/* | |
FreeRTOS.org V5.1.2 - 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 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. | |
*************************************************************************** | |
*************************************************************************** | |
* * | |
* 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. * | |
* * | |
*************************************************************************** | |
*************************************************************************** | |
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 ARM CM3 port. | |
*----------------------------------------------------------*/ | |
/* Scheduler includes. */ | |
#include "FreeRTOS.h" | |
#include "task.h" | |
#ifndef configKERNEL_INTERRUPT_PRIORITY | |
#define configKERNEL_INTERRUPT_PRIORITY 255 | |
#endif | |
/* Constants required to manipulate the NVIC. */ | |
#define portNVIC_SYSTICK_CTRL ( ( volatile unsigned portLONG *) 0xe000e010 ) | |
#define portNVIC_SYSTICK_LOAD ( ( volatile unsigned portLONG *) 0xe000e014 ) | |
#define portNVIC_INT_CTRL ( ( volatile unsigned portLONG *) 0xe000ed04 ) | |
#define portNVIC_SYSPRI2 ( ( volatile unsigned portLONG *) 0xe000ed20 ) | |
#define portNVIC_SYSTICK_CLK 0x00000004 | |
#define portNVIC_SYSTICK_INT 0x00000002 | |
#define portNVIC_SYSTICK_ENABLE 0x00000001 | |
#define portNVIC_PENDSVSET 0x10000000 | |
#define portNVIC_PENDSV_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 16 ) | |
#define portNVIC_SYSTICK_PRI ( ( ( unsigned portLONG ) configKERNEL_INTERRUPT_PRIORITY ) << 24 ) | |
/* Constants required to set up the initial stack. */ | |
#define portINITIAL_XPSR ( 0x01000000 ) | |
/* Each task maintains its own interrupt status in the critical nesting | |
variable. */ | |
static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa; | |
/* | |
* Setup the timer to generate the tick interrupts. | |
*/ | |
static void prvSetupTimerInterrupt( void ); | |
/* | |
* Exception handlers. | |
*/ | |
void xPortPendSVHandler( void ); | |
void xPortSysTickHandler( void ); | |
void vPortSVCHandler( void ); | |
/* | |
* Start first task is a separate function so it can be tested in isolation. | |
*/ | |
void vPortStartFirstTask( void ); | |
/*-----------------------------------------------------------*/ | |
/* | |
* 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. */ | |
*pxTopOfStack = portINITIAL_XPSR; /* xPSR */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) pxCode; /* PC */ | |
pxTopOfStack--; | |
*pxTopOfStack = 0; /* LR */ | |
pxTopOfStack -= 5; /* R12, R3, R2 and R1. */ | |
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters; /* R0 */ | |
pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */ | |
return pxTopOfStack; | |
} | |
/*-----------------------------------------------------------*/ | |
__asm void vPortSVCHandler( void ) | |
{ | |
PRESERVE8 | |
ldr r3, =pxCurrentTCB /* Restore the context. */ | |
ldr r1, [r3] /* Use pxCurrentTCBConst to get the pxCurrentTCB address. */ | |
ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */ | |
ldmia r0!, {r4-r11} /* Pop the registers that are not automatically saved on exception entry and the critical nesting count. */ | |
msr psp, r0 /* Restore the task stack pointer. */ | |
mov r0, #0 | |
msr basepri, r0 | |
orr r14, #0xd | |
bx r14 | |
} | |
/*-----------------------------------------------------------*/ | |
__asm void vPortStartFirstTask( void ) | |
{ | |
PRESERVE8 | |
/* Use the NVIC offset register to locate the stack. */ | |
ldr r0, =0xE000ED08 | |
ldr r0, [r0] | |
ldr r0, [r0] | |
/* Set the msp back to the start of the stack. */ | |
msr msp, r0 | |
/* Call SVC to start the first task. */ | |
svc 0 | |
} | |
/*-----------------------------------------------------------*/ | |
/* | |
* See header file for description. | |
*/ | |
portBASE_TYPE 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 not get here! */ | |
return 0; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEndScheduler( void ) | |
{ | |
/* It is unlikely that the CM3 port will require this function as there | |
is nothing to return to. */ | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortYieldFromISR( void ) | |
{ | |
/* Set a PendSV to request a context switch. */ | |
*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEnterCritical( void ) | |
{ | |
portDISABLE_INTERRUPTS(); | |
uxCriticalNesting++; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortExitCritical( void ) | |
{ | |
uxCriticalNesting--; | |
if( uxCriticalNesting == 0 ) | |
{ | |
portENABLE_INTERRUPTS(); | |
} | |
} | |
/*-----------------------------------------------------------*/ | |
__asm void xPortPendSVHandler( void ) | |
{ | |
extern uxCriticalNesting; | |
extern pxCurrentTCB; | |
extern vTaskSwitchContext; | |
PRESERVE8 | |
mrs r0, psp | |
ldr r3, =pxCurrentTCB /* Get the location of the current TCB. */ | |
ldr r2, [r3] | |
stmdb r0!, {r4-r11} /* Save the remaining registers. */ | |
str r0, [r2] /* Save the new top of stack into the first member of the TCB. */ | |
stmdb sp!, {r3, r14} | |
mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY | |
msr basepri, r0 | |
bl vTaskSwitchContext | |
mov r0, #0 | |
msr basepri, r0 | |
ldmia sp!, {r3, r14} | |
ldr r1, [r3] | |
ldr r0, [r1] /* The first item in pxCurrentTCB is the task top of stack. */ | |
ldmia r0!, {r4-r11} /* Pop the registers and the critical nesting count. */ | |
msr psp, r0 | |
bx r14 | |
nop | |
} | |
/*-----------------------------------------------------------*/ | |
void xPortSysTickHandler( void ) | |
{ | |
unsigned portLONG ulDummy; | |
/* If using preemption, also force a context switch. */ | |
#if configUSE_PREEMPTION == 1 | |
*(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; | |
#endif | |
ulDummy = portSET_INTERRUPT_MASK_FROM_ISR(); | |
{ | |
vTaskIncrementTick(); | |
} | |
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; | |
} | |
/*-----------------------------------------------------------*/ | |
__asm void vPortSetInterruptMask( void ) | |
{ | |
PRESERVE8 | |
push { r0 } | |
mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY | |
msr basepri, r0 | |
pop { r0 } | |
bx r14 | |
} | |
/*-----------------------------------------------------------*/ | |
__asm void vPortClearInterruptMask( void ) | |
{ | |
PRESERVE8 | |
push { r0 } | |
mov r0, #0 | |
msr basepri, r0 | |
pop { r0 } | |
bx r14 | |
} |