diff options
Diffstat (limited to 'portable/IAR/ARM_CM0/port.c')
| -rw-r--r-- | portable/IAR/ARM_CM0/port.c | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/portable/IAR/ARM_CM0/port.c b/portable/IAR/ARM_CM0/port.c index f4d77120c..1b9caa13a 100644 --- a/portable/IAR/ARM_CM0/port.c +++ b/portable/IAR/ARM_CM0/port.c @@ -37,6 +37,9 @@ #include "FreeRTOS.h" #include "task.h" +/* Prototype of all Interrupt Service Routines (ISRs). */ +typedef void ( * portISR_t )( void ); + /* Constants required to manipulate the NVIC. */ #define portNVIC_SYSTICK_CTRL_REG ( *( ( volatile uint32_t * ) 0xe000e010 ) ) #define portNVIC_SYSTICK_LOAD_REG ( *( ( volatile uint32_t * ) 0xe000e014 ) ) @@ -53,6 +56,10 @@ #define portNVIC_PENDSV_PRI ( portMIN_INTERRUPT_PRIORITY << 16UL ) #define portNVIC_SYSTICK_PRI ( portMIN_INTERRUPT_PRIORITY << 24UL ) +/* Constants used to check the installation of the FreeRTOS interrupt handlers. */ +#define portSCB_VTOR_REG ( *( ( portISR_t ** ) 0xe000ed08 ) ) +#define portVECTOR_INDEX_PENDSV ( 14 ) + /* Constants required to set up the initial stack. */ #define portINITIAL_XPSR ( 0x01000000 ) @@ -121,6 +128,10 @@ extern void vPortStartFirstTask( void ); */ static void prvTaskExitError( void ); +/* + * FreeRTOS handlers implemented in assembly. + */ +extern void xPortPendSVHandler( void ); /*-----------------------------------------------------------*/ /* @@ -168,6 +179,41 @@ static void prvTaskExitError( void ) */ BaseType_t xPortStartScheduler( void ) { + /* An application can install FreeRTOS interrupt handlers in one of the + * folllowing ways: + * 1. Direct Routing - Install the function xPortPendSVHandler for PendSV + * interrupt. + * 2. Indirect Routing - Install separate handler for PendSV interrupt and + * route program control from that handler to xPortPendSVHandler function. + * + * Applications that use Indirect Routing must set + * configCHECK_HANDLER_INSTALLATION to 0 in their FreeRTOSConfig.h. Direct + * routing, which is validated here when configCHECK_HANDLER_INSTALLATION + * is 1, should be preferred when possible. */ + #if ( configCHECK_HANDLER_INSTALLATION == 1 ) + { + /* Point pxVectorTable to the interrupt vector table. Systems without + * a VTOR register provide the value zero in the VTOR register and + * the vector table itself is located at the address 0x00000000. */ + const portISR_t * const pxVectorTable = portSCB_VTOR_REG; + + /* Validate that the application has correctly installed the FreeRTOS + * handler for PendSV interrupt. We do not check the installation of the + * SysTick handler because the application may choose to drive the RTOS + * tick using a timer other than the SysTick timer by overriding the + * weak function vPortSetupTimerInterrupt(). + * + * Assertion failures here indicate incorrect installation of the + * FreeRTOS handler. For help installing the FreeRTOS handler, see + * https://www.FreeRTOS.org/FAQHelp.html. + * + * Systems with a configurable address for the interrupt vector table + * can also encounter assertion failures or even system faults here if + * VTOR is not set correctly to point to the application's vector table. */ + configASSERT( pxVectorTable[ portVECTOR_INDEX_PENDSV ] == xPortPendSVHandler ); + } + #endif /* configCHECK_HANDLER_INSTALLATION */ + /* Make PendSV and SysTick the lowest priority interrupts. */ portNVIC_SHPR3_REG |= portNVIC_PENDSV_PRI; portNVIC_SHPR3_REG |= portNVIC_SYSTICK_PRI; |