/**

  * $Id: asic.c,v 1.25 2007-01-18 11:14:01 nkeynes Exp $

  *

  * Support for the miscellaneous ASIC functions (Primarily event multiplexing,

  * and DMA). 

  *

  * Copyright (c) 2005 Nathan Keynes.

  *

  * This program is free software; you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation; either version 2 of the License, or

  * (at your option) any later version.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

  * GNU General Public License for more details.

  */

 #define MODULE asic_module

 #include <assert.h>

 #include <stdlib.h>

 #include "dream.h"

 #include "mem.h"

 #include "sh4/intc.h"

 #include "sh4/dmac.h"

 #include "dreamcast.h"

 #include "maple/maple.h"

 #include "gdrom/ide.h"

 #include "asic.h"

 #define MMIO_IMPL

 #include "asic.h"

 /*

  * Open questions:

  *   1) Does changing the mask after event occurance result in the

  *      interrupt being delivered immediately?

  * TODO: Logic diagram of ASIC event/interrupt logic.

  *

  * ... don't even get me started on the "EXTDMA" page, about which, apparently,

  * practically nothing is publicly known...

  */

 static void asic_check_cleared_events( void );

 static void asic_init( void );

 static void asic_reset( void );

 static uint32_t asic_run_slice( uint32_t nanosecs );

 static void asic_save_state( FILE *f );

 static int asic_load_state( FILE *f );

 static uint32_t g2_update_fifo_status( uint32_t slice_cycle );

 struct dreamcast_module asic_module = { "ASIC", asic_init, asic_reset, NULL, asic_run_slice,

 					NULL, asic_save_state, asic_load_state };

 #define G2_BIT5_TICKS 60

 #define G2_BIT4_TICKS 160

 #define G2_BIT0_ON_TICKS 120

 #define G2_BIT0_OFF_TICKS 420

 struct asic_g2_state {

     int bit5_off_timer;

     int bit4_on_timer;

     int bit4_off_timer;

     int bit0_on_timer;

     int bit0_off_timer;

 };

 static struct asic_g2_state g2_state;

 static uint32_t asic_run_slice( uint32_t nanosecs )

 {

     g2_update_fifo_status(nanosecs);

     if( g2_state.bit5_off_timer <= (int32_t)nanosecs ) {

 	g2_state.bit5_off_timer = -1;

     } else {

 	g2_state.bit5_off_timer -= nanosecs;

     }

     if( g2_state.bit4_off_timer <= (int32_t)nanosecs ) {

 	g2_state.bit4_off_timer = -1;

     } else {

 	g2_state.bit4_off_timer -= nanosecs;

     }

     if( g2_state.bit4_on_timer <= (int32_t)nanosecs ) {

 	g2_state.bit4_on_timer = -1;

     } else {

 	g2_state.bit4_on_timer -= nanosecs;

     }

     if( g2_state.bit0_off_timer <= (int32_t)nanosecs ) {

 	g2_state.bit0_off_timer = -1;

     } else {

 	g2_state.bit0_off_timer -= nanosecs;

     }

     if( g2_state.bit0_on_timer <= (int32_t)nanosecs ) {

 	g2_state.bit0_on_timer = -1;

     } else {

 	g2_state.bit0_on_timer -= nanosecs;

     }

     return nanosecs;

 }

 static void asic_init( void )

 {

     register_io_region( &mmio_region_ASIC );

     register_io_region( &mmio_region_EXTDMA );

     asic_reset();

 }

 static void asic_reset( void )

 {

     memset( &g2_state, 0xFF, sizeof(g2_state) );

 }    

 static void asic_save_state( FILE *f )

 {

     fwrite( &g2_state, sizeof(g2_state), 1, f );

 }

 static int asic_load_state( FILE *f )

 {

     if( fread( &g2_state, sizeof(g2_state), 1, f ) != 1 )

 	return 1;

     else

 	return 0;

 }

 /**

  * Setup the timers for the 3 FIFO status bits following a write through the G2

  * bus from the SH4 side. The timing is roughly as follows: (times are

  * approximate based on software readings - I wouldn't take this as gospel but

  * it seems to be enough to fool most programs). 

  *    0ns: Bit 5 (Input fifo?) goes high immediately on the write

  *   40ns: Bit 5 goes low and bit 4 goes high

  *  120ns: Bit 4 goes low, bit 0 goes high

  *  240ns: Bit 0 goes low.

  *

  * Additional writes while the FIFO is in operation extend the time that the

  * bits remain high as one might expect, without altering the time at which

  * they initially go high.

  */

 void asic_g2_write_word()

 {

     if( g2_state.bit5_off_timer < (int32_t)sh4r.slice_cycle ) {

 	g2_state.bit5_off_timer = sh4r.slice_cycle + G2_BIT5_TICKS;

     } else {

 	g2_state.bit5_off_timer += G2_BIT5_TICKS;

     }

     if( g2_state.bit4_on_timer < (int32_t)sh4r.slice_cycle ) {

 	g2_state.bit4_on_timer = sh4r.slice_cycle + G2_BIT5_TICKS;

     }

     if( g2_state.bit4_off_timer < (int32_t)sh4r.slice_cycle ) {

 	g2_state.bit4_off_timer = g2_state.bit4_on_timer + G2_BIT4_TICKS;

     } else {

 	g2_state.bit4_off_timer += G2_BIT4_TICKS;

     }

     if( g2_state.bit0_on_timer < (int32_t)sh4r.slice_cycle ) {

 	g2_state.bit0_on_timer = sh4r.slice_cycle + G2_BIT0_ON_TICKS;

     }

     if( g2_state.bit0_off_timer < (int32_t)sh4r.slice_cycle ) {

 	g2_state.bit0_off_timer = g2_state.bit0_on_timer + G2_BIT0_OFF_TICKS;

     } else {

 	g2_state.bit0_off_timer += G2_BIT0_OFF_TICKS;

     }

     MMIO_WRITE( ASIC, G2STATUS, MMIO_READ(ASIC, G2STATUS) | 0x20 );

 }

 static uint32_t g2_update_fifo_status( uint32_t nanos )

 {

     uint32_t val = MMIO_READ( ASIC, G2STATUS );

     if( ((uint32_t)g2_state.bit5_off_timer) <= nanos ) {

 	val = val & (~0x20);

 	g2_state.bit5_off_timer = -1;

     }

     if( ((uint32_t)g2_state.bit4_on_timer) <= nanos ) {

 	val = val | 0x10;

 	g2_state.bit4_on_timer = -1;

     }

     if( ((uint32_t)g2_state.bit4_off_timer) <= nanos ) {

 	val = val & (~0x10);

 	g2_state.bit4_off_timer = -1;

     } 

     if( ((uint32_t)g2_state.bit0_on_timer) <= nanos ) {

 	val = val | 0x01;

 	g2_state.bit0_on_timer = -1;

     }

     if( ((uint32_t)g2_state.bit0_off_timer) <= nanos ) {

 	val = val & (~0x01);

 	g2_state.bit0_off_timer = -1;

     } 

     MMIO_WRITE( ASIC, G2STATUS, val );

     return val;

 }   

 static int g2_read_status() {

     return g2_update_fifo_status( sh4r.slice_cycle );

 }

 void asic_event( int event )

 {

     int offset = ((event&0x60)>>3);

     int result = (MMIO_READ(ASIC, PIRQ0 + offset))  |=  (1<<(event&0x1F));

     if( result & MMIO_READ(ASIC, IRQA0 + offset) )

         intc_raise_interrupt( INT_IRQ13 );

     if( result & MMIO_READ(ASIC, IRQB0 + offset) )

         intc_raise_interrupt( INT_IRQ11 );

     if( result & MMIO_READ(ASIC, IRQC0 + offset) )

         intc_raise_interrupt( INT_IRQ9 );

     if( event >= 64 ) { /* Third word */

 	asic_event( EVENT_CASCADE2 );

     } else if( event >= 32 ) { /* Second word */

 	asic_event( EVENT_CASCADE1 );

     }

 }

 void asic_clear_event( int event ) {

     int offset = ((event&0x60)>>3);

     uint32_t result = MMIO_READ(ASIC, PIRQ0 + offset)  & (~(1<<(event&0x1F)));

     MMIO_WRITE( ASIC, PIRQ0 + offset, result );

     if( result == 0 ) {

 	/* clear cascades if necessary */

 	if( event >= 64 ) {

 	    MMIO_WRITE( ASIC, PIRQ0, MMIO_READ( ASIC, PIRQ0 ) & 0x7FFFFFFF );

 	} else if( event >= 32 ) {

 	    MMIO_WRITE( ASIC, PIRQ0, MMIO_READ( ASIC, PIRQ0 ) & 0xBFFFFFFF );

 	}

     }

     asic_check_cleared_events();

 }

 void asic_check_cleared_events( )

 {

     int i, setA = 0, setB = 0, setC = 0;

     uint32_t bits;

     for( i=0; i<3; i++ ) {

 	bits = MMIO_READ( ASIC, PIRQ0 + i );

 	setA |= (bits & MMIO_READ(ASIC, IRQA0 + i ));

 	setB |= (bits & MMIO_READ(ASIC, IRQB0 + i ));

 	setC |= (bits & MMIO_READ(ASIC, IRQC0 + i ));

     }

     if( setA == 0 )

 	intc_clear_interrupt( INT_IRQ13 );

     if( setB == 0 )

 	intc_clear_interrupt( INT_IRQ11 );

     if( setC == 0 )

 	intc_clear_interrupt( INT_IRQ9 );

 }

 void g2_dma_transfer( int channel )

 {

     uint32_t offset = channel << 5;

     if( MMIO_READ( EXTDMA, G2DMA0CTL1 + offset ) == 1 ) {

 	if( MMIO_READ( EXTDMA, G2DMA0CTL2 + offset ) == 1 ) {

 	    uint32_t extaddr = MMIO_READ( EXTDMA, G2DMA0EXT + offset );

 	    uint32_t sh4addr = MMIO_READ( EXTDMA, G2DMA0SH4 + offset );

 	    uint32_t length = MMIO_READ( EXTDMA, G2DMA0SIZ + offset ) & 0x1FFFFFFF;

 	    uint32_t dir = MMIO_READ( EXTDMA, G2DMA0DIR + offset );

 	    uint32_t mode = MMIO_READ( EXTDMA, G2DMA0MOD + offset );

 	    char buf[length];

 	    if( dir == 0 ) { /* SH4 to device */

 		mem_copy_from_sh4( buf, sh4addr, length );

 		mem_copy_to_sh4( extaddr, buf, length );

 	    } else { /* Device to SH4 */

 		mem_copy_from_sh4( buf, extaddr, length );

 		mem_copy_to_sh4( sh4addr, buf, length );

 	    }

 	    MMIO_WRITE( EXTDMA, G2DMA0CTL2 + offset, 0 );

 	    asic_event( EVENT_G2_DMA0 + channel );

 	} else {

 	    MMIO_WRITE( EXTDMA, G2DMA0CTL2 + offset, 0 );

 	}

     }

 }

 void asic_ide_dma_transfer( )

 {	

     if( MMIO_READ( EXTDMA, IDEDMACTL2 ) == 1 ) {

 	if( MMIO_READ( EXTDMA, IDEDMACTL1 ) == 1 ) {

 	    MMIO_WRITE( EXTDMA, IDEDMATXSIZ, 0 );

 	    uint32_t addr = MMIO_READ( EXTDMA, IDEDMASH4 );

 	    uint32_t length = MMIO_READ( EXTDMA, IDEDMASIZ );

 	    int dir = MMIO_READ( EXTDMA, IDEDMADIR );

 	    uint32_t xfer = ide_read_data_dma( addr, length );

 	    MMIO_WRITE( EXTDMA, IDEDMATXSIZ, xfer );

 	    MMIO_WRITE( EXTDMA, IDEDMACTL2, 0 );

 	} else { /* 0 */

 	    MMIO_WRITE( EXTDMA, IDEDMACTL2, 0 );

 	}

     }

 }

 void mmio_region_ASIC_write( uint32_t reg, uint32_t val )

 {

     switch( reg ) {

     case PIRQ1:

 	break; /* Treat this as read-only for the moment */

     case PIRQ0:

 	val = val & 0x3FFFFFFF; /* Top two bits aren't clearable */

 	MMIO_WRITE( ASIC, reg, MMIO_READ(ASIC, reg)&~val );

 	asic_check_cleared_events();

 	break;

     case PIRQ2:

 	/* Clear any events */

 	val = MMIO_READ(ASIC, reg)&(~val);

 	MMIO_WRITE( ASIC, reg, val );

 	if( val == 0 ) { /* all clear - clear the cascade bit */

 	    MMIO_WRITE( ASIC, PIRQ0, MMIO_READ( ASIC, PIRQ0 ) & 0x7FFFFFFF );

 	}

 	asic_check_cleared_events();

 	break;

     case SYSRESET:

 	if( val == 0x7611 ) {

 	    dreamcast_reset();

 	    sh4r.new_pc = sh4r.pc;

 	} else {

 	    WARN( "Unknown value %08X written to SYSRESET port", val );

 	}

 	break;

     case MAPLE_STATE:

 	MMIO_WRITE( ASIC, reg, val );

 	if( val & 1 ) {

 	    uint32_t maple_addr = MMIO_READ( ASIC, MAPLE_DMA) &0x1FFFFFE0;

 	    maple_handle_buffer( maple_addr );

 	    MMIO_WRITE( ASIC, reg, 0 );

 	}

 	break;

     case PVRDMACTL: /* Initiate PVR DMA transfer */

 	MMIO_WRITE( ASIC, reg, val );

 	if( val & 1 ) {

 	    uint32_t dest_addr = MMIO_READ( ASIC, PVRDMADEST) &0x1FFFFFE0;

 	    uint32_t count = MMIO_READ( ASIC, PVRDMACNT );

 	    char *data = alloca( count );

 	    uint32_t rcount = DMAC_get_buffer( 2, data, count );

 	    if( rcount != count )

 		WARN( "PVR received %08X bytes from DMA, expected %08X", rcount, count );

 	    mem_copy_to_sh4( dest_addr, data, rcount );

 	    asic_event( EVENT_PVR_DMA );

 	    MMIO_WRITE( ASIC, PVRDMACTL, 0 );

 	    MMIO_WRITE( ASIC, PVRDMACNT, 0 );

 	}

 	break;

     case PVRDMADEST: case PVRDMACNT: case MAPLE_DMA:

 	MMIO_WRITE( ASIC, reg, val );

 	break;

     default:

 	MMIO_WRITE( ASIC, reg, val );

     }

 }

 int32_t mmio_region_ASIC_read( uint32_t reg )

 {

     int32_t val;

     switch( reg ) {

         /*

         case 0x89C:

             sh4_stop();

             return 0x000000B;

         */     

     case PIRQ0:

     case PIRQ1:

     case PIRQ2:

     case IRQA0:

     case IRQA1:

     case IRQA2:

     case IRQB0:

     case IRQB1:

     case IRQB2:

     case IRQC0:

     case IRQC1:

     case IRQC2:

     case MAPLE_STATE:

 	val = MMIO_READ(ASIC, reg);

 	return val;            

     case G2STATUS:

 	return g2_read_status();

     default:

 	val = MMIO_READ(ASIC, reg);

 	return val;

     }

 }

 MMIO_REGION_WRITE_FN( EXTDMA, reg, val )

 {

     if( !idereg.interface_enabled && IS_IDE_REGISTER(reg) ) {

 	return; /* disabled */

     }

     switch( reg ) {

     case IDEALTSTATUS: /* Device control */

 	ide_write_control( val );

 	break;

     case IDEDATA:

 	ide_write_data_pio( val );

 	break;

     case IDEFEAT:

 	if( ide_can_write_regs() )

 	    idereg.feature = (uint8_t)val;

 	break;

     case IDECOUNT:

 	if( ide_can_write_regs() )

 	    idereg.count = (uint8_t)val;

 	break;

     case IDELBA0:

 	if( ide_can_write_regs() )

 	    idereg.lba0 = (uint8_t)val;

 	break;

     case IDELBA1:

 	if( ide_can_write_regs() )

 	    idereg.lba1 = (uint8_t)val;

 	break;

     case IDELBA2:

 	if( ide_can_write_regs() )

 	    idereg.lba2 = (uint8_t)val;

 	break;

     case IDEDEV:

 	if( ide_can_write_regs() )

 	    idereg.device = (uint8_t)val;

 	break;

     case IDECMD:

 	if( ide_can_write_regs() || val == IDE_CMD_NOP ) {

 	    ide_write_command( (uint8_t)val );

 	}

 	break;

     case IDEDMACTL1:

     case IDEDMACTL2:

 	MMIO_WRITE( EXTDMA, reg, val );

 	asic_ide_dma_transfer( );

 	break;

     case IDEACTIVATE:

 	if( val == 0x001FFFFF ) {

 	    idereg.interface_enabled = TRUE;

 	    /* Conventional wisdom says that this is necessary but not

 	     * sufficient to enable the IDE interface.

 	     */

 	} else if( val == 0x000042FE ) {

 	    idereg.interface_enabled = FALSE;

 	}

 	break;

     case G2DMA0CTL1:

     case G2DMA0CTL2:

 	MMIO_WRITE( EXTDMA, reg, val );

 	g2_dma_transfer( 0 );

 	break;

     case G2DMA0STOP:

 	break;

     case G2DMA1CTL1:

     case G2DMA1CTL2:

 	MMIO_WRITE( EXTDMA, reg, val );

 	g2_dma_transfer( 1 );

 	break;

     case G2DMA1STOP:

 	break;

     case G2DMA2CTL1:

     case G2DMA2CTL2:

 	MMIO_WRITE( EXTDMA, reg, val );

 	g2_dma_transfer( 2 );

 	break;

     case G2DMA2STOP:

 	break;

     case G2DMA3CTL1:

     case G2DMA3CTL2:

 	MMIO_WRITE( EXTDMA, reg, val );

 	g2_dma_transfer( 3 );

 	break;

     case G2DMA3STOP:

 	break;

     case PVRDMA2CTL1:

     case PVRDMA2CTL2:

 	if( val != 0 ) {

 	    ERROR( "Write to unimplemented DMA control register %08X", reg );

 	    //dreamcast_stop();

 	    //sh4_stop();

 	}

 	break;

     default:

             MMIO_WRITE( EXTDMA, reg, val );

     }

 }

 MMIO_REGION_READ_FN( EXTDMA, reg )

 {

     uint32_t val;

     if( !idereg.interface_enabled && IS_IDE_REGISTER(reg) ) {

 	return 0xFFFFFFFF; /* disabled */

     }

     switch( reg ) {

     case IDEALTSTATUS: 

 	val = idereg.status;

 	return val;

     case IDEDATA: return ide_read_data_pio( );

     case IDEFEAT: return idereg.error;

     case IDECOUNT:return idereg.count;

     case IDELBA0: return idereg.disc;

     case IDELBA1: return idereg.lba1;

     case IDELBA2: return idereg.lba2;

     case IDEDEV: return idereg.device;

     case IDECMD:

 	val = ide_read_status();

 	return val;

     default:

 	val = MMIO_READ( EXTDMA, reg );

 	return val;

     }

 }