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