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- /*
- * FreeRTOS Kernel V10.0.0
- * 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. If you wish to use our Amazon
- * FreeRTOS name, please do so in a fair use way that does not cause confusion.
- *
- * 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"
- #ifdef SOFTDEVICE_PRESENT
- #include "nrf_soc.h"
- #endif
- /* Make sure that all elements in isr state fits in uint32_t element*/
- #include "portmacro_cmsis.h"
- STATIC_ASSERT(sizeof(portISRState_t) == sizeof(uint32_t));
- /* Constants used for assertion check of the selected CPU */
- #define portCORTEX_M0_r0p0_ID ( 0x410CC200UL )
- /* Constants required to check the validity of an interrupt priority. */
- #define portFIRST_USER_INTERRUPT_NUMBER ( 16 )
- #define portMAX_8_BIT_VALUE ( ( uint8_t ) 0xff )
- #define portTOP_BIT_OF_BYTE ( ( uint8_t ) 0x80 )
- /* Constants required to set up the initial stack. */
- #define portINITIAL_XPSR (((xPSR_Type){.b.T = 1}).w)
- #define portINITIAL_EXEC_RETURN ( 0xfffffffd )
- /* Let the user override the pre-loading of the initial LR with the address of
- prvTaskExitError() in case is 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
- /* Each task maintains its own interrupt status in the critical nesting
- variable. */
- static UBaseType_t uxCriticalNesting = 0;
- #ifdef SOFTDEVICE_PRESENT
- /* Flag that is set when yielding should be done after critical section exiting */
- static UBaseType_t uxYieldFlag = 0;
- #endif
- /*
- * 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.
- */
- extern void vPortSetupTimerInterrupt( void );
- /*
- * Exception handlers.
- */
- void xPortSysTickHandler( void );
- /*
- * Start first task is a separate function so it can be tested in isolation.
- */
- extern void vPortStartFirstTask( void );
- /*
- * Used to catch tasks that attempt to return from their implementing function.
- */
- static void prvTaskExitError( void );
- /*-----------------------------------------------------------*/
- /*
- * 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. */
- /* Offset added to account for the way the MCU uses the stack on entry/exit
- of interrupts, and to ensure alignment. */
- pxTopOfStack--;
- *pxTopOfStack = portINITIAL_XPSR; /* xPSR */
- pxTopOfStack--;
- *pxTopOfStack = ( StackType_t ) pxCode; /* PC */
- pxTopOfStack--;
- *pxTopOfStack = ( StackType_t ) portTASK_RETURN_ADDRESS; /* LR */
- /* Save code space by skipping register initialisation. */
- pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
- *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
- pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */
- return pxTopOfStack;
- }
- /*-----------------------------------------------------------*/
- static void prvTaskExitError( void )
- {
- /* 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();
- for ( ;; );
- }
- /*-----------------------------------------------------------*/
- /*
- * See header file for description.
- */
- BaseType_t xPortStartScheduler( void )
- {
- /* This port can be used only on Cortex-M0 processor */
- configASSERT( SCB->CPUID == portCORTEX_M0_r0p0_ID );
- /* Make PendSV the lowest priority interrupts. */
- NVIC_SetPriority(PendSV_IRQn, configKERNEL_INTERRUPT_PRIORITY);
- /* 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;
- /* Finally this port requires SEVONPEND to be active */
- SCB->SCR |= SCB_SCR_SEVONPEND_Msk;
- /* 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. */
- 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 vPortTaskYield( void )
- {
- #ifdef SOFTDEVICE_PRESENT
- if (uxCriticalNesting > 0)
- {
- uxYieldFlag = 1;
- }
- else
- {
- portPendSVSchedule();
- }
- #else
- portPendSVSchedule();
- #endif
- }
- /*-----------------------------------------------------------*/
- void vPortEnterCritical( void )
- {
- portDISABLE_INTERRUPTS();
- uxCriticalNesting++;
- /* This is not the interrupt safe version of the enter critical function so
- assert() if it is being called from an interrupt context. Only API
- functions that end in "FromISR" can be used in an interrupt. Only assert if
- the critical nesting count is 1 to protect against recursive calls if the
- assert function also uses a critical section. */
- if ( uxCriticalNesting == 1 )
- {
- configASSERT( ( SCB->ICSR & SCB_ICSR_VECTACTIVE_Msk ) == 0 );
- }
- }
- /*-----------------------------------------------------------*/
- void vPortExitCritical( void )
- {
- configASSERT( uxCriticalNesting );
- uxCriticalNesting--;
- if ( uxCriticalNesting == 0 )
- {
- portENABLE_INTERRUPTS();
- #ifdef SOFTDEVICE_PRESENT
- if (uxYieldFlag)
- {
- uxYieldFlag = 0;
- portPendSVSchedule();
- }
- #endif
- }
- }
- /*-----------------------------------------------------------*/
- void vPortSafeTaskSwitchContext( void )
- {
- uint32_t isrstate = portSET_INTERRUPT_MASK_FROM_ISR();
- vTaskSwitchContext();
- portCLEAR_INTERRUPT_MASK_FROM_ISR(isrstate);
- }
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