/* | |
* FreeRTOS Kernel V10.0.1 | |
* Copyright (C) 2017 Amazon.com, Inc. or its affiliates. All Rights Reserved. | |
* | |
* Permission is hereby granted, free of charge, to any person obtaining a copy of | |
* this software and associated documentation files (the "Software"), to deal in | |
* the Software without restriction, including without limitation the rights to | |
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of | |
* the Software, and to permit persons to whom the Software is furnished to do so, | |
* subject to the following conditions: | |
* | |
* The above copyright notice and this permission notice shall be included in all | |
* copies or substantial portions of the Software. | |
* | |
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS | |
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR | |
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER | |
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. | |
* | |
* http://www.FreeRTOS.org | |
* http://aws.amazon.com/freertos | |
* | |
* 1 tab == 4 spaces! | |
*/ | |
/*----------------------------------------------------------- | |
* Implementation of functions defined in portable.h for the ARM CM0 port. | |
*----------------------------------------------------------*/ | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "task.h" | |
/* Constants required to manipulate the NVIC. */ | |
#define portNVIC_SYSTICK_CTRL ( ( volatile uint32_t * ) 0xe000e010 ) | |
#define portNVIC_SYSTICK_LOAD ( ( volatile uint32_t * ) 0xe000e014 ) | |
#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 ) | |
#define portNVIC_INT_CTRL ( ( volatile uint32_t *) 0xe000ed04 ) | |
#define portNVIC_SYSPRI2 ( ( volatile uint32_t *) 0xe000ed20 ) | |
#define portNVIC_SYSTICK_CLK 0x00000004 | |
#define portNVIC_SYSTICK_INT 0x00000002 | |
#define portNVIC_SYSTICK_ENABLE 0x00000001 | |
#define portNVIC_PENDSVSET 0x10000000 | |
#define portMIN_INTERRUPT_PRIORITY ( 255UL ) | |
#define portNVIC_PENDSV_PRI ( portMIN_INTERRUPT_PRIORITY << 16UL ) | |
#define portNVIC_SYSTICK_PRI ( portMIN_INTERRUPT_PRIORITY << 24UL ) | |
/* Constants required to set up the initial stack. */ | |
#define portINITIAL_XPSR ( 0x01000000 ) | |
/* Let the user override the pre-loading of the initial LR with the address of | |
prvTaskExitError() in case it messes up unwinding of the stack in the | |
debugger. */ | |
#ifdef configTASK_RETURN_ADDRESS | |
#define portTASK_RETURN_ADDRESS configTASK_RETURN_ADDRESS | |
#else | |
#define portTASK_RETURN_ADDRESS prvTaskExitError | |
#endif | |
/* | |
* Setup the timer to generate the tick interrupts. | |
*/ | |
static void prvSetupTimerInterrupt( void ); | |
/* | |
* Exception handlers. | |
*/ | |
void xPortPendSVHandler( void ) __attribute__ (( naked )); | |
void xPortSysTickHandler( void ); | |
void vPortSVCHandler( void ); | |
/* | |
* Start first task is a separate function so it can be tested in isolation. | |
*/ | |
static void vPortStartFirstTask( void ) __attribute__ (( naked )); | |
/* | |
* Used to catch tasks that attempt to return from their implementing function. | |
*/ | |
static void prvTaskExitError( void ); | |
/*-----------------------------------------------------------*/ | |
/* Each task maintains its own interrupt status in the critical nesting | |
variable. */ | |
static UBaseType_t uxCriticalNesting = 0xaaaaaaaa; | |
/*-----------------------------------------------------------*/ | |
/* | |
* See header file for description. | |
*/ | |
StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t 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 = ( StackType_t ) pxCode; /* PC */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) portTASK_RETURN_ADDRESS; /* LR */ | |
pxTopOfStack -= 5; /* R12, R3, R2 and R1. */ | |
*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */ | |
pxTopOfStack -= 8; /* R11..R4. */ | |
return pxTopOfStack; | |
} | |
/*-----------------------------------------------------------*/ | |
static void prvTaskExitError( void ) | |
{ | |
volatile uint32_t ulDummy = 0UL; | |
/* A function that implements a task must not exit or attempt to return to | |
its caller as there is nothing to return to. If a task wants to exit it | |
should instead call vTaskDelete( NULL ). | |
Artificially force an assert() to be triggered if configASSERT() is | |
defined, then stop here so application writers can catch the error. */ | |
configASSERT( uxCriticalNesting == ~0UL ); | |
portDISABLE_INTERRUPTS(); | |
while( ulDummy == 0 ) | |
{ | |
/* This file calls prvTaskExitError() after the scheduler has been | |
started to remove a compiler warning about the function being defined | |
but never called. ulDummy is used purely to quieten other warnings | |
about code appearing after this function is called - making ulDummy | |
volatile makes the compiler think the function could return and | |
therefore not output an 'unreachable code' warning for code that appears | |
after it. */ | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortSVCHandler( void ) | |
{ | |
/* This function is no longer used, but retained for backward | |
compatibility. */ | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortStartFirstTask( void ) | |
{ | |
/* The MSP stack is not reset as, unlike on M3/4 parts, there is no vector | |
table offset register that can be used to locate the initial stack value. | |
Not all M0 parts have the application vector table at address 0. */ | |
__asm volatile( | |
" .syntax unified \n" | |
" ldr r2, pxCurrentTCBConst2 \n" /* Obtain location of pxCurrentTCB. */ | |
" ldr r3, [r2] \n" | |
" ldr r0, [r3] \n" /* The first item in pxCurrentTCB is the task top of stack. */ | |
" adds r0, #32 \n" /* Discard everything up to r0. */ | |
" msr psp, r0 \n" /* This is now the new top of stack to use in the task. */ | |
" movs r0, #2 \n" /* Switch to the psp stack. */ | |
" msr CONTROL, r0 \n" | |
" isb \n" | |
" pop {r0-r5} \n" /* Pop the registers that are saved automatically. */ | |
" mov lr, r5 \n" /* lr is now in r5. */ | |
" pop {r3} \n" /* Return address is now in r3. */ | |
" pop {r2} \n" /* Pop and discard XPSR. */ | |
" cpsie i \n" /* The first task has its context and interrupts can be enabled. */ | |
" bx r3 \n" /* Finally, jump to the user defined task code. */ | |
" \n" | |
" .align 4 \n" | |
" .syntax divided \n" | |
"pxCurrentTCBConst2: .word pxCurrentTCB " | |
); | |
} | |
/*-----------------------------------------------------------*/ | |
/* | |
* See header file for description. | |
*/ | |
BaseType_t xPortStartScheduler( void ) | |
{ | |
/* Make PendSV, CallSV and SysTick the same priroity as the kernel. */ | |
*(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI; | |
*(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI; | |
/* Start the timer that generates the tick ISR. Interrupts are disabled | |
here already. */ | |
prvSetupTimerInterrupt(); | |
/* Initialise the critical nesting count ready for the first task. */ | |
uxCriticalNesting = 0; | |
/* Start the first task. */ | |
vPortStartFirstTask(); | |
/* Should never get here as the tasks will now be executing! Call the task | |
exit error function to prevent compiler warnings about a static function | |
not being called in the case that the application writer overrides this | |
functionality by defining configTASK_RETURN_ADDRESS. Call | |
vTaskSwitchContext() so link time optimisation does not remove the | |
symbol. */ | |
vTaskSwitchContext(); | |
prvTaskExitError(); | |
/* Should not get here! */ | |
return 0; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEndScheduler( void ) | |
{ | |
/* Not implemented in ports where there is nothing to return to. | |
Artificially force an assert. */ | |
configASSERT( uxCriticalNesting == 1000UL ); | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortYield( void ) | |
{ | |
/* Set a PendSV to request a context switch. */ | |
*( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET; | |
/* Barriers are normally not required but do ensure the code is completely | |
within the specified behaviour for the architecture. */ | |
__asm volatile( "dsb" ::: "memory" ); | |
__asm volatile( "isb" ); | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEnterCritical( void ) | |
{ | |
portDISABLE_INTERRUPTS(); | |
uxCriticalNesting++; | |
__asm volatile( "dsb" ::: "memory" ); | |
__asm volatile( "isb" ); | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortExitCritical( void ) | |
{ | |
configASSERT( uxCriticalNesting ); | |
uxCriticalNesting--; | |
if( uxCriticalNesting == 0 ) | |
{ | |
portENABLE_INTERRUPTS(); | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
uint32_t ulSetInterruptMaskFromISR( void ) | |
{ | |
__asm volatile( | |
" mrs r0, PRIMASK \n" | |
" cpsid i \n" | |
" bx lr " | |
::: "memory" | |
); | |
#if !defined (__ARMCC_VERSION) && (__ARMCC_VERSION >= 6010050) | |
/* To avoid compiler warnings. The return statement will nevere be reached, | |
but some compilers warn if it is not included, while others won't compile if | |
it is. */ | |
return 0; | |
#endif | |
} | |
/*-----------------------------------------------------------*/ | |
void vClearInterruptMaskFromISR( __attribute__( ( unused ) ) uint32_t ulMask ) | |
{ | |
__asm volatile( | |
" msr PRIMASK, r0 \n" | |
" bx lr " | |
::: "memory" | |
); | |
#if !defined (__ARMCC_VERSION) && (__ARMCC_VERSION >= 6010050) | |
/* Just to avoid compiler warning. ulMask is used from the asm code but | |
the compiler can't see that. Some compilers generate warnings without the | |
following line, while others generate warnings if the line is included. */ | |
( void ) ulMask; | |
#endif | |
} | |
/*-----------------------------------------------------------*/ | |
void xPortPendSVHandler( void ) | |
{ | |
/* This is a naked function. */ | |
__asm volatile | |
( | |
" .syntax unified \n" | |
" mrs r0, psp \n" | |
" \n" | |
" ldr r3, pxCurrentTCBConst \n" /* Get the location of the current TCB. */ | |
" ldr r2, [r3] \n" | |
" \n" | |
" subs r0, r0, #32 \n" /* Make space for the remaining low registers. */ | |
" str r0, [r2] \n" /* Save the new top of stack. */ | |
" stmia r0!, {r4-r7} \n" /* Store the low registers that are not saved automatically. */ | |
" mov r4, r8 \n" /* Store the high registers. */ | |
" mov r5, r9 \n" | |
" mov r6, r10 \n" | |
" mov r7, r11 \n" | |
" stmia r0!, {r4-r7} \n" | |
" \n" | |
" push {r3, r14} \n" | |
" cpsid i \n" | |
" bl vTaskSwitchContext \n" | |
" cpsie i \n" | |
" pop {r2, r3} \n" /* lr goes in r3. r2 now holds tcb pointer. */ | |
" \n" | |
" ldr r1, [r2] \n" | |
" ldr r0, [r1] \n" /* The first item in pxCurrentTCB is the task top of stack. */ | |
" adds r0, r0, #16 \n" /* Move to the high registers. */ | |
" ldmia r0!, {r4-r7} \n" /* Pop the high registers. */ | |
" mov r8, r4 \n" | |
" mov r9, r5 \n" | |
" mov r10, r6 \n" | |
" mov r11, r7 \n" | |
" \n" | |
" msr psp, r0 \n" /* Remember the new top of stack for the task. */ | |
" \n" | |
" subs r0, r0, #32 \n" /* Go back for the low registers that are not automatically restored. */ | |
" ldmia r0!, {r4-r7} \n" /* Pop low registers. */ | |
" \n" | |
" bx r3 \n" | |
" \n" | |
" .align 4 \n" | |
" .syntax divided \n" | |
"pxCurrentTCBConst: .word pxCurrentTCB " | |
); | |
} | |
/*-----------------------------------------------------------*/ | |
void xPortSysTickHandler( void ) | |
{ | |
uint32_t ulPreviousMask; | |
ulPreviousMask = portSET_INTERRUPT_MASK_FROM_ISR(); | |
{ | |
/* Increment the RTOS tick. */ | |
if( xTaskIncrementTick() != pdFALSE ) | |
{ | |
/* Pend a context switch. */ | |
*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; | |
} | |
} | |
portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask ); | |
} | |
/*-----------------------------------------------------------*/ | |
/* | |
* Setup the systick timer to generate the tick interrupts at the required | |
* frequency. | |
*/ | |
void prvSetupTimerInterrupt( void ) | |
{ | |
/* Stop and reset the SysTick. */ | |
*(portNVIC_SYSTICK_CTRL) = 0UL; | |
*(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL; | |
/* Configure SysTick to interrupt at the requested rate. */ | |
*(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; | |
*(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE; | |
} | |
/*-----------------------------------------------------------*/ | |