/**

  * $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;

 }