FreeRTOS/Source/portable/CCS/ARM_Cortex-R4/port.c

/*
    FreeRTOS V7.2.0 - Copyright (C) 2012 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.
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*/

/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"

/*-----------------------------------------------------------*/

/* Count of the critical section nesting depth. */
unsigned portLONG ulCriticalNesting = 9999;

/*-----------------------------------------------------------*/

/* Registers required to configure the RTI. */
#define portRTI_GCTRL_REG  		( * ( ( volatile unsigned long * ) 0xFFFFFC00 ) )
#define portRTI_TBCTRL_REG  	( * ( ( volatile unsigned long * ) 0xFFFFFC04 ) )
#define portRTI_COMPCTRL_REG  	( * ( ( volatile unsigned long * ) 0xFFFFFC0C ) )
#define portRTI_CNT0_FRC0_REG  	( * ( ( volatile unsigned long * ) 0xFFFFFC10 ) )
#define portRTI_CNT0_UC0_REG  	( * ( ( volatile unsigned long * ) 0xFFFFFC14 ) )
#define portRTI_CNT0_CPUC0_REG  ( * ( ( volatile unsigned long * ) 0xFFFFFC18 ) )
#define portRTI_CNT0_COMP0_REG  ( * ( ( volatile unsigned long * ) 0xFFFFFC50 ) )
#define portRTI_CNT0_UDCP0_REG  ( * ( ( volatile unsigned long * ) 0xFFFFFC54 ) )
#define portRTI_SETINTENA_REG  	( * ( ( volatile unsigned long * ) 0xFFFFFC80 ) )
#define portRTI_CLEARINTENA_REG ( * ( ( volatile unsigned long * ) 0xFFFFFC84 ) )
#define portRTI_INTFLAG_REG  	( * ( ( volatile unsigned long * ) 0xFFFFFC88 ) )


/* Constants required to set up the initial stack of each task. */
#define portINITIAL_SPSR	   	( ( portSTACK_TYPE ) 0x1F )
#define portINITIAL_FPSCR	  	( ( portSTACK_TYPE ) 0x00 )
#define portINSTRUCTION_SIZE   	( ( portSTACK_TYPE ) 0x04 )
#define portTHUMB_MODE_BIT		( ( portSTACK_TYPE ) 0x20 )

/* The number of words on the stack frame between the saved Top Of Stack and
R0 (in which the parameters are passed. */
#define portSPACE_BETWEEN_TOS_AND_PARAMETERS	( 12 )

/*-----------------------------------------------------------*/

/* vPortStartFirstSTask() is defined in portASM.asm */
extern void vPortStartFirstTask( void );

/*-----------------------------------------------------------*/

/* Saved as part of the task context.  Set to pdFALSE if the task does not
require an FPU context. */
unsigned long ulTaskHasFPUContext = 0;

/*-----------------------------------------------------------*/


/*
 * See header file for description.
 */
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
portSTACK_TYPE *pxOriginalTOS;

	pxOriginalTOS = pxTopOfStack;

	#if __TI_VFP_SUPPORT__
	{
		/* Ensure the stack is correctly aligned on exit. */
		pxTopOfStack--;
	}
	#endif

	/* Setup the initial stack of the task.  The stack is set exactly as
	expected by the portRESTORE_CONTEXT() macro. */

	/* First on the stack is the return address - which is the start of the as
	the task has not executed yet.  The offset is added to make the return
	address appear as it would within an IRQ ISR. */
	*pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE;
	pxTopOfStack--;

	*pxTopOfStack = ( portSTACK_TYPE ) 0x00000000;	/* R14 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */
	pxTopOfStack--;

	#ifdef portPRELOAD_TASK_REGISTERS
	{
		*pxTopOfStack = ( portSTACK_TYPE ) 0x12121212;	/* R12 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x11111111;	/* R11 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x10101010;	/* R10 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x09090909;	/* R9 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x08080808;	/* R8 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x07070707;	/* R7 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x06060606;	/* R6 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x05050505;	/* R5 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x04040404;	/* R4 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x03030303;	/* R3 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x02020202;	/* R2 */
		pxTopOfStack--;
		*pxTopOfStack = ( portSTACK_TYPE ) 0x01010101;	/* R1 */
		pxTopOfStack--;
	}
	#else
	{
		pxTopOfStack -= portSPACE_BETWEEN_TOS_AND_PARAMETERS;
	}
	#endif

	/* Function parameters are passed in R0. */
	*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */
	pxTopOfStack--;

	/* Set the status register for system mode, with interrupts enabled. */
	*pxTopOfStack = ( portSTACK_TYPE ) ( ( _get_CPSR() & ~0xFF ) | portINITIAL_SPSR );

	if( ( ( unsigned long ) pxCode & 0x01UL ) != 0x00 )
	{
		/* The task will start in thumb mode. */
		*pxTopOfStack |= portTHUMB_MODE_BIT;
	}

	#ifdef __TI_VFP_SUPPORT__
	{
		pxTopOfStack--;

		/* The last thing on the stack is the tasks ulUsingFPU value, which by
		default is set to indicate that the stack frame does not include FPU
		registers. */
		*pxTopOfStack = pdFALSE;
	}
	#endif

	return pxTopOfStack;
}
/*-----------------------------------------------------------*/

static void prvSetupTimerInterrupt(void)
{
	/* Disable timer 0. */
	portRTI_GCTRL_REG &= 0xFFFFFFFEUL;

	/* Use the internal counter. */
	portRTI_TBCTRL_REG = 0x00000000U;

	/* COMPSEL0 will use the RTIFRC0 counter. */
	portRTI_COMPCTRL_REG = 0x00000000U;

	/* Initialise the counter and the prescale counter registers. */
	portRTI_CNT0_UC0_REG =  0x00000000U;
	portRTI_CNT0_FRC0_REG =  0x00000000U;

	/* Set Prescalar for RTI clock. */
	portRTI_CNT0_CPUC0_REG = 0x00000001U;
	portRTI_CNT0_COMP0_REG = ( configCPU_CLOCK_HZ / 2 ) / configTICK_RATE_HZ;
	portRTI_CNT0_UDCP0_REG = ( configCPU_CLOCK_HZ / 2 ) / configTICK_RATE_HZ;

	/* Clear interrupts. */
	portRTI_INTFLAG_REG =  0x0007000FU;
	portRTI_CLEARINTENA_REG	= 0x00070F0FU;

	/* Enable the compare 0 interrupt. */
	portRTI_SETINTENA_REG = 0x00000001U;
	portRTI_GCTRL_REG |= 0x00000001U;
}
/*-----------------------------------------------------------*/

/*
 * See header file for description.
 */
portBASE_TYPE xPortStartScheduler(void)
{
	/* Start the timer that generates the tick ISR. */
	prvSetupTimerInterrupt();

	/* Reset the critical section nesting count read to execute the first task. */
	ulCriticalNesting = 0;

	/* Start the first task.  This is done from portASM.asm as ARM mode must be
	used. */
	vPortStartFirstTask();

	/* Should not get here! */
	return pdFAIL;
}
/*-----------------------------------------------------------*/

/*
 * See header file for description.
 */
void vPortEndScheduler(void)
{
	/* It is unlikely that the port will require this function as there
	is nothing to return to. */
}
/*-----------------------------------------------------------*/

#if configUSE_PREEMPTION == 0

	/* The cooperative scheduler requires a normal IRQ service routine to
	 * simply increment the system tick. */
	__interrupt void vPortNonPreemptiveTick( void )
	{
		/* clear clock interrupt flag */
		RTI->INTFLAG = 0x00000001;

		/* Increment the tick count - this may make a delaying task ready
		to run - but a context switch is not performed. */
		vTaskIncrementTick();
	}

 #else

	/*
	 **************************************************************************
	 * The preemptive scheduler ISR is written in assembler and can be found
	 * in the portASM.asm file. This will only get used if portUSE_PREEMPTION
	 * is set to 1 in portmacro.h
	 **************************************************************************
	 */
	void vPortPreemptiveTick( void );

#endif
/*-----------------------------------------------------------*/


/*
 * Disable interrupts, and keep a count of the nesting depth.
 */
void vPortEnterCritical( void )
{
	/* Disable interrupts as per portDISABLE_INTERRUPTS(); */
	portDISABLE_INTERRUPTS();

	/* Now interrupts are disabled ulCriticalNesting can be accessed
	directly.  Increment ulCriticalNesting to keep a count of how many times
	portENTER_CRITICAL() has been called. */
	ulCriticalNesting++;
}
/*-----------------------------------------------------------*/

/*
 * Decrement the critical nesting count, and if it has reached zero, re-enable
 * interrupts.
 */
void vPortExitCritical( void )
{
	if( ulCriticalNesting > 0 )
	{
		/* Decrement the nesting count as we are leaving a critical section. */
		ulCriticalNesting--;

		/* If the nesting level has reached zero then interrupts should be
		re-enabled. */
		if( ulCriticalNesting == 0 )
		{
			/* Enable interrupts as per portENABLE_INTERRUPTS(). */
			portENABLE_INTERRUPTS();
		}
	}
}
/*-----------------------------------------------------------*/

#if __TI_VFP_SUPPORT__

	void vPortTaskUsesFPU( void )
	{
	extern void vPortInitialiseFPSCR( void );

		/* A task is registering the fact that it needs an FPU context.  Set the
		FPU flag (saved as part of the task context. */
		ulTaskHasFPUContext = pdTRUE;

		/* Initialise the floating point status register. */
		vPortInitialiseFPSCR();
	}

#endif /* __TI_VFP_SUPPORT__ */

/*-----------------------------------------------------------*/