FreeRTOS-Kernel/Demo/ColdFire_MCF5282_Eclipse/RTOSDemo/FreeRTOS_Tick_Setup.c

/*
    FreeRTOS V6.0.0 - Copyright (C) 2009 Real Time Engineers Ltd.

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    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 exception to the GPL is included to allow you to distribute
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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
}