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/jiffies.h>
  13 #include <linux/timer.h>
  14 #include <linux/init.h>
  15 #include <linux/string.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       (sizeof(sine_data)/sizeof(sine_data[0]))
  26
  27     /*
  28      * The minimum period for audio may be modified by the frame buffer
  29      * device since it depends on htotal (for OCS/ECS/AGA)
  30      */
  31
  32 volatile unsigned short amiga_audio_min_period = 124; /* Default for pre-OCS */
  33
  34 #define MAX_PERIOD      (65535)
  35
  36
  37     /*
  38      *  Current period (set by dmasound.c)
  39      */
  40
  41 unsigned short amiga_audio_period = MAX_PERIOD;
  42
  43 static unsigned long clock_constant;
  44
  45 void __init amiga_init_sound(void)
  46 {
  47         static struct resource beep_res = { .name = "Beep" };
  48
  49         snd_data = amiga_chip_alloc_res(sizeof(sine_data), &beep_res);
  50         if (!snd_data) {
  51                 printk (KERN_CRIT "amiga init_sound: failed to allocate chipmem\n");
  52                 return;
  53         }
  54         memcpy (snd_data, sine_data, sizeof(sine_data));
  55
  56         /* setup divisor */
  57         clock_constant = (amiga_colorclock+DATA_SIZE/2)/DATA_SIZE;
  58
  59         /* without amifb, turn video off and enable high quality sound */
  60 #ifndef CONFIG_FB_AMIGA
  61         amifb_video_off();
  62 #endif
  63 }
  64
  65 static void nosound( unsigned long ignored );
  66 static struct timer_list sound_timer = TIMER_INITIALIZER(nosound, 0, 0);
  67
  68 void amiga_mksound( unsigned int hz, unsigned int ticks )
  69 {
  70         unsigned long flags;
  71
  72         if (!snd_data)
  73                 return;
  74
  75         local_irq_save(flags);
  76         del_timer( &sound_timer );
  77
  78         if (hz > 20 && hz < 32767) {
  79                 unsigned 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 = (unsigned 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         } else
 101                 nosound( 0 );
 102
 103         local_irq_restore(flags);
 104 }
 105
 106
 107 static void nosound( unsigned long ignored )
 108 {
 109         /* turn off DMA for audio channel 2 */
 110         custom.dmacon = DMAF_AUD2;
 111         /* restore period to previous value after beeping */
 112         custom.aud[2].audper = amiga_audio_period;
 113 }