/**

 * $Id$

 * 

 * 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 <assert.h>

#include "lxdream.h"

#include "mem.h"

#include "clock.h"

#include "eventq.h"

#include "sh4/sh4core.h"

#include "sh4/sh4mmio.h"

#include "sh4/intc.h"

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

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

 * Note: The real clock runs at 33Mhz, which is multiplied by the PLL to

 * run the instruction clock at 200Mhz. For sake of simplicity/precision,

 * we instead use 200Mhz as the base rate and divide everything down instead.

 **/

uint32_t sh4_input_freq = SH4_BASE_RATE;

uint32_t sh4_cpu_multiplier = 2000; /* = 0.5 * frequency */

uint32_t sh4_cpu_freq = SH4_BASE_RATE;

uint32_t sh4_bus_freq = SH4_BASE_RATE / 2;

uint32_t sh4_peripheral_freq = SH4_BASE_RATE / 4;

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

uint32_t sh4_bus_period = 2* 1000 / SH4_BASE_RATE;

uint32_t sh4_peripheral_period = 4 * 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;

    uint32_t primary_clock = sh4_input_freq;

    switch( reg ) {

    case FRQCR: /* Frequency control */

        if( (val & FRQCR_PLL1EN) == 0 )

            primary_clock /= 6;

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

        sh4_cpu_freq = primary_clock / div;

        sh4_cpu_period = sh4_cpu_multiplier * div / sh4_input_freq;

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

        sh4_bus_freq = primary_clock / div;

        sh4_bus_period = 1000 * div / sh4_input_freq;

        div = pfc_divider[val & 0x07];

        sh4_peripheral_freq = primary_clock / 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 );

}

/**

 * We don't really know what the default reset value is as it's determined

 * by the mode select pins. This is the standard value that the BIOS sets,

 * however, so it works for now.

 */

void CPG_reset( )

{

    mmio_region_CPG_write( FRQCR, 0x0E0A );

}

/********************************** 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 TMU_IS_RUNNING(timer)  (MMIO_READ(TMU,TSTR) & (1<<timer))

uint32_t TMU_count( int timer, uint32_t nanosecs );

void TMU_event_callback( int eventid )

{

    TMU_count( eventid - EVENT_TMU0, sh4r.slice_cycle );

}

void TMU_init(void)

{

    register_event_callback( EVENT_TMU0, TMU_event_callback );

    register_event_callback( EVENT_TMU1, TMU_event_callback );

    register_event_callback( EVENT_TMU2, TMU_event_callback );

}    

#define TCR_ICPF 0x0200

#define TCR_UNF  0x0100

#define TCR_UNIE 0x0020

#define TCR_IRQ_ACTIVE (TCR_UNF|TCR_UNIE)

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 */

};

static struct TMU_timer TMU_timers[3];

int32_t mmio_region_TMU_read( uint32_t reg )

{

    switch( reg ) {

    case TCNT0:

        TMU_count( 0, sh4r.slice_cycle );

        break;

    case TCNT1:

        TMU_count( 1, sh4r.slice_cycle );

        break;

    case TCNT2:

        TMU_count( 2, sh4r.slice_cycle );

        break;

    }

    return MMIO_READ( TMU, reg );

}

void TMU_set_timer_control( int timer,  int tcr )

{

    uint32_t period = 1;

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

    if( (oldtcr & TCR_UNF) == 0 ) {

        tcr = tcr & (~TCR_UNF);

    } else {

        if( ((oldtcr & TCR_UNIE) == 0) && 

                (tcr & TCR_IRQ_ACTIVE) == TCR_IRQ_ACTIVE ) {

            intc_raise_interrupt( INT_TMU_TUNI0 + timer );

        } else if( (oldtcr & TCR_UNIE) != 0 && 

                (tcr & TCR_IRQ_ACTIVE) != TCR_IRQ_ACTIVE ) {

            intc_clear_interrupt( INT_TMU_TUNI0 + timer );

        }

    }

    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;

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

}

void TMU_schedule_timer( int timer )

{

    uint64_t duration = (uint64_t)((uint32_t)(MMIO_READ( TMU, TCNT0 + 12*timer )+1)) * 

    (uint64_t)TMU_timers[timer].timer_period - TMU_timers[timer].timer_remainder;

    event_schedule_long( EVENT_TMU0+timer, (uint32_t)(duration / 1000000000), 

                         (uint32_t)(duration % 1000000000) );

}

void TMU_start( int timer )

{

    TMU_timers[timer].timer_run = sh4r.slice_cycle;

    TMU_timers[timer].timer_remainder = 0;

    TMU_schedule_timer( timer );

}

/**

 * Stop the given timer. Run it up to the current time and leave it there.

 */

void TMU_stop( int timer )

{

    TMU_count( timer, sh4r.slice_cycle );

    event_cancel( EVENT_TMU0+timer );

}

/**

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

 */

uint32_t TMU_count( int timer, uint32_t nanosecs ) 

{

    uint32_t run_ns = nanosecs + TMU_timers[timer].timer_remainder -

    TMU_timers[timer].timer_run;

    TMU_timers[timer].timer_remainder = 

        run_ns % TMU_timers[timer].timer_period;

    TMU_timers[timer].timer_run = nanosecs;

    uint32_t count = run_ns / 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) + 1;

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

        if( tcr & TCR_UNIE ) 

            intc_raise_interrupt( INT_TMU_TUNI0 + timer );

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

        TMU_schedule_timer(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) != 0 && (val&tmp) == 0  )

                TMU_stop(i);

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

                TMU_start(i);

        }

        break;

    case TCR0:

        TMU_set_timer_control( 0, val );

        return;

    case TCR1:

        TMU_set_timer_control( 1, val );

        return;

    case TCR2:

        TMU_set_timer_control( 2, val );

        return;

    case TCNT0:

        MMIO_WRITE( TMU, reg, val );

        if( TMU_IS_RUNNING(0) ) { // reschedule

            TMU_timers[0].timer_run = sh4r.slice_cycle;

            TMU_schedule_timer( 0 );

        }

        return;

    case TCNT1:

        MMIO_WRITE( TMU, reg, val );

        if( TMU_IS_RUNNING(1) ) { // reschedule

            TMU_timers[1].timer_run = sh4r.slice_cycle;

            TMU_schedule_timer( 1 );

        }

        return;

    case TCNT2:

        MMIO_WRITE( TMU, reg, val );

        if( TMU_IS_RUNNING(2) ) { // reschedule

            TMU_timers[2].timer_run = sh4r.slice_cycle;

            TMU_schedule_timer( 2 );

        }

        return;

    }

    MMIO_WRITE( TMU, reg, val );

}

void TMU_count_all( uint32_t nanosecs )

{

    int tcr = MMIO_READ( TMU, TSTR );

    if( tcr & 0x01 ) {

        TMU_count( 0, nanosecs );

    }

    if( tcr & 0x02 ) {

        TMU_count( 1, nanosecs );

    }

    if( tcr & 0x04 ) {

        TMU_count( 2, nanosecs );

    }

}

void TMU_run_slice( uint32_t nanosecs )

{

    TMU_count_all( nanosecs );

    TMU_timers[0].timer_run = 0;

    TMU_timers[1].timer_run = 0;

    TMU_timers[2].timer_run = 0;

}

void TMU_update_clocks()

{

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

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

    TMU_set_timer_control( 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;

}