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Refine the default tickless idle implementation in the Cortex-M3 port layers.

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This commit is contained in:
Richard Barry 2013-06-30 10:38:31 +00:00
parent 08ca5dead5
commit 0c0b54c175
6 changed files with 273 additions and 246 deletions
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78
FreeRTOS/Source/portable/GCC/ARM_CM3/port.c
View file

@ -95,14 +95,12 @@ FreeRTOS.org versions prior to V4.4.0 did not include this definition. */
#define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile unsigned long * ) 0xe000e010 ) ) #define portNVIC_SYSTICK_CTRL_REG ( * ( ( volatile unsigned long * ) 0xe000e010 ) )
#define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile unsigned long * ) 0xe000e014 ) ) #define portNVIC_SYSTICK_LOAD_REG ( * ( ( volatile unsigned long * ) 0xe000e014 ) )
#define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile unsigned long * ) 0xe000e018 ) ) #define portNVIC_SYSTICK_CURRENT_VALUE_REG ( * ( ( volatile unsigned long * ) 0xe000e018 ) )
#define portNVIC_INT_CTRL_REG ( * ( ( volatile unsigned long * ) 0xe000ed04 ) )
#define portNVIC_SYSPRI2_REG ( * ( ( volatile unsigned long * ) 0xe000ed20 ) ) #define portNVIC_SYSPRI2_REG ( * ( ( volatile unsigned long * ) 0xe000ed20 ) )
/* ...then bits in the registers. */ /* ...then bits in the registers. */
#define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL ) #define portNVIC_SYSTICK_CLK_BIT ( 1UL << 2UL )
#define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL ) #define portNVIC_SYSTICK_INT_BIT ( 1UL << 1UL )
#define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL ) #define portNVIC_SYSTICK_ENABLE_BIT ( 1UL << 0UL )
#define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL ) #define portNVIC_SYSTICK_COUNT_FLAG_BIT ( 1UL << 16UL )
#define portNVIC_PENDSVSET_BIT ( 1UL << 28UL )
#define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL )
#define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL )
@ -112,9 +110,13 @@ FreeRTOS.org versions prior to V4.4.0 did not include this definition. */
/* Constants required to set up the initial stack. */ /* Constants required to set up the initial stack. */
#define portINITIAL_XPSR ( 0x01000000 ) #define portINITIAL_XPSR ( 0x01000000 )
/* The priority used by the kernel is assigned to a variable to make access /* The systick is a 24-bit counter. */
from inline assembler easier. */ #define portMAX_24_BIT_NUMBER ( 0xffffffUL )
const unsigned long ulKernelPriority = configKERNEL_INTERRUPT_PRIORITY;
/* 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 )
/* Each task maintains its own interrupt status in the critical nesting /* Each task maintains its own interrupt status in the critical nesting
variable. */ variable. */
@ -145,8 +147,8 @@ static void prvPortStartFirstTask( void ) __attribute__ (( naked ));
* The number of SysTick increments that make up one tick period. * The number of SysTick increments that make up one tick period.
*/ */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
static unsigned long ulTimerReloadValueForOneTick = 0; static unsigned long ulTimerCountsForOneTick = 0;
#endif #endif /* configUSE_TICKLESS_IDLE */
/* /*
* The maximum number of tick periods that can be suppressed is limited by the * The maximum number of tick periods that can be suppressed is limited by the
@ -229,7 +231,7 @@ portBASE_TYPE xPortStartScheduler( void )
See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */ See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */
configASSERT( configMAX_SYSCALL_INTERRUPT_PRIORITY ); configASSERT( configMAX_SYSCALL_INTERRUPT_PRIORITY );
/* Make PendSV, CallSV and SysTick the same priroity as the kernel. */ /* Make PendSV and SysTick the lowest priority interrupts. */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
@ -354,20 +356,13 @@ void xPortPendSVHandler( void )
void xPortSysTickHandler( void ) void xPortSysTickHandler( void )
{ {
/* Only reset the systick load register if configUSE_TICKLESS_IDLE is set to
1. If it is set to 0 tickless idle is not being used. If it is set to a
value other than 0 or 1 then a timer other than the SysTick is being used
to generate the tick interrupt. */
#if configUSE_TICKLESS_IDLE == 1
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick;
#endif
/* The SysTick runs at the lowest interrupt priority, so when this interrupt /* The SysTick runs at the lowest interrupt priority, so when this interrupt
executes all interrupts must be unmasked. There is therefore no need to 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 save and then restore the interrupt mask value as its value is already
known. */ known. */
( void ) portSET_INTERRUPT_MASK_FROM_ISR(); ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
{ {
/* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE ) if( xTaskIncrementTick() != pdFALSE )
{ {
/* A context switch is required. Context switching is performed in /* A context switch is required. Context switching is performed in
@ -383,7 +378,7 @@ void xPortSysTickHandler( void )
__attribute__((weak)) void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime ) __attribute__((weak)) void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
{ {
unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickIncrements; unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
portTickType xModifiableIdleTime; portTickType xModifiableIdleTime;
/* Make sure the SysTick reload value does not overflow the counter. */ /* Make sure the SysTick reload value does not overflow the counter. */
@ -392,25 +387,20 @@ void xPortSysTickHandler( void )
xExpectedIdleTime = xMaximumPossibleSuppressedTicks; xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
} }
/* 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, and the fraction of a tick period is
accounted for later. */
ulReloadValue = ( ulTimerReloadValueForOneTick * ( xExpectedIdleTime - 1UL ) );
if( ulReloadValue > ulStoppedTimerCompensation )
{
ulReloadValue -= ulStoppedTimerCompensation;
}
/* Stop the SysTick momentarily. The time the SysTick is stopped for /* 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 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 inevitably result in some tiny drift of the time maintained by the
kernel with respect to calendar time. */ kernel with respect to calendar time. */
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
/* Adjust the reload value to take into account that the current time /* Calculate the reload value required to wait xExpectedIdleTime
slice is already partially complete. */ tick periods. -1 is used because this code will execute part way
ulReloadValue += ( portNVIC_SYSTICK_LOAD_REG - ( portNVIC_SYSTICK_LOAD_REG - portNVIC_SYSTICK_CURRENT_VALUE_REG ) ); 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() /* Enter a critical section but don't use the taskENTER_CRITICAL()
method as that will mask interrupts that should exit sleep mode. */ method as that will mask interrupts that should exit sleep mode. */
@ -467,10 +457,10 @@ void xPortSysTickHandler( void )
if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
{ {
/* The tick interrupt has already executed, and the SysTick /* The tick interrupt has already executed, and the SysTick
count reloaded with the portNVIC_SYSTICK_LOAD_REG value. count reloaded with ulReloadValue. Reset the
Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
this tick period. */ period. */
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); portNVIC_SYSTICK_LOAD_REG = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
/* The tick interrupt handler will already have pended the tick /* The tick interrupt handler will already have pended the tick
processing in the kernel. As the pending tick will be processing in the kernel. As the pending tick will be
@ -482,16 +472,18 @@ void xPortSysTickHandler( void )
else else
{ {
/* Something other than the tick interrupt ended the sleep. /* Something other than the tick interrupt ended the sleep.
Work out how long the sleep lasted. */ Work out how long the sleep lasted rounded to complete tick
ulCompletedSysTickIncrements = ( xExpectedIdleTime * ulTimerReloadValueForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; 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 /* How many complete tick periods passed while the processor
was waiting? */ was waiting? */
ulCompleteTickPeriods = ulCompletedSysTickIncrements / ulTimerReloadValueForOneTick; ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
/* The reload value is set to whatever fraction of a single tick /* The reload value is set to whatever fraction of a single tick
period remains. */ period remains. */
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerReloadValueForOneTick ) - ulCompletedSysTickIncrements; portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
} }
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
@ -501,6 +493,10 @@ void xPortSysTickHandler( void )
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
vTaskStepTick( ulCompleteTickPeriods ); vTaskStepTick( ulCompleteTickPeriods );
/* The counter must start by the time the reload value is reset. */
configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
} }
} }
@ -516,9 +512,9 @@ __attribute__(( weak )) void vPortSetupTimerInterrupt( void )
/* Calculate the constants required to configure the tick interrupt. */ /* Calculate the constants required to configure the tick interrupt. */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
{ {
ulTimerReloadValueForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
xMaximumPossibleSuppressedTicks = 0xffffffUL / ( ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL ); xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
ulStoppedTimerCompensation = 45UL / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
} }
#endif /* configUSE_TICKLESS_IDLE */ #endif /* configUSE_TICKLESS_IDLE */

84
FreeRTOS/Source/portable/GCC/ARM_CM4F/port.c
View file

@ -112,9 +112,13 @@
#define portINITIAL_XPSR ( 0x01000000 ) #define portINITIAL_XPSR ( 0x01000000 )
#define portINITIAL_EXEC_RETURN ( 0xfffffffd ) #define portINITIAL_EXEC_RETURN ( 0xfffffffd )
/* The priority used by the kernel is assigned to a variable to make access /* The systick is a 24-bit counter. */
from inline assembler easier. */ #define portMAX_24_BIT_NUMBER ( 0xffffffUL )
const unsigned long ulKernelPriority = configKERNEL_INTERRUPT_PRIORITY;
/* 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 )
/* Each task maintains its own interrupt status in the critical nesting /* Each task maintains its own interrupt status in the critical nesting
variable. */ variable. */
@ -150,8 +154,8 @@ static void prvPortStartFirstTask( void ) __attribute__ (( naked ));
* The number of SysTick increments that make up one tick period. * The number of SysTick increments that make up one tick period.
*/ */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
static unsigned long ulTimerReloadValueForOneTick = 0; static unsigned long ulTimerCountsForOneTick = 0;
#endif #endif /* configUSE_TICKLESS_IDLE */
/* /*
* The maximum number of tick periods that can be suppressed is limited by the * The maximum number of tick periods that can be suppressed is limited by the
@ -245,7 +249,7 @@ portBASE_TYPE xPortStartScheduler( void )
See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */ See http://www.FreeRTOS.org/RTOS-Cortex-M3-M4.html */
configASSERT( configMAX_SYSCALL_INTERRUPT_PRIORITY ); configASSERT( configMAX_SYSCALL_INTERRUPT_PRIORITY );
/* Make PendSV, CallSV and SysTick the same priroity as the kernel. */ /* Make PendSV and SysTick the lowest priority interrupts. */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
@ -387,20 +391,17 @@ void xPortPendSVHandler( void )
void xPortSysTickHandler( void ) void xPortSysTickHandler( void )
{ {
/* Only reset the systick load register if configUSE_TICKLESS_IDLE is set to /* The SysTick runs at the lowest interrupt priority, so when this interrupt
1. If it is set to 0 tickless idle is not being used. If it is set to a executes all interrupts must be unmasked. There is therefore no need to
value other than 0 or 1 then a timer other than the SysTick is being used save and then restore the interrupt mask value as its value is already
to generate the tick interrupt. */ known. */
#if configUSE_TICKLESS_IDLE == 1
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick;
#endif
( void ) portSET_INTERRUPT_MASK_FROM_ISR(); ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
{ {
/* Increment the RTOS tick count. */ /* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE ) if( xTaskIncrementTick() != pdFALSE )
{ {
/* Pend a context switch. */ /* A context switch is required. Context switching is performed in
the PendSV interrupt. Pend the PendSV interrupt. */
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
} }
} }
@ -412,7 +413,7 @@ void xPortSysTickHandler( void )
__attribute__((weak)) void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime ) __attribute__((weak)) void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
{ {
unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickIncrements; unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
portTickType xModifiableIdleTime; portTickType xModifiableIdleTime;
/* Make sure the SysTick reload value does not overflow the counter. */ /* Make sure the SysTick reload value does not overflow the counter. */
@ -421,25 +422,20 @@ void xPortSysTickHandler( void )
xExpectedIdleTime = xMaximumPossibleSuppressedTicks; xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
} }
/* 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, and the fraction of a tick period is
accounted for later. */
ulReloadValue = ( ulTimerReloadValueForOneTick * ( xExpectedIdleTime - 1UL ) );
if( ulReloadValue > ulStoppedTimerCompensation )
{
ulReloadValue -= ulStoppedTimerCompensation;
}
/* Stop the SysTick momentarily. The time the SysTick is stopped for /* 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 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 inevitably result in some tiny drift of the time maintained by the
kernel with respect to calendar time. */ kernel with respect to calendar time. */
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
/* Adjust the reload value to take into account that the current time /* Calculate the reload value required to wait xExpectedIdleTime
slice is already partially complete. */ tick periods. -1 is used because this code will execute part way
ulReloadValue += ( portNVIC_SYSTICK_LOAD_REG - ( portNVIC_SYSTICK_LOAD_REG - portNVIC_SYSTICK_CURRENT_VALUE_REG ) ); 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() /* Enter a critical section but don't use the taskENTER_CRITICAL()
method as that will mask interrupts that should exit sleep mode. */ method as that will mask interrupts that should exit sleep mode. */
@ -496,10 +492,10 @@ void xPortSysTickHandler( void )
if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
{ {
/* The tick interrupt has already executed, and the SysTick /* The tick interrupt has already executed, and the SysTick
count reloaded with the portNVIC_SYSTICK_LOAD_REG value. count reloaded with ulReloadValue. Reset the
Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
this tick period. */ period. */
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); portNVIC_SYSTICK_LOAD_REG = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
/* The tick interrupt handler will already have pended the tick /* The tick interrupt handler will already have pended the tick
processing in the kernel. As the pending tick will be processing in the kernel. As the pending tick will be
@ -511,16 +507,18 @@ void xPortSysTickHandler( void )
else else
{ {
/* Something other than the tick interrupt ended the sleep. /* Something other than the tick interrupt ended the sleep.
Work out how long the sleep lasted. */ Work out how long the sleep lasted rounded to complete tick
ulCompletedSysTickIncrements = ( xExpectedIdleTime * ulTimerReloadValueForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; 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 /* How many complete tick periods passed while the processor
was waiting? */ was waiting? */
ulCompleteTickPeriods = ulCompletedSysTickIncrements / ulTimerReloadValueForOneTick; ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
/* The reload value is set to whatever fraction of a single tick /* The reload value is set to whatever fraction of a single tick
period remains. */ period remains. */
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerReloadValueForOneTick ) - ulCompletedSysTickIncrements; portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
} }
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
@ -530,6 +528,10 @@ void xPortSysTickHandler( void )
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
vTaskStepTick( ulCompleteTickPeriods ); vTaskStepTick( ulCompleteTickPeriods );
/* The counter must start by the time the reload value is reset. */
configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
} }
} }
@ -545,9 +547,9 @@ __attribute__(( weak )) void vPortSetupTimerInterrupt( void )
/* Calculate the constants required to configure the tick interrupt. */ /* Calculate the constants required to configure the tick interrupt. */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
{ {
ulTimerReloadValueForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
xMaximumPossibleSuppressedTicks = 0xffffffUL / ( ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL ); xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
ulStoppedTimerCompensation = 45UL / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
} }
#endif /* configUSE_TICKLESS_IDLE */ #endif /* configUSE_TICKLESS_IDLE */

84
FreeRTOS/Source/portable/IAR/ARM_CM3/port.c
View file

@ -104,17 +104,25 @@
#define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL )
#define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL )
#define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16 ) #define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24 ) #define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL )
/* Constants required to set up the initial stack. */ /* Constants required to set up the initial stack. */
#define portINITIAL_XPSR ( 0x01000000 ) #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. */
#define portMISSED_COUNTS_FACTOR ( 45UL )
/* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is /* For backward compatibility, ensure configKERNEL_INTERRUPT_PRIORITY is
defined. The value 255 should also ensure backward compatibility. defined. The value 255 should also ensure backward compatibility.
FreeRTOS.org versions prior to V4.3.0 did not include this definition. */ FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
#ifndef configKERNEL_INTERRUPT_PRIORITY #ifndef configKERNEL_INTERRUPT_PRIORITY
#define configKERNEL_INTERRUPT_PRIORITY 0 #define configKERNEL_INTERRUPT_PRIORITY 255
#endif #endif
/* Each task maintains its own interrupt status in the critical nesting /* Each task maintains its own interrupt status in the critical nesting
@ -144,8 +152,8 @@ extern void vPortStartFirstTask( void );
* The number of SysTick increments that make up one tick period. * The number of SysTick increments that make up one tick period.
*/ */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
static unsigned long ulTimerReloadValueForOneTick = 0; static unsigned long ulTimerCountsForOneTick = 0;
#endif #endif /* configUSE_TICKLESS_IDLE */
/* /*
* The maximum number of tick periods that can be suppressed is limited by the * The maximum number of tick periods that can be suppressed is limited by the
@ -250,18 +258,17 @@ void vPortExitCritical( void )
void xPortSysTickHandler( void ) void xPortSysTickHandler( void )
{ {
/* Only reset the systick load register if configUSE_TICKLESS_IDLE is set to /* The SysTick runs at the lowest interrupt priority, so when this interrupt
1. If it is set to 0 tickless idle is not being used. If it is set to a executes all interrupts must be unmasked. There is therefore no need to
value other than 0 or 1 then a timer other than the SysTick is being used save and then restore the interrupt mask value as its value is already
to generate the tick interrupt. */ known. */
#if configUSE_TICKLESS_IDLE == 1
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick;
#endif
( void ) portSET_INTERRUPT_MASK_FROM_ISR(); ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
{ {
/* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE ) 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; portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
} }
} }
@ -273,7 +280,7 @@ void xPortSysTickHandler( void )
__weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime ) __weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
{ {
unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickIncrements; unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
portTickType xModifiableIdleTime; portTickType xModifiableIdleTime;
/* Make sure the SysTick reload value does not overflow the counter. */ /* Make sure the SysTick reload value does not overflow the counter. */
@ -282,25 +289,20 @@ void xPortSysTickHandler( void )
xExpectedIdleTime = xMaximumPossibleSuppressedTicks; xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
} }
/* 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, and the fraction of a tick period is
accounted for later. */
ulReloadValue = ( ulTimerReloadValueForOneTick * ( xExpectedIdleTime - 1UL ) );
if( ulReloadValue > ulStoppedTimerCompensation )
{
ulReloadValue -= ulStoppedTimerCompensation;
}
/* Stop the SysTick momentarily. The time the SysTick is stopped for /* 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 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 inevitably result in some tiny drift of the time maintained by the
kernel with respect to calendar time. */ kernel with respect to calendar time. */
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
/* Adjust the reload value to take into account that the current /* Calculate the reload value required to wait xExpectedIdleTime
time slice is already partially complete. */ tick periods. -1 is used because this code will execute part way
ulReloadValue += ( portNVIC_SYSTICK_LOAD_REG - ( portNVIC_SYSTICK_LOAD_REG - portNVIC_SYSTICK_CURRENT_VALUE_REG ) ); 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() /* Enter a critical section but don't use the taskENTER_CRITICAL()
method as that will mask interrupts that should exit sleep mode. */ method as that will mask interrupts that should exit sleep mode. */
@ -357,10 +359,10 @@ void xPortSysTickHandler( void )
if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
{ {
/* The tick interrupt has already executed, and the SysTick /* The tick interrupt has already executed, and the SysTick
count reloaded with the portNVIC_SYSTICK_LOAD_REG value. count reloaded with ulReloadValue. Reset the
Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
this tick period. */ period. */
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); portNVIC_SYSTICK_LOAD_REG = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
/* The tick interrupt handler will already have pended the tick /* The tick interrupt handler will already have pended the tick
processing in the kernel. As the pending tick will be processing in the kernel. As the pending tick will be
@ -372,16 +374,18 @@ void xPortSysTickHandler( void )
else else
{ {
/* Something other than the tick interrupt ended the sleep. /* Something other than the tick interrupt ended the sleep.
Work out how long the sleep lasted. */ Work out how long the sleep lasted rounded to complete tick
ulCompletedSysTickIncrements = ( xExpectedIdleTime * ulTimerReloadValueForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; 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 /* How many complete tick periods passed while the processor
was waiting? */ was waiting? */
ulCompleteTickPeriods = ulCompletedSysTickIncrements / ulTimerReloadValueForOneTick; ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
/* The reload value is set to whatever fraction of a single tick /* The reload value is set to whatever fraction of a single tick
period remains. */ period remains. */
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerReloadValueForOneTick ) - ulCompletedSysTickIncrements; portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
} }
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
@ -391,6 +395,10 @@ void xPortSysTickHandler( void )
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
vTaskStepTick( ulCompleteTickPeriods ); vTaskStepTick( ulCompleteTickPeriods );
/* The counter must start by the time the reload value is reset. */
configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
} }
} }
@ -406,9 +414,9 @@ __weak void vPortSetupTimerInterrupt( void )
/* Calculate the constants required to configure the tick interrupt. */ /* Calculate the constants required to configure the tick interrupt. */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
{ {
ulTimerReloadValueForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
xMaximumPossibleSuppressedTicks = 0xffffffUL / ( ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL ); xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
ulStoppedTimerCompensation = 45UL / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
} }
#endif /* configUSE_TICKLESS_IDLE */ #endif /* configUSE_TICKLESS_IDLE */

83
FreeRTOS/Source/portable/IAR/ARM_CM4F/port.c
View file

@ -108,8 +108,8 @@
#define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL )
#define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL )
#define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16 ) #define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24 ) #define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL )
/* Constants required to manipulate the VFP. */ /* Constants required to manipulate the VFP. */
#define portFPCCR ( ( volatile unsigned long * ) 0xe000ef34 ) /* Floating point context control register. */ #define portFPCCR ( ( volatile unsigned long * ) 0xe000ef34 ) /* Floating point context control register. */
@ -119,6 +119,15 @@
#define portINITIAL_XPSR ( 0x01000000 ) #define portINITIAL_XPSR ( 0x01000000 )
#define portINITIAL_EXEC_RETURN ( 0xfffffffd ) #define portINITIAL_EXEC_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 )
/* Each task maintains its own interrupt status in the critical nesting /* Each task maintains its own interrupt status in the critical nesting
variable. */ variable. */
static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa; static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
@ -151,8 +160,8 @@ extern void vPortEnableVFP( void );
* The number of SysTick increments that make up one tick period. * The number of SysTick increments that make up one tick period.
*/ */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
static unsigned long ulTimerReloadValueForOneTick = 0; static unsigned long ulTimerCountsForOneTick = 0;
#endif #endif /* configUSE_TICKLESS_IDLE */
/* /*
* The maximum number of tick periods that can be suppressed is limited by the * The maximum number of tick periods that can be suppressed is limited by the
@ -275,20 +284,17 @@ void vPortExitCritical( void )
void xPortSysTickHandler( void ) void xPortSysTickHandler( void )
{ {
/* Only reset the systick load register if configUSE_TICKLESS_IDLE is set to /* The SysTick runs at the lowest interrupt priority, so when this interrupt
1. If it is set to 0 tickless idle is not being used. If it is set to a executes all interrupts must be unmasked. There is therefore no need to
value other than 0 or 1 then a timer other than the SysTick is being used save and then restore the interrupt mask value as its value is already
to generate the tick interrupt. */ known. */
#if configUSE_TICKLESS_IDLE == 1
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick;
#endif
( void ) portSET_INTERRUPT_MASK_FROM_ISR(); ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
{ {
/* Increment the RTOS tick. */ /* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE ) if( xTaskIncrementTick() != pdFALSE )
{ {
/* Pend a context switch. */ /* A context switch is required. Context switching is performed in
the PendSV interrupt. Pend the PendSV interrupt. */
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
} }
} }
@ -300,7 +306,7 @@ void xPortSysTickHandler( void )
__weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime ) __weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
{ {
unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickIncrements; unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
portTickType xModifiableIdleTime; portTickType xModifiableIdleTime;
/* Make sure the SysTick reload value does not overflow the counter. */ /* Make sure the SysTick reload value does not overflow the counter. */
@ -309,25 +315,20 @@ void xPortSysTickHandler( void )
xExpectedIdleTime = xMaximumPossibleSuppressedTicks; xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
} }
/* 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, and the fraction of a tick period is
accounted for later. */
ulReloadValue = ( ulTimerReloadValueForOneTick * ( xExpectedIdleTime - 1UL ) );
if( ulReloadValue > ulStoppedTimerCompensation )
{
ulReloadValue -= ulStoppedTimerCompensation;
}
/* Stop the SysTick momentarily. The time the SysTick is stopped for /* 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 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 inevitably result in some tiny drift of the time maintained by the
kernel with respect to calendar time. */ kernel with respect to calendar time. */
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
/* Adjust the reload value to take into account that the current /* Calculate the reload value required to wait xExpectedIdleTime
time slice is already partially complete. */ tick periods. -1 is used because this code will execute part way
ulReloadValue += ( portNVIC_SYSTICK_LOAD_REG - ( portNVIC_SYSTICK_LOAD_REG - portNVIC_SYSTICK_CURRENT_VALUE_REG ) ); 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() /* Enter a critical section but don't use the taskENTER_CRITICAL()
method as that will mask interrupts that should exit sleep mode. */ method as that will mask interrupts that should exit sleep mode. */
@ -384,10 +385,10 @@ void xPortSysTickHandler( void )
if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
{ {
/* The tick interrupt has already executed, and the SysTick /* The tick interrupt has already executed, and the SysTick
count reloaded with the portNVIC_SYSTICK_LOAD_REG value. count reloaded with ulReloadValue. Reset the
Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
this tick period. */ period. */
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); portNVIC_SYSTICK_LOAD_REG = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
/* The tick interrupt handler will already have pended the tick /* The tick interrupt handler will already have pended the tick
processing in the kernel. As the pending tick will be processing in the kernel. As the pending tick will be
@ -399,16 +400,18 @@ void xPortSysTickHandler( void )
else else
{ {
/* Something other than the tick interrupt ended the sleep. /* Something other than the tick interrupt ended the sleep.
Work out how long the sleep lasted. */ Work out how long the sleep lasted rounded to complete tick
ulCompletedSysTickIncrements = ( xExpectedIdleTime * ulTimerReloadValueForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; 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 /* How many complete tick periods passed while the processor
was waiting? */ was waiting? */
ulCompleteTickPeriods = ulCompletedSysTickIncrements / ulTimerReloadValueForOneTick; ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
/* The reload value is set to whatever fraction of a single tick /* The reload value is set to whatever fraction of a single tick
period remains. */ period remains. */
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerReloadValueForOneTick ) - ulCompletedSysTickIncrements; portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
} }
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
@ -418,6 +421,10 @@ void xPortSysTickHandler( void )
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
vTaskStepTick( ulCompleteTickPeriods ); vTaskStepTick( ulCompleteTickPeriods );
/* The counter must start by the time the reload value is reset. */
configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
} }
} }
@ -433,9 +440,9 @@ __weak void vPortSetupTimerInterrupt( void )
/* Calculate the constants required to configure the tick interrupt. */ /* Calculate the constants required to configure the tick interrupt. */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
{ {
ulTimerReloadValueForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
xMaximumPossibleSuppressedTicks = 0xffffffUL / ( ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL ); xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
ulStoppedTimerCompensation = 45UL / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
} }
#endif /* configUSE_TICKLESS_IDLE */ #endif /* configUSE_TICKLESS_IDLE */

85
FreeRTOS/Source/portable/RVDS/ARM_CM3/port.c
View file

@ -114,8 +114,8 @@ is defined. */
#define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL )
#define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL )
#define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16 ) #define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24 ) #define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL )
/* Constants required to set up the initial stack. */ /* Constants required to set up the initial stack. */
#define portINITIAL_XPSR ( 0x01000000 ) #define portINITIAL_XPSR ( 0x01000000 )
@ -123,6 +123,14 @@ is defined. */
/* Constants used with memory barrier intrinsics. */ /* Constants used with memory barrier intrinsics. */
#define portSY_FULL_READ_WRITE ( 15 ) #define portSY_FULL_READ_WRITE ( 15 )
/* 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 )
/* Each task maintains its own interrupt status in the critical nesting /* Each task maintains its own interrupt status in the critical nesting
variable. */ variable. */
static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa; static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
@ -152,8 +160,8 @@ static void prvStartFirstTask( void );
* The number of SysTick increments that make up one tick period. * The number of SysTick increments that make up one tick period.
*/ */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
static unsigned long ulTimerReloadValueForOneTick = 0; static unsigned long ulTimerCountsForOneTick = 0;
#endif #endif /* configUSE_TICKLESS_IDLE */
/* /*
* The maximum number of tick periods that can be suppressed is limited by the * The maximum number of tick periods that can be suppressed is limited by the
@ -233,7 +241,7 @@ __asm void prvStartFirstTask( void )
*/ */
portBASE_TYPE xPortStartScheduler( void ) portBASE_TYPE xPortStartScheduler( void )
{ {
/* Make PendSV, CallSV and SysTick the same priority as the kernel. */ /* Make PendSV and SysTick the lowest priority interrupts. */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
@ -325,19 +333,17 @@ __asm void xPortPendSVHandler( void )
void xPortSysTickHandler( void ) void xPortSysTickHandler( void )
{ {
/* Only reset the systick load register if configUSE_TICKLESS_IDLE is set to /* The SysTick runs at the lowest interrupt priority, so when this interrupt
1. If it is set to 0 tickless idle is not being used. If it is set to a executes all interrupts must be unmasked. There is therefore no need to
value other than 0 or 1 then a timer other than the SysTick is being used save and then restore the interrupt mask value as its value is already
to generate the tick interrupt. */ known. */
#if configUSE_TICKLESS_IDLE == 1
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick;
#endif
( void ) portSET_INTERRUPT_MASK_FROM_ISR(); ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
{ {
/* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE ) if( xTaskIncrementTick() != pdFALSE )
{ {
/* Pend a context switch. */ /* A context switch is required. Context switching is performed in
the PendSV interrupt. Pend the PendSV interrupt. */
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
} }
} }
@ -349,7 +355,7 @@ void xPortSysTickHandler( void )
__weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime ) __weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
{ {
unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickIncrements; unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
portTickType xModifiableIdleTime; portTickType xModifiableIdleTime;
/* Make sure the SysTick reload value does not overflow the counter. */ /* Make sure the SysTick reload value does not overflow the counter. */
@ -358,25 +364,20 @@ void xPortSysTickHandler( void )
xExpectedIdleTime = xMaximumPossibleSuppressedTicks; xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
} }
/* 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, and the fraction of a tick period is
accounted for later. */
ulReloadValue = ( ulTimerReloadValueForOneTick * ( xExpectedIdleTime - 1UL ) );
if( ulReloadValue > ulStoppedTimerCompensation )
{
ulReloadValue -= ulStoppedTimerCompensation;
}
/* Stop the SysTick momentarily. The time the SysTick is stopped for /* 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 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 inevitably result in some tiny drift of the time maintained by the
kernel with respect to calendar time. */ kernel with respect to calendar time. */
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
/* Adjust the reload value to take into account that the current /* Calculate the reload value required to wait xExpectedIdleTime
time slice is already partially complete. */ tick periods. -1 is used because this code will execute part way
ulReloadValue += ( portNVIC_SYSTICK_LOAD_REG - ( portNVIC_SYSTICK_LOAD_REG - portNVIC_SYSTICK_CURRENT_VALUE_REG ) ); 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() /* Enter a critical section but don't use the taskENTER_CRITICAL()
method as that will mask interrupts that should exit sleep mode. */ method as that will mask interrupts that should exit sleep mode. */
@ -433,10 +434,10 @@ void xPortSysTickHandler( void )
if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
{ {
/* The tick interrupt has already executed, and the SysTick /* The tick interrupt has already executed, and the SysTick
count reloaded with the portNVIC_SYSTICK_LOAD_REG value. count reloaded with ulReloadValue. Reset the
Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
this tick period. */ period. */
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); portNVIC_SYSTICK_LOAD_REG = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
/* The tick interrupt handler will already have pended the tick /* The tick interrupt handler will already have pended the tick
processing in the kernel. As the pending tick will be processing in the kernel. As the pending tick will be
@ -448,16 +449,18 @@ void xPortSysTickHandler( void )
else else
{ {
/* Something other than the tick interrupt ended the sleep. /* Something other than the tick interrupt ended the sleep.
Work out how long the sleep lasted. */ Work out how long the sleep lasted rounded to complete tick
ulCompletedSysTickIncrements = ( xExpectedIdleTime * ulTimerReloadValueForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; 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 /* How many complete tick periods passed while the processor
was waiting? */ was waiting? */
ulCompleteTickPeriods = ulCompletedSysTickIncrements / ulTimerReloadValueForOneTick; ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
/* The reload value is set to whatever fraction of a single tick /* The reload value is set to whatever fraction of a single tick
period remains. */ period remains. */
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerReloadValueForOneTick ) - ulCompletedSysTickIncrements; portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
} }
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
@ -467,6 +470,10 @@ void xPortSysTickHandler( void )
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
vTaskStepTick( ulCompleteTickPeriods ); vTaskStepTick( ulCompleteTickPeriods );
/* The counter must start by the time the reload value is reset. */
configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
} }
} }
@ -485,9 +492,9 @@ void xPortSysTickHandler( void )
/* Calculate the constants required to configure the tick interrupt. */ /* Calculate the constants required to configure the tick interrupt. */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
{ {
ulTimerReloadValueForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
xMaximumPossibleSuppressedTicks = 0xffffffUL / ( ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL ); xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
ulStoppedTimerCompensation = 45UL / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
} }
#endif /* configUSE_TICKLESS_IDLE */ #endif /* configUSE_TICKLESS_IDLE */

85
FreeRTOS/Source/portable/RVDS/ARM_CM4F/port.c
View file

@ -114,8 +114,8 @@ is defined. */
#define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL ) #define portNVIC_PENDSVCLEAR_BIT ( 1UL << 27UL )
#define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL ) #define portNVIC_PEND_SYSTICK_CLEAR_BIT ( 1UL << 25UL )
#define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16 ) #define portNVIC_PENDSV_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 16UL )
#define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24 ) #define portNVIC_SYSTICK_PRI ( ( ( unsigned long ) configKERNEL_INTERRUPT_PRIORITY ) << 24UL )
/* Constants required to manipulate the VFP. */ /* Constants required to manipulate the VFP. */
#define portFPCCR ( ( volatile unsigned long * ) 0xe000ef34 ) /* Floating point context control register. */ #define portFPCCR ( ( volatile unsigned long * ) 0xe000ef34 ) /* Floating point context control register. */
@ -128,6 +128,14 @@ is defined. */
/* Constants used with memory barrier intrinsics. */ /* Constants used with memory barrier intrinsics. */
#define portSY_FULL_READ_WRITE ( 15 ) #define portSY_FULL_READ_WRITE ( 15 )
/* 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 )
/* Each task maintains its own interrupt status in the critical nesting /* Each task maintains its own interrupt status in the critical nesting
variable. */ variable. */
static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa; static unsigned portBASE_TYPE uxCriticalNesting = 0xaaaaaaaa;
@ -161,8 +169,8 @@ static void prvEnableVFP( void );
* The number of SysTick increments that make up one tick period. * The number of SysTick increments that make up one tick period.
*/ */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
static unsigned long ulTimerReloadValueForOneTick = 0; static unsigned long ulTimerCountsForOneTick = 0;
#endif #endif /* configUSE_TICKLESS_IDLE */
/* /*
* The maximum number of tick periods that can be suppressed is limited by the * The maximum number of tick periods that can be suppressed is limited by the
@ -271,7 +279,7 @@ __asm void prvEnableVFP( void )
*/ */
portBASE_TYPE xPortStartScheduler( void ) portBASE_TYPE xPortStartScheduler( void )
{ {
/* Make PendSV, CallSV and SysTick the same priroity as the kernel. */ /* Make PendSV and SysTick the lowest priority interrupts. */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI; portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI; portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
@ -388,19 +396,17 @@ __asm void xPortPendSVHandler( void )
void xPortSysTickHandler( void ) void xPortSysTickHandler( void )
{ {
/* Only reset the systick load register if configUSE_TICKLESS_IDLE is set to /* The SysTick runs at the lowest interrupt priority, so when this interrupt
1. If it is set to 0 tickless idle is not being used. If it is set to a executes all interrupts must be unmasked. There is therefore no need to
value other than 0 or 1 then a timer other than the SysTick is being used save and then restore the interrupt mask value as its value is already
to generate the tick interrupt. */ known. */
#if configUSE_TICKLESS_IDLE == 1
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick;
#endif
( void ) portSET_INTERRUPT_MASK_FROM_ISR(); ( void ) portSET_INTERRUPT_MASK_FROM_ISR();
{ {
/* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE ) if( xTaskIncrementTick() != pdFALSE )
{ {
/* Pend a context switch. */ /* A context switch is required. Context switching is performed in
the PendSV interrupt. Pend the PendSV interrupt. */
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT; portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
} }
} }
@ -412,7 +418,7 @@ void xPortSysTickHandler( void )
__weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime ) __weak void vPortSuppressTicksAndSleep( portTickType xExpectedIdleTime )
{ {
unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickIncrements; unsigned long ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
portTickType xModifiableIdleTime; portTickType xModifiableIdleTime;
/* Make sure the SysTick reload value does not overflow the counter. */ /* Make sure the SysTick reload value does not overflow the counter. */
@ -421,25 +427,20 @@ void xPortSysTickHandler( void )
xExpectedIdleTime = xMaximumPossibleSuppressedTicks; xExpectedIdleTime = xMaximumPossibleSuppressedTicks;
} }
/* 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, and the fraction of a tick period is
accounted for later. */
ulReloadValue = ( ulTimerReloadValueForOneTick * ( xExpectedIdleTime - 1UL ) );
if( ulReloadValue > ulStoppedTimerCompensation )
{
ulReloadValue -= ulStoppedTimerCompensation;
}
/* Stop the SysTick momentarily. The time the SysTick is stopped for /* 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 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 inevitably result in some tiny drift of the time maintained by the
kernel with respect to calendar time. */ kernel with respect to calendar time. */
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT;
/* Adjust the reload value to take into account that the current /* Calculate the reload value required to wait xExpectedIdleTime
time slice is already partially complete. */ tick periods. -1 is used because this code will execute part way
ulReloadValue += ( portNVIC_SYSTICK_LOAD_REG - ( portNVIC_SYSTICK_LOAD_REG - portNVIC_SYSTICK_CURRENT_VALUE_REG ) ); 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() /* Enter a critical section but don't use the taskENTER_CRITICAL()
method as that will mask interrupts that should exit sleep mode. */ method as that will mask interrupts that should exit sleep mode. */
@ -496,10 +497,10 @@ void xPortSysTickHandler( void )
if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 ) if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )
{ {
/* The tick interrupt has already executed, and the SysTick /* The tick interrupt has already executed, and the SysTick
count reloaded with the portNVIC_SYSTICK_LOAD_REG value. count reloaded with ulReloadValue. Reset the
Reset the portNVIC_SYSTICK_LOAD_REG with whatever remains of portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick
this tick period. */ period. */
portNVIC_SYSTICK_LOAD_REG = ulTimerReloadValueForOneTick - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG ); portNVIC_SYSTICK_LOAD_REG = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );
/* The tick interrupt handler will already have pended the tick /* The tick interrupt handler will already have pended the tick
processing in the kernel. As the pending tick will be processing in the kernel. As the pending tick will be
@ -511,16 +512,18 @@ void xPortSysTickHandler( void )
else else
{ {
/* Something other than the tick interrupt ended the sleep. /* Something other than the tick interrupt ended the sleep.
Work out how long the sleep lasted. */ Work out how long the sleep lasted rounded to complete tick
ulCompletedSysTickIncrements = ( xExpectedIdleTime * ulTimerReloadValueForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG; 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 /* How many complete tick periods passed while the processor
was waiting? */ was waiting? */
ulCompleteTickPeriods = ulCompletedSysTickIncrements / ulTimerReloadValueForOneTick; ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
/* The reload value is set to whatever fraction of a single tick /* The reload value is set to whatever fraction of a single tick
period remains. */ period remains. */
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerReloadValueForOneTick ) - ulCompletedSysTickIncrements; portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1 ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
} }
/* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG
@ -530,6 +533,10 @@ void xPortSysTickHandler( void )
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT; portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
vTaskStepTick( ulCompleteTickPeriods ); vTaskStepTick( ulCompleteTickPeriods );
/* The counter must start by the time the reload value is reset. */
configASSERT( portNVIC_SYSTICK_CURRENT_VALUE_REG );
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
} }
} }
@ -548,9 +555,9 @@ void xPortSysTickHandler( void )
/* Calculate the constants required to configure the tick interrupt. */ /* Calculate the constants required to configure the tick interrupt. */
#if configUSE_TICKLESS_IDLE == 1 #if configUSE_TICKLESS_IDLE == 1
{ {
ulTimerReloadValueForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL; ulTimerCountsForOneTick = ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ );
xMaximumPossibleSuppressedTicks = 0xffffffUL / ( ( configSYSTICK_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL ); xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;
ulStoppedTimerCompensation = 45UL / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ ); ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR / ( configCPU_CLOCK_HZ / configSYSTICK_CLOCK_HZ );
} }
#endif /* configUSE_TICKLESS_IDLE */ #endif /* configUSE_TICKLESS_IDLE */