122
 123
 124/*
 125 *  ENTRY functions
 126 */
 127static int __init rtctimer_init(void)
 128{
 129        int err;
 130        struct snd_timer *timer;
 131
 132        if (rtctimer_freq < 2 || rtctimer_freq > 8192 ||
 133            !is_power_of_2(rtctimer_freq)) {
 134                snd_printk(KERN_ERR "rtctimer: invalid frequency %d\n",
 135                           rtctimer_freq);
 136                return -EINVAL;
 137        }
 138
 139        /* Create a new timer and set up the fields */
 140        err = snd_timer_global_new("rtc", SNDRV_TIMER_GLOBAL_RTC, &timer);
 141        if (err < 0)
 142                return err;
 143
 144        timer->module = THIS_MODULE;
 145        strcpy(timer->name, "RTC timer");
 146        timer->hw = rtc_hw;
 147        timer->hw.resolution = NANO_SEC / rtctimer_freq;
 148
 149        tasklet_init(&rtc_tasklet, rtctimer_tasklet, (unsigned long)timer);
 150
 151        /* set up RTC callback */
 152        rtc_task.func = rtctimer_interrupt;
 153        rtc_task.private_data = &rtc_tasklet;
 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
 165static void __exit rtctimer_exit(void)
 166{
 167        if (rtctimer) {
 168                snd_timer_global_free(rtctimer);
 169                rtctimer = NULL;
 170        }
 171}
 172
 173
 174/*
 175 * exported stuff
 176 */
 177module_init(rtctimer_init)
 178module_exit(rtctimer_exit)
 179
 180module_param(rtctimer_freq, int, 0444);
 181MODULE_PARM_DESC(rtctimer_freq, "timer frequency in Hz");
 182
 183MODULE_LICENSE("GPL");
 184
 185MODULE_ALIAS("snd-timer-" __stringify(SNDRV_TIMER_GLOBAL_RTC));
 186
 187#endif /* CONFIG_RTC || CONFIG_RTC_MODULE */
 188