/* * FreeRTOS Kernel * Copyright (C) 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved. * * SPDX-License-Identifier: MIT * * Permission is hereby granted, free of charge, to any person obtaining a copy of * this software and associated documentation files (the "Software"), to deal in * the Software without restriction, including without limitation the rights to * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of * the Software, and to permit persons to whom the Software is furnished to do so, * subject to the following conditions: * * The above copyright notice and this permission notice shall be included in all * copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * * https://www.FreeRTOS.org * https://github.com/FreeRTOS * */ /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the RX100 port. *----------------------------------------------------------*/ /* Standard C includes. */ #include "limits.h" /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" /* Library includes. */ #include "string.h" /* Hardware specifics. */ #include "iodefine.h" /*-----------------------------------------------------------*/ /* Tasks should start with interrupts enabled and in Supervisor mode, therefore * PSW is set with U and I set, and PM and IPL clear. */ #define portINITIAL_PSW ( ( StackType_t ) 0x00030000 ) /* The peripheral clock is divided by this value before being supplying the * CMT. */ #if ( configUSE_TICKLESS_IDLE == 0 ) /* If tickless idle is not used then the divisor can be fixed. */ #define portCLOCK_DIVISOR 8UL #elif ( configPERIPHERAL_CLOCK_HZ >= 12000000 ) #define portCLOCK_DIVISOR 512UL #elif ( configPERIPHERAL_CLOCK_HZ >= 6000000 ) #define portCLOCK_DIVISOR 128UL #elif ( configPERIPHERAL_CLOCK_HZ >= 1000000 ) #define portCLOCK_DIVISOR 32UL #else #define portCLOCK_DIVISOR 8UL #endif /* Keys required to lock and unlock access to certain system registers * respectively. */ #define portUNLOCK_KEY 0xA50B #define portLOCK_KEY 0xA500 /*-----------------------------------------------------------*/ /* The following lines are to ensure vSoftwareInterruptEntry can be referenced, * and therefore installed in the vector table, when the FreeRTOS code is built * as a library. */ extern BaseType_t vSoftwareInterruptEntry; const BaseType_t * p_vSoftwareInterruptEntry = &vSoftwareInterruptEntry; /*-----------------------------------------------------------*/ /* * Function to start the first task executing - written in asm code as direct * access to registers is required. */ static void prvStartFirstTask( void ); /* * Software interrupt handler. Performs the actual context switch (saving and * restoring of registers). Written in asm code as direct register access is * required. */ static void prvYieldHandler( void ); /* * The entry point for the software interrupt handler. This is the function * that calls the inline asm function prvYieldHandler(). It is installed in * the vector table, but the code that installs it is in prvYieldHandler rather * than using a #pragma. */ void vSoftwareInterruptISR( void ); /* * Sets up the periodic ISR used for the RTOS tick using the CMT. * The application writer can define configSETUP_TICK_INTERRUPT() (in * FreeRTOSConfig.h) such that their own tick interrupt configuration is used * in place of prvSetupTimerInterrupt(). */ static void prvSetupTimerInterrupt( void ); #ifndef configSETUP_TICK_INTERRUPT /* The user has not provided their own tick interrupt configuration so use * the definition in this file (which uses the interval timer). */ #define configSETUP_TICK_INTERRUPT() prvSetupTimerInterrupt() #endif /* configSETUP_TICK_INTERRUPT */ /* * Called after the sleep mode registers have been configured, prvSleep() * executes the pre and post sleep macros, and actually calls the wait * instruction. */ #if configUSE_TICKLESS_IDLE == 1 static void prvSleep( TickType_t xExpectedIdleTime ); #endif /* configUSE_TICKLESS_IDLE */ /*-----------------------------------------------------------*/ /* These is accessed by the inline assembler functions. */ extern void * pxCurrentTCB; extern void vTaskSwitchContext( void ); /*-----------------------------------------------------------*/ /* Calculate how many clock increments make up a single tick period. */ static const uint32_t ulMatchValueForOneTick = ( ( configPERIPHERAL_CLOCK_HZ / portCLOCK_DIVISOR ) / configTICK_RATE_HZ ); #if configUSE_TICKLESS_IDLE == 1 /* Holds the maximum number of ticks that can be suppressed - which is * basically how far into the future an interrupt can be generated. Set * during initialisation. This is the maximum possible value that the * compare match register can hold divided by ulMatchValueForOneTick. */ static const TickType_t xMaximumPossibleSuppressedTicks = USHRT_MAX / ( ( configPERIPHERAL_CLOCK_HZ / portCLOCK_DIVISOR ) / configTICK_RATE_HZ ); /* Flag set from the tick interrupt to allow the sleep processing to know if * sleep mode was exited because of a tick interrupt, or an interrupt * generated by something else. */ static volatile uint32_t ulTickFlag = pdFALSE; /* The CMT counter is stopped temporarily each time it is re-programmed. * The following constant offsets the CMT counter match value by the number of * CMT counts that would typically be missed while the counter was stopped to * compensate for the lost time. The large difference between the divided CMT * clock and the CPU clock means it is likely ulStoppedTimerCompensation will * equal zero - and be optimised away. */ static const uint32_t ulStoppedTimerCompensation = 100UL / ( configCPU_CLOCK_HZ / ( configPERIPHERAL_CLOCK_HZ / portCLOCK_DIVISOR ) ); #endif /* if configUSE_TICKLESS_IDLE == 1 */ /*-----------------------------------------------------------*/ /* * See header file for description. */ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack, TaskFunction_t pxCode, void * pvParameters ) { /* Offset to end up on 8 byte boundary. */ pxTopOfStack--; /* R0 is not included as it is the stack pointer. */ *pxTopOfStack = 0x00; pxTopOfStack--; *pxTopOfStack = 0x00; pxTopOfStack--; *pxTopOfStack = portINITIAL_PSW; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) pxCode; /* When debugging it can be useful if every register is set to a known * value. Otherwise code space can be saved by just setting the registers * that need to be set. */ #ifdef USE_FULL_REGISTER_INITIALISATION { pxTopOfStack--; *pxTopOfStack = 0x12345678; /* r15. */ pxTopOfStack--; *pxTopOfStack = 0xaaaabbbb; pxTopOfStack--; *pxTopOfStack = 0xdddddddd; pxTopOfStack--; *pxTopOfStack = 0xcccccccc; pxTopOfStack--; *pxTopOfStack = 0xbbbbbbbb; pxTopOfStack--; *pxTopOfStack = 0xaaaaaaaa; pxTopOfStack--; *pxTopOfStack = 0x99999999; pxTopOfStack--; *pxTopOfStack = 0x88888888; pxTopOfStack--; *pxTopOfStack = 0x77777777; pxTopOfStack--; *pxTopOfStack = 0x66666666; pxTopOfStack--; *pxTopOfStack = 0x55555555; pxTopOfStack--; *pxTopOfStack = 0x44444444; pxTopOfStack--; *pxTopOfStack = 0x33333333; pxTopOfStack--; *pxTopOfStack = 0x22222222; pxTopOfStack--; } #else /* ifdef USE_FULL_REGISTER_INITIALISATION */ { /* Leave space for the registers that will get popped from the stack * when the task first starts executing. */ pxTopOfStack -= 15; } #endif /* ifdef USE_FULL_REGISTER_INITIALISATION */ *pxTopOfStack = ( StackType_t ) pvParameters; /* R1 */ pxTopOfStack--; *pxTopOfStack = 0x12345678; /* Accumulator. */ pxTopOfStack--; *pxTopOfStack = 0x87654321; /* Accumulator. */ return pxTopOfStack; } /*-----------------------------------------------------------*/ BaseType_t xPortStartScheduler( void ) { /* Use pxCurrentTCB just so it does not get optimised away. */ if( pxCurrentTCB != NULL ) { /* Call an application function to set up the timer that will generate * the tick interrupt. This way the application can decide which * peripheral to use. If tickless mode is used then the default * implementation defined in this file (which uses CMT0) should not be * overridden. */ configSETUP_TICK_INTERRUPT(); /* Enable the software interrupt. */ _IEN( _ICU_SWINT ) = 1; /* Ensure the software interrupt is clear. */ _IR( _ICU_SWINT ) = 0; /* Ensure the software interrupt is set to the kernel priority. */ _IPR( _ICU_SWINT ) = configKERNEL_INTERRUPT_PRIORITY; /* Start the first task. */ prvStartFirstTask(); } /* Execution should not reach here as the tasks are now running! * prvSetupTimerInterrupt() is called here to prevent the compiler outputting * a warning about a statically declared function not being referenced in the * case that the application writer has provided their own tick interrupt * configuration routine (and defined configSETUP_TICK_INTERRUPT() such that * their own routine will be called in place of prvSetupTimerInterrupt()). */ prvSetupTimerInterrupt(); /* Just to make sure the function is not optimised away. */ ( void ) vSoftwareInterruptISR(); /* Should not get here. */ return pdFAIL; } /*-----------------------------------------------------------*/ #pragma inline_asm prvStartFirstTask static void prvStartFirstTask( void ) { /* When starting the scheduler there is nothing that needs moving to the * interrupt stack because the function is not called from an interrupt. * Just ensure the current stack is the user stack. */ SETPSW U /* Obtain the location of the stack associated with which ever task * pxCurrentTCB is currently pointing to. */ MOV.L # _pxCurrentTCB, R15 MOV.L[ R15 ], R15 MOV.L[ R15 ], R0 /* Restore the registers from the stack of the task pointed to by * pxCurrentTCB. */ POP R15 MVTACLO R15 /* Accumulator low 32 bits. */ POP R15 MVTACHI R15 /* Accumulator high 32 bits. */ POPM R1 - R15 /* R1 to R15 - R0 is not included as it is the SP. */ RTE /* This pops the remaining registers. */ NOP NOP } /*-----------------------------------------------------------*/ #pragma interrupt ( prvTickISR( vect = _VECT( configTICK_VECTOR ), enable ) ) void prvTickISR( void ) { /* Increment the tick, and perform any processing the new tick value * necessitates. */ set_ipl( configMAX_SYSCALL_INTERRUPT_PRIORITY ); { if( xTaskIncrementTick() != pdFALSE ) { taskYIELD(); } } set_ipl( configKERNEL_INTERRUPT_PRIORITY ); #if configUSE_TICKLESS_IDLE == 1 { /* The CPU woke because of a tick. */ ulTickFlag = pdTRUE; /* If this is the first tick since exiting tickless mode then the CMT * compare match value needs resetting. */ CMT0.CMCOR = ( uint16_t ) ulMatchValueForOneTick; } #endif } /*-----------------------------------------------------------*/ void vSoftwareInterruptISR( void ) { prvYieldHandler(); } /*-----------------------------------------------------------*/ #pragma inline_asm prvYieldHandler static void prvYieldHandler( void ) { /* Re-enable interrupts. */ SETPSW I /* Move the data that was automatically pushed onto the interrupt stack * when the interrupt occurred from the interrupt stack to the user stack. * * R15 is saved before it is clobbered. */ PUSH.L R15 /* Read the user stack pointer. */ MVFC USP, R15 /* Move the address down to the data being moved. */ SUB # 12, R15 MVTC R15, USP /* Copy the data across. */ MOV.L[ R0 ], [ R15 ]; R15 MOV.L 4[ R0 ], 4[ R15 ]; PC MOV.L 8[ R0 ], 8[ R15 ]; PSW /* Move the interrupt stack pointer to its new correct position. */ ADD # 12, R0 /* All the rest of the registers are saved directly to the user stack. */ SETPSW U /* Save the rest of the general registers (R15 has been saved already). */ PUSHM R1 - R14 /* Save the accumulator. */ MVFACHI R15 PUSH.L R15 MVFACMI R15; Middle order word. SHLL # 16, R15; Shifted left as it is restored to the low order word. PUSH.L R15 /* Save the stack pointer to the TCB. */ MOV.L # _pxCurrentTCB, R15 MOV.L[ R15 ], R15 MOV.L R0, [ R15 ] /* Ensure the interrupt mask is set to the syscall priority while the * kernel structures are being accessed. */ MVTIPL # configMAX_SYSCALL_INTERRUPT_PRIORITY /* Select the next task to run. */ BSR.A _vTaskSwitchContext /* Reset the interrupt mask as no more data structure access is * required. */ MVTIPL # configKERNEL_INTERRUPT_PRIORITY /* Load the stack pointer of the task that is now selected as the Running * state task from its TCB. */ MOV.L # _pxCurrentTCB, R15 MOV.L[ R15 ], R15 MOV.L[ R15 ], R0 /* Restore the context of the new task. The PSW (Program Status Word) and * PC will be popped by the RTE instruction. */ POP R15 MVTACLO R15 POP R15 MVTACHI R15 POPM R1 - R15 RTE NOP NOP } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* Not implemented in ports where there is nothing to return to. * Artificially force an assert. */ configASSERT( pxCurrentTCB == NULL ); /* The following line is just to prevent the symbol getting optimised away. */ ( void ) vTaskSwitchContext(); } /*-----------------------------------------------------------*/ static void prvSetupTimerInterrupt( void ) { /* Unlock. */ SYSTEM.PRCR.WORD = portUNLOCK_KEY; /* Enable CMT0. */ MSTP( CMT0 ) = 0; /* Lock again. */ SYSTEM.PRCR.WORD = portLOCK_KEY; /* Interrupt on compare match. */ CMT0.CMCR.BIT.CMIE = 1; /* Set the compare match value. */ CMT0.CMCOR = ( uint16_t ) ulMatchValueForOneTick; /* Divide the PCLK. */ #if portCLOCK_DIVISOR == 512 { CMT0.CMCR.BIT.CKS = 3; } #elif portCLOCK_DIVISOR == 128 { CMT0.CMCR.BIT.CKS = 2; } #elif portCLOCK_DIVISOR == 32 { CMT0.CMCR.BIT.CKS = 1; } #elif portCLOCK_DIVISOR == 8 { CMT0.CMCR.BIT.CKS = 0; } #else /* if portCLOCK_DIVISOR == 512 */ { #error Invalid portCLOCK_DIVISOR setting } #endif /* if portCLOCK_DIVISOR == 512 */ /* Enable the interrupt... */ _IEN( _CMT0_CMI0 ) = 1; /* ...and set its priority to the application defined kernel priority. */ _IPR( _CMT0_CMI0 ) = configKERNEL_INTERRUPT_PRIORITY; /* Start the timer. */ CMT.CMSTR0.BIT.STR0 = 1; } /*-----------------------------------------------------------*/ #if configUSE_TICKLESS_IDLE == 1 static void prvSleep( TickType_t xExpectedIdleTime ) { /* Allow the application to define some pre-sleep processing. */ configPRE_SLEEP_PROCESSING( xExpectedIdleTime ); /* xExpectedIdleTime being set to 0 by configPRE_SLEEP_PROCESSING() * means the application defined code has already executed the WAIT * instruction. */ if( xExpectedIdleTime > 0 ) { wait(); } /* Allow the application to define some post sleep processing. */ configPOST_SLEEP_PROCESSING( xExpectedIdleTime ); } #endif /* configUSE_TICKLESS_IDLE */ /*-----------------------------------------------------------*/ #if configUSE_TICKLESS_IDLE == 1 void vPortSuppressTicksAndSleep( TickType_t xExpectedIdleTime ) { uint32_t ulMatchValue, ulCompleteTickPeriods, ulCurrentCount; eSleepModeStatus eSleepAction; /* THIS FUNCTION IS CALLED WITH THE SCHEDULER SUSPENDED. */ /* Make sure the CMT reload value does not overflow the counter. */ if( xExpectedIdleTime > xMaximumPossibleSuppressedTicks ) { xExpectedIdleTime = xMaximumPossibleSuppressedTicks; } /* Calculate the reload value required to wait xExpectedIdleTime tick * periods. */ ulMatchValue = ulMatchValueForOneTick * xExpectedIdleTime; if( ulMatchValue > ulStoppedTimerCompensation ) { /* Compensate for the fact that the CMT is going to be stopped * momentarily. */ ulMatchValue -= ulStoppedTimerCompensation; } /* Stop the CMT momentarily. The time the CMT 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. */ CMT.CMSTR0.BIT.STR0 = 0; while( CMT.CMSTR0.BIT.STR0 == 1 ) { /* Nothing to do here. */ } /* Critical section using the global interrupt bit as the i bit is * automatically reset by the WAIT instruction. */ clrpsw_i(); /* The tick flag is set to false before sleeping. If it is true when * sleep mode is exited then sleep mode was probably exited because the * tick was suppressed for the entire xExpectedIdleTime period. */ ulTickFlag = pdFALSE; /* If a context switch is pending then abandon the low power entry as * the context switch might have been pended by an external interrupt that * requires processing. */ eSleepAction = eTaskConfirmSleepModeStatus(); if( eSleepAction == eAbortSleep ) { /* Restart tick. */ CMT.CMSTR0.BIT.STR0 = 1; setpsw_i(); } else if( eSleepAction == eNoTasksWaitingTimeout ) { /* Protection off. */ SYSTEM.PRCR.WORD = portUNLOCK_KEY; /* Ready for software standby with all clocks stopped. */ SYSTEM.SBYCR.BIT.SSBY = 1; /* Protection on. */ SYSTEM.PRCR.WORD = portLOCK_KEY; /* Sleep until something happens. Calling prvSleep() will * automatically reset the i bit in the PSW. */ prvSleep( xExpectedIdleTime ); /* Restart the CMT. */ CMT.CMSTR0.BIT.STR0 = 1; } else { /* Protection off. */ SYSTEM.PRCR.WORD = portUNLOCK_KEY; /* Ready for deep sleep mode. */ SYSTEM.MSTPCRC.BIT.DSLPE = 1; SYSTEM.MSTPCRA.BIT.MSTPA28 = 1; SYSTEM.SBYCR.BIT.SSBY = 0; /* Protection on. */ SYSTEM.PRCR.WORD = portLOCK_KEY; /* Adjust the match value to take into account that the current * time slice is already partially complete. */ ulMatchValue -= ( uint32_t ) CMT0.CMCNT; CMT0.CMCOR = ( uint16_t ) ulMatchValue; /* Restart the CMT to count up to the new match value. */ CMT0.CMCNT = 0; CMT.CMSTR0.BIT.STR0 = 1; /* Sleep until something happens. Calling prvSleep() will * automatically reset the i bit in the PSW. */ prvSleep( xExpectedIdleTime ); /* Stop CMT. 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. */ CMT.CMSTR0.BIT.STR0 = 0; while( CMT.CMSTR0.BIT.STR0 == 1 ) { /* Nothing to do here. */ } ulCurrentCount = ( uint32_t ) CMT0.CMCNT; if( ulTickFlag != pdFALSE ) { /* The tick interrupt has already executed, although because * this function is called with the scheduler suspended the actual * tick processing will not occur until after this function has * exited. Reset the match value with whatever remains of this * tick period. */ ulMatchValue = ulMatchValueForOneTick - ulCurrentCount; CMT0.CMCOR = ( uint16_t ) ulMatchValue; /* The tick interrupt handler will already have pended the tick * processing in the kernel. 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 sleeping. The actual stepping of the tick appears * later in this function. */ ulCompleteTickPeriods = xExpectedIdleTime - 1UL; } else { /* Something other than the tick interrupt ended the sleep. * How many complete tick periods passed while the processor was * sleeping? */ ulCompleteTickPeriods = ulCurrentCount / ulMatchValueForOneTick; /* The match value is set to whatever fraction of a single tick * period remains. */ ulMatchValue = ulCurrentCount - ( ulCompleteTickPeriods * ulMatchValueForOneTick ); CMT0.CMCOR = ( uint16_t ) ulMatchValue; } /* Restart the CMT so it runs up to the match value. The match value * will get set to the value required to generate exactly one tick period * the next time the CMT interrupt executes. */ CMT0.CMCNT = 0; CMT.CMSTR0.BIT.STR0 = 1; /* Wind the tick forward by the number of tick periods that the CPU * remained in a low power state. */ vTaskStepTick( ulCompleteTickPeriods ); } } #endif /* configUSE_TICKLESS_IDLE */