/*
    FreeRTOS V7.5.3 - Copyright (C) 2013 Real Time Engineers Ltd. 
    All rights reserved

    VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS provides completely free yet professionally developed,    *
     *    robust, strictly quality controlled, supported, and cross          *
     *    platform software that has become a de facto standard.             *
     *                                                                       *
     *    Help yourself get started quickly and support the FreeRTOS         *
     *    project by purchasing a FreeRTOS tutorial book, reference          *
     *    manual, or both from: http://www.FreeRTOS.org/Documentation        *
     *                                                                       *
     *    Thank you!                                                         *
     *                                                                       *
    ***************************************************************************

    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation >>!AND MODIFIED BY!<< the FreeRTOS exception.

    >>! NOTE: The modification to the GPL is included to allow you to distribute
    >>! a combined work that includes FreeRTOS without being obliged to provide
    >>! the source code for proprietary components outside of the FreeRTOS
    >>! kernel.

    FreeRTOS 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.  Full license text is available from the following
    link: http://www.freertos.org/a00114.html

    1 tab == 4 spaces!

    ***************************************************************************
     *                                                                       *
     *    Having a problem?  Start by reading the FAQ "My application does   *
     *    not run, what could be wrong?"                                     *
     *                                                                       *
     *    http://www.FreeRTOS.org/FAQHelp.html                               *
     *                                                                       *
    ***************************************************************************

    http://www.FreeRTOS.org - Documentation, books, training, latest versions,
    license and Real Time Engineers Ltd. contact details.

    http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
    including FreeRTOS+Trace - an indispensable productivity tool, a DOS
    compatible FAT file system, and our tiny thread aware UDP/IP stack.

    http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
    Integrity Systems to sell under the OpenRTOS brand.  Low cost OpenRTOS
    licenses offer ticketed support, indemnification and middleware.

    http://www.SafeRTOS.com - High Integrity Systems also provide a safety
    engineered and independently SIL3 certified version for use in safety and
    mission critical applications that require provable dependability.

    1 tab == 4 spaces!
*/

/*
 * This file implements functions to access and manipulate the PIC32 hardware
 * without reliance on third party library functions that may be liable to
 * change.
 */

/* FreeRTOS includes. */
#include "FreeRTOS.h"

/* Demo includes. */
#include "ConfigPerformance.h"

/* Hardware specific definitions. */
#define hwCHECON_PREFEN_BITS	  		( 0x03UL << 0x04UL )
#define hwCHECON_WAIT_STAT_BITS			( 0x07UL << 0UL )
#define hwMAX_FLASH_SPEED		  		( 30000000UL )
#define hwPERIPHERAL_CLOCK_DIV_BY_2		( 1UL << 0x13UL )
#define hwUNLOCK_KEY_0					( 0xAA996655UL )
#define hwUNLOCK_KEY_1					( 0x556699AAUL )
#define hwLOCK_KEY						( 0x33333333UL )
#define hwGLOBAL_INTERRUPT_BIT			( 0x01UL )
#define hwBEV_BIT 						( 0x00400000 )
#define hwEXL_BIT 						( 0x00000002 )
#define hwIV_BIT 						( 0x00800000 )

/*
 * Set the flash wait states for the configured CPU clock speed.
 */
static void prvConfigureWaitStates( void );

/*
 * Use a divisor of 2 on the peripheral bus.
 */
static void prvConfigurePeripheralBus( void );

/*
 * Enable the cache.
 */
static void __attribute__ ((nomips16)) prvKSeg0CacheOn( void );

/*-----------------------------------------------------------*/

void vHardwareConfigurePerformance( void )
{
unsigned long ulStatus;
#ifdef _PCACHE
	unsigned long ulCacheStatus;
#endif

	/* Disable interrupts - not taskDISABLE_INTERRUPTS() cannot be used here as
	FreeRTOS does not globally disable interrupt. */
	ulStatus = _CP0_GET_STATUS();
	_CP0_SET_STATUS( ulStatus & ~hwGLOBAL_INTERRUPT_BIT );

	prvConfigurePeripheralBus();
	prvConfigureWaitStates();

	/* Disable DRM wait state. */
	BMXCONCLR = _BMXCON_BMXWSDRM_MASK;

	#ifdef _PCACHE
	{
		/* Read the current CHECON value. */
		ulCacheStatus = CHECON;

		/* All the PREFEN bits are being set, so no need to clear first. */
		ulCacheStatus |= hwCHECON_PREFEN_BITS;

		/* Write back the new value. */
		CHECON = ulCacheStatus;
		prvKSeg0CacheOn();
	}
	#endif

	/* Reset the status register back to its original value so the original
	interrupt enable status is retored. */
	_CP0_SET_STATUS( ulStatus );
}
/*-----------------------------------------------------------*/

void vHardwareUseMultiVectoredInterrupts( void )
{
unsigned long ulStatus, ulCause;
extern unsigned long _ebase_address[];

	/* Get current status. */
	ulStatus = _CP0_GET_STATUS();

	/* Disable interrupts. */
	ulStatus &= ~hwGLOBAL_INTERRUPT_BIT;

	/* Set BEV bit. */
	ulStatus |= hwBEV_BIT;

	/* Write status back. */
	_CP0_SET_STATUS( ulStatus );

	/* Setup EBase. */
	_CP0_SET_EBASE( ( unsigned long ) _ebase_address );
	
	/* Space vectors by 0x20 bytes. */
	_CP0_XCH_INTCTL( 0x20 );

	/* Set the IV bit in the CAUSE register. */
	ulCause = _CP0_GET_CAUSE();
	ulCause |= hwIV_BIT;
	_CP0_SET_CAUSE( ulCause );

	/* Clear BEV and EXL bits in status. */
	ulStatus &= ~( hwBEV_BIT | hwEXL_BIT );
	_CP0_SET_STATUS( ulStatus );

	/* Set MVEC bit. */
	INTCONbits.MVEC = 1;
	
	/* Finally enable interrupts again. */
	ulStatus |= hwGLOBAL_INTERRUPT_BIT;
	_CP0_SET_STATUS( ulStatus );
}
/*-----------------------------------------------------------*/

static void prvConfigurePeripheralBus( void )
{
unsigned long ulDMAStatus;
__OSCCONbits_t xOSCCONBits;

	/* Unlock after suspending. */
	ulDMAStatus = DMACONbits.SUSPEND;
	if( ulDMAStatus == 0 )
	{
		DMACONSET = _DMACON_SUSPEND_MASK;

		/* Wait until actually suspended. */
		while( DMACONbits.SUSPEND == 0 );
	}

	SYSKEY = 0;
	SYSKEY = hwUNLOCK_KEY_0;
	SYSKEY = hwUNLOCK_KEY_1;

	/* Read to start in sync. */
	xOSCCONBits.w = OSCCON;
	xOSCCONBits.PBDIV = 0;
	xOSCCONBits.w |= hwPERIPHERAL_CLOCK_DIV_BY_2;

	/* Write back. */
	OSCCON = xOSCCONBits.w;

	/* Ensure the write occurred. */
	xOSCCONBits.w = OSCCON;

	/* Lock again. */
	SYSKEY = hwLOCK_KEY;

	/* Resume DMA activity. */
	if( ulDMAStatus == 0 )
	{
		DMACONCLR=_DMACON_SUSPEND_MASK;
	}
}
/*-----------------------------------------------------------*/

static void prvConfigureWaitStates( void )
{
unsigned long ulInterruptStatus, ulSystemClock = configCPU_CLOCK_HZ - 1;
unsigned long ulWaitStates, ulCHECONVal;

	/* 1 wait state for every hwMAX_FLASH_SPEED MHz. */
	ulWaitStates = 0;

	while( ulSystemClock > hwMAX_FLASH_SPEED )
	{
		ulWaitStates++;
		ulSystemClock -= hwMAX_FLASH_SPEED;
	}

	/* Obtain current CHECON value. */
	ulCHECONVal = CHECON;

	/* Clear the wait state bits, then set the calculated wait state bits. */
	ulCHECONVal &= ~hwCHECON_WAIT_STAT_BITS;
	ulCHECONVal |= ulWaitStates;

	/* Write back the new value. */
	CHECON = ulWaitStates;
}
/*-----------------------------------------------------------*/

static void __attribute__ ((nomips16)) prvKSeg0CacheOn( void )
{
unsigned long ulValue;

	__asm volatile( "mfc0 %0, $16, 0" :  "=r"( ulValue ) );
	ulValue = ( ulValue & ~0x07) | 0x03;
	__asm volatile( "mtc0 %0, $16, 0" :: "r" ( ulValue ) );
}