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/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       ARRAY_SIZE(sine_data)
  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 EXPORT_SYMBOL(amiga_audio_min_period);
  35
  36 #define MAX_PERIOD      (65535)
  37
  38
  39     /*
  40      *  Current period (set by dmasound.c)
  41      */
  42
  43 unsigned short amiga_audio_period = MAX_PERIOD;
  44 EXPORT_SYMBOL(amiga_audio_period);
  45
  46 static unsigned long clock_constant;
  47
  48 void __init amiga_init_sound(void)
  49 {
  50         static struct resource beep_res = { .name = "Beep" };
  51
  52         snd_data = amiga_chip_alloc_res(sizeof(sine_data), &beep_res);
  53         if (!snd_data) {
  54                 pr_crit("amiga init_sound: failed to allocate chipmem\n");
  55                 return;
  56         }
  57         memcpy (snd_data, sine_data, sizeof(sine_data));
  58
  59         /* setup divisor */
  60         clock_constant = (amiga_colorclock+DATA_SIZE/2)/DATA_SIZE;
  61
  62         /* without amifb, turn video off and enable high quality sound */
  63 #ifndef CONFIG_FB_AMIGA
  64         amifb_video_off();
  65 #endif
  66 }
  67
  68 static void nosound(struct timer_list *unused);
  69 static DEFINE_TIMER(sound_timer, nosound);
  70
  71 void amiga_mksound( unsigned int hz, unsigned int ticks )
  72 {
  73         unsigned long flags;
  74
  75         if (!snd_data)
  76                 return;
  77
  78         local_irq_save(flags);
  79         del_timer( &sound_timer );
  80
  81         if (hz > 20 && hz < 32767) {
  82                 unsigned long period = (clock_constant / hz);
  83
  84                 if (period < amiga_audio_min_period)
  85                         period = amiga_audio_min_period;
  86                 if (period > MAX_PERIOD)
  87                         period = MAX_PERIOD;
  88
  89                 /* setup pointer to data, period, length and volume */
  90                 custom.aud[2].audlc = snd_data;
  91                 custom.aud[2].audlen = sizeof(sine_data)/2;
  92                 custom.aud[2].audper = (unsigned short)period;
  93                 custom.aud[2].audvol = 32; /* 50% of maxvol */
  94
  95                 if (ticks) {
  96                         sound_timer.expires = jiffies + ticks;
  97                         add_timer( &sound_timer );
  98                 }
  99
 100                 /* turn on DMA for audio channel 2 */
 101                 custom.dmacon = DMAF_SETCLR | DMAF_AUD2;
 102
 103         } else
 104                 nosound( 0 );
 105
 106         local_irq_restore(flags);
 107 }
 108
 109
 110 static void nosound(struct timer_list *unused)
 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 }