/* FreeRTOS V7.5.2 - Copyright (C) 2013 Real Time Engineers Ltd. VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION. *************************************************************************** * * * FreeRTOS provides completely free yet professionally developed, * * robust, strictly quality controlled, supported, and cross * * platform software that has become a de facto standard. * * * * Help yourself get started quickly and support the FreeRTOS * * project by purchasing a FreeRTOS tutorial book, reference * * manual, or both from: http://www.FreeRTOS.org/Documentation * * * * Thank you! * * * *************************************************************************** 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 distribute >>! a combined work that includes FreeRTOS without being obliged to provide >>! the source code for proprietary components outside of the FreeRTOS >>! kernel. FreeRTOS is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Full license text is available from the following link: http://www.freertos.org/a00114.html 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. http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products, including FreeRTOS+Trace - an indispensable productivity tool, a DOS compatible FAT file system, and our tiny thread aware UDP/IP stack. http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS licenses offer ticketed support, indemnification and middleware. http://www.SafeRTOS.com - High Integrity Systems also provide a safety engineered and independently SIL3 certified version for use in safety and mission critical applications that require provable dependability. 1 tab == 4 spaces! */ /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the ARM CM4F port. *----------------------------------------------------------*/ /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" /* Constants required to manipulate the NVIC. */ #define portNVIC_SYSTICK_CTRL ( ( volatile unsigned long * ) 0xe000e010 ) #define portNVIC_SYSTICK_LOAD ( ( volatile unsigned long * ) 0xe000e014 ) #define portNVIC_SYSPRI2 ( ( volatile unsigned long * ) 0xe000ed20 ) #define portNVIC_SYSTICK_CLK 0x00000004 #define portNVIC_SYSTICK_INT 0x00000002 #define portNVIC_SYSTICK_ENABLE 0x00000001 #define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16 ) #define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24 ) /* Constants required to manipulate the VFP. */ #define portFPCCR ( ( volatile unsigned long * ) 0xe000ef34 ) /* Floating point context control register. */ #define portASPEN_AND_LSPEN_BITS ( 0x3UL << 30UL ) /* Constants required to set up the initial stack. */ #define portINITIAL_XPSR ( 0x01000000 ) #define portINITIAL_EXEC_RETURN ( 0xfffffffd ) /* 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 long ulCriticalNesting = 0xaaaaaaaaUL; /* * Setup the timer to generate the tick interrupts. */ static void prvSetupTimerInterrupt( void ); /* * Exception handlers. */ void SysTick_Handler( void ); /* * Functions defined in port_asm.asm. */ extern void vPortEnableVFP( void ); extern void vPortStartFirstTask( void ); /* This exists purely to allow the const to be used from within the port_asm.asm assembly file. */ const unsigned long ulMaxSyscallInterruptPriorityConst = configMAX_SYSCALL_INTERRUPT_PRIORITY; /*-----------------------------------------------------------*/ /* * 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. */ /* 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 = ( portSTACK_TYPE ) pxCode; /* PC */ pxTopOfStack--; *pxTopOfStack = 0; /* LR */ /* Save code space by skipping register initialisation. */ pxTopOfStack -= 5; /* R12, R3, R2 and R1. */ *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */ /* A save method is being used that requires each task to maintain its own exec return value. */ pxTopOfStack--; *pxTopOfStack = portINITIAL_EXEC_RETURN; pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */ return pxTopOfStack; } /*-----------------------------------------------------------*/ /* * 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 and SysTick the lowest priority interrupts. */ *(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. */ ulCriticalNesting = 0; /* Ensure the VFP is enabled - it should be anyway. */ vPortEnableVFP(); /* Lazy save always. */ *( portFPCCR ) |= portASPEN_AND_LSPEN_BITS; /* Start the first task. */ vPortStartFirstTask(); /* Should not get here! */ return 0; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* It is unlikely that the CM4F 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) = portNVIC_PENDSVSET; /* Barriers are normally not required but do ensure the code is completely within the specified behaviour for the architecture. */ __DSB(); __ISB(); } /*-----------------------------------------------------------*/ void vPortEnterCritical( void ) { portDISABLE_INTERRUPTS(); ulCriticalNesting++; __DSB(); __ISB(); } /*-----------------------------------------------------------*/ void vPortExitCritical( void ) { ulCriticalNesting--; if( ulCriticalNesting == 0 ) { portENABLE_INTERRUPTS(); } } /*-----------------------------------------------------------*/ void SysTick_Handler( void ) { unsigned long ulDummy; ulDummy = portSET_INTERRUPT_MASK_FROM_ISR(); { if( xTaskIncrementTick() != pdFALSE ) { /* Pend a context switch. */ *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; } } portCLEAR_INTERRUPT_MASK_FROM_ISR( ulDummy ); } /*-----------------------------------------------------------*/ /* * Setup the systick timer to generate the tick interrupts at the required * frequency. */ void prvSetupTimerInterrupt( void ) { /* 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; } /*-----------------------------------------------------------*/