amisound.c
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/*
* linux/arch/m68k/amiga/amisound.c
*
* amiga sound driver for Linux/m68k
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file COPYING in the main directory of this archive
* for more details.
*/
#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/module.h>
#include <asm/amigahw.h>
static unsigned short *snd_data;
static const signed char sine_data[] = {
0, 39, 75, 103, 121, 127, 121, 103, 75, 39,
0, -39, -75, -103, -121, -127, -121, -103, -75, -39
};
#define DATA_SIZE ARRAY_SIZE(sine_data)
#define custom amiga_custom
/*
* The minimum period for audio may be modified by the frame buffer
* device since it depends on htotal (for OCS/ECS/AGA)
*/
volatile unsigned short amiga_audio_min_period = 124; /* Default for pre-OCS */
EXPORT_SYMBOL(amiga_audio_min_period);
#define MAX_PERIOD (65535)
/*
* Current period (set by dmasound.c)
*/
unsigned short amiga_audio_period = MAX_PERIOD;
EXPORT_SYMBOL(amiga_audio_period);
static unsigned long clock_constant;
void __init amiga_init_sound(void)
{
static struct resource beep_res = { .name = "Beep" };
snd_data = amiga_chip_alloc_res(sizeof(sine_data), &beep_res);
if (!snd_data) {
printk (KERN_CRIT "amiga init_sound: failed to allocate chipmem\n");
return;
}
memcpy (snd_data, sine_data, sizeof(sine_data));
/* setup divisor */
clock_constant = (amiga_colorclock+DATA_SIZE/2)/DATA_SIZE;
/* without amifb, turn video off and enable high quality sound */
#ifndef CONFIG_FB_AMIGA
amifb_video_off();
#endif
}
static void nosound( unsigned long ignored );
static DEFINE_TIMER(sound_timer, nosound, 0, 0);
void amiga_mksound( unsigned int hz, unsigned int ticks )
{
unsigned long flags;
if (!snd_data)
return;
local_irq_save(flags);
del_timer( &sound_timer );
if (hz > 20 && hz < 32767) {
unsigned long period = (clock_constant / hz);
if (period < amiga_audio_min_period)
period = amiga_audio_min_period;
if (period > MAX_PERIOD)
period = MAX_PERIOD;
/* setup pointer to data, period, length and volume */
custom.aud[2].audlc = snd_data;
custom.aud[2].audlen = sizeof(sine_data)/2;
custom.aud[2].audper = (unsigned short)period;
custom.aud[2].audvol = 32; /* 50% of maxvol */
if (ticks) {
sound_timer.expires = jiffies + ticks;
add_timer( &sound_timer );
}
/* turn on DMA for audio channel 2 */
custom.dmacon = DMAF_SETCLR | DMAF_AUD2;
} else
nosound( 0 );
local_irq_restore(flags);
}
static void nosound( unsigned long ignored )
{
/* turn off DMA for audio channel 2 */
custom.dmacon = DMAF_AUD2;
/* restore period to previous value after beeping */
custom.aud[2].audper = amiga_audio_period;
}