arch/m68k/amiga/amisound.c

   1 /*
   2  * linux/arch/m68k/amiga/amisound.c
   3  *
   4  * amiga sound driver for Linux/m68k
   5  *
   6  * This file is subject to the terms and conditions of the GNU General Public
   7  * License.  See the file COPYING in the main directory of this archive
   8  * for more details.
   9  */
  10
  11 #include <linux/sched.h>
  12 #include <linux/timer.h>
  13 #include <linux/init.h>
  14
  15 #include <asm/system.h>
  16 #include <asm/amigahw.h>
  17
  18 static u_short *snd_data = NULL;
  19 static const signed char sine_data[] = {
  20         0,  39,  75,  103,  121,  127,  121,  103,  75,  39,
  21         0, -39, -75, -103, -121, -127, -121, -103, -75, -39
  22 };
  23 #define DATA_SIZE       (sizeof(sine_data)/sizeof(sine_data[0]))
  24
  25     /*
  26      * The minimum period for audio may be modified by the frame buffer
  27      * device since it depends on htotal (for OCS/ECS/AGA)
  28      */
  29
  30 volatile u_short amiga_audio_min_period = 124;  /* Default for pre-OCS */
  31
  32 #define MAX_PERIOD      (65535)
  33
  34
  35     /*
  36      *  Current period (set by dmasound.c)
  37      */
  38
  39 u_short amiga_audio_period = MAX_PERIOD;
  40
  41 static u_long clock_constant;
  42
  43 void __init amiga_init_sound(void)
  44 {
  45         snd_data = amiga_chip_alloc(sizeof(sine_data), "Beep");
  46         if (!snd_data) {
  47                 printk (KERN_CRIT "amiga init_sound: failed to allocate chipmem\n");
  48                 return;
  49         }
  50         memcpy (snd_data, sine_data, sizeof(sine_data));
  51
  52         /* setup divisor */
  53         clock_constant = (amiga_colorclock+DATA_SIZE/2)/DATA_SIZE;
  54 }
  55
  56 static void nosound( unsigned long ignored );
  57 static struct timer_list sound_timer = { NULL, NULL, 0, 0, nosound };
  58
  59 void amiga_mksound( unsigned int hz, unsigned int ticks )
  60 {
  61         unsigned long flags;
  62
  63         if (!snd_data)
  64                 return;
  65
  66         save_flags(flags);
  67         cli();
  68         del_timer( &sound_timer );
  69
  70         if (hz > 20 && hz < 32767) {
  71                 u_long period = (clock_constant / hz);
  72
  73                 if (period < amiga_audio_min_period)
  74                         period = amiga_audio_min_period;
  75                 if (period > MAX_PERIOD)
  76                         period = MAX_PERIOD;
  77
  78                 /* setup pointer to data, period, length and volume */
  79                 custom.aud[2].audlc = snd_data;
  80                 custom.aud[2].audlen = sizeof(sine_data)/2;
  81                 custom.aud[2].audper = (u_short)period;
  82                 custom.aud[2].audvol = 32; /* 50% of maxvol */
  83
  84                 if (ticks) {
  85                         sound_timer.expires = jiffies + ticks;
  86                         add_timer( &sound_timer );
  87                 }
  88
  89                 /* turn on DMA for audio channel 2 */
  90                 custom.dmacon = DMAF_SETCLR | DMAF_AUD2;
  91
  92                 restore_flags(flags);
  93                 return;
  94         } else {
  95                 nosound( 0 );
  96                 restore_flags(flags);
  97                 return;
  98         }
  99 }
 100
 101
 102 static void nosound( unsigned long ignored )
 103 {
 104         /* turn off DMA for audio channel 2 */
 105         custom.dmacon = DMAF_AUD2;
 106         /* restore period to previous value after beeping */
 107         custom.aud[2].audper = amiga_audio_period;
 108 }