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/config.h>
  12 #include <linux/sched.h>
  13 #include <linux/timer.h>
  14 #include <linux/init.h>
  15
  16 #include <asm/system.h>
  17 #include <asm/amigahw.h>
  18
  19 static u_short *snd_data = NULL;
  20 static const signed char sine_data[] = {
  21         0,  39,  75,  103,  121,  127,  121,  103,  75,  39,
  22         0, -39, -75, -103, -121, -127, -121, -103, -75, -39
  23 };
  24 #define DATA_SIZE       (sizeof(sine_data)/sizeof(sine_data[0]))
  25
  26     /*
  27      * The minimum period for audio may be modified by the frame buffer
  28      * device since it depends on htotal (for OCS/ECS/AGA)
  29      */
  30
  31 volatile u_short amiga_audio_min_period = 124;  /* Default for pre-OCS */
  32
  33 #define MAX_PERIOD      (65535)
  34
  35
  36     /*
  37      *  Current period (set by dmasound.c)
  38      */
  39
  40 u_short amiga_audio_period = MAX_PERIOD;
  41
  42 static u_long clock_constant;
  43
  44 void __init amiga_init_sound(void)
  45 {
  46         static struct resource beep_res = { "Beep" };
  47
  48         snd_data = amiga_chip_alloc_res(sizeof(sine_data), &beep_res);
  49         if (!snd_data) {
  50                 printk (KERN_CRIT "amiga init_sound: failed to allocate chipmem\n");
  51                 return;
  52         }
  53         memcpy (snd_data, sine_data, sizeof(sine_data));
  54
  55         /* setup divisor */
  56         clock_constant = (amiga_colorclock+DATA_SIZE/2)/DATA_SIZE;
  57
  58         /* without amifb, turn video off and enable high quality sound */
  59 #ifndef CONFIG_FB_AMIGA
  60         amifb_video_off();
  61 #endif
  62 }
  63
  64 static void nosound( unsigned long ignored );
  65 static struct timer_list sound_timer = { function: nosound };
  66
  67 void amiga_mksound( unsigned int hz, unsigned int ticks )
  68 {
  69         unsigned long flags;
  70
  71         if (!snd_data)
  72                 return;
  73
  74         save_flags(flags);
  75         cli();
  76         del_timer( &sound_timer );
  77
  78         if (hz > 20 && hz < 32767) {
  79                 u_long period = (clock_constant / hz);
  80
  81                 if (period < amiga_audio_min_period)
  82                         period = amiga_audio_min_period;
  83                 if (period > MAX_PERIOD)
  84                         period = MAX_PERIOD;
  85
  86                 /* setup pointer to data, period, length and volume */
  87                 custom.aud[2].audlc = snd_data;
  88                 custom.aud[2].audlen = sizeof(sine_data)/2;
  89                 custom.aud[2].audper = (u_short)period;
  90                 custom.aud[2].audvol = 32; /* 50% of maxvol */
  91
  92                 if (ticks) {
  93                         sound_timer.expires = jiffies + ticks;
  94                         add_timer( &sound_timer );
  95                 }
  96
  97                 /* turn on DMA for audio channel 2 */
  98                 custom.dmacon = DMAF_SETCLR | DMAF_AUD2;
  99
 100                 restore_flags(flags);
 101                 return;
 102         } else {
 103                 nosound( 0 );
 104                 restore_flags(flags);
 105                 return;
 106         }
 107 }
 108
 109
 110 static void nosound( unsigned long ignored )
 111 {
 112         /* turn off DMA for audio channel 2 */
 113         custom.dmacon = DMAF_AUD2;
 114         /* restore period to previous value after beeping */
 115         custom.aud[2].audper = amiga_audio_period;
 116 }