| /* | |
| FreeRTOS.org V5.2.0 - Copyright (C) 2003-2009 Richard Barry. | |
| This file is part of the FreeRTOS.org distribution. | |
| FreeRTOS.org 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. | |
| FreeRTOS.org 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. See the GNU General Public License for | |
| more details. | |
| You should have received a copy of the GNU General Public License along | |
| with FreeRTOS.org; if not, write to the Free Software Foundation, Inc., 59 | |
| Temple Place, Suite 330, Boston, MA 02111-1307 USA. | |
| A special exception to the GPL is included to allow you to distribute a | |
| combined work that includes FreeRTOS.org without being obliged to provide | |
| the source code for any proprietary components. See the licensing section | |
| of http://www.FreeRTOS.org for full details. | |
| *************************************************************************** | |
| * * | |
| * 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. | |
| */ | |
| /*----------------------------------------------------------- | |
| * Components that can be compiled to either ARM or THUMB mode are | |
| * contained in port.c The ISR routines, which can only be compiled | |
| * to ARM mode, are contained in this file. | |
| *----------------------------------------------------------*/ | |
| /* | |
| Changes from V3.2.4 | |
| + The assembler statements are now included in a single asm block rather | |
| than each line having its own asm block. | |
| */ | |
| /* Scheduler includes. */ | |
| #include "FreeRTOS.h" | |
| #include "task.h" | |
| /* Constants required to handle interrupts. */ | |
| #define portCLEAR_AIC_INTERRUPT ( ( unsigned portLONG ) 0 ) | |
| /* Constants required to handle critical sections. */ | |
| #define portNO_CRITICAL_NESTING ( ( unsigned portLONG ) 0 ) | |
| volatile unsigned portLONG ulCriticalNesting = 9999UL; | |
| /*-----------------------------------------------------------*/ | |
| /* ISR to handle manual context switches (from a call to taskYIELD()). */ | |
| void vPortYieldProcessor( void ) __attribute__((interrupt("SWI"), naked)); | |
| /* | |
| * The scheduler can only be started from ARM mode, hence the inclusion of this | |
| * function here. | |
| */ | |
| void vPortISRStartFirstTask( void ); | |
| /*-----------------------------------------------------------*/ | |
| void vPortISRStartFirstTask( void ) | |
| { | |
| /* Simply start the scheduler. This is included here as it can only be | |
| called from ARM mode. */ | |
| portRESTORE_CONTEXT(); | |
| } | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * Called by portYIELD() or taskYIELD() to manually force a context switch. | |
| * | |
| * When a context switch is performed from the task level the saved task | |
| * context is made to look as if it occurred from within the tick ISR. This | |
| * way the same restore context function can be used when restoring the context | |
| * saved from the ISR or that saved from a call to vPortYieldProcessor. | |
| */ | |
| void vPortYieldProcessor( void ) | |
| { | |
| /* Within an IRQ ISR the link register has an offset from the true return | |
| address, but an SWI ISR does not. Add the offset manually so the same | |
| ISR return code can be used in both cases. */ | |
| asm volatile ( "ADD LR, LR, #4" ); | |
| /* Perform the context switch. First save the context of the current task. */ | |
| portSAVE_CONTEXT(); | |
| /* Find the highest priority task that is ready to run. */ | |
| vTaskSwitchContext(); | |
| /* Restore the context of the new task. */ | |
| portRESTORE_CONTEXT(); | |
| } | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * The ISR used for the scheduler tick depends on whether the cooperative or | |
| * the preemptive scheduler is being used. | |
| */ | |
| #if configUSE_PREEMPTION == 0 | |
| /* The cooperative scheduler requires a normal IRQ service routine to | |
| simply increment the system tick. */ | |
| void vNonPreemptiveTick( void ) __attribute__ ((interrupt ("IRQ"))); | |
| void vNonPreemptiveTick( void ) | |
| { | |
| static volatile unsigned portLONG ulDummy; | |
| /* Clear tick timer interrupt indication. */ | |
| ulDummy = portTIMER_REG_BASE_PTR->TC_SR; | |
| vTaskIncrementTick(); | |
| /* Acknowledge the interrupt at AIC level... */ | |
| AT91C_BASE_AIC->AIC_EOICR = portCLEAR_AIC_INTERRUPT; | |
| } | |
| #else /* else preemption is turned on */ | |
| /* The preemptive scheduler is defined as "naked" as the full context is | |
| saved on entry as part of the context switch. */ | |
| void vPreemptiveTick( void ) __attribute__((naked)); | |
| void vPreemptiveTick( void ) | |
| { | |
| /* Save the context of the interrupted task. */ | |
| portSAVE_CONTEXT(); | |
| /* WARNING - Do not use local (stack) variables here. Use globals | |
| if you must! */ | |
| static volatile unsigned portLONG ulDummy; | |
| /* Clear tick timer interrupt indication. */ | |
| ulDummy = portTIMER_REG_BASE_PTR->TC_SR; | |
| /* Increment the RTOS tick count, then look for the highest priority | |
| task that is ready to run. */ | |
| vTaskIncrementTick(); | |
| vTaskSwitchContext(); | |
| /* Acknowledge the interrupt at AIC level... */ | |
| AT91C_BASE_AIC->AIC_EOICR = portCLEAR_AIC_INTERRUPT; | |
| /* Restore the context of the new task. */ | |
| portRESTORE_CONTEXT(); | |
| } | |
| #endif | |
| /*-----------------------------------------------------------*/ | |
| /* | |
| * The interrupt management utilities can only be called from ARM mode. When | |
| * THUMB_INTERWORK is defined the utilities are defined as functions here to | |
| * ensure a switch to ARM mode. When THUMB_INTERWORK is not defined then | |
| * the utilities are defined as macros in portmacro.h - as per other ports. | |
| */ | |
| #ifdef THUMB_INTERWORK | |
| void vPortDisableInterruptsFromThumb( void ) __attribute__ ((naked)); | |
| void vPortEnableInterruptsFromThumb( void ) __attribute__ ((naked)); | |
| void vPortDisableInterruptsFromThumb( void ) | |
| { | |
| asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0} \n\t" /* Pop R0. */ | |
| "BX R14" ); /* Return back to thumb. */ | |
| } | |
| void vPortEnableInterruptsFromThumb( void ) | |
| { | |
| asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0} \n\t" /* Pop R0. */ | |
| "BX R14" ); /* Return back to thumb. */ | |
| } | |
| #endif /* THUMB_INTERWORK */ | |
| /* The code generated by the GCC compiler uses the stack in different ways at | |
| different optimisation levels. The interrupt flags can therefore not always | |
| be saved to the stack. Instead the critical section nesting level is stored | |
| in a variable, which is then saved as part of the stack context. */ | |
| void vPortEnterCritical( void ) | |
| { | |
| /* Disable interrupts as per portDISABLE_INTERRUPTS(); */ | |
| asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "ORR R0, R0, #0xC0 \n\t" /* Disable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0}" ); /* Pop R0. */ | |
| /* 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 interrupts as per portEXIT_CRITICAL(). */ | |
| asm volatile ( | |
| "STMDB SP!, {R0} \n\t" /* Push R0. */ | |
| "MRS R0, CPSR \n\t" /* Get CPSR. */ | |
| "BIC R0, R0, #0xC0 \n\t" /* Enable IRQ, FIQ. */ | |
| "MSR CPSR, R0 \n\t" /* Write back modified value. */ | |
| "LDMIA SP!, {R0}" ); /* Pop R0. */ | |
| } | |
| } | |
| } | |