Demo/ColdFire_MCF5282_Eclipse/RTOSDemo/FreeRTOS_Tick_Setup.c

/*
	FreeRTOS.org V5.2.0 - Copyright (C) 2003-2009 Richard Barry.

	This file is part of the FreeRTOS.org distribution.

	FreeRTOS.org 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.

	FreeRTOS.org 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.

	You should have received a copy of the GNU General Public License along 
	with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59 
	Temple Place, Suite 330, Boston, MA  02111-1307  USA.

	A special exception to the GPL is included to allow you to distribute a 
	combined work that includes FreeRTOS.org without being obliged to provide
	the source code for any proprietary components.  See the licensing section
	of http://www.FreeRTOS.org for full details.


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	Please ensure to read the configuration and relevant port sections of the
	online documentation.

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*/

#include "FreeRTOS.h"
#include "task.h"

/* Constants used to configure the interrupts. */
#define portPRESCALE_VALUE			64
#define portPRESCALE_REG_SETTING	( 5 << 8 )
#define portPIT_INTERRUPT_ENABLED	( 0x08 )
#define configPIT0_INTERRUPT_VECTOR	( 55 )

/*
 * FreeRTOS.org requires two interrupts - a tick interrupt generated from a
 * timer source, and a spare interrupt vector used for context switching.
 * The configuration below uses PIT0 for the former, and vector 16 for the
 * latter.  **IF YOUR APPLICATION HAS BOTH OF THESE INTERRUPTS FREE THEN YOU DO
 * NOT NEED TO CHANGE ANY OF THIS CODE** - otherwise instructions are provided
 * here for using alternative interrupt sources.
 *
 * To change the tick interrupt source:
 *
 *	1) Modify vApplicationSetupInterrupts() below to be correct for whichever
 *	peripheral is to be used to generate the tick interrupt.
 *
 *	2) Change the name of the function __cs3_isr_interrupt_119() defined within
 *	this file to be correct for the interrupt vector used by the timer peripheral.
 *	The name of the function should contain the vector number, so by default vector
 *	number 119 is being used.
 *
 *	3) Make sure the tick interrupt is cleared within the interrupt handler function.
 *  Currently __cs3_isr_interrupt_119() clears the PIT0 interrupt.
 *
 * To change the spare interrupt source:
 *
 *  1) Modify vApplicationSetupInterrupts() below to be correct for whichever
 *  interrupt vector is to be used.  Make sure you use a spare interrupt on interrupt
 *  controller 0, otherwise the register used to request context switches will also
 *  require modification.  By default vector 16 is used which is free on most MCF52xxx
 *  devices.
 *
 *  2) Change the definition of configYIELD_INTERRUPT_VECTOR within FreeRTOSConfig.h
 *  to be correct for your chosen interrupt vector.
 *
 *  3) Change the name of the function __cs3_isr_interrupt_80() within portasm.S
 *  to be correct for whichever vector number is being used.  By default interrupt
 *  controller 0 vector number 16 is used, which corresponds to vector number 80.
 */
void vApplicationSetupInterrupts( void )
{
const unsigned portSHORT usCompareMatchValue = ( ( configCPU_CLOCK_HZ / portPRESCALE_VALUE ) / configTICK_RATE_HZ );

    /* Configure interrupt priority and level and unmask interrupt for PIT0. */
    MCF_INTC0_ICR55 = ( 1 | ( configKERNEL_INTERRUPT_PRIORITY << 3 ) );
    MCF_INTC0_IMRH &= ~( MCF_INTC_IMRH_INT_MASK55 );

    /* Do the same for vector 16 (interrupt controller 0).  I don't think the
    write to MCF_INTC0_IMRH is actually required here but is included for
    completeness. */
    MCF_INTC0_ICR16 = ( 0 | ( configKERNEL_INTERRUPT_PRIORITY << 3 ) );
    MCF_INTC0_IMRH &= ~( MCF_INTC_IPRL_INT16 );

    /* Configure PIT0 to generate the RTOS tick. */
    MCF_PIT0_PCSR |= MCF_PIT_PCSR_PIF;
    MCF_PIT0_PCSR = ( portPRESCALE_REG_SETTING | MCF_PIT_PCSR_PIE | MCF_PIT_PCSR_RLD | MCF_PIT_PCSR_EN );
	MCF_PIT0_PMR = usCompareMatchValue;
}
/*-----------------------------------------------------------*/

void __attribute__ ((interrupt)) __cs3_isr_interrupt_119( void )
{
unsigned portLONG ulSavedInterruptMask;

	/* Clear the PIT0 interrupt. */
	MCF_PIT0_PCSR |= MCF_PIT_PCSR_PIF;

	/* Increment the RTOS tick. */
	ulSavedInterruptMask = portSET_INTERRUPT_MASK_FROM_ISR();
		vTaskIncrementTick();
	portCLEAR_INTERRUPT_MASK_FROM_ISR( ulSavedInterruptMask );

	/* If we are using the pre-emptive scheduler then also request a
	context switch as incrementing the tick could have unblocked a task. */
	#if configUSE_PREEMPTION == 1
	{
		taskYIELD();
	}
	#endif
}