/* | |
FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd. | |
FEATURES AND PORTS ARE ADDED TO FREERTOS ALL THE TIME. PLEASE VISIT | |
http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION. | |
*************************************************************************** | |
* * | |
* FreeRTOS tutorial books are available in pdf and paperback. * | |
* Complete, revised, and edited pdf reference manuals are also * | |
* available. * | |
* * | |
* Purchasing FreeRTOS documentation will not only help you, by * | |
* ensuring you get running as quickly as possible and with an * | |
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* the FreeRTOS project to continue with its mission of providing * | |
* professional grade, cross platform, de facto standard solutions * | |
* for microcontrollers - completely free of charge! * | |
* * | |
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< * | |
* * | |
* Thank you for using FreeRTOS, and thank you for your support! * | |
* * | |
*************************************************************************** | |
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 modification to the GPL is included to allow you to | |
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writing to Real Time Engineers Ltd., contact details for whom are available | |
on the FreeRTOS WEB site. | |
1 tab == 4 spaces! | |
*************************************************************************** | |
* * | |
* Having a problem? Start by reading the FAQ "My application does * | |
* not run, what could be wrong?" * | |
* * | |
* http://www.FreeRTOS.org/FAQHelp.html * | |
* * | |
*************************************************************************** | |
http://www.FreeRTOS.org - Documentation, books, training, latest versions, | |
license and Real Time Engineers Ltd. contact details. | |
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including FreeRTOS+Trace - an indispensable productivity tool, and our new | |
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mission critical applications that require provable dependability. | |
*/ | |
/*----------------------------------------------------------- | |
* Implementation of functions defined in portable.h for the ARM CM3 port. | |
*----------------------------------------------------------*/ | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "task.h" | |
/* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is | |
defined. The value should also ensure backward compatibility. | |
FreeRTOS.org versions prior to V4.4.0 did not include this definition. */ | |
#ifndef configKERNEL_INTERRUPT_PRIORITY | |
#define configKERNEL_INTERRUPT_PRIORITY 255 | |
#endif | |
#ifndef configSYSTICK_CLOCK_HZ | |
#define configSYSTICK_CLOCK_HZ configCPU_CLOCK_HZ | |
#endif | |
/* Constants required to manipulate the core. Registers first... */ | |
#define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile unsigned long * ) 0xe000e010 ) ) | |
#define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile unsigned long * ) 0xe000e014 ) ) | |
#define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile unsigned long * ) 0xe000e018 ) ) | |
#define portNVIC_INT_CTRL_REG ( * ( ( volatile unsigned long * ) 0xe000ed04 ) ) | |
#define portNVIC_SYSPRI2_REG ( * ( ( volatile unsigned long * ) 0xe000ed20 ) ) | |
/* ...then bits in the registers. */ | |
#define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL ) | |
#define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL ) | |
#define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL ) | |
#define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL ) | |
#define portNVIC_PENDSVSET_BIT ( 1UL << 28UL ) | |
#define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) | |
#define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) | |
#define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL ) | |
#define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL ) | |
/* Constants required to set up the initial stack. */ | |
#define portINITIAL_XPSR ( 0x01000000 ) | |
/* The priority used by the kernel is assigned to a variable to make access | |
from inline assembler easier. */ | |
const unsigned long ulKernelPriority = configKERNEL_INTERRUPT_PRIORITY; | |
/* Each task maintains its own interrupt status in the critical nesting | |
variable. */ | |
static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa; | |
/* | |
* Setup the timer to generate the tick interrupts. The implementation in this | |
* file is weak to allow application writers to change the timer used to | |
* generate the tick interrupt. | |
*/ | |
void vPortSetupTimerInterrupt( void ); | |
/* | |
* Exception handlers. | |
*/ | |
void xPortPendSVHandler( void ) __attribute__ (( naked )); | |
void xPortSysTickHandler( void ); | |
void vPortSVCHandler( void ) __attribute__ (( naked )); | |
/* | |
* Start first task is a separate function so it can be tested in isolation. | |
*/ | |
static void prvPortStartFirstTask( void ) __attribute__ (( naked )); | |
/*-----------------------------------------------------------*/ | |
/* | |
* The number of SysTick increments that make up one tick period. | |
*/ | |
#if configUSE_TICKLESS_IDLE == 1 | |
static unsigned long ulTimerReloadValueForOneTick = 0; | |
#endif | |
/* | |
* The maximum number of tick periods that can be suppressed is limited by the | |
* 24 bit resolution of the SysTick timer. | |
*/ | |
#if configUSE_TICKLESS_IDLE == 1 | |
static unsigned long xMaximumPossibleSuppressedTicks = 0; | |
#endif /* configUSE_TICKLESS_IDLE */ | |
/* | |
* Compensate for the CPU cycles that pass while the SysTick is stopped (low | |
* power functionality only. | |
*/ | |
#if configUSE_TICKLESS_IDLE == 1 | |
static unsigned long ulStoppedTimerCompensation = 0; | |
#endif /* configUSE_TICKLESS_IDLE */ | |
/*-----------------------------------------------------------*/ | |
/* | |
* See header file for description. | |
*/ | |
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters ) | |
{ | |
/* Simulate the stack frame as it would be created by a context switch | |
interrupt. */ | |
pxTopOfStack--; /* Offset added to account for the way the MCU uses the stack on entry/exit of interrupts. */ | |
*pxTopOfStack = portINITIAL_XPSR; /* xPSR */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */ | |
pxTopOfStack--; | |
*pxTopOfStack = 0; /* LR */ | |
pxTopOfStack -= 5; /* R12, R3, R2 and R1. */ | |
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */ | |
pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */ | |
return pxTopOfStack; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortSVCHandler( void ) | |
{ | |
__asm volatile ( | |
" ldr r3, pxCurrentTCBConst2 \n" /* Restore the context. */ | |
" ldr r1, [r3] \n" /* Use pxCurrentTCBConst to get the pxCurrentTCB address. */ | |
" ldr r0, [r1] \n" /* The first item in pxCurrentTCB is the task top of stack. */ | |
" ldmia r0!, {r4-r11} \n" /* Pop the registers that are not automatically saved on exception entry and the critical nesting count. */ | |
" msr psp, r0 \n" /* Restore the task stack pointer. */ | |
" mov r0, #0 \n" | |
" msr basepri, r0 \n" | |
" orr r14, #0xd \n" | |
" bx r14 \n" | |
" \n" | |
" .align 2 \n" | |
"pxCurrentTCBConst2: .word pxCurrentTCB \n" | |
); | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvPortStartFirstTask( void ) | |
{ | |
__asm volatile( | |
" ldr r0, =0xE000ED08 \n" /* Use the NVIC offset register to locate the stack. */ | |
" ldr r0, [r0] \n" | |
" ldr r0, [r0] \n" | |
" msr msp, r0 \n" /* Set the msp back to the start of the stack. */ | |
" cpsie i \n" /* Globally enable interrupts. */ | |
" svc 0 \n" /* System call to start first task. */ | |
" nop \n" | |
); | |
} | |
/*-----------------------------------------------------------*/ | |
/* | |
* See header file for description. | |
*/ | |
portBASE_TYPE xPortStartScheduler( void ) | |
{ | |
/* configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to 0. | |
See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */ | |
configASSERT( configMAX_SYSCALL_INTERRUPT_PRIORITY ); | |
/* Make PendSV, CallSV and SysTick the same priroity as the kernel. */ | |
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; | |
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; | |
/* Start the timer that generates the tick ISR. Interrupts are disabled | |
here already. */ | |
vPortSetupTimerInterrupt(); | |
/* Initialise the critical nesting count ready for the first task. */ | |
uxCriticalNesting = 0; | |
/* Start the first task. */ | |
prvPortStartFirstTask(); | |
/* Should not get here! */ | |
return 0; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEndScheduler( void ) | |
{ | |
/* It is unlikely that the CM3 port will require this function as there | |
is nothing to return to. */ | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortYield( void ) | |
{ | |
/* Set a PendSV to request a context switch. */ | |
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; | |
/* Barriers are normally not required but do ensure the code is completely | |
within the specified behaviour for the architecture. */ | |
__asm volatile( "dsb" ); | |
__asm volatile( "isb" ); | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEnterCritical( void ) | |
{ | |
portDISABLE_INTERRUPTS(); | |
uxCriticalNesting++; | |
__asm volatile( "dsb" ); | |
__asm volatile( "isb" ); | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortExitCritical( void ) | |
{ | |
uxCriticalNesting--; | |
if( uxCriticalNesting == 0 ) | |
{ | |
portENABLE_INTERRUPTS(); | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
__attribute__(( naked )) unsigned long ulPortSetInterruptMask( void ) | |
{ | |
__asm volatile \ | |
( \ | |
" mrs r0, basepri \n" \ | |
" mov r1, %0 \n" \ | |
" msr basepri, r1 \n" \ | |
" bx lr \n" \ | |
:: "i" ( configMAX_SYSCALL_INTERRUPT_PRIORITY ) : "r0", "r1" \ | |
); | |
/* This return will not be reached but is necessary to prevent compiler | |
warnings. */ | |
return 0; | |
} | |
/*-----------------------------------------------------------*/ | |
__attribute__(( naked )) void vPortClearInterruptMask( unsigned long ulNewMaskValue ) | |
{ | |
__asm volatile \ | |
( \ | |
" msr basepri, r0 \n" \ | |
" bx lr \n" \ | |
:::"r0" \ | |
); | |
/* Just to avoid compiler warnings. */ | |
( void ) ulNewMaskValue; | |
} | |
/*-----------------------------------------------------------*/ | |
void xPortPendSVHandler( void ) | |
{ | |
/* This is a naked function. */ | |
__asm volatile | |
( | |
" mrs r0, psp \n" | |
" \n" | |
" ldr r3, pxCurrentTCBConst \n" /* Get the location of the current TCB. */ | |
" ldr r2, [r3] \n" | |
" \n" | |
" stmdb r0!, {r4-r11} \n" /* Save the remaining registers. */ | |
" str r0, [r2] \n" /* Save the new top of stack into the first member of the TCB. */ | |
" \n" | |
" stmdb sp!, {r3, r14} \n" | |
" mov r0, %0 \n" | |
" msr basepri, r0 \n" | |
" bl vTaskSwitchContext \n" | |
" mov r0, #0 \n" | |
" msr basepri, r0 \n" | |
" ldmia sp!, {r3, r14} \n" | |
" \n" /* Restore the context, including the critical nesting count. */ | |
" ldr r1, [r3] \n" | |
" ldr r0, [r1] \n" /* The first item in pxCurrentTCB is the task top of stack. */ | |
" ldmia r0!, {r4-r11} \n" /* Pop the registers. */ | |
" msr psp, r0 \n" | |
" bx r14 \n" | |
" \n" | |
" .align 2 \n" | |
"pxCurrentTCBConst: .word pxCurrentTCB \n" | |
::"i"(configMAX_SYSCALL_INTERRUPT_PRIORITY) | |
); | |
} | |
/*-----------------------------------------------------------*/ | |
void xPortSysTickHandler( void ) | |
{ | |
/* If using preemption, also force a context switch. */ | |
#if configUSE_PREEMPTION == 1 | |
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; | |
#endif | |
/* Only reset the systick load register if configUSE_TICKLESS_IDLE is set to | |
1. If it is set to 0 tickless idle is not being used. If it is set to a | |
value other than 0 or 1 then a timer other than the SysTick is being used | |
to generate the tick interrupt. */ | |
#if configUSE_TICKLESS_IDLE == 1 | |
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick; | |
#endif | |
( void ) portSET_INTERRUPT_MASK_FROM_ISR(); | |
{ | |
vTaskIncrementTick(); | |
} | |
portCLEAR_INTERRUPT_MASK_FROM_ISR( 0 ); | |
} | |
/*-----------------------------------------------------------*/ | |
#if configUSE_TICKLESS_IDLE == 1 | |
__attribute__((weak)) void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime ) | |
{ | |
unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickIncrements; | |
portTickType xModifiableIdleTime; | |
/* Make sure the SysTick reload value does not overflow the counter. */ | |
if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks ) | |
{ | |
xExpectedIdleTime = xMaximumPossibleSuppressedTicks; | |
} | |
/* Calculate the reload value required to wait xExpectedIdleTime | |
tick periods. -1 is used because this code will execute part way | |
through one of the tick periods, and the fraction of a tick period is | |
accounted for later. */ | |
ulReloadValue = ( ulTimerReloadValueForOneTick * ( xExpectedIdleTime - 1UL ) ); | |
if( ulReloadValue > ulStoppedTimerCompensation ) | |
{ | |
ulReloadValue -= ulStoppedTimerCompensation; | |
} | |
/* Stop the SysTick momentarily. The time the SysTick is stopped for | |
is accounted for as best it can be, but using the tickless mode will | |
inevitably result in some tiny drift of the time maintained by the | |
kernel with respect to calendar time. */ | |
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; | |
/* Adjust the reload value to take into account that the current time | |
slice is already partially complete. */ | |
ulReloadValue += ( portNVIC_SYSTICK_LOAD_REG - ( portNVIC_SYSTICK_LOAD_REG - portNVIC_SYSTICK_CURRENT_VALUE_REG ) ); | |
/* Enter a critical section but don't use the taskENTER_CRITICAL() | |
method as that will mask interrupts that should exit sleep mode. */ | |
__asm volatile( "cpsid i" ); | |
/* If a context switch is pending or a task is waiting for the scheduler | |
to be unsuspended then abandon the low power entry. */ | |
if( eTaskConfirmSleepModeStatus() == eAbortSleep ) | |
{ | |
/* Restart SysTick. */ | |
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; | |
/* Re-enable interrupts - see comments above the cpsid instruction() | |
above. */ | |
__asm volatile( "cpsie i" ); | |
} | |
else | |
{ | |
/* Set the new reload value. */ | |
portNVIC_SYSTICK_LOAD_REG = ulReloadValue; | |
/* Clear the SysTick count flag and set the count value back to | |
zero. */ | |
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; | |
/* Restart SysTick. */ | |
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; | |
/* Sleep until something happens. configPRE_SLEEP_PROCESSING() can | |
set its parameter to 0 to indicate that its implementation contains | |
its own wait for interrupt or wait for event instruction, and so wfi | |
should not be executed again. However, the original expected idle | |
time variable must remain unmodified, so a copy is taken. */ | |
xModifiableIdleTime = xExpectedIdleTime; | |
configPRE_SLEEP_PROCESSING( xModifiableIdleTime ); | |
if( xModifiableIdleTime > 0 ) | |
{ | |
__asm volatile( "wfi" ); | |
__asm volatile( "dsb" ); | |
__asm volatile( "isb" ); | |
} | |
configPOST_SLEEP_PROCESSING( xExpectedIdleTime ); | |
/* Stop SysTick. Again, the time the SysTick is stopped for is | |
accounted for as best it can be, but using the tickless mode will | |
inevitably result in some tiny drift of the time maintained by the | |
kernel with respect to calendar time. */ | |
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; | |
/* Re-enable interrupts - see comments above the cpsid instruction() | |
above. */ | |
__asm volatile( "cpsie i" ); | |
if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) | |
{ | |
/* The tick interrupt has already executed, and the SysTick | |
count reloaded with the portNVIC_SYSTICK_LOAD_REG value. | |
Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of | |
this tick period. */ | |
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); | |
/* The tick interrupt handler will already have pended the tick | |
processing in the kernel. As the pending tick will be | |
processed as soon as this function exits, the tick value | |
maintained by the tick is stepped forward by one less than the | |
time spent waiting. */ | |
ulCompleteTickPeriods = xExpectedIdleTime - 1UL; | |
} | |
else | |
{ | |
/* Something other than the tick interrupt ended the sleep. | |
Work out how long the sleep lasted. */ | |
ulCompletedSysTickIncrements = ( xExpectedIdleTime * ulTimerReloadValueForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; | |
/* How many complete tick periods passed while the processor | |
was waiting? */ | |
ulCompleteTickPeriods = ulCompletedSysTickIncrements / ulTimerReloadValueForOneTick; | |
/* The reload value is set to whatever fraction of a single tick | |
period remains. */ | |
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerReloadValueForOneTick ) - ulCompletedSysTickIncrements; | |
} | |
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG | |
again, then set portNVIC_SYSTICK_LOAD_REG back to its standard | |
value. */ | |
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; | |
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; | |
vTaskStepTick( ulCompleteTickPeriods ); | |
} | |
} | |
#endif /* #if configUSE_TICKLESS_IDLE */ | |
/*-----------------------------------------------------------*/ | |
/* | |
* Setup the systick timer to generate the tick interrupts at the required | |
* frequency. | |
*/ | |
__attribute__(( weak )) void vPortSetupTimerInterrupt( void ) | |
{ | |
/* Calculate the constants required to configure the tick interrupt. */ | |
#if configUSE_TICKLESS_IDLE == 1 | |
{ | |
ulTimerReloadValueForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; | |
xMaximumPossibleSuppressedTicks = 0xffffffUL / ( ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL ); | |
ulStoppedTimerCompensation = 45UL / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); | |
} | |
#endif /* configUSE_TICKLESS_IDLE */ | |
/* Configure SysTick to interrupt at the requested rate. */ | |
portNVIC_SYSTICK_LOAD_REG = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;; | |
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; | |
} | |
/*-----------------------------------------------------------*/ | |