]> git.sur5r.net Git - freertos/commitdiff
Cortex M0 GCC/IAR/Keil ports -- tickless support.
authoryuhzheng <yuhzheng@1d2547de-c912-0410-9cb9-b8ca96c0e9e2>
Wed, 18 Dec 2019 09:55:08 +0000 (09:55 +0000)
committeryuhzheng <yuhzheng@1d2547de-c912-0410-9cb9-b8ca96c0e9e2>
Wed, 18 Dec 2019 09:55:08 +0000 (09:55 +0000)
The default portMISSED_COUNTS_FACTOR is set to 45 cycles. User could override this value, if a more accurate count is available.

git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@2764 1d2547de-c912-0410-9cb9-b8ca96c0e9e2

FreeRTOS/Source/portable/GCC/ARM_CM0/port.c
FreeRTOS/Source/portable/GCC/ARM_CM0/portmacro.h
FreeRTOS/Source/portable/IAR/ARM_CM0/port.c
FreeRTOS/Source/portable/IAR/ARM_CM0/portmacro.h
FreeRTOS/Source/portable/RVDS/ARM_CM0/port.c
FreeRTOS/Source/portable/RVDS/ARM_CM0/portmacro.h

index d0b50c3927e9747504aa895c49140933e15d064f..18a668b9b64c57dfa18bd2da429dd75a8300df98 100644 (file)
 #include "task.h"\r
 \r
 /* Constants required to manipulate the NVIC. */\r
-#define portNVIC_SYSTICK_CTRL                  ( ( volatile uint32_t * ) 0xe000e010 )\r
-#define portNVIC_SYSTICK_LOAD                  ( ( volatile uint32_t * ) 0xe000e014 )\r
-#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 )\r
-#define portNVIC_INT_CTRL                              ( ( volatile uint32_t *) 0xe000ed04 )\r
-#define portNVIC_SYSPRI2                               ( ( volatile uint32_t *) 0xe000ed20 )\r
-#define portNVIC_SYSTICK_CLK                   0x00000004\r
-#define portNVIC_SYSTICK_INT                   0x00000002\r
-#define portNVIC_SYSTICK_ENABLE                        0x00000001\r
-#define portNVIC_PENDSVSET                             0x10000000\r
+#define portNVIC_SYSTICK_CTRL_REG                      ( * ( ( volatile uint32_t * ) 0xe000e010 ) )\r
+#define portNVIC_SYSTICK_LOAD_REG                      ( * ( ( volatile uint32_t * ) 0xe000e014 ) )\r
+#define portNVIC_SYSTICK_CURRENT_VALUE_REG     ( * ( ( volatile uint32_t * ) 0xe000e018 ) )\r
+#define portNVIC_INT_CTRL_REG                          ( * ( ( volatile uint32_t * ) 0xe000ed04 ) )\r
+#define portNVIC_SYSPRI2_REG                           ( * ( ( volatile uint32_t * ) 0xe000ed20 ) )\r
+#define portNVIC_SYSTICK_CLK_BIT                       ( 1UL << 2UL )\r
+#define portNVIC_SYSTICK_INT_BIT                       ( 1UL << 1UL )\r
+#define portNVIC_SYSTICK_ENABLE_BIT                    ( 1UL << 0UL )\r
+#define portNVIC_SYSTICK_COUNT_FLAG_BIT                ( 1UL << 16UL )\r
+#define portNVIC_PENDSVSET_BIT                         ( 1UL << 28UL )\r
 #define portMIN_INTERRUPT_PRIORITY             ( 255UL )\r
 #define portNVIC_PENDSV_PRI                            ( portMIN_INTERRUPT_PRIORITY << 16UL )\r
 #define portNVIC_SYSTICK_PRI                   ( portMIN_INTERRUPT_PRIORITY << 24UL )\r
 /* Constants required to set up the initial stack. */\r
 #define portINITIAL_XPSR                       ( 0x01000000 )\r
 \r
+/* The systick is a 24-bit counter. */\r
+#define portMAX_24_BIT_NUMBER                          ( 0xffffffUL )\r
+\r
+/* A fiddle factor to estimate the number of SysTick counts that would have\r
+occurred while the SysTick counter is stopped during tickless idle\r
+calculations. */\r
+#ifndef portMISSED_COUNTS_FACTOR\r
+       #define portMISSED_COUNTS_FACTOR                        ( 45UL )\r
+#endif\r
+\r
 /* Let the user override the pre-loading of the initial LR with the address of\r
 prvTaskExitError() in case it messes up unwinding of the stack in the\r
 debugger. */\r
@@ -89,6 +100,31 @@ static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;
 \r
 /*-----------------------------------------------------------*/\r
 \r
+/*\r
+* The number of SysTick increments that make up one tick period.\r
+*/\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t ulTimerCountsForOneTick = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
+/*\r
+ * The maximum number of tick periods that can be suppressed is limited by the\r
+ * 24 bit resolution of the SysTick timer.\r
+ */\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t xMaximumPossibleSuppressedTicks = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
+/*\r
+ * Compensate for the CPU cycles that pass while the SysTick is stopped (low\r
+ * power functionality only.\r
+ */\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t ulStoppedTimerCompensation = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
+/*-----------------------------------------------------------*/\r
+\r
 /*\r
  * See header file for description.\r
  */\r
@@ -176,8 +212,8 @@ void vPortStartFirstTask( void )
 BaseType_t xPortStartScheduler( void )\r
 {\r
        /* Make PendSV, CallSV and SysTick the same priority as the kernel. */\r
-       *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;\r
-       *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;\r
+       portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;\r
+       portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;\r
 \r
        /* Start the timer that generates the tick ISR.  Interrupts are disabled\r
        here already. */\r
@@ -214,7 +250,7 @@ void vPortEndScheduler( void )
 void vPortYield( void )\r
 {\r
        /* Set a PendSV to request a context switch. */\r
-       *( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET;\r
+       portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;\r
 \r
        /* Barriers are normally not required but do ensure the code is completely\r
        within the specified behaviour for the architecture. */\r
@@ -323,7 +359,7 @@ uint32_t ulPreviousMask;
                if( xTaskIncrementTick() != pdFALSE )\r
                {\r
                        /* Pend a context switch. */\r
-                       *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;\r
+                       portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;\r
                }\r
        }\r
        portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );\r
@@ -336,13 +372,187 @@ uint32_t ulPreviousMask;
  */\r
 void prvSetupTimerInterrupt( void )\r
 {\r
+       /* Calculate the constants required to configure the tick interrupt. */\r
+       #if( configUSE_TICKLESS_IDLE == 1 )\r
+       {\r
+               ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ );\r
+               xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;\r
+               ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR;\r
+       }\r
+       #endif /* configUSE_TICKLESS_IDLE */\r
+\r
        /* Stop and reset the SysTick. */\r
-       *(portNVIC_SYSTICK_CTRL) = 0UL;\r
-       *(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL;\r
+       portNVIC_SYSTICK_CTRL_REG = 0UL;\r
+       portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
 \r
        /* Configure SysTick to interrupt at the requested rate. */\r
-       *(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;\r
-       *(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;\r
+       portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;\r
+       portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;\r
 }\r
 /*-----------------------------------------------------------*/\r
 \r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+\r
+       __attribute__((weak)) void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )\r
+       {\r
+       uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;\r
+       TickType_t xModifiableIdleTime;\r
+\r
+               /* Make sure the SysTick reload value does not overflow the counter. */\r
+               if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )\r
+               {\r
+                       xExpectedIdleTime = xMaximumPossibleSuppressedTicks;\r
+               }\r
+\r
+               /* Stop the SysTick momentarily.  The time the SysTick is stopped for\r
+               is accounted for as best it can be, but using the tickless mode will\r
+               inevitably result in some tiny drift of the time maintained by the\r
+               kernel with respect to calendar time. */\r
+               portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+               /* Calculate the reload value required to wait xExpectedIdleTime\r
+               tick periods.  -1 is used because this code will execute part way\r
+               through one of the tick periods. */\r
+               ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );\r
+               if( ulReloadValue > ulStoppedTimerCompensation )\r
+               {\r
+                       ulReloadValue -= ulStoppedTimerCompensation;\r
+               }\r
+\r
+               /* Enter a critical section but don't use the taskENTER_CRITICAL()\r
+               method as that will mask interrupts that should exit sleep mode. */\r
+               __asm volatile( "cpsid i" ::: "memory" );\r
+               __asm volatile( "dsb" );\r
+               __asm volatile( "isb" );\r
+\r
+               /* If a context switch is pending or a task is waiting for the scheduler\r
+               to be unsuspended then abandon the low power entry. */\r
+               if( eTaskConfirmSleepModeStatus() == eAbortSleep )\r
+               {\r
+                       /* Restart from whatever is left in the count register to complete\r
+                       this tick period. */\r
+                       portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG;\r
+\r
+                       /* Restart SysTick. */\r
+                       portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+                       /* Reset the reload register to the value required for normal tick\r
+                       periods. */\r
+                       portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
+\r
+                       /* Re-enable interrupts - see comments above the cpsid instruction()\r
+                       above. */\r
+                       __asm volatile( "cpsie i" ::: "memory" );\r
+               }\r
+               else\r
+               {\r
+                       /* Set the new reload value. */\r
+                       portNVIC_SYSTICK_LOAD_REG = ulReloadValue;\r
+\r
+                       /* Clear the SysTick count flag and set the count value back to\r
+                       zero. */\r
+                       portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
+\r
+                       /* Restart SysTick. */\r
+                       portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+                       /* Sleep until something happens.  configPRE_SLEEP_PROCESSING() can\r
+                       set its parameter to 0 to indicate that its implementation contains\r
+                       its own wait for interrupt or wait for event instruction, and so wfi\r
+                       should not be executed again.  However, the original expected idle\r
+                       time variable must remain unmodified, so a copy is taken. */\r
+                       xModifiableIdleTime = xExpectedIdleTime;\r
+                       configPRE_SLEEP_PROCESSING( xModifiableIdleTime );\r
+                       if( xModifiableIdleTime > 0 )\r
+                       {\r
+                               __asm volatile( "dsb" ::: "memory" );\r
+                               __asm volatile( "wfi" );\r
+                               __asm volatile( "isb" );\r
+                       }\r
+                       configPOST_SLEEP_PROCESSING( xExpectedIdleTime );\r
+\r
+                       /* Re-enable interrupts to allow the interrupt that brought the MCU\r
+                       out of sleep mode to execute immediately.  see comments above\r
+                       __disable_interrupt() call above. */\r
+                       __asm volatile( "cpsie i" ::: "memory" );\r
+                       __asm volatile( "dsb" );\r
+                       __asm volatile( "isb" );\r
+\r
+                       /* Disable interrupts again because the clock is about to be stopped\r
+                       and interrupts that execute while the clock is stopped will increase\r
+                       any slippage between the time maintained by the RTOS and calendar\r
+                       time. */\r
+                       __asm volatile( "cpsid i" ::: "memory" );\r
+                       __asm volatile( "dsb" );\r
+                       __asm volatile( "isb" );\r
+\r
+                       /* Disable the SysTick clock without reading the\r
+                       portNVIC_SYSTICK_CTRL_REG register to ensure the\r
+                       portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set.  Again,\r
+                       the time the SysTick is stopped for is accounted for as best it can\r
+                       be, but using the tickless mode will inevitably result in some tiny\r
+                       drift of the time maintained by the kernel with respect to calendar\r
+                       time*/\r
+                       portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT );\r
+\r
+                       /* Determine if the SysTick clock has already counted to zero and\r
+                       been set back to the current reload value (the reload back being\r
+                       correct for the entire expected idle time) or if the SysTick is yet\r
+                       to count to zero (in which case an interrupt other than the SysTick\r
+                       must have brought the system out of sleep mode). */\r
+                       if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )\r
+                       {\r
+                               uint32_t ulCalculatedLoadValue;\r
+\r
+                               /* The tick interrupt is already pending, and the SysTick count\r
+                               reloaded with ulReloadValue.  Reset the\r
+                               portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick\r
+                               period. */\r
+                               ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );\r
+\r
+                               /* Don't allow a tiny value, or values that have somehow\r
+                               underflowed because the post sleep hook did something\r
+                               that took too long. */\r
+                               if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) )\r
+                               {\r
+                                       ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL );\r
+                               }\r
+\r
+                               portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;\r
+\r
+                               /* As the pending tick will be processed as soon as this\r
+                               function exits, the tick value maintained by the tick is stepped\r
+                               forward by one less than the time spent waiting. */\r
+                               ulCompleteTickPeriods = xExpectedIdleTime - 1UL;\r
+                       }\r
+                       else\r
+                       {\r
+                               /* Something other than the tick interrupt ended the sleep.\r
+                               Work out how long the sleep lasted rounded to complete tick\r
+                               periods (not the ulReload value which accounted for part\r
+                               ticks). */\r
+                               ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG;\r
+\r
+                               /* How many complete tick periods passed while the processor\r
+                               was waiting? */\r
+                               ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;\r
+\r
+                               /* The reload value is set to whatever fraction of a single tick\r
+                               period remains. */\r
+                               portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;\r
+                       }\r
+\r
+                       /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG\r
+                       again, then set portNVIC_SYSTICK_LOAD_REG back to its standard\r
+                       value. */\r
+                       portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
+                       portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+                       vTaskStepTick( ulCompleteTickPeriods );\r
+                       portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
+\r
+                       /* Exit with interrpts enabled. */\r
+                       __asm volatile( "cpsie i" ::: "memory" );\r
+               }\r
+       }\r
+\r
+#endif /* configUSE_TICKLESS_IDLE */\r
index 108a55ed7ab70f73937053208655918ac98748d0..9ad565518c84457a11e2aea744456a78379877d8 100644 (file)
@@ -101,6 +101,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask )  __attribute__((naked)
 \r
 /*-----------------------------------------------------------*/\r
 \r
+/* Tickless idle/low power functionality. */\r
+#ifndef portSUPPRESS_TICKS_AND_SLEEP\r
+       extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime );\r
+       #define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime )\r
+#endif\r
+/*-----------------------------------------------------------*/\r
+\r
 /* Task function macros as described on the FreeRTOS.org WEB site. */\r
 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )\r
 #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )\r
index 41b7d43e4d84b676e7f0dd730a258089e5053af2..3dd08209d07ad4a5dd67f79b90c953d1e8507824 100644 (file)
 #include "task.h"\r
 \r
 /* Constants required to manipulate the NVIC. */\r
-#define portNVIC_SYSTICK_CTRL                  ( ( volatile uint32_t * ) 0xe000e010 )\r
-#define portNVIC_SYSTICK_LOAD                  ( ( volatile uint32_t * ) 0xe000e014 )\r
-#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 )\r
-#define portNVIC_SYSPRI2                       ( ( volatile uint32_t *) 0xe000ed20 )\r
-#define portNVIC_SYSTICK_CLK           0x00000004\r
-#define portNVIC_SYSTICK_INT           0x00000002\r
-#define portNVIC_SYSTICK_ENABLE                0x00000001\r
+#define portNVIC_SYSTICK_CTRL_REG                      ( * ( ( volatile uint32_t * ) 0xe000e010 ) )\r
+#define portNVIC_SYSTICK_LOAD_REG                      ( * ( ( volatile uint32_t * ) 0xe000e014 ) )\r
+#define portNVIC_SYSTICK_CURRENT_VALUE_REG     ( * ( ( volatile uint32_t * ) 0xe000e018 ) )\r
+#define portNVIC_INT_CTRL_REG                          ( * ( ( volatile uint32_t * ) 0xe000ed04 ) )\r
+#define portNVIC_SYSPRI2_REG                           ( * ( ( volatile uint32_t *) 0xe000ed20 ) )\r
+#define portNVIC_SYSTICK_CLK_BIT                       ( 1UL << 2UL )\r
+#define portNVIC_SYSTICK_INT_BIT                       ( 1UL << 1UL )\r
+#define portNVIC_SYSTICK_ENABLE_BIT                    ( 1UL << 0UL )\r
+#define portNVIC_SYSTICK_COUNT_FLAG_BIT                ( 1UL << 16UL )\r
 #define portMIN_INTERRUPT_PRIORITY     ( 255UL )\r
 #define portNVIC_PENDSV_PRI                    ( portMIN_INTERRUPT_PRIORITY << 16UL )\r
 #define portNVIC_SYSTICK_PRI           ( portMIN_INTERRUPT_PRIORITY << 24UL )\r
@@ -62,6 +64,33 @@ FreeRTOS.org versions prior to V4.3.0 did not include this definition. */
 variable. */\r
 static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;\r
 \r
+/* The systick is a 24-bit counter. */\r
+#define portMAX_24_BIT_NUMBER                          ( 0xffffffUL )\r
+\r
+/* A fiddle factor to estimate the number of SysTick counts that would have\r
+occurred while the SysTick counter is stopped during tickless idle\r
+calculations. */\r
+#ifndef portMISSED_COUNTS_FACTOR\r
+       #define portMISSED_COUNTS_FACTOR                        ( 45UL )\r
+#endif\r
+\r
+/* The number of SysTick increments that make up one tick period. */\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t ulTimerCountsForOneTick = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
+/* The maximum number of tick periods that can be suppressed is limited by the\r
+24 bit resolution of the SysTick timer. */\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t xMaximumPossibleSuppressedTicks = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
+/* Compensate for the CPU cycles that pass while the SysTick is stopped (low\r
+power functionality only. */\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t ulStoppedTimerCompensation = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
 /*\r
  * Setup the timer to generate the tick interrupts.\r
  */\r
@@ -125,8 +154,8 @@ static void prvTaskExitError( void )
 BaseType_t xPortStartScheduler( void )\r
 {\r
        /* Make PendSV and SysTick the lowest priority interrupts. */\r
-       *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;\r
-       *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;\r
+       portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;\r
+       portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;\r
 \r
        /* Start the timer that generates the tick ISR.  Interrupts are disabled\r
        here already. */\r
@@ -154,7 +183,7 @@ void vPortEndScheduler( void )
 void vPortYield( void )\r
 {\r
        /* Set a PendSV to request a context switch. */\r
-       *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;\r
+       portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET;\r
 \r
        /* Barriers are normally not required but do ensure the code is completely\r
        within the specified behaviour for the architecture. */\r
@@ -193,7 +222,7 @@ uint32_t ulPreviousMask;
                if( xTaskIncrementTick() != pdFALSE )\r
                {\r
                        /* Pend a context switch. */\r
-                       *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;\r
+                       portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET;\r
                }\r
        }\r
        portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );\r
@@ -206,13 +235,187 @@ uint32_t ulPreviousMask;
  */\r
 static void prvSetupTimerInterrupt( void )\r
 {\r
+       /* Calculate the constants required to configure the tick interrupt. */\r
+       #if( configUSE_TICKLESS_IDLE == 1 )\r
+       {\r
+               ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ );\r
+               xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;\r
+               ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR;\r
+       }\r
+       #endif /* configUSE_TICKLESS_IDLE */\r
+        \r
        /* Stop and reset the SysTick. */\r
-       *(portNVIC_SYSTICK_CTRL) = 0UL;\r
-       *(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL;\r
+       portNVIC_SYSTICK_CTRL_REG = 0UL;\r
+       portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
 \r
        /* Configure SysTick to interrupt at the requested rate. */\r
-       *(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;\r
-       *(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;\r
+       portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;\r
+       portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;\r
 }\r
 /*-----------------------------------------------------------*/\r
 \r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+\r
+__weak void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )\r
+{\r
+uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;\r
+TickType_t xModifiableIdleTime;\r
+\r
+       /* Make sure the SysTick reload value does not overflow the counter. */\r
+       if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )\r
+       {\r
+               xExpectedIdleTime = xMaximumPossibleSuppressedTicks;\r
+       }\r
+\r
+       /* Stop the SysTick momentarily.  The time the SysTick is stopped for\r
+       is accounted for as best it can be, but using the tickless mode will\r
+       inevitably result in some tiny drift of the time maintained by the\r
+       kernel with respect to calendar time. */\r
+       portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+       /* Calculate the reload value required to wait xExpectedIdleTime\r
+       tick periods.  -1 is used because this code will execute part way\r
+       through one of the tick periods. */\r
+       ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );\r
+       if( ulReloadValue > ulStoppedTimerCompensation )\r
+       {\r
+               ulReloadValue -= ulStoppedTimerCompensation;\r
+       }\r
+\r
+       /* Enter a critical section but don't use the taskENTER_CRITICAL()\r
+       method as that will mask interrupts that should exit sleep mode. */\r
+       __disable_interrupt();\r
+       __DSB();\r
+       __ISB();\r
+\r
+       /* If a context switch is pending or a task is waiting for the scheduler\r
+       to be unsuspended then abandon the low power entry. */\r
+       if( eTaskConfirmSleepModeStatus() == eAbortSleep )\r
+       {\r
+               /* Restart from whatever is left in the count register to complete\r
+               this tick period. */\r
+               portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG;\r
+\r
+               /* Restart SysTick. */\r
+               portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+               /* Reset the reload register to the value required for normal tick\r
+               periods. */\r
+               portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
+\r
+               /* Re-enable interrupts - see comments above __disable_interrupt()\r
+               call above. */\r
+               __enable_interrupt();\r
+       }\r
+       else\r
+       {\r
+               /* Set the new reload value. */\r
+               portNVIC_SYSTICK_LOAD_REG = ulReloadValue;\r
+\r
+               /* Clear the SysTick count flag and set the count value back to\r
+               zero. */\r
+               portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
+\r
+               /* Restart SysTick. */\r
+               portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+               /* Sleep until something happens.  configPRE_SLEEP_PROCESSING() can\r
+               set its parameter to 0 to indicate that its implementation contains\r
+               its own wait for interrupt or wait for event instruction, and so wfi\r
+               should not be executed again.  However, the original expected idle\r
+               time variable must remain unmodified, so a copy is taken. */\r
+               xModifiableIdleTime = xExpectedIdleTime;\r
+               configPRE_SLEEP_PROCESSING( xModifiableIdleTime );\r
+               if( xModifiableIdleTime > 0 )\r
+               {\r
+                       __DSB();\r
+                       __WFI();\r
+                       __ISB();\r
+               }\r
+               configPOST_SLEEP_PROCESSING( xExpectedIdleTime );\r
+\r
+               /* Re-enable interrupts to allow the interrupt that brought the MCU\r
+               out of sleep mode to execute immediately.  see comments above\r
+               __disable_interrupt() call above. */\r
+               __enable_interrupt();\r
+               __DSB();\r
+               __ISB();\r
+\r
+               /* Disable interrupts again because the clock is about to be stopped\r
+               and interrupts that execute while the clock is stopped will increase\r
+               any slippage between the time maintained by the RTOS and calendar\r
+               time. */\r
+               __disable_interrupt();\r
+               __DSB();\r
+               __ISB();\r
+\r
+               /* Disable the SysTick clock without reading the \r
+               portNVIC_SYSTICK_CTRL_REG register to ensure the\r
+               portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set.  Again, \r
+               the time the SysTick is stopped for is accounted for as best it can \r
+               be, but using the tickless mode will inevitably result in some tiny \r
+               drift of the time maintained by the kernel with respect to calendar \r
+               time*/\r
+               portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT );\r
+\r
+               /* Determine if the SysTick clock has already counted to zero and\r
+               been set back to the current reload value (the reload back being\r
+               correct for the entire expected idle time) or if the SysTick is yet\r
+               to count to zero (in which case an interrupt other than the SysTick\r
+               must have brought the system out of sleep mode). */\r
+               if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )\r
+               {\r
+                       uint32_t ulCalculatedLoadValue;\r
+\r
+                       /* The tick interrupt is already pending, and the SysTick count\r
+                       reloaded with ulReloadValue.  Reset the\r
+                       portNVIC_SYSTICK_LOAD_REG with whatever remains of this tick\r
+                       period. */\r
+                       ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );\r
+\r
+                       /* Don't allow a tiny value, or values that have somehow\r
+                       underflowed because the post sleep hook did something\r
+                       that took too long. */\r
+                       if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) )\r
+                       {\r
+                               ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL );\r
+                       }\r
+\r
+                       portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;\r
+\r
+                       /* As the pending tick will be processed as soon as this\r
+                       function exits, the tick value maintained by the tick is stepped\r
+                       forward by one less than the time spent waiting. */\r
+                       ulCompleteTickPeriods = xExpectedIdleTime - 1UL;\r
+               }\r
+               else\r
+               {\r
+                       /* Something other than the tick interrupt ended the sleep.\r
+                       Work out how long the sleep lasted rounded to complete tick\r
+                       periods (not the ulReload value which accounted for part\r
+                       ticks). */\r
+                       ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG ;\r
+\r
+                       /* How many complete tick periods passed while the processor\r
+                       was waiting? */\r
+                       ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;\r
+\r
+                       /* The reload value is set to whatever fraction of a single tick\r
+                       period remains. */\r
+                       portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;\r
+               }\r
+\r
+               /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD_REG\r
+               again, then set portNVIC_SYSTICK_LOAD_REG back to its standard\r
+               value. */\r
+               portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
+               portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+               vTaskStepTick( ulCompleteTickPeriods );\r
+               portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
+\r
+               /* Exit with interrpts enabled. */\r
+               __enable_interrupt();\r
+       }\r
+}\r
+\r
+#endif /* configUSE_TICKLESS_IDLE */\r
index 11f362c4d7fbeda85c4566274b1b0c19b72a8d0a..8103f9cc180cbabd35f70746a98a88fe92d0ddb3 100644 (file)
@@ -103,6 +103,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask );
 \r
 /*-----------------------------------------------------------*/\r
 \r
+/* Tickless idle/low power functionality. */\r
+#ifndef portSUPPRESS_TICKS_AND_SLEEP\r
+       extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime );\r
+       #define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime )\r
+#endif\r
+/*-----------------------------------------------------------*/\r
+\r
 /* Task function macros as described on the FreeRTOS.org WEB site. */\r
 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )\r
 #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )\r
index 646dd8e61c501b1e9b461baa8a6ef9b72db444b5..8282984b507a06e5c83bf6c7f318c36550d0126f 100644 (file)
 #include "task.h"\r
 \r
 /* Constants required to manipulate the NVIC. */\r
-#define portNVIC_SYSTICK_CTRL                  ( ( volatile uint32_t * ) 0xe000e010 )\r
-#define portNVIC_SYSTICK_LOAD                  ( ( volatile uint32_t * ) 0xe000e014 )\r
-#define portNVIC_SYSTICK_CURRENT_VALUE ( ( volatile uint32_t * ) 0xe000e018 )\r
-#define portNVIC_INT_CTRL                      ( ( volatile uint32_t *) 0xe000ed04 )\r
-#define portNVIC_SYSPRI2                       ( ( volatile uint32_t *) 0xe000ed20 )\r
-#define portNVIC_SYSTICK_CLK           0x00000004\r
-#define portNVIC_SYSTICK_INT           0x00000002\r
-#define portNVIC_SYSTICK_ENABLE                0x00000001\r
-#define portNVIC_PENDSVSET                     0x10000000\r
-#define portMIN_INTERRUPT_PRIORITY     ( 255UL )\r
-#define portNVIC_PENDSV_PRI                    ( portMIN_INTERRUPT_PRIORITY << 16UL )\r
-#define portNVIC_SYSTICK_PRI           ( portMIN_INTERRUPT_PRIORITY << 24UL )\r
+#define portNVIC_SYSTICK_CTRL_REG                      ( * ( ( volatile uint32_t * ) 0xe000e010 ) )\r
+#define portNVIC_SYSTICK_LOAD_REG                      ( * ( ( volatile uint32_t * ) 0xe000e014 ) )\r
+#define portNVIC_SYSTICK_CURRENT_VALUE_REG     ( * ( ( volatile uint32_t * ) 0xe000e018 ) )\r
+#define portNVIC_INT_CTRL_REG                          ( * ( ( volatile uint32_t * ) 0xe000ed04 ) )\r
+#define portNVIC_SYSPRI2_REG                           ( * ( ( volatile uint32_t * ) 0xe000ed20 ) )\r
+#define portNVIC_SYSTICK_CLK_BIT                       ( 1UL << 2UL )\r
+#define portNVIC_SYSTICK_INT_BIT                       ( 1UL << 1UL )\r
+#define portNVIC_SYSTICK_ENABLE_BIT                    ( 1UL << 0UL )\r
+#define portNVIC_SYSTICK_COUNT_FLAG_BIT                ( 1UL << 16UL )\r
+#define portNVIC_PENDSVSET_BIT                         ( 1UL << 28UL )\r
+#define portMIN_INTERRUPT_PRIORITY                     ( 255UL )\r
+#define portNVIC_PENDSV_PRI                                    ( portMIN_INTERRUPT_PRIORITY << 16UL )\r
+#define portNVIC_SYSTICK_PRI                           ( portMIN_INTERRUPT_PRIORITY << 24UL )\r
 \r
 /* Constants required to set up the initial stack. */\r
 #define portINITIAL_XPSR                       ( 0x01000000 )\r
 \r
+/* The systick is a 24-bit counter. */\r
+#define portMAX_24_BIT_NUMBER          ( 0xffffffUL )\r
+\r
+/* A fiddle factor to estimate the number of SysTick counts that would have\r
+ occurred while the SysTick counter is stopped during tickless idle\r
+ calculations. */\r
+#ifndef portMISSED_COUNTS_FACTOR\r
+       #define portMISSED_COUNTS_FACTOR        ( 45UL )\r
+#endif\r
+\r
 /* Constants used with memory barrier intrinsics. */\r
 #define portSY_FULL_READ_WRITE         ( 15 )\r
 \r
 variable. */\r
 static UBaseType_t uxCriticalNesting = 0xaaaaaaaa;\r
 \r
+/* The number of SysTick increments that make up one tick period. */\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t ulTimerCountsForOneTick = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
+/* The maximum number of tick periods that can be suppressed is limited by the\r
+ 24 bit resolution of the SysTick timer. */\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t xMaximumPossibleSuppressedTicks = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
+ /* Compensate for the CPU cycles that pass while the SysTick is stopped (low\r
+ power functionality only.\r
+*/\r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+       static uint32_t ulStoppedTimerCompensation = 0;\r
+#endif /* configUSE_TICKLESS_IDLE */\r
+\r
 /*\r
  * Setup the timer to generate the tick interrupts.\r
  */\r
@@ -158,8 +187,8 @@ __asm void prvPortStartFirstTask( void )
 BaseType_t xPortStartScheduler( void )\r
 {\r
        /* Make PendSV, CallSV and SysTick the same priority as the kernel. */\r
-       *(portNVIC_SYSPRI2) |= portNVIC_PENDSV_PRI;\r
-       *(portNVIC_SYSPRI2) |= portNVIC_SYSTICK_PRI;\r
+       portNVIC_SYSPRI2_REG |= portNVIC_PENDSV_PRI;\r
+       portNVIC_SYSPRI2_REG |= portNVIC_SYSTICK_PRI;\r
 \r
        /* Start the timer that generates the tick ISR.  Interrupts are disabled\r
        here already. */\r
@@ -187,7 +216,7 @@ void vPortEndScheduler( void )
 void vPortYield( void )\r
 {\r
        /* Set a PendSV to request a context switch. */\r
-       *( portNVIC_INT_CTRL ) = portNVIC_PENDSVSET;\r
+       portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;\r
 \r
        /* Barriers are normally not required but do ensure the code is completely\r
        within the specified behaviour for the architecture. */\r
@@ -287,7 +316,7 @@ uint32_t ulPreviousMask;
                if( xTaskIncrementTick() != pdFALSE )\r
                {\r
                        /* Pend a context switch. */\r
-                       *(portNVIC_INT_CTRL) = portNVIC_PENDSVSET;\r
+                       portNVIC_INT_CTRL_REG = portNVIC_PENDSVSET_BIT;\r
                }\r
        }\r
        portCLEAR_INTERRUPT_MASK_FROM_ISR( ulPreviousMask );\r
@@ -300,13 +329,187 @@ uint32_t ulPreviousMask;
  */\r
 void prvSetupTimerInterrupt( void )\r
 {\r
+       /* Calculate the constants required to configure the tick interrupt. */\r
+       #if( configUSE_TICKLESS_IDLE == 1 )\r
+               ulTimerCountsForOneTick = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ );\r
+               xMaximumPossibleSuppressedTicks = portMAX_24_BIT_NUMBER / ulTimerCountsForOneTick;\r
+               ulStoppedTimerCompensation = portMISSED_COUNTS_FACTOR;\r
+       #endif /* configUSE_TICKLESS_IDLE */\r
+\r
        /* Stop and reset the SysTick. */\r
-       *(portNVIC_SYSTICK_CTRL) = 0UL;\r
-       *(portNVIC_SYSTICK_CURRENT_VALUE) = 0UL;\r
+       portNVIC_SYSTICK_CTRL_REG = 0UL;\r
+       portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
 \r
        /* Configure SysTick to interrupt at the requested rate. */\r
-       *(portNVIC_SYSTICK_LOAD) = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;\r
-       *(portNVIC_SYSTICK_CTRL) = portNVIC_SYSTICK_CLK | portNVIC_SYSTICK_INT | portNVIC_SYSTICK_ENABLE;\r
+       portNVIC_SYSTICK_LOAD_REG = ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) - 1UL;\r
+       portNVIC_SYSTICK_CTRL_REG = portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT | portNVIC_SYSTICK_ENABLE_BIT;\r
 }\r
 /*-----------------------------------------------------------*/\r
 \r
+#if( configUSE_TICKLESS_IDLE == 1 )\r
+\r
+__weak void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime )\r
+{\r
+uint32_t ulReloadValue, ulCompleteTickPeriods, ulCompletedSysTickDecrements;\r
+TickType_t xModifiableIdleTime;\r
+\r
+       /* Make sure the SysTick reload value does not overflow the counter. */\r
+       if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks )\r
+       {\r
+               xExpectedIdleTime = xMaximumPossibleSuppressedTicks;\r
+       }\r
+\r
+       /* Stop the SysTick momentarily. The time the SysTick is stopped for\r
+       is accounted for as best it can be, but using the tickless mode will\r
+       inevitably result in some tiny drift of the time maintained by the\r
+       kernel with respect to calendar time. */\r
+       portNVIC_SYSTICK_CTRL_REG &= ~portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+       /* Calculate the reload value required to wait xExpectedIdleTime\r
+       tick periods.  -1 is used because this code will execute part way\r
+       through one of the tick periods. */\r
+       ulReloadValue = portNVIC_SYSTICK_CURRENT_VALUE_REG + ( ulTimerCountsForOneTick * ( xExpectedIdleTime - 1UL ) );\r
+       if( ulReloadValue > ulStoppedTimerCompensation )\r
+       {\r
+               ulReloadValue -= ulStoppedTimerCompensation;\r
+       }\r
+\r
+       /* Enter a critical section but don't use the taskENTER_CRITICAL()\r
+       method as that will mask interrupts that should exit sleep mode. */\r
+       __disable_irq();\r
+       __dsb( portSY_FULL_READ_WRITE );\r
+       __isb( portSY_FULL_READ_WRITE );\r
+\r
+       /* If a context switch is pending or a task is waiting for the scheduler\r
+       to be unsuspended then abandon the low power entry. */\r
+       if( eTaskConfirmSleepModeStatus() == eAbortSleep )\r
+       {\r
+               /* Restart from whatever is left in the count register to complete\r
+               this tick period. */\r
+               portNVIC_SYSTICK_LOAD_REG = portNVIC_SYSTICK_CURRENT_VALUE_REG;\r
+\r
+               /* Restart SysTick. */\r
+               portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+               /* Reset the reload register to the value required for normal tick\r
+               periods. */\r
+               portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
+\r
+               /* Re-enable interrupts - see comments above __disable_irq() call\r
+               above. */\r
+               __enable_irq();\r
+       }\r
+       else\r
+       {\r
+               /* Set the new reload value. */\r
+               portNVIC_SYSTICK_LOAD_REG = ulReloadValue;\r
+\r
+               /* Clear the SysTick count flag and set the count value back to\r
+               zero. */\r
+               portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
+\r
+               /* Restart SysTick. */\r
+               portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+\r
+               /* Sleep until something happens. configPRE_SLEEP_PROCESSING() can\r
+               set its parameter to 0 to indicate that its implementation contains\r
+               its own wait for interrupt or wait for event instruction, and so wfi\r
+               should not be executed again. However, the original expected idle\r
+               time variable must remain unmodified, so a copy is taken. */\r
+               xModifiableIdleTime = xExpectedIdleTime;\r
+               configPRE_SLEEP_PROCESSING( xModifiableIdleTime );\r
+               if( xModifiableIdleTime > 0 )\r
+               {\r
+                       __dsb( portSY_FULL_READ_WRITE );\r
+                       __wfi();\r
+                       __isb( portSY_FULL_READ_WRITE );\r
+               }\r
+               configPOST_SLEEP_PROCESSING( xExpectedIdleTime );\r
+\r
+               /* Re-enable interrupts to allow the interrupt that brought the MCU\r
+               out of sleep mode to execute immediately. see comments above\r
+               __disable_interrupt() call above. */\r
+               __enable_irq();\r
+               __dsb( portSY_FULL_READ_WRITE );\r
+               __isb( portSY_FULL_READ_WRITE );\r
+\r
+               /* Disable interrupts again because the clock is about to be stopped\r
+               and interrupts that execute while the clock is stopped will increase\r
+               any slippage between the time maintained by the RTOS and calendar\r
+               time. */\r
+               __disable_irq();\r
+               __dsb( portSY_FULL_READ_WRITE );\r
+               __isb( portSY_FULL_READ_WRITE );\r
+\r
+               /* Disable the SysTick clock without reading the\r
+               portNVIC_SYSTICK_CTRL_REG register to ensure the\r
+               portNVIC_SYSTICK_COUNT_FLAG_BIT is not cleared if it is set.  Again,\r
+               the time the SysTick is stopped for is accounted for as best it can\r
+               be, but using the tickless mode will inevitably result in some tiny\r
+               drift of the time maintained by the kernel with respect to calendar\r
+               time*/\r
+               portNVIC_SYSTICK_CTRL_REG = ( portNVIC_SYSTICK_CLK_BIT | portNVIC_SYSTICK_INT_BIT );\r
+\r
+               /* Determine if the SysTick clock has already counted to zero and\r
+               been set back to the current reload value (the reload back being\r
+               correct for the entire expected idle time) or if the SysTick is yet\r
+               to count to zero (in which case an interrupt other than the SysTick\r
+               must have brought the system out of sleep mode). */\r
+               if( ( portNVIC_SYSTICK_CTRL_REG & portNVIC_SYSTICK_COUNT_FLAG_BIT ) != 0 )\r
+               {\r
+                       uint32_t ulCalculatedLoadValue;\r
+\r
+                       /* The tick interrupt is already pending, and the SysTick count\r
+                       reloaded with ulReloadValue.  Reset the\r
+                       portNVIC_SYSTICK_LOAD with whatever remains of this tick\r
+                       period. */\r
+                       ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL ) - ( ulReloadValue - portNVIC_SYSTICK_CURRENT_VALUE_REG );\r
+\r
+                       /* Don't allow a tiny value, or values that have somehow\r
+                       underflowed because the post sleep hook did something\r
+                       that took too long. */\r
+                       if( ( ulCalculatedLoadValue < ulStoppedTimerCompensation ) || ( ulCalculatedLoadValue > ulTimerCountsForOneTick ) )\r
+                       {\r
+                               ulCalculatedLoadValue = ( ulTimerCountsForOneTick - 1UL );\r
+                       }\r
+\r
+                       portNVIC_SYSTICK_LOAD_REG = ulCalculatedLoadValue;\r
+\r
+                       /* As the pending tick will be processed as soon as this\r
+                       function exits, the tick value maintained by the tick is stepped\r
+                       forward by one less than the time spent waiting. */\r
+                       ulCompleteTickPeriods = xExpectedIdleTime - 1UL;\r
+               }\r
+               else\r
+               {\r
+                       /* Something other than the tick interrupt ended the sleep.\r
+                       Work out how long the sleep lasted rounded to complete tick\r
+                       periods (not the ulReload value which accounted for part\r
+                       ticks). */\r
+                       ulCompletedSysTickDecrements = ( xExpectedIdleTime * ulTimerCountsForOneTick ) - portNVIC_SYSTICK_CURRENT_VALUE_REG;\r
+\r
+                       /* How many complete tick periods passed while the processor\r
+                       was waiting? */\r
+                       ulCompleteTickPeriods = ulCompletedSysTickDecrements / ulTimerCountsForOneTick;\r
+\r
+                       /* The reload value is set to whatever fraction of a single tick\r
+                       period remains. */\r
+                       portNVIC_SYSTICK_LOAD_REG = ( ( ulCompleteTickPeriods + 1UL ) * ulTimerCountsForOneTick ) - ulCompletedSysTickDecrements;\r
+               }\r
+\r
+               /* Restart SysTick so it runs from portNVIC_SYSTICK_LOAD\r
+               again, then set portNVIC_SYSTICK_LOAD back to its standard\r
+               value. */\r
+               portNVIC_SYSTICK_CURRENT_VALUE_REG = 0UL;\r
+               portNVIC_SYSTICK_CTRL_REG |= portNVIC_SYSTICK_ENABLE_BIT;\r
+               vTaskStepTick( ulCompleteTickPeriods );\r
+               portNVIC_SYSTICK_LOAD_REG = ulTimerCountsForOneTick - 1UL;\r
+\r
+               /* Exit with interrpts enabled. */\r
+               __enable_irq();\r
+       }\r
+}\r
+\r
+#endif /* #if configUSE_TICKLESS_IDLE */\r
+\r
+/*-----------------------------------------------------------*/\r
index 44e7567d8eb2841d47bcafe74d5bc913d1b88cea..5f3b9f44edbd283570e22d18892bd633d1582f33 100644 (file)
@@ -100,6 +100,13 @@ extern void vClearInterruptMaskFromISR( uint32_t ulMask );
 \r
 /*-----------------------------------------------------------*/\r
 \r
+/* Tickless idle/low power functionality. */\r
+#ifndef portSUPPRESS_TICKS_AND_SLEEP\r
+       extern void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime );\r
+       #define portSUPPRESS_TICKS_AND_SLEEP( xExpectedIdleTime ) vPortSuppressTicksAndSleep( xExpectedIdleTime )\r
+#endif\r
+/*-----------------------------------------------------------*/\r
+\r
 /* Task function macros as described on the FreeRTOS.org WEB site. */\r
 #define portTASK_FUNCTION_PROTO( vFunction, pvParameters ) void vFunction( void *pvParameters )\r
 #define portTASK_FUNCTION( vFunction, pvParameters ) void vFunction( void *pvParameters )\r