From: yuhzheng Date: Wed, 18 Dec 2019 09:55:08 +0000 (+0000) Subject: Cortex M0 GCC/IAR/Keil ports -- tickless support. X-Git-Tag: V10.3.0~59 X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=242c5762008b65c36750bc9873ded41dce1ba223;p=freertos Cortex M0 GCC/IAR/Keil ports -- tickless support. The default portMISSED_COUNTS_FACTOR is set to 45 cycles. User could override this value, if a more accurate count is available. git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@2764 1d2547de-c912-0410-9cb9-b8ca96c0e9e2 --- diff --git a/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c b/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c index d0b50c392..18a668b9b 100644 --- a/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c +++ b/FreeRTOS/Source/portable/GCC/ARM_CM0/port.c @@ -34,15 +34,16 @@ #include "task.h" /* Constants required to manipulate the NVIC. */ -#define portNVIC_SYSTICK_CTRL ( ( volatile uint32_t * ) 0xe000e010 ) -#define portNVIC_SYSTICK_LOAD ( ( volatile uint32_t * ) 0xe000e014 ) -#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 ) -#define portNVIC_INT_CTRL ( ( volatile uint32_t *) 0xe000ed04 ) -#define portNVIC_SYSPRI2 ( ( volatile uint32_t *) 0xe000ed20 ) -#define portNVIC_SYSTICK_CLK 0x00000004 -#define portNVIC_SYSTICK_INT 0x00000002 -#define portNVIC_SYSTICK_ENABLE 0x00000001 -#define portNVIC_PENDSVSET 0x10000000 +#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_INT_CTRL_REG ( * ( ( volatile uint32_t * ) 0xe000ed04 ) ) +#define portNVIC_SYSPRI2_REG ( * ( ( volatile uint32_t * ) 0xe000ed20 ) ) +#define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL ) +#define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL ) +#define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL ) +#define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL ) +#define portNVIC_PENDSVSET_BIT ( 1UL << 28UL ) #define portMIN_INTERRUPT_PRIORITY ( 255UL ) #define portNVIC_PENDSV_PRI ( portMIN_INTERRUPT_PRIORITY << 16UL ) #define portNVIC_SYSTICK_PRI ( portMIN_INTERRUPT_PRIORITY << 24UL ) @@ -50,6 +51,16 @@ /* Constants required to set up the initial stack. */ #define portINITIAL_XPSR ( 0x01000000 ) +/* 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. */ +#ifndef portMISSED_COUNTS_FACTOR + #define portMISSED_COUNTS_FACTOR ( 45UL ) +#endif + /* Let the user override the pre-loading of the initial LR with the address of prvTaskExitError() in case it messes up unwinding of the stack in the debugger. */ @@ -89,6 +100,31 @@ 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 */ + +/*-----------------------------------------------------------*/ + /* * See header file for description. */ @@ -176,8 +212,8 @@ void vPortStartFirstTask( void ) BaseType_t xPortStartScheduler( void ) { /* Make PendSV, CallSV and SysTick the same priority as the kernel. */ - *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI; - *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI; + 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. */ @@ -214,7 +250,7 @@ void vPortEndScheduler( void ) void vPortYield( void ) { /* Set a PendSV to request a context switch. */ - *( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET; + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; /* Barriers are normally not required but do ensure the code is completely within the specified behaviour for the architecture. */ @@ -323,7 +359,7 @@ uint32_t ulPreviousMask; if( xTaskIncrementTick() != pdFALSE ) { /* Pend a context switch. */ - *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; } } portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask ); @@ -336,13 +372,187 @@ uint32_t ulPreviousMask; */ void prvSetupTimerInterrupt( void ) { + /* Calculate the constants required to configure the tick interrupt. */ + #if( configUSE_TICKLESS_IDLE == 1 ) + { + ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ); + xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick; + ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR; + } + #endif /* configUSE_TICKLESS_IDLE */ + /* Stop and reset the SysTick. */ - *(portNVIC_SYSTICK_CTRL) = 0UL; - *(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL; + portNVIC_SYSTICK_CTRL_REG = 0UL; + portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* 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; + portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; } /*-----------------------------------------------------------*/ +#if( configUSE_TICKLESS_IDLE == 1 ) + + __attribute__((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. */ + __asm volatile( "cpsid i" ::: "memory" ); + __asm volatile( "dsb" ); + __asm volatile( "isb" ); + + /* 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 the cpsid instruction() + above. */ + __asm volatile( "cpsie i" ::: "memory" ); + } + 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 ) + { + __asm volatile( "dsb" ::: "memory" ); + __asm volatile( "wfi" ); + __asm volatile( "isb" ); + } + 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. */ + __asm volatile( "cpsie i" ::: "memory" ); + __asm volatile( "dsb" ); + __asm volatile( "isb" ); + + /* 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. */ + __asm volatile( "cpsid i" ::: "memory" ); + __asm volatile( "dsb" ); + __asm volatile( "isb" ); + + /* 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. */ + __asm volatile( "cpsie i" ::: "memory" ); + } + } + +#endif /* configUSE_TICKLESS_IDLE */ diff --git a/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h b/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h index 108a55ed7..9ad565518 100644 --- a/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h +++ b/FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h @@ -101,6 +101,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask ) __attribute__((naked) /*-----------------------------------------------------------*/ +/* Tickless idle/low power functionality. */ +#ifndef portSUPPRESS_TICKS_AND_SLEEP + extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime ); + #define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime ) +#endif +/*-----------------------------------------------------------*/ + /* Task function macros as described on the FreeRTOS.org WEB site. */ #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters ) #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters ) diff --git a/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c b/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c index 41b7d43e4..3dd08209d 100644 --- a/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c +++ b/FreeRTOS/Source/portable/IAR/ARM_CM0/port.c @@ -37,13 +37,15 @@ #include "task.h" /* Constants required to manipulate the NVIC. */ -#define portNVIC_SYSTICK_CTRL ( ( volatile uint32_t * ) 0xe000e010 ) -#define portNVIC_SYSTICK_LOAD ( ( volatile uint32_t * ) 0xe000e014 ) -#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 ) -#define portNVIC_SYSPRI2 ( ( volatile uint32_t *) 0xe000ed20 ) -#define portNVIC_SYSTICK_CLK 0x00000004 -#define portNVIC_SYSTICK_INT 0x00000002 -#define portNVIC_SYSTICK_ENABLE 0x00000001 +#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_INT_CTRL_REG ( * ( ( volatile uint32_t * ) 0xe000ed04 ) ) +#define portNVIC_SYSPRI2_REG ( * ( ( volatile uint32_t *) 0xe000ed20 ) ) +#define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL ) +#define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL ) +#define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL ) +#define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL ) #define portMIN_INTERRUPT_PRIORITY ( 255UL ) #define portNVIC_PENDSV_PRI ( portMIN_INTERRUPT_PRIORITY << 16UL ) #define portNVIC_SYSTICK_PRI ( portMIN_INTERRUPT_PRIORITY << 24UL ) @@ -62,6 +64,33 @@ FreeRTOS.org versions prior to V4.3.0 did not include this definition. */ variable. */ static UBaseType_t uxCriticalNesting = 0xaaaaaaaa; +/* 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. */ +#ifndef portMISSED_COUNTS_FACTOR + #define portMISSED_COUNTS_FACTOR ( 45UL ) +#endif + +/* 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 */ + /* * Setup the timer to generate the tick interrupts. */ @@ -125,8 +154,8 @@ static void prvTaskExitError( void ) BaseType_t xPortStartScheduler( void ) { /* Make PendSV and SysTick the lowest priority interrupts. */ - *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI; - *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI; + 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. */ @@ -154,7 +183,7 @@ void vPortEndScheduler( void ) void vPortYield( void ) { /* Set a PendSV to request a context switch. */ - *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET; /* Barriers are normally not required but do ensure the code is completely within the specified behaviour for the architecture. */ @@ -193,7 +222,7 @@ uint32_t ulPreviousMask; if( xTaskIncrementTick() != pdFALSE ) { /* Pend a context switch. */ - *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET; } } portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask ); @@ -206,13 +235,187 @@ uint32_t ulPreviousMask; */ static void prvSetupTimerInterrupt( void ) { + /* Calculate the constants required to configure the tick interrupt. */ + #if( configUSE_TICKLESS_IDLE == 1 ) + { + ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ); + xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick; + ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR; + } + #endif /* configUSE_TICKLESS_IDLE */ + /* Stop and reset the SysTick. */ - *(portNVIC_SYSTICK_CTRL) = 0UL; - *(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL; + portNVIC_SYSTICK_CTRL_REG = 0UL; + portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* 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; + portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; } /*-----------------------------------------------------------*/ +#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_interrupt(); + __DSB(); + __ISB(); + + /* 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_interrupt() + call above. */ + __enable_interrupt(); + } + 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(); + __WFI(); + __ISB(); + } + 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_interrupt(); + __DSB(); + __ISB(); + + /* 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_interrupt(); + __DSB(); + __ISB(); + + /* 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_interrupt(); + } +} + +#endif /* configUSE_TICKLESS_IDLE */ diff --git a/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h b/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h index 11f362c4d..8103f9cc1 100644 --- a/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h +++ b/FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h @@ -103,6 +103,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask ); /*-----------------------------------------------------------*/ +/* Tickless idle/low power functionality. */ +#ifndef portSUPPRESS_TICKS_AND_SLEEP + extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime ); + #define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime ) +#endif +/*-----------------------------------------------------------*/ + /* Task function macros as described on the FreeRTOS.org WEB site. */ #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters ) #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters ) diff --git a/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c b/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c index 646dd8e61..8282984b5 100644 --- a/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c +++ b/FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c @@ -34,22 +34,33 @@ #include "task.h" /* Constants required to manipulate the NVIC. */ -#define portNVIC_SYSTICK_CTRL ( ( volatile uint32_t * ) 0xe000e010 ) -#define portNVIC_SYSTICK_LOAD ( ( volatile uint32_t * ) 0xe000e014 ) -#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 ) -#define portNVIC_INT_CTRL ( ( volatile uint32_t *) 0xe000ed04 ) -#define portNVIC_SYSPRI2 ( ( volatile uint32_t *) 0xe000ed20 ) -#define portNVIC_SYSTICK_CLK 0x00000004 -#define portNVIC_SYSTICK_INT 0x00000002 -#define portNVIC_SYSTICK_ENABLE 0x00000001 -#define portNVIC_PENDSVSET 0x10000000 -#define portMIN_INTERRUPT_PRIORITY ( 255UL ) -#define portNVIC_PENDSV_PRI ( portMIN_INTERRUPT_PRIORITY << 16UL ) -#define portNVIC_SYSTICK_PRI ( portMIN_INTERRUPT_PRIORITY << 24UL ) +#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_INT_CTRL_REG ( * ( ( volatile uint32_t * ) 0xe000ed04 ) ) +#define portNVIC_SYSPRI2_REG ( * ( ( volatile uint32_t * ) 0xe000ed20 ) ) +#define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL ) +#define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL ) +#define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL ) +#define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL ) +#define portNVIC_PENDSVSET_BIT ( 1UL << 28UL ) +#define portMIN_INTERRUPT_PRIORITY ( 255UL ) +#define portNVIC_PENDSV_PRI ( portMIN_INTERRUPT_PRIORITY << 16UL ) +#define portNVIC_SYSTICK_PRI ( portMIN_INTERRUPT_PRIORITY << 24UL ) /* Constants required to set up the initial stack. */ #define portINITIAL_XPSR ( 0x01000000 ) +/* 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. */ +#ifndef portMISSED_COUNTS_FACTOR + #define portMISSED_COUNTS_FACTOR ( 45UL ) +#endif + /* Constants used with memory barrier intrinsics. */ #define portSY_FULL_READ_WRITE ( 15 ) @@ -57,6 +68,24 @@ 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 */ + /* * Setup the timer to generate the tick interrupts. */ @@ -158,8 +187,8 @@ __asm void prvPortStartFirstTask( void ) BaseType_t xPortStartScheduler( void ) { /* Make PendSV, CallSV and SysTick the same priority as the kernel. */ - *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI; - *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI; + 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. */ @@ -187,7 +216,7 @@ void vPortEndScheduler( void ) void vPortYield( void ) { /* Set a PendSV to request a context switch. */ - *( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET; + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; /* Barriers are normally not required but do ensure the code is completely within the specified behaviour for the architecture. */ @@ -287,7 +316,7 @@ uint32_t ulPreviousMask; if( xTaskIncrementTick() != pdFALSE ) { /* Pend a context switch. */ - *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET; + portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; } } portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask ); @@ -300,13 +329,187 @@ uint32_t ulPreviousMask; */ void prvSetupTimerInterrupt( void ) { + /* Calculate the constants required to configure the tick interrupt. */ + #if( configUSE_TICKLESS_IDLE == 1 ) + ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ); + xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick; + ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR; + #endif /* configUSE_TICKLESS_IDLE */ + /* Stop and reset the SysTick. */ - *(portNVIC_SYSTICK_CTRL) = 0UL; - *(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL; + portNVIC_SYSTICK_CTRL_REG = 0UL; + portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL; /* 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; + portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; + portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; } /*-----------------------------------------------------------*/ +#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 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 + again, then set portNVIC_SYSTICK_LOAD 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 */ + +/*-----------------------------------------------------------*/ diff --git a/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h b/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h index 44e7567d8..5f3b9f44e 100644 --- a/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h +++ b/FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h @@ -100,6 +100,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask ); /*-----------------------------------------------------------*/ +/* Tickless idle/low power functionality. */ +#ifndef portSUPPRESS_TICKS_AND_SLEEP + extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime ); + #define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime ) +#endif +/*-----------------------------------------------------------*/ + /* Task function macros as described on the FreeRTOS.org WEB site. */ #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters ) #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )