/* | |
FreeRTOS.org V5.3.0 - Copyright (C) 2003-2009 Richard Barry. | |
This file is part of the FreeRTOS.org distribution. | |
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under the terms of the GNU General Public License (version 2) as published | |
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You should have received a copy of the GNU General Public License along | |
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*************************************************************************** | |
* * | |
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation * | |
* * | |
* This is a concise, step by step, 'hands on' guide that describes both * | |
* general multitasking concepts and FreeRTOS specifics. It presents and * | |
* explains numerous examples that are written using the FreeRTOS API. * | |
* Full source code for all the examples is provided in an accompanying * | |
* .zip file. * | |
* * | |
*************************************************************************** | |
1 tab == 4 spaces! | |
Please ensure to read the configuration and relevant port sections of the | |
online documentation. | |
http://www.FreeRTOS.org - Documentation, latest information, license and | |
contact details. | |
http://www.SafeRTOS.com - A version that is certified for use in safety | |
critical systems. | |
http://www.OpenRTOS.com - Commercial support, development, porting, | |
licensing and training services. | |
*/ | |
/*----------------------------------------------------------- | |
* Implementation of functions defined in portable.h for the Philips ARM7 port. | |
*----------------------------------------------------------*/ | |
/* | |
Changes from V3.2.2 | |
+ Bug fix - The prescale value for the timer setup is now written to T0PR | |
instead of T0PC. This bug would have had no effect unless a prescale | |
value was actually used. | |
*/ | |
/* Standard includes. */ | |
#include <stdlib.h> | |
#include <intrinsics.h> | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "task.h" | |
/* Constants required to setup the tick ISR. */ | |
#define portENABLE_TIMER ( ( unsigned portCHAR ) 0x01 ) | |
#define portPRESCALE_VALUE 0x00 | |
#define portINTERRUPT_ON_MATCH ( ( unsigned portLONG ) 0x01 ) | |
#define portRESET_COUNT_ON_MATCH ( ( unsigned portLONG ) 0x02 ) | |
/* Constants required to setup the initial stack. */ | |
#define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x3f ) /* System mode, THUMB mode, interrupts enabled. */ | |
#define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 ) | |
/* Constants required to setup the PIT. */ | |
#define portPIT_CLOCK_DIVISOR ( ( unsigned portLONG ) 16 ) | |
#define portPIT_COUNTER_VALUE ( ( ( configCPU_CLOCK_HZ / portPIT_CLOCK_DIVISOR ) / 1000UL ) * portTICK_RATE_MS ) | |
/* Constants required to handle interrupts. */ | |
#define portTIMER_MATCH_ISR_BIT ( ( unsigned portCHAR ) 0x01 ) | |
#define portCLEAR_VIC_INTERRUPT ( ( unsigned portLONG ) 0 ) | |
/* Constants required to handle critical sections. */ | |
#define portNO_CRITICAL_NESTING ( ( unsigned portLONG ) 0 ) | |
#define portINT_LEVEL_SENSITIVE 0 | |
#define portPIT_ENABLE ( ( unsigned portSHORT ) 0x1 << 24 ) | |
#define portPIT_INT_ENABLE ( ( unsigned portSHORT ) 0x1 << 25 ) | |
/* Constants required to setup the VIC for the tick ISR. */ | |
#define portTIMER_VIC_CHANNEL ( ( unsigned portLONG ) 0x0004 ) | |
#define portTIMER_VIC_CHANNEL_BIT ( ( unsigned portLONG ) 0x0010 ) | |
#define portTIMER_VIC_ENABLE ( ( unsigned portLONG ) 0x0020 ) | |
/*-----------------------------------------------------------*/ | |
/* Setup the PIT to generate the tick interrupts. */ | |
static void prvSetupTimerInterrupt( void ); | |
/* ulCriticalNesting will get set to zero when the first task starts. It | |
cannot be initialised to 0 as this will cause interrupts to be enabled | |
during the kernel initialisation process. */ | |
unsigned portLONG ulCriticalNesting = ( unsigned portLONG ) 9999; | |
/*-----------------------------------------------------------*/ | |
/* | |
* Initialise the stack of a task to look exactly as if a call to | |
* portSAVE_CONTEXT had been called. | |
* | |
* See header file for description. | |
*/ | |
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters ) | |
{ | |
portSTACK_TYPE *pxOriginalTOS; | |
pxOriginalTOS = pxTopOfStack; | |
/* 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 in this case is the | |
start of the task. 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 ) 0xaaaaaaaa; /* R14 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */ | |
pxTopOfStack--; | |
*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--; | |
/* When the task starts is will expect to find the function parameter in | |
R0. */ | |
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */ | |
pxTopOfStack--; | |
/* The status register is set for system mode, with interrupts enabled. */ | |
*pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR; | |
pxTopOfStack--; | |
/* Interrupt flags cannot always be stored on the stack and will | |
instead be stored in a variable, which is then saved as part of the | |
tasks context. */ | |
*pxTopOfStack = portNO_CRITICAL_NESTING; | |
return pxTopOfStack; | |
} | |
/*-----------------------------------------------------------*/ | |
portBASE_TYPE xPortStartScheduler( void ) | |
{ | |
extern void vPortStartFirstTask( void ); | |
/* Start the timer that generates the tick ISR. Interrupts are disabled | |
here already. */ | |
prvSetupTimerInterrupt(); | |
/* Start the first task. */ | |
vPortStartFirstTask(); | |
/* Should not get here! */ | |
return 0; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEndScheduler( void ) | |
{ | |
/* It is unlikely that the ARM 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. */ | |
static __arm __irq void vPortNonPreemptiveTick( void ); | |
static __arm __irq void vPortNonPreemptiveTick( void ) | |
{ | |
/* Increment the tick count - which may wake some tasks but as the | |
preemptive scheduler is not being used any woken task is not given | |
processor time no matter what its priority. */ | |
vTaskIncrementTick(); | |
/* Ready for the next interrupt. */ | |
T0IR = portTIMER_MATCH_ISR_BIT; | |
VICVectAddr = portCLEAR_VIC_INTERRUPT; | |
} | |
#else | |
/* This function is called from an asm wrapper, so does not require the __irq | |
keyword. */ | |
void vPortPreemptiveTick( void ); | |
void vPortPreemptiveTick( void ) | |
{ | |
/* Increment the tick counter. */ | |
vTaskIncrementTick(); | |
/* The new tick value might unblock a task. Ensure the highest task that | |
is ready to execute is the task that will execute when the tick ISR | |
exits. */ | |
vTaskSwitchContext(); | |
/* Ready for the next interrupt. */ | |
T0IR = portTIMER_MATCH_ISR_BIT; | |
VICVectAddr = portCLEAR_VIC_INTERRUPT; | |
} | |
#endif | |
/*-----------------------------------------------------------*/ | |
static void prvSetupTimerInterrupt( void ) | |
{ | |
unsigned portLONG ulCompareMatch; | |
/* A 1ms tick does not require the use of the timer prescale. This is | |
defaulted to zero but can be used if necessary. */ | |
T0PR = portPRESCALE_VALUE; | |
/* Calculate the match value required for our wanted tick rate. */ | |
ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ; | |
/* Protect against divide by zero. Using an if() statement still results | |
in a warning - hence the #if. */ | |
#if portPRESCALE_VALUE != 0 | |
{ | |
ulCompareMatch /= ( portPRESCALE_VALUE + 1 ); | |
} | |
#endif | |
T0MR0 = ulCompareMatch; | |
/* Generate tick with timer 0 compare match. */ | |
T0MCR = portRESET_COUNT_ON_MATCH | portINTERRUPT_ON_MATCH; | |
/* Setup the VIC for the timer. */ | |
VICIntSelect &= ~( portTIMER_VIC_CHANNEL_BIT ); | |
VICIntEnable |= portTIMER_VIC_CHANNEL_BIT; | |
/* The ISR installed depends on whether the preemptive or cooperative | |
scheduler is being used. */ | |
#if configUSE_PREEMPTION == 1 | |
{ | |
extern void ( vPortPreemptiveTickEntry )( void ); | |
VICVectAddr0 = ( unsigned portLONG ) vPortPreemptiveTickEntry; | |
} | |
#else | |
{ | |
extern void ( vNonPreemptiveTick )( void ); | |
VICVectAddr0 = ( portLONG ) vPortNonPreemptiveTick; | |
} | |
#endif | |
VICVectCntl0 = portTIMER_VIC_CHANNEL | portTIMER_VIC_ENABLE; | |
/* Start the timer - interrupts are disabled when this function is called | |
so it is okay to do this here. */ | |
T0TCR = portENABLE_TIMER; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEnterCritical( void ) | |
{ | |
/* Disable interrupts first! */ | |
__disable_interrupt(); | |
/* 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++; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortExitCritical( void ) | |
{ | |
if( ulCriticalNesting > portNO_CRITICAL_NESTING ) | |
{ | |
/* 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 == portNO_CRITICAL_NESTING ) | |
{ | |
__enable_interrupt(); | |
} | |
} | |
} | |
/*-----------------------------------------------------------*/ | |