/* * FreeRTOS Kernel V10.1.1 * Copyright (C) 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a copy of * this software and associated documentation files (the "Software"), to deal in * the Software without restriction, including without limitation the rights to * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of * the Software, and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * * http://www.FreeRTOS.org * http://aws.amazon.com/freertos * * 1 tab == 4 spaces! */ /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the ARM CM4F port. *----------------------------------------------------------*/ /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" #ifndef __TARGET_FPU_VFP #error This port can only be used when the project options are configured to enable hardware floating point support. #endif #if configMAX_SYSCALL_INTERRUPT_PRIORITY == 0 #error configMAX_SYSCALL_INTERRUPT_PRIORITY must not be set to 0. See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html #endif #ifndef configSYSTICK_CLOCK_HZ #define configSYSTICK_CLOCK_HZ configCPU_CLOCK_HZ /* Ensure the SysTick is clocked at the same frequency as the core. */ #define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL ) #else /* The way the SysTick is clocked is not modified in case it is not the same as the core. */ #define portNVIC_SYSTICK_CLK_BIT ( 0 ) #endif /* The __weak attribute does not work as you might expect with the Keil tools so the configOVERRIDE_DEFAULT_TICK_CONFIGURATION constant must be set to 1 if the application writer wants to provide their own implementation of vPortSetupTimerInterrupt(). Ensure configOVERRIDE_DEFAULT_TICK_CONFIGURATION is defined. */ #ifndef configOVERRIDE_DEFAULT_TICK_CONFIGURATION #define configOVERRIDE_DEFAULT_TICK_CONFIGURATION 0 #endif /* Constants required to manipulate the core. Registers first... */ #define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile uint32_t * ) 0xe000e010 ) ) #define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile uint32_t * ) 0xe000e014 ) ) #define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile uint32_t * ) 0xe000e018 ) ) #define portNVIC_SYSPRI2_REG ( * ( ( volatile uint32_t * ) 0xe000ed20 ) ) /* ...then bits in the registers. */ #define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL ) #define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL ) #define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL ) #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) /* Constants used to detect a Cortex-M7 r0p1 core, which should use the ARM_CM7 r0p1 port. */ #define portCPUID ( * ( ( volatile uint32_t * ) 0xE000ed00 ) ) #define portCORTEX_M7_r0p1_ID ( 0x410FC271UL ) #define portCORTEX_M7_r0p0_ID ( 0x410FC270UL ) #define portNVIC_PENDSV_PRI ( ( ( uint32_t ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL ) #define portNVIC_SYSTICK_PRI ( ( ( uint32_t ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL ) /* Constants required to check the validity of an interrupt priority. */ #define portFIRST_USER_INTERRUPT_NUMBER ( 16 ) #define portNVIC_IP_REGISTERS_OFFSET_16 ( 0xE000E3F0 ) #define portAIRCR_REG ( * ( ( volatile uint32_t * ) 0xE000ED0C ) ) #define portMAX_8_BIT_VALUE ( ( uint8_t ) 0xff ) #define portTOP_BIT_OF_BYTE ( ( uint8_t ) 0x80 ) #define portMAX_PRIGROUP_BITS ( ( uint8_t ) 7 ) #define portPRIORITY_GROUP_MASK ( 0x07UL << 8UL ) #define portPRIGROUP_SHIFT ( 8UL ) /* Masks off all bits but the VECTACTIVE bits in the ICSR register. */ #define portVECTACTIVE_MASK ( 0xFFUL ) /* Constants required to manipulate the VFP. */ #define portFPCCR ( ( volatile uint32_t * ) 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_EXC_RETURN ( 0xfffffffd ) /* The systick is a 24-bit counter. */ #define portMAX_24_BIT_NUMBER ( 0xffffffUL ) /* A fiddle factor to estimate the number of SysTick counts that would have occurred while the SysTick counter is stopped during tickless idle calculations. */ #define portMISSED_COUNTS_FACTOR ( 45UL ) /* For strict compliance with the Cortex-M spec the task start address should have bit-0 clear, as it is loaded into the PC on exit from an ISR. */ #define portSTART_ADDRESS_MASK ( ( StackType_t ) 0xfffffffeUL ) /* * Setup the timer to generate the tick interrupts. The implementation in this * file is weak to allow application writers to change the timer used to * generate the tick interrupt. */ void vPortSetupTimerInterrupt( 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. */ static void prvStartFirstTask( void ); /* * Functions defined in portasm.s to enable the VFP. */ static void prvEnableVFP( void ); /* * Used to catch tasks that attempt to return from their implementing function. */ static void prvTaskExitError( void ); /*-----------------------------------------------------------*/ /* Each task maintains its own interrupt status in the critical nesting variable. */ static UBaseType_t uxCriticalNesting = 0xaaaaaaaa; /* * The number of SysTick increments that make up one tick period. */ #if( configUSE_TICKLESS_IDLE == 1 ) static uint32_t ulTimerCountsForOneTick = 0; #endif /* configUSE_TICKLESS_IDLE */ /* * The maximum number of tick periods that can be suppressed is limited by the * 24 bit resolution of the SysTick timer. */ #if( configUSE_TICKLESS_IDLE == 1 ) static uint32_t xMaximumPossibleSuppressedTicks = 0; #endif /* configUSE_TICKLESS_IDLE */ /* * Compensate for the CPU cycles that pass while the SysTick is stopped (low * power functionality only. */ #if( configUSE_TICKLESS_IDLE == 1 ) static uint32_t ulStoppedTimerCompensation = 0; #endif /* configUSE_TICKLESS_IDLE */ /* * Used by the portASSERT_IF_INTERRUPT_PRIORITY_INVALID() macro to ensure * FreeRTOS API functions are not called from interrupts that have been assigned * a priority above configMAX_SYSCALL_INTERRUPT_PRIORITY. */ #if ( configASSERT_DEFINED == 1 ) static uint8_t ucMaxSysCallPriority = 0; static uint32_t ulMaxPRIGROUPValue = 0; static const volatile uint8_t * const pcInterruptPriorityRegisters = ( uint8_t * ) portNVIC_IP_REGISTERS_OFFSET_16; #endif /* configASSERT_DEFINED */ /*-----------------------------------------------------------*/ /* * See header file for description. */ StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t 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 = ( ( StackType_t ) pxCode ) & portSTART_ADDRESS_MASK; /* PC */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) prvTaskExitError; /* LR */ /* Save code space by skipping register initialisation. */ pxTopOfStack -= 5; /* R12, R3, R2 and R1. */ *pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */ /* A save method is being used that requires each task to maintain its own exec return value. */ pxTopOfStack--; *pxTopOfStack = portINITIAL_EXC_RETURN; pxTopOfStack -= 8; /* R11, R10, R9, R8, R7, R6, R5 and R4. */ return pxTopOfStack; } /*-----------------------------------------------------------*/ static void prvTaskExitError( void ) { /* A function that implements a task must not exit or attempt to return to its caller as there is nothing to return to. If a task wants to exit it should instead call vTaskDelete( NULL ). Artificially force an assert() to be triggered if configASSERT() is defined, then stop here so application writers can catch the error. */ configASSERT( uxCriticalNesting == ~0UL ); portDISABLE_INTERRUPTS(); for( ;; ); } /*-----------------------------------------------------------*/ __asm void vPortSVCHandler( void ) { PRESERVE8 /* Get the location of the current TCB. */ ldr r3, =pxCurrentTCB ldr r1, [r3] ldr r0, [r1] /* Pop the core registers. */ ldmia r0!, {r4-r11, r14} msr psp, r0 isb mov r0, #0 msr basepri, r0 bx r14 } /*-----------------------------------------------------------*/ __asm void prvStartFirstTask( 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 /* Clear the bit that indicates the FPU is in use in case the FPU was used before the scheduler was started - which would otherwise result in the unnecessary leaving of space in the SVC stack for lazy saving of FPU registers. */ mov r0, #0 msr control, r0 /* Globally enable interrupts. */ cpsie i cpsie f dsb isb /* Call SVC to start the first task. */ svc 0 nop nop } /*-----------------------------------------------------------*/ __asm void prvEnableVFP( void ) { PRESERVE8 /* The FPU enable bits are in the CPACR. */ ldr.w r0, =0xE000ED88 ldr r1, [r0] /* Enable CP10 and CP11 coprocessors, then save back. */ orr r1, r1, #( 0xf << 20 ) str r1, [r0] bx r14 nop } /*-----------------------------------------------------------*/ /* * See header file for description. */ BaseType_t 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 ); /* This port can be used on all revisions of the Cortex-M7 core other than the r0p1 parts. r0p1 parts should use the port from the /source/portable/GCC/ARM_CM7/r0p1 directory. */ configASSERT( portCPUID != portCORTEX_M7_r0p1_ID ); configASSERT( portCPUID != portCORTEX_M7_r0p0_ID ); #if( configASSERT_DEFINED == 1 ) { volatile uint32_t ulOriginalPriority; volatile uint8_t * const pucFirstUserPriorityRegister = ( uint8_t * ) ( portNVIC_IP_REGISTERS_OFFSET_16 + portFIRST_USER_INTERRUPT_NUMBER ); volatile uint8_t ucMaxPriorityValue; /* Determine the maximum priority from which ISR safe FreeRTOS API functions can be called. ISR safe functions are those that end in "FromISR". FreeRTOS maintains separate thread and ISR API functions to ensure interrupt entry is as fast and simple as possible. Save the interrupt priority value that is about to be clobbered. */ ulOriginalPriority = *pucFirstUserPriorityRegister; /* Determine the number of priority bits available. First write to all possible bits. */ *pucFirstUserPriorityRegister = portMAX_8_BIT_VALUE; /* Read the value back to see how many bits stuck. */ ucMaxPriorityValue = *pucFirstUserPriorityRegister; /* The kernel interrupt priority should be set to the lowest priority. */ configASSERT( ucMaxPriorityValue == ( configKERNEL_INTERRUPT_PRIORITY & ucMaxPriorityValue ) ); /* Use the same mask on the maximum system call priority. */ ucMaxSysCallPriority = configMAX_SYSCALL_INTERRUPT_PRIORITY & ucMaxPriorityValue; /* Calculate the maximum acceptable priority group value for the number of bits read back. */ ulMaxPRIGROUPValue = portMAX_PRIGROUP_BITS; while( ( ucMaxPriorityValue & portTOP_BIT_OF_BYTE ) == portTOP_BIT_OF_BYTE ) { ulMaxPRIGROUPValue--; ucMaxPriorityValue <<= ( uint8_t ) 0x01; } #ifdef __NVIC_PRIO_BITS { /* Check the CMSIS configuration that defines the number of priority bits matches the number of priority bits actually queried from the hardware. */ configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == __NVIC_PRIO_BITS ); } #endif #ifdef configPRIO_BITS { /* Check the FreeRTOS configuration that defines the number of priority bits matches the number of priority bits actually queried from the hardware. */ configASSERT( ( portMAX_PRIGROUP_BITS - ulMaxPRIGROUPValue ) == configPRIO_BITS ); } #endif /* Shift the priority group value back to its position within the AIRCR register. */ ulMaxPRIGROUPValue <<= portPRIGROUP_SHIFT; ulMaxPRIGROUPValue &= portPRIORITY_GROUP_MASK; /* Restore the clobbered interrupt priority register to its original value. */ *pucFirstUserPriorityRegister = ulOriginalPriority; } #endif /* conifgASSERT_DEFINED */ /* Make PendSV and SysTick the lowest priority interrupts. */ portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; /* Start the timer that generates the tick ISR. Interrupts are disabled here already. */ vPortSetupTimerInterrupt(); /* Initialise the critical nesting count ready for the first task. */ uxCriticalNesting = 0; /* Ensure the VFP is enabled - it should be anyway. */ prvEnableVFP(); /* Lazy save always. */ *( portFPCCR ) |= portASPEN_AND_LSPEN_BITS; /* Start the first task. */ prvStartFirstTask(); /* Should not get here! */ return 0; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* Not implemented in ports where there is nothing to return to. Artificially force an assert. */ configASSERT( uxCriticalNesting == 1000UL ); } /*-----------------------------------------------------------*/ void vPortEnterCritical( void ) { portDISABLE_INTERRUPTS(); uxCriticalNesting++; /* This is not the interrupt safe version of the enter critical function so assert() if it is being called from an interrupt context. Only API functions that end in "FromISR" can be used in an interrupt. Only assert if the critical nesting count is 1 to protect against recursive calls if the assert function also uses a critical section. */ if( uxCriticalNesting == 1 ) { configASSERT( ( portNVIC_INT_CTRL_REG & portVECTACTIVE_MASK ) == 0 ); } } /*-----------------------------------------------------------*/ void vPortExitCritical( void ) { configASSERT( uxCriticalNesting ); uxCriticalNesting--; if( uxCriticalNesting == 0 ) { portENABLE_INTERRUPTS(); } } /*-----------------------------------------------------------*/ __asm void xPortPendSVHandler( void ) { extern uxCriticalNesting; extern pxCurrentTCB; extern vTaskSwitchContext; PRESERVE8 mrs r0, psp isb /* Get the location of the current TCB. */ ldr r3, =pxCurrentTCB ldr r2, [r3] /* Is the task using the FPU context? If so, push high vfp registers. */ tst r14, #0x10 it eq vstmdbeq r0!, {s16-s31} /* Save the core registers. */ stmdb r0!, {r4-r11, r14} /* Save the new top of stack into the first member of the TCB. */ str r0, [r2] stmdb sp!, {r0, r3} mov r0, #configMAX_SYSCALL_INTERRUPT_PRIORITY msr basepri, r0 dsb isb bl vTaskSwitchContext mov r0, #0 msr basepri, r0 ldmia sp!, {r0, r3} /* The first item in pxCurrentTCB is the task top of stack. */ ldr r1, [r3] ldr r0, [r1] /* Pop the core registers. */ ldmia r0!, {r4-r11, r14} /* Is the task using the FPU context? If so, pop the high vfp registers too. */ tst r14, #0x10 it eq vldmiaeq r0!, {s16-s31} msr psp, r0 isb #ifdef WORKAROUND_PMU_CM001 /* XMC4000 specific errata */ #if WORKAROUND_PMU_CM001 == 1 push { r14 } pop { pc } nop #endif #endif bx r14 } /*-----------------------------------------------------------*/ void xPortSysTickHandler( void ) { /* The SysTick runs at the lowest interrupt priority, so when this interrupt executes all interrupts must be unmasked. There is therefore no need to save and then restore the interrupt mask value as its value is already known - therefore the slightly faster vPortRaiseBASEPRI() function is used in place of portSET_INTERRUPT_MASK_FROM_ISR(). */ vPortRaiseBASEPRI(); { /* Increment the RTOS tick. */ if( xTaskIncrementTick() != pdFALSE ) { /* A context switch is required. Context switching is performed in the PendSV interrupt. Pend the PendSV interrupt. */ portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; } } vPortClearBASEPRIFromISR(); } /*-----------------------------------------------------------*/ #if( configUSE_TICKLESS_IDLE == 1 ) __weak void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime ) { uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements; TickType_t xModifiableIdleTime; /* Make sure the SysTick reload value does not overflow the counter. */ if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks ) { xExpectedIdleTime = xMaximumPossibleSuppressedTicks; } /* Stop the SysTick momentarily. The time the SysTick is stopped for is accounted for as best it can be, but using the tickless mode will inevitably result in some tiny drift of the time maintained by the kernel with respect to calendar time. */ portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT; /* Calculate the reload value required to wait xExpectedIdleTime tick periods. -1 is used because this code will execute part way through one of the tick periods. */ ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) ); if( ulReloadValue > ulStoppedTimerCompensation ) { ulReloadValue -= ulStoppedTimerCompensation; } /* Enter a critical section but don't use the taskENTER_CRITICAL() method as that will mask interrupts that should exit sleep mode. */ __disable_irq(); __dsb( portSY_FULL_READ_WRITE ); __isb( portSY_FULL_READ_WRITE ); /* If a context switch is pending or a task is waiting for the scheduler to be unsuspended then abandon the low power entry. */ if( eTaskConfirmSleepModeStatus() == eAbortSleep ) { /* Restart from whatever is left in the count register to complete this tick period. */ portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG; /* Restart SysTick. */ portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT; /* Reset the reload register to the value required for normal tick periods. */ portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL; /* Re-enable interrupts - see comments above __disable_irq() call above. */ __enable_irq(); } else { /* Set the new reload value. */ portNVIC_SYSTICK_LOAD_REG = ulReloadValue; /* Clear the SysTick count flag and set the count value back to zero. */ portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Restart SysTick. */ portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT; /* Sleep until something happens. configPRE_SLEEP_PROCESSING() can set its parameter to 0 to indicate that its implementation contains its own wait for interrupt or wait for event instruction, and so wfi should not be executed again. However, the original expected idle time variable must remain unmodified, so a copy is taken. */ xModifiableIdleTime = xExpectedIdleTime; configPRE_SLEEP_PROCESSING( xModifiableIdleTime ); if( xModifiableIdleTime > 0 ) { __dsb( portSY_FULL_READ_WRITE ); __wfi(); __isb( portSY_FULL_READ_WRITE ); } configPOST_SLEEP_PROCESSING( xExpectedIdleTime ); /* Re-enable interrupts to allow the interrupt that brought the MCU out of sleep mode to execute immediately. see comments above __disable_interrupt() call above. */ __enable_irq(); __dsb( portSY_FULL_READ_WRITE ); __isb( portSY_FULL_READ_WRITE ); /* Disable interrupts again because the clock is about to be stopped and interrupts that execute while the clock is stopped will increase any slippage between the time maintained by the RTOS and calendar time. */ __disable_irq(); __dsb( portSY_FULL_READ_WRITE ); __isb( portSY_FULL_READ_WRITE ); /* Disable the SysTick clock without reading the portNVIC_SYSTICK_CTRL_REG register to ensure the portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set. Again, the time the SysTick is stopped for is accounted for as best it can be, but using the tickless mode will inevitably result in some tiny drift of the time maintained by the kernel with respect to calendar time*/ portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT ); /* Determine if the SysTick clock has already counted to zero and been set back to the current reload value (the reload back being correct for the entire expected idle time) or if the SysTick is yet to count to zero (in which case an interrupt other than the SysTick must have brought the system out of sleep mode). */ if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) { uint32_t ulCalculatedLoadValue; /* The tick interrupt is already pending, and the SysTick count reloaded with ulReloadValue. Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick period. */ ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); /* Don't allow a tiny value, or values that have somehow underflowed because the post sleep hook did something that took too long. */ if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) ) { ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ); } portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue; /* As the pending tick will be processed as soon as this function exits, the tick value maintained by the tick is stepped forward by one less than the time spent waiting. */ ulCompleteTickPeriods = xExpectedIdleTime - 1UL; } else { /* Something other than the tick interrupt ended the sleep. Work out how long the sleep lasted rounded to complete tick periods (not the ulReload value which accounted for part ticks). */ ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; /* How many complete tick periods passed while the processor was waiting? */ ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick; /* The reload value is set to whatever fraction of a single tick period remains. */ portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements; } /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG again, then set portNVIC_SYSTICK_LOAD_REG back to its standard value. */ portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT; vTaskStepTick( ulCompleteTickPeriods ); portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL; /* Exit with interrpts enabled. */ __enable_irq(); } } #endif /* #if configUSE_TICKLESS_IDLE */ /*-----------------------------------------------------------*/ /* * Setup the SysTick timer to generate the tick interrupts at the required * frequency. */ #if( configOVERRIDE_DEFAULT_TICK_CONFIGURATION == 0 ) void vPortSetupTimerInterrupt( void ) { /* Calculate the constants required to configure the tick interrupt. */ #if( configUSE_TICKLESS_IDLE == 1 ) { ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ); xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick; ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); } #endif /* configUSE_TICKLESS_IDLE */ /* Stop and clear the SysTick. */ portNVIC_SYSTICK_CTRL_REG = 0UL; portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* Configure SysTick to interrupt at the requested rate. */ portNVIC_SYSTICK_LOAD_REG = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT ); } #endif /* configOVERRIDE_DEFAULT_TICK_CONFIGURATION */ /*-----------------------------------------------------------*/ __asm uint32_t vPortGetIPSR( void ) { PRESERVE8 mrs r0, ipsr bx r14 } /*-----------------------------------------------------------*/ #if( configASSERT_DEFINED == 1 ) void vPortValidateInterruptPriority( void ) { uint32_t ulCurrentInterrupt; uint8_t ucCurrentPriority; /* Obtain the number of the currently executing interrupt. */ ulCurrentInterrupt = vPortGetIPSR(); /* Is the interrupt number a user defined interrupt? */ if( ulCurrentInterrupt >= portFIRST_USER_INTERRUPT_NUMBER ) { /* Look up the interrupt's priority. */ ucCurrentPriority = pcInterruptPriorityRegisters[ ulCurrentInterrupt ]; /* The following assertion will fail if a service routine (ISR) for an interrupt that has been assigned a priority above configMAX_SYSCALL_INTERRUPT_PRIORITY calls an ISR safe FreeRTOS API function. ISR safe FreeRTOS API functions must *only* be called from interrupts that have been assigned a priority at or below configMAX_SYSCALL_INTERRUPT_PRIORITY. Numerically low interrupt priority numbers represent logically high interrupt priorities, therefore the priority of the interrupt must be set to a value equal to or numerically *higher* than configMAX_SYSCALL_INTERRUPT_PRIORITY. Interrupts that use the FreeRTOS API must not be left at their default priority of zero as that is the highest possible priority, which is guaranteed to be above configMAX_SYSCALL_INTERRUPT_PRIORITY, and therefore also guaranteed to be invalid. FreeRTOS maintains separate thread and ISR API functions to ensure interrupt entry is as fast and simple as possible. The following links provide detailed information: http://www.freertos.org/RTOS-Cortex-M3-M4.html http://www.freertos.org/FAQHelp.html */ configASSERT( ucCurrentPriority >= ucMaxSysCallPriority ); } /* Priority grouping: The interrupt controller (NVIC) allows the bits that define each interrupt's priority to be split between bits that define the interrupt's pre-emption priority bits and bits that define the interrupt's sub-priority. For simplicity all bits must be defined to be pre-emption priority bits. The following assertion will fail if this is not the case (if some bits represent a sub-priority). If the application only uses CMSIS libraries for interrupt configuration then the correct setting can be achieved on all Cortex-M devices by calling NVIC_SetPriorityGrouping( 0 ); before starting the scheduler. Note however that some vendor specific peripheral libraries assume a non-zero priority group setting, in which cases using a value of zero will result in unpredictable behaviour. */ configASSERT( ( portAIRCR_REG & portPRIORITY_GROUP_MASK ) <= ulMaxPRIGROUPValue ); } #endif /* configASSERT_DEFINED */