/**

 * $Id: timer.c,v 1.3 2005-12-29 12:52:29 nkeynes Exp $

 * 

 * SH4 Timer/Clock peripheral modules (CPG, TMU, RTC), combined together to

 * keep things simple (they intertwine a bit).

 *

 * 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.

 */

#include "dream.h"

#include "mem.h"

#include "clock.h"

#include "sh4core.h"

#include "sh4mmio.h"

#include "intc.h"

/********************************* CPG *************************************/

/* This is the base clock from which all other clocks are derived */

uint32_t sh4_input_freq = SH4_BASE_RATE;

uint32_t sh4_cpu_freq = SH4_BASE_RATE;

uint32_t sh4_bus_freq = SH4_BASE_RATE;

uint32_t sh4_peripheral_freq = SH4_BASE_RATE / 2;

uint32_t sh4_cpu_period = 1000 / SH4_BASE_RATE; /* in nanoseconds */

uint32_t sh4_bus_period = 1000 / SH4_BASE_RATE;

uint32_t sh4_peripheral_period = 2000 / SH4_BASE_RATE;

int32_t mmio_region_CPG_read( uint32_t reg )

{

    return MMIO_READ( CPG, reg );

}

/* CPU + bus dividers (note officially only the first 6 values are valid) */

int ifc_divider[8] = { 1, 2, 3, 4, 5, 8, 8, 8 };

/* Peripheral clock dividers (only first 5 are officially valid) */

int pfc_divider[8] = { 2, 3, 4, 6, 8, 8, 8, 8 };

void mmio_region_CPG_write( uint32_t reg, uint32_t val )

{

    uint32_t div;

    switch( reg ) {

    case FRQCR: /* Frequency control */

	div = ifc_divider[(val >> 6) & 0x07];

	sh4_cpu_freq = sh4_input_freq / div;

	sh4_cpu_period = 1000 * div / sh4_input_freq;

	div = ifc_divider[(val >> 3) & 0x07];

	sh4_bus_freq = sh4_input_freq / div;

	sh4_bus_period = 1000 * div / sh4_input_freq;

	div = pfc_divider[val & 0x07];

	sh4_peripheral_freq = sh4_input_freq / div;

	sh4_peripheral_period = 1000 * div / sh4_input_freq;

	/* Update everything that depends on the peripheral frequency */

	SCIF_update_line_speed();

	break;

    case WTCSR: /* Watchdog timer */

	break;

    }

    MMIO_WRITE( CPG, reg, val );

}

/********************************** RTC *************************************/

uint32_t rtc_output_period;

int32_t mmio_region_RTC_read( uint32_t reg )

{

    return MMIO_READ( RTC, reg );

}

void mmio_region_RTC_write( uint32_t reg, uint32_t val )

{

    MMIO_WRITE( RTC, reg, val );

}

/********************************** TMU *************************************/

#define TCR_ICPF 0x0200

#define TCR_UNF  0x0100

#define TCR_UNIE 0x0020

struct TMU_timer {

    uint32_t timer_period;

    uint32_t timer_remainder; /* left-over cycles from last count */

    uint32_t timer_run; /* cycles already run from this slice */

};

struct TMU_timer TMU_timers[3];

int32_t mmio_region_TMU_read( uint32_t reg )

{

    return MMIO_READ( TMU, reg );

}

void TMU_set_timer_period( int timer,  int tcr )

{

    uint32_t period = 1;

    switch( tcr & 0x07 ) {

    case 0:

	period = sh4_peripheral_period << 2 ;

	break;

    case 1: 

	period = sh4_peripheral_period << 4;

	break;

    case 2:

	period = sh4_peripheral_period << 6;

	break;

    case 3: 

	period = sh4_peripheral_period << 8;

	break;

    case 4:

	period = sh4_peripheral_period << 10;

	break;

    case 5:

	/* Illegal value. */

	ERROR( "TMU %d period set to illegal value (5)", timer );

	period = sh4_peripheral_period << 12; /* for something to do */

	break;

    case 6:

	period = rtc_output_period;

	break;

    case 7:

	/* External clock... Hrm? */

	period = sh4_peripheral_period; /* I dunno... */

	break;

    }

    TMU_timers[timer].timer_period = period;

}

void TMU_start( int timer )

{

    TMU_timers[timer].timer_run = 0;

    TMU_timers[timer].timer_remainder = 0;

}

void TMU_stop( int timer )

{

}

/**

 * Count the specified timer for a given number of nanoseconds.

 */

uint32_t TMU_count( int timer, uint32_t nanosecs ) 

{

    nanosecs = nanosecs + TMU_timers[timer].timer_remainder -

	TMU_timers[timer].timer_run;

    TMU_timers[timer].timer_remainder = 

	nanosecs % TMU_timers[timer].timer_period;

    uint32_t count = nanosecs / TMU_timers[timer].timer_period;

    uint32_t value = MMIO_READ( TMU, TCNT0 + 12*timer );

    uint32_t reset = MMIO_READ( TMU, TCOR0 + 12*timer );

    if( count > value ) {

	uint32_t tcr = MMIO_READ( TMU, TCR0 + 12*timer );

	tcr |= TCR_UNF;

	count -= value;

        value = reset - (count % reset);

	MMIO_WRITE( TMU, TCR0 + 12*timer, tcr );

	if( tcr & TCR_UNIE ) 

	    intc_raise_interrupt( INT_TMU_TUNI0 + timer );

    } else {

	value -= count;

    }

    MMIO_WRITE( TMU, TCNT0 + 12*timer, value );

    return value;

}

void mmio_region_TMU_write( uint32_t reg, uint32_t val )

{

    uint32_t oldval;

    int i;

    switch( reg ) {

    case TSTR:

	oldval = MMIO_READ( TMU, TSTR );

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

	    uint32_t tmp = 1<<i;

	    if( (oldval & tmp) == 1 && (val&tmp) == 0  )

		TMU_stop(i);

	    else if( (oldval&tmp) == 0 && (val&tmp) == 1 )

		TMU_start(i);

	}

	break;

    case TCR0:

	TMU_set_timer_period( 0, val );

	break;

    case TCR1:

	TMU_set_timer_period( 1, val );

	break;

    case TCR2:

	TMU_set_timer_period( 2, val );

	break;

    }

    MMIO_WRITE( TMU, reg, val );

}

void TMU_run_slice( uint32_t nanosecs )

{

    int tcr = MMIO_READ( TMU, TSTR );

    if( tcr & 0x01 ) {

	TMU_count( 0, nanosecs );

	TMU_timers[0].timer_run = 0;

    }

    if( tcr & 0x02 ) {

	TMU_count( 1, nanosecs );

	TMU_timers[1].timer_run = 0;

    }

    if( tcr & 0x04 ) {

	TMU_count( 2, nanosecs );

	TMU_timers[2].timer_run = 0;

    }

}

void TMU_update_clocks()

{

    TMU_set_timer_period( 0, MMIO_READ( TMU, TCR0 ) );

    TMU_set_timer_period( 1, MMIO_READ( TMU, TCR1 ) );

    TMU_set_timer_period( 2, MMIO_READ( TMU, TCR2 ) );

}

void TMU_reset( )

{

    TMU_timers[0].timer_remainder = 0;

    TMU_timers[0].timer_run = 0;

    TMU_timers[1].timer_remainder = 0;

    TMU_timers[1].timer_run = 0;

    TMU_timers[2].timer_remainder = 0;

    TMU_timers[2].timer_run = 0;

    TMU_update_clocks();

}

void TMU_save_state( FILE *f ) {

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

}

int TMU_load_state( FILE *f ) 

{

    fread( &TMU_timers, sizeof(TMU_timers), 1, f );

    return 0;

}