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 #include <linux/module.h>
  16
  17 #include <asm/system.h>
  18 #include <asm/amigahw.h>
  19
  20 static unsigned short *snd_data;
  21 static const signed char sine_data[] = {
  22         0,  39,  75,  103,  121,  127,  121,  103,  75,  39,
  23         0, -39, -75, -103, -121, -127, -121, -103, -75, -39
  24 };
  25 #define DATA_SIZE       ARRAY_SIZE(sine_data)
  26
  27 #define custom amiga_custom
  28
  29     /*
  30      * The minimum period for audio may be modified by the frame buffer
  31      * device since it depends on htotal (for OCS/ECS/AGA)
  32      */
  33
  34 volatile unsigned short amiga_audio_min_period = 124; /* Default for pre-OCS */
  35 EXPORT_SYMBOL(amiga_audio_min_period);
  36
  37 #define MAX_PERIOD      (65535)
  38
  39
  40     /*
  41      *  Current period (set by dmasound.c)
  42      */
  43
  44 unsigned short amiga_audio_period = MAX_PERIOD;
  45 EXPORT_SYMBOL(amiga_audio_period);
  46
  47 static unsigned long clock_constant;
  48
  49 void __init amiga_init_sound(void)
  50 {
  51         static struct resource beep_res = { .name = "Beep" };
  52
  53         snd_data = amiga_chip_alloc_res(sizeof(sine_data), &beep_res);
  54         if (!snd_data) {
  55                 printk (KERN_CRIT "amiga init_sound: failed to allocate chipmem\n");
  56                 return;
  57         }
  58         memcpy (snd_data, sine_data, sizeof(sine_data));
  59
  60         /* setup divisor */
  61         clock_constant = (amiga_colorclock+DATA_SIZE/2)/DATA_SIZE;
  62
  63         /* without amifb, turn video off and enable high quality sound */
  64 #ifndef CONFIG_FB_AMIGA
  65         amifb_video_off();
  66 #endif
  67 }
  68
  69 static void nosound( unsigned long ignored );
  70 static DEFINE_TIMER(sound_timer, nosound, 0, 0);
  71
  72 void amiga_mksound( unsigned int hz, unsigned int ticks )
  73 {
  74         unsigned long flags;
  75
  76         if (!snd_data)
  77                 return;
  78
  79         local_irq_save(flags);
  80         del_timer( &sound_timer );
  81
  82         if (hz > 20 && hz < 32767) {
  83                 unsigned long period = (clock_constant / hz);
  84
  85                 if (period < amiga_audio_min_period)
  86                         period = amiga_audio_min_period;
  87                 if (period > MAX_PERIOD)
  88                         period = MAX_PERIOD;
  89
  90                 /* setup pointer to data, period, length and volume */
  91                 custom.aud[2].audlc = snd_data;
  92                 custom.aud[2].audlen = sizeof(sine_data)/2;
  93                 custom.aud[2].audper = (unsigned short)period;
  94                 custom.aud[2].audvol = 32; /* 50% of maxvol */
  95
  96                 if (ticks) {
  97                         sound_timer.expires = jiffies + ticks;
  98                         add_timer( &sound_timer );
  99                 }
 100
 101                 /* turn on DMA for audio channel 2 */
 102                 custom.dmacon = DMAF_SETCLR | DMAF_AUD2;
 103
 104         } else
 105                 nosound( 0 );
 106
 107         local_irq_restore(flags);
 108 }
 109
 110
 111 static void nosound( unsigned long ignored )
 112 {
 113         /* turn off DMA for audio channel 2 */
 114         custom.dmacon = DMAF_AUD2;
 115         /* restore period to previous value after beeping */
 116         custom.aud[2].audper = amiga_audio_period;
 117 }