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Alfred Gedeon 2020-07-01 22:27:40 -07:00 • committed by alfred gedeon
parent a5dbc2b1de
commit 718178c68a
406 changed files with 108795 additions and 106323 deletions
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707
portable/GCC/ARM_CM0/port.c
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@ -25,48 +25,48 @@
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the ARM CM0 port.
*----------------------------------------------------------*/
* Implementation of functions defined in portable.h for the ARM CM0 port.
*----------------------------------------------------------*/
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Constants required to manipulate the NVIC. */
#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 )
#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 )
#define portINITIAL_XPSR ( 0x01000000 )
/* The systick is a 24-bit counter. */
#define portMAX_24_BIT_NUMBER ( 0xffffffUL )
#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. */
* occurred while the SysTick counter is stopped during tickless idle
* calculations. */
#ifndef portMISSED_COUNTS_FACTOR
#define portMISSED_COUNTS_FACTOR ( 45UL )
#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. */
* prvTaskExitError() in case it messes up unwinding of the stack in the
* debugger. */
#ifdef configTASK_RETURN_ADDRESS
#define portTASK_RETURN_ADDRESS configTASK_RETURN_ADDRESS
#define portTASK_RETURN_ADDRESS configTASK_RETURN_ADDRESS
#else
#define portTASK_RETURN_ADDRESS prvTaskExitError
#define portTASK_RETURN_ADDRESS prvTaskExitError
#endif
/*
@ -79,14 +79,14 @@ void vPortSetupTimerInterrupt( void );
/*
* Exception handlers.
*/
void xPortPendSVHandler( void ) __attribute__ (( naked ));
void xPortPendSVHandler( void ) __attribute__( ( naked ) );
void xPortSysTickHandler( void );
void vPortSVCHandler( void );
/*
* Start first task is a separate function so it can be tested in isolation.
*/
static void vPortStartFirstTask( void ) __attribute__ (( naked ));
static void vPortStartFirstTask( void ) __attribute__( ( naked ) );
/*
* Used to catch tasks that attempt to return from their implementing function.
@ -96,32 +96,32 @@ static void prvTaskExitError( void );
/*-----------------------------------------------------------*/
/* Each task maintains its own interrupt status in the critical nesting
variable. */
static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;
* 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;
* 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;
#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;
#if ( configUSE_TICKLESS_IDLE == 1 )
static uint32_t ulStoppedTimerCompensation = 0;
#endif /* configUSE_TICKLESS_IDLE */
/*-----------------------------------------------------------*/
@ -129,81 +129,84 @@ static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;
/*
* See header file for description.
*/
StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
TaskFunction_t pxCode,
void * pvParameters )
{
/* Simulate the stack frame as it would be created by a context switch
interrupt. */
pxTopOfStack--; /* Offset added to account for the way the MCU uses the stack on entry/exit of interrupts. */
*pxTopOfStack = portINITIAL_XPSR; /* xPSR */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) pxCode; /* PC */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) portTASK_RETURN_ADDRESS; /* LR */
pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
pxTopOfStack -= 8; /* R11..R4. */
/* Simulate the stack frame as it would be created by a context switch
* interrupt. */
pxTopOfStack--; /* Offset added to account for the way the MCU uses the stack on entry/exit of interrupts. */
*pxTopOfStack = portINITIAL_XPSR; /* xPSR */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) pxCode; /* PC */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) portTASK_RETURN_ADDRESS; /* LR */
pxTopOfStack -= 5; /* R12, R3, R2 and R1. */
*pxTopOfStack = ( StackType_t ) pvParameters; /* R0 */
pxTopOfStack -= 8; /* R11..R4. */
return pxTopOfStack;
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
static void prvTaskExitError( void )
{
volatile uint32_t ulDummy = 0UL;
volatile uint32_t ulDummy = 0UL;
/* A function that implements a task must not exit or attempt to return to
its caller as there is nothing to return to. If a task wants to exit it
should instead call vTaskDelete( NULL ).
/* A function that implements a task must not exit or attempt to return to
* its caller as there is nothing to return to. If a task wants to exit it
* should instead call vTaskDelete( NULL ).
*
* Artificially force an assert() to be triggered if configASSERT() is
* defined, then stop here so application writers can catch the error. */
configASSERT( uxCriticalNesting == ~0UL );
portDISABLE_INTERRUPTS();
Artificially force an assert() to be triggered if configASSERT() is
defined, then stop here so application writers can catch the error. */
configASSERT( uxCriticalNesting == ~0UL );
portDISABLE_INTERRUPTS();
while( ulDummy == 0 )
{
/* This file calls prvTaskExitError() after the scheduler has been
started to remove a compiler warning about the function being defined
but never called. ulDummy is used purely to quieten other warnings
about code appearing after this function is called - making ulDummy
volatile makes the compiler think the function could return and
therefore not output an 'unreachable code' warning for code that appears
after it. */
}
while( ulDummy == 0 )
{
/* This file calls prvTaskExitError() after the scheduler has been
* started to remove a compiler warning about the function being defined
* but never called. ulDummy is used purely to quieten other warnings
* about code appearing after this function is called - making ulDummy
* volatile makes the compiler think the function could return and
* therefore not output an 'unreachable code' warning for code that appears
* after it. */
}
}
/*-----------------------------------------------------------*/
void vPortSVCHandler( void )
{
/* This function is no longer used, but retained for backward
compatibility. */
/* This function is no longer used, but retained for backward
* compatibility. */
}
/*-----------------------------------------------------------*/
void vPortStartFirstTask( void )
{
/* The MSP stack is not reset as, unlike on M3/4 parts, there is no vector
table offset register that can be used to locate the initial stack value.
Not all M0 parts have the application vector table at address 0. */
__asm volatile(
" .syntax unified \n"
" ldr r2, pxCurrentTCBConst2 \n" /* Obtain location of pxCurrentTCB. */
" ldr r3, [r2] \n"
" ldr r0, [r3] \n" /* The first item in pxCurrentTCB is the task top of stack. */
" adds r0, #32 \n" /* Discard everything up to r0. */
" msr psp, r0 \n" /* This is now the new top of stack to use in the task. */
" movs r0, #2 \n" /* Switch to the psp stack. */
" msr CONTROL, r0 \n"
" isb \n"
" pop {r0-r5} \n" /* Pop the registers that are saved automatically. */
" mov lr, r5 \n" /* lr is now in r5. */
" pop {r3} \n" /* Return address is now in r3. */
" pop {r2} \n" /* Pop and discard XPSR. */
" cpsie i \n" /* The first task has its context and interrupts can be enabled. */
" bx r3 \n" /* Finally, jump to the user defined task code. */
" \n"
" .align 4 \n"
"pxCurrentTCBConst2: .word pxCurrentTCB "
);
/* The MSP stack is not reset as, unlike on M3/4 parts, there is no vector
* table offset register that can be used to locate the initial stack value.
* Not all M0 parts have the application vector table at address 0. */
__asm volatile (
" .syntax unified \n"
" ldr r2, pxCurrentTCBConst2 \n"/* Obtain location of pxCurrentTCB. */
" ldr r3, [r2] \n"
" ldr r0, [r3] \n"/* The first item in pxCurrentTCB is the task top of stack. */
" adds r0, #32 \n"/* Discard everything up to r0. */
" msr psp, r0 \n"/* This is now the new top of stack to use in the task. */
" movs r0, #2 \n"/* Switch to the psp stack. */
" msr CONTROL, r0 \n"
" isb \n"
" pop {r0-r5} \n"/* Pop the registers that are saved automatically. */
" mov lr, r5 \n"/* lr is now in r5. */
" pop {r3} \n"/* Return address is now in r3. */
" pop {r2} \n"/* Pop and discard XPSR. */
" cpsie i \n"/* The first task has its context and interrupts can be enabled. */
" bx r3 \n"/* Finally, jump to the user defined task code. */
" \n"
" .align 4 \n"
"pxCurrentTCBConst2: .word pxCurrentTCB "
);
}
/*-----------------------------------------------------------*/
@ -212,158 +215,159 @@ void vPortStartFirstTask( void )
*/
BaseType_t xPortStartScheduler( void )
{
/* Make PendSV, CallSV and SysTick the same priority as the kernel. */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
/* Make PendSV, CallSV and SysTick the same priority as the kernel. */
portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;
portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;
/* Start the timer that generates the tick ISR. Interrupts are disabled
here already. */
vPortSetupTimerInterrupt();
/* Start the timer that generates the tick ISR. Interrupts are disabled
* here already. */
vPortSetupTimerInterrupt();
/* Initialise the critical nesting count ready for the first task. */
uxCriticalNesting = 0;
/* Initialise the critical nesting count ready for the first task. */
uxCriticalNesting = 0;
/* Start the first task. */
vPortStartFirstTask();
/* Start the first task. */
vPortStartFirstTask();
/* Should never get here as the tasks will now be executing! Call the task
exit error function to prevent compiler warnings about a static function
not being called in the case that the application writer overrides this
functionality by defining configTASK_RETURN_ADDRESS. Call
vTaskSwitchContext() so link time optimisation does not remove the
symbol. */
vTaskSwitchContext();
prvTaskExitError();
/* Should never get here as the tasks will now be executing! Call the task
* exit error function to prevent compiler warnings about a static function
* not being called in the case that the application writer overrides this
* functionality by defining configTASK_RETURN_ADDRESS. Call
* vTaskSwitchContext() so link time optimisation does not remove the
* symbol. */
vTaskSwitchContext();
prvTaskExitError();
/* Should not get here! */
return 0;
/* Should not get here! */
return 0;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* Not implemented in ports where there is nothing to return to.
Artificially force an assert. */
configASSERT( uxCriticalNesting == 1000UL );
/* Not implemented in ports where there is nothing to return to.
* Artificially force an assert. */
configASSERT( uxCriticalNesting == 1000UL );
}
/*-----------------------------------------------------------*/
void vPortYield( void )
{
/* Set a PendSV to request a context switch. */
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
/* Set a PendSV to request a context switch. */
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. */
__asm volatile( "dsb" ::: "memory" );
__asm volatile( "isb" );
/* Barriers are normally not required but do ensure the code is completely
* within the specified behaviour for the architecture. */
__asm volatile ( "dsb" ::: "memory" );
__asm volatile ( "isb" );
}
/*-----------------------------------------------------------*/
void vPortEnterCritical( void )
{
portDISABLE_INTERRUPTS();
uxCriticalNesting++;
__asm volatile( "dsb" ::: "memory" );
__asm volatile( "isb" );
portDISABLE_INTERRUPTS();
uxCriticalNesting++;
__asm volatile ( "dsb" ::: "memory" );
__asm volatile ( "isb" );
}
/*-----------------------------------------------------------*/
void vPortExitCritical( void )
{
configASSERT( uxCriticalNesting );
uxCriticalNesting--;
if( uxCriticalNesting == 0 )
{
portENABLE_INTERRUPTS();
}
configASSERT( uxCriticalNesting );
uxCriticalNesting--;
if( uxCriticalNesting == 0 )
{
portENABLE_INTERRUPTS();
}
}
/*-----------------------------------------------------------*/
uint32_t ulSetInterruptMaskFromISR( void )
{
__asm volatile(
" mrs r0, PRIMASK \n"
" cpsid i \n"
" bx lr "
::: "memory"
);
__asm volatile (
" mrs r0, PRIMASK \n"
" cpsid i \n"
" bx lr "
::: "memory"
);
}
/*-----------------------------------------------------------*/
void vClearInterruptMaskFromISR( __attribute__( ( unused ) ) uint32_t ulMask )
{
__asm volatile(
" msr PRIMASK, r0 \n"
" bx lr "
::: "memory"
);
__asm volatile (
" msr PRIMASK, r0 \n"
" bx lr "
::: "memory"
);
}
/*-----------------------------------------------------------*/
void xPortPendSVHandler( void )
{
/* This is a naked function. */
/* This is a naked function. */
__asm volatile
(
" .syntax unified \n"
" mrs r0, psp \n"
" \n"
" ldr r3, pxCurrentTCBConst \n" /* Get the location of the current TCB. */
" ldr r2, [r3] \n"
" \n"
" subs r0, r0, #32 \n" /* Make space for the remaining low registers. */
" str r0, [r2] \n" /* Save the new top of stack. */
" stmia r0!, {r4-r7} \n" /* Store the low registers that are not saved automatically. */
" mov r4, r8 \n" /* Store the high registers. */
" mov r5, r9 \n"
" mov r6, r10 \n"
" mov r7, r11 \n"
" stmia r0!, {r4-r7} \n"
" \n"
" push {r3, r14} \n"
" cpsid i \n"
" bl vTaskSwitchContext \n"
" cpsie i \n"
" pop {r2, r3} \n" /* lr goes in r3. r2 now holds tcb pointer. */
" \n"
" ldr r1, [r2] \n"
" ldr r0, [r1] \n" /* The first item in pxCurrentTCB is the task top of stack. */
" adds r0, r0, #16 \n" /* Move to the high registers. */
" ldmia r0!, {r4-r7} \n" /* Pop the high registers. */
" mov r8, r4 \n"
" mov r9, r5 \n"
" mov r10, r6 \n"
" mov r11, r7 \n"
" \n"
" msr psp, r0 \n" /* Remember the new top of stack for the task. */
" \n"
" subs r0, r0, #32 \n" /* Go back for the low registers that are not automatically restored. */
" ldmia r0!, {r4-r7} \n" /* Pop low registers. */
" \n"
" bx r3 \n"
" \n"
" .align 4 \n"
"pxCurrentTCBConst: .word pxCurrentTCB "
);
__asm volatile
(
" .syntax unified \n"
" mrs r0, psp \n"
" \n"
" ldr r3, pxCurrentTCBConst \n"/* Get the location of the current TCB. */
" ldr r2, [r3] \n"
" \n"
" subs r0, r0, #32 \n"/* Make space for the remaining low registers. */
" str r0, [r2] \n"/* Save the new top of stack. */
" stmia r0!, {r4-r7} \n"/* Store the low registers that are not saved automatically. */
" mov r4, r8 \n"/* Store the high registers. */
" mov r5, r9 \n"
" mov r6, r10 \n"
" mov r7, r11 \n"
" stmia r0!, {r4-r7} \n"
" \n"
" push {r3, r14} \n"
" cpsid i \n"
" bl vTaskSwitchContext \n"
" cpsie i \n"
" pop {r2, r3} \n"/* lr goes in r3. r2 now holds tcb pointer. */
" \n"
" ldr r1, [r2] \n"
" ldr r0, [r1] \n"/* The first item in pxCurrentTCB is the task top of stack. */
" adds r0, r0, #16 \n"/* Move to the high registers. */
" ldmia r0!, {r4-r7} \n"/* Pop the high registers. */
" mov r8, r4 \n"
" mov r9, r5 \n"
" mov r10, r6 \n"
" mov r11, r7 \n"
" \n"
" msr psp, r0 \n"/* Remember the new top of stack for the task. */
" \n"
" subs r0, r0, #32 \n"/* Go back for the low registers that are not automatically restored. */
" ldmia r0!, {r4-r7} \n"/* Pop low registers. */
" \n"
" bx r3 \n"
" \n"
" .align 4 \n"
"pxCurrentTCBConst: .word pxCurrentTCB "
);
}
/*-----------------------------------------------------------*/
void xPortSysTickHandler( void )
{
uint32_t ulPreviousMask;
uint32_t ulPreviousMask;
ulPreviousMask = portSET_INTERRUPT_MASK_FROM_ISR();
{
/* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE )
{
/* Pend a context switch. */
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
}
}
portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );
ulPreviousMask = portSET_INTERRUPT_MASK_FROM_ISR();
{
/* Increment the RTOS tick. */
if( xTaskIncrementTick() != pdFALSE )
{
/* Pend a context switch. */
portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;
}
}
portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );
}
/*-----------------------------------------------------------*/
@ -371,189 +375,192 @@ uint32_t ulPreviousMask;
* Setup the systick timer to generate the tick interrupts at the required
* frequency.
*/
__attribute__(( weak )) void vPortSetupTimerInterrupt( void )
__attribute__( ( weak ) ) void vPortSetupTimerInterrupt( 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 */
/* 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_REG = 0UL;
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
/* Stop and reset the SysTick. */
portNVIC_SYSTICK_CTRL_REG = 0UL;
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
/* Configure SysTick to interrupt at the requested rate. */
portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;
portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;
/* Configure SysTick to interrupt at the requested rate. */
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 )
#if ( configUSE_TICKLESS_IDLE == 1 )
__attribute__((weak)) void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )
{
uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;
TickType_t xModifiableIdleTime;
__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;
}
/* 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;
/* 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;
}
/* 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 ) );
/* 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( ulReloadValue > ulStoppedTimerCompensation )
{
ulReloadValue -= ulStoppedTimerCompensation;
}
/* 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;
/* 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" );
/* Restart SysTick. */
portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;
/* 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;
/* Reset the reload register to the value required for normal tick
periods. */
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
/* Restart SysTick. */
portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;
/* 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;
/* Reset the reload register to the value required for normal tick
* periods. */
portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;
/* Clear the SysTick count flag and set the count value back to
zero. */
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
/* 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;
/* Restart SysTick. */
portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;
/* Clear the SysTick count flag and set the count value back to
* zero. */
portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;
/* 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 );
/* Restart SysTick. */
portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;
/* 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" );
/* 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 );
/* 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" );
if( xModifiableIdleTime > 0 )
{
__asm volatile ( "dsb" ::: "memory" );
__asm volatile ( "wfi" );
__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 );
configPOST_SLEEP_PROCESSING( xExpectedIdleTime );
/* 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;
/* 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" );
/* 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 );
/* 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" );
/* 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 );
}
/* 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 );
portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;
/* 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;
/* 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;
/* 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 );
/* How many complete tick periods passed while the processor
was waiting? */
ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;
/* 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 );
}
/* The reload value is set to whatever fraction of a single tick
period remains. */
portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;
}
portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;
/* 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;
/* 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;
/* Exit with interrpts enabled. */
__asm volatile( "cpsie i" ::: "memory" );
}
}
/* 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 */