/* FreeRTOS.org V5.1.1 - Copyright (C) 2003-2008 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 as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. 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 can be applied should you wish 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 of how and when the exception can be applied. *************************************************************************** *************************************************************************** * * * SAVE TIME AND MONEY! We can port FreeRTOS.org to your own hardware, * * and even write all or part of your application on your behalf. * * See http://www.OpenRTOS.com for details of the services we provide to * * expedite your project. * * * *************************************************************************** *************************************************************************** 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. */ /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the Atmel ARM7 port. *----------------------------------------------------------*/ /* Standard includes. */ #include /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" /* Hardware includes. */ #include #include #include #include #include #include #include #include /*-----------------------------------------------------------*/ /* Constants required to setup the initial stack. */ #define portINITIAL_SPSR ( ( portSTACK_TYPE ) 0x1f ) /* System mode, ARM mode, interrupts enabled. */ #define portTHUMB_MODE_BIT ( ( portSTACK_TYPE ) 0x20 ) #define portINSTRUCTION_SIZE ( ( portSTACK_TYPE ) 4 ) /* Constants required to setup the PIT. */ #define port1MHz_IN_Hz ( 1000000ul ) #define port1SECOND_IN_uS ( 1000000ul ) /* Constants required to handle critical sections. */ #define portNO_CRITICAL_NESTING ( ( unsigned portLONG ) 0 ) #define portINT_LEVEL_SENSITIVE 0 #define portPIT_ENABLE ( ( unsigned portSHORT ) 0x1 << 24 ) #define portPIT_INT_ENABLE ( ( unsigned portSHORT ) 0x1 << 25 ) /*-----------------------------------------------------------*/ /* Setup the PIT to generate the tick interrupts. */ static void prvSetupTimerInterrupt( void ); /* The PIT interrupt handler - the RTOS tick. */ static void vPortTickISR( void ); /* ulCriticalNesting will get set to zero when the first task starts. It cannot be initialised to 0 as this will cause interrupts to be enabled during the kernel initialisation process. */ unsigned portLONG ulCriticalNesting = ( unsigned portLONG ) 9999; /*-----------------------------------------------------------*/ /* * Initialise the stack of a task to look exactly as if a call to * portSAVE_CONTEXT had been called. * * See header file for description. */ portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters ) { portSTACK_TYPE *pxOriginalTOS; pxOriginalTOS = pxTopOfStack; /* Setup the initial stack of the task. The stack is set exactly as expected by the portRESTORE_CONTEXT() macro. */ /* First on the stack is the return address - which in this case is the start of the task. The offset is added to make the return address appear as it would within an IRQ ISR. */ *pxTopOfStack = ( portSTACK_TYPE ) pxCode + portINSTRUCTION_SIZE; pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaaaaaa; /* R14 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) pxOriginalTOS; /* Stack used when task starts goes in R13. */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x12121212; /* R12 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x11111111; /* R11 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x10101010; /* R10 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x09090909; /* R9 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x08080808; /* R8 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x07070707; /* R7 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x06060606; /* R6 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x05050505; /* R5 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x04040404; /* R4 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x03030303; /* R3 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x02020202; /* R2 */ pxTopOfStack--; *pxTopOfStack = ( portSTACK_TYPE ) 0x01010101; /* R1 */ pxTopOfStack--; /* When the task starts is will expect to find the function parameter in R0. */ *pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */ pxTopOfStack--; /* The status register is set for system mode, with interrupts enabled. */ *pxTopOfStack = ( portSTACK_TYPE ) portINITIAL_SPSR; #ifdef THUMB_INTERWORK { /* We want the task to start in thumb mode. */ *pxTopOfStack |= portTHUMB_MODE_BIT; } #endif pxTopOfStack--; /* Interrupt flags cannot always be stored on the stack and will instead be stored in a variable, which is then saved as part of the tasks context. */ *pxTopOfStack = portNO_CRITICAL_NESTING; return pxTopOfStack; } /*-----------------------------------------------------------*/ portBASE_TYPE xPortStartScheduler( void ) { extern void vPortStartFirstTask( void ); /* Start the timer that generates the tick ISR. Interrupts are disabled here already. */ prvSetupTimerInterrupt(); /* Start the first task. */ vPortStartFirstTask(); /* Should not get here! */ return 0; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* It is unlikely that the ARM port will require this function as there is nothing to return to. */ } /*-----------------------------------------------------------*/ static __arm void vPortTickISR( void ) { volatile unsigned portLONG ulDummy; /* Increment the tick count - which may wake some tasks but as the preemptive scheduler is not being used any woken task is not given processor time no matter what its priority. */ vTaskIncrementTick(); #if configUSE_PREEMPTION == 0 vTaskSwitchContext(); #endif /* Clear the PIT interrupt. */ ulDummy = AT91C_BASE_PITC->PITC_PIVR; /* To remove compiler warning. */ ( void ) ulDummy; /* The AIC is cleared in the asm wrapper, outside of this function. */ } /*-----------------------------------------------------------*/ static void prvSetupTimerInterrupt( void ) { const unsigned portLONG ulPeriodIn_uS = ( 1 / configTICK_RATE_HZ ) * port1SECOND_IN_uS; /* Setup the PIT for the required frequency. */ PIT_Init( ulPeriodIn_uS, BOARD_MCK / port1MHz_IN_Hz ); /* Setup the PIT interrupt. */ AIC_DisableIT( AT91C_ID_SYS ); AIC_ConfigureIT( AT91C_ID_SYS, AT91C_AIC_PRIOR_LOWEST, vPortTickISR ); AIC_EnableIT( AT91C_ID_SYS ); PIT_EnableIT(); /* Enable the PIT itself. */ PIT_Enable(); } /*-----------------------------------------------------------*/ void vPortEnterCritical( void ) { /* Disable interrupts first! */ __disable_irq(); /* 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_irq(); } } } /*-----------------------------------------------------------*/