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