/*
 * FreeRTOS Kernel V10.0.1
 * Copyright (C) 2017 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * http://www.FreeRTOS.org
 * http://aws.amazon.com/freertos
 *
 * 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 - note 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 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 ) );
}