macboing.c

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/*
 *  Mac bong noise generator. Note - we ought to put a boingy noise
 *  here 8)
 *
 *  ----------------------------------------------------------------------
 *  16.11.98:
 *  rewrote some functions, added support for Enhanced ASC (Quadras)
 *  after the NetBSD asc.c console bell patch by Colin Wood/Frederick Bruck
 *  Juergen Mellinger ([email protected])
 */

#include <linux/sched.h>
#include <linux/timer.h>

#include <asm/macintosh.h>
#include <asm/mac_asc.h>

static int mac_asc_inited;
/*
 * dumb triangular wave table
 */
static __u8 mac_asc_wave_tab[ 0x800 ];

/*
 * Alan's original sine table; needs interpolating to 0x800
 * (hint: interpolate or hardwire [0 -> Pi/2[, it's symmetric)
 */
static const signed char sine_data[] = {
    0,  39,  75,  103,  121,  127,  121,  103,  75,  39,
    0, -39, -75, -103, -121, -127, -121, -103, -75, -39
};

/*
 * where the ASC hides ...
 */
static volatile __u8* mac_asc_regs = ( void* )0x50F14000;

/*
 * sample rate; is this a good default value?
 */
static unsigned long mac_asc_samplespersec = 11050;
static int mac_bell_duration;
static unsigned long mac_bell_phase; /* 0..2*Pi -> 0..0x800 (wavetable size) */
static unsigned long mac_bell_phasepersample;

/*
 * some function protos
 */
static void mac_init_asc( void );
static void mac_nosound( unsigned long );
static void mac_quadra_start_bell( unsigned int, unsigned int, unsigned int );
static void mac_quadra_ring_bell( unsigned long );
static void mac_av_start_bell( unsigned int, unsigned int, unsigned int );
static void ( *mac_special_bell )( unsigned int, unsigned int, unsigned int );

/*
 * our timer to start/continue/stop the bell
 */
static DEFINE_TIMER(mac_sound_timer, mac_nosound, 0, 0);

/*
 * Sort of initialize the sound chip (called from mac_mksound on the first
 * beep).
 */
static void mac_init_asc( void )
{
    int i;

    /*
     * do some machine specific initialization
     * BTW:
     * the NetBSD Quadra patch identifies the Enhanced Apple Sound Chip via
     *  mac_asc_regs[ 0x800 ] & 0xF0 != 0
     * this makes no sense here, because we have to set the default sample
     * rate anyway if we want correct frequencies
     */
    switch ( macintosh_config->ident )
    {
        case MAC_MODEL_IIFX:
            /*
             * The IIfx is always special ...
             */
            mac_asc_regs = ( void* )0x50010000;
            break;
            /*
             * not sure about how correct this list is
             * machines with the EASC enhanced apple sound chip
             */
        case MAC_MODEL_Q630:
        case MAC_MODEL_P475:
            mac_special_bell = mac_quadra_start_bell;
            mac_asc_samplespersec = 22150;
            break;
        case MAC_MODEL_C660:
        case MAC_MODEL_Q840:
            /*
             * The Quadra 660AV and 840AV use the "Singer" custom ASIC for sound I/O.
             * It appears to be similar to the "AWACS" custom ASIC in the Power Mac
             * [678]100.  Because Singer and AWACS may have a similar hardware
             * interface, this would imply that the code in drivers/sound/dmasound.c
             * for AWACS could be used as a basis for Singer support.  All we have to
             * do is figure out how to do DMA on the 660AV/840AV through the PSC and
             * figure out where the Singer hardware sits in memory. (I'd look in the
             * vicinity of the AWACS location in a Power Mac [678]100 first, or the
             * current location of the Apple Sound Chip--ASC--in other Macs.)  The
             * Power Mac [678]100 info can be found in MkLinux Mach kernel sources.
             *
             * Quoted from Apple's Tech Info Library, article number 16405:
             *   "Among desktop Macintosh computers, only the 660AV, 840AV, and Power
             *   Macintosh models have 16-bit audio input and output capability
             *   because of the AT&T DSP3210 hardware circuitry and the 16-bit Singer
             *   codec circuitry in the AVs.  The Audio Waveform Amplifier and
             *   Converter (AWAC) chip in the Power Macintosh performs the same
             *   16-bit I/O functionality.  The PowerBook 500 series computers
             *   support 16-bit stereo output, but only mono input."
             *
             *   Technical Information Library (TIL) article number 16405. 
             *   http://support.apple.com/kb/TA32601 
             *
             * --David Kilzer
             */
            mac_special_bell = mac_av_start_bell;
            break;
        case MAC_MODEL_Q650:
        case MAC_MODEL_Q700:
        case MAC_MODEL_Q800:
        case MAC_MODEL_Q900:
        case MAC_MODEL_Q950:
            /*
             * Currently not implemented!
             */
            mac_special_bell = NULL;
            break;
        default:
            /*
             * Every switch needs a default
             */
            mac_special_bell = NULL;
            break;
    }

    /*
     * init the wave table with a simple triangular wave
     * A sine wave would sure be nicer here ...
     */
    for ( i = 0; i < 0x400; i++ )
    {
        mac_asc_wave_tab[ i ] = i / 4;
        mac_asc_wave_tab[ i + 0x400 ] = 0xFF - i / 4;
    }
    mac_asc_inited = 1;
}

/*
 * Called to make noise; current single entry to the boing driver.
 * Does the job for simple ASC, calls other routines else.
 * XXX Fixme:
 * Should be split into asc_mksound, easc_mksound, av_mksound and
 * function pointer set in mac_init_asc which would be called at
 * init time.
 * _This_ is rather ugly ...
 */
void mac_mksound( unsigned int freq, unsigned int length )
{
    __u32 cfreq = ( freq << 5 ) / 468;
    unsigned long flags;
    int i;

    if ( mac_special_bell == NULL )
    {
        /* Do nothing */
        return;
    }

    if ( !mac_asc_inited )
        mac_init_asc();

    if ( mac_special_bell )
    {
        mac_special_bell( freq, length, 128 );
        return;
    }

    if ( freq < 20 || freq > 20000 || length == 0 )
    {
        mac_nosound( 0 );
        return;
    }

    local_irq_save(flags);

    del_timer( &mac_sound_timer );

    for ( i = 0; i < 0x800; i++ )
        mac_asc_regs[ i ] = 0;
    for ( i = 0; i < 0x800; i++ )
        mac_asc_regs[ i ] = mac_asc_wave_tab[ i ];

    for ( i = 0; i < 8; i++ )
        *( __u32* )( ( __u32 )mac_asc_regs + ASC_CONTROL + 0x814 + 8 * i ) = cfreq;

    mac_asc_regs[ 0x807 ] = 0;
    mac_asc_regs[ ASC_VOLUME ] = 128;
    mac_asc_regs[ 0x805 ] = 0;
    mac_asc_regs[ 0x80F ] = 0;
    mac_asc_regs[ ASC_MODE ] = ASC_MODE_SAMPLE;
    mac_asc_regs[ ASC_ENABLE ] = ASC_ENABLE_SAMPLE;

    mac_sound_timer.expires = jiffies + length;
    add_timer( &mac_sound_timer );

    local_irq_restore(flags);
}

/*
 * regular ASC: stop whining ..
 */
static void mac_nosound( unsigned long ignored )
{
    mac_asc_regs[ ASC_ENABLE ] = 0;
}

/*
 * EASC entry; init EASC, don't load wavetable, schedule 'start whining'.
 */
static void mac_quadra_start_bell( unsigned int freq, unsigned int length, unsigned int volume )
{
    unsigned long flags;

    /* if the bell is already ringing, ring longer */
    if ( mac_bell_duration > 0 )
    {
        mac_bell_duration += length;
        return;
    }

    mac_bell_duration = length;
    mac_bell_phase = 0;
    mac_bell_phasepersample = ( freq * sizeof( mac_asc_wave_tab ) ) / mac_asc_samplespersec;
    /* this is reasonably big for small frequencies */

    local_irq_save(flags);

    /* set the volume */
    mac_asc_regs[ 0x806 ] = volume;

    /* set up the ASC registers */
    if ( mac_asc_regs[ 0x801 ] != 1 )
    {
        /* select mono mode */
        mac_asc_regs[ 0x807 ] = 0;
        /* select sampled sound mode */
        mac_asc_regs[ 0x802 ] = 0;
        /* ??? */
        mac_asc_regs[ 0x801 ] = 1;
        mac_asc_regs[ 0x803 ] |= 0x80;
        mac_asc_regs[ 0x803 ] &= 0x7F;
    }

    mac_sound_timer.function = mac_quadra_ring_bell;
    mac_sound_timer.expires = jiffies + 1;
    add_timer( &mac_sound_timer );

    local_irq_restore(flags);
}

/*
 * EASC 'start/continue whining'; I'm not sure why the above function didn't
 * already load the wave table, or at least call this one...
 * This piece keeps reloading the wave table until done.
 */
static void mac_quadra_ring_bell( unsigned long ignored )
{
    int i, count = mac_asc_samplespersec / HZ;
    unsigned long flags;

    /*
     * we neither want a sound buffer overflow nor underflow, so we need to match
     * the number of samples per timer interrupt as exactly as possible.
     * using the asc interrupt will give better results in the future
     * ...and the possibility to use a real sample (a boingy noise, maybe...)
     */

    local_irq_save(flags);

    del_timer( &mac_sound_timer );

    if ( mac_bell_duration-- > 0 )
    {
        for ( i = 0; i < count; i++ )
        {
            mac_bell_phase += mac_bell_phasepersample;
            mac_asc_regs[ 0 ] = mac_asc_wave_tab[ mac_bell_phase & ( sizeof( mac_asc_wave_tab ) - 1 ) ];
        }
        mac_sound_timer.expires = jiffies + 1;
        add_timer( &mac_sound_timer );
    }
    else
        mac_asc_regs[ 0x801 ] = 0;

    local_irq_restore(flags);
}

/*
 * AV code - please fill in.
 */
static void mac_av_start_bell( unsigned int freq, unsigned int length, unsigned int volume )
{
}