/* * FreeRTOS Kernel V11.1.0 * 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 * */ /* * Changes from V2.5.2 * + usCriticalNesting now has a volatile qualifier. */ /* Standard includes. */ #include #include /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the MSP430 port. *----------------------------------------------------------*/ /* Constants required for hardware setup. The tick ISR runs off the ACLK, * not the MCLK. */ #define portACLK_FREQUENCY_HZ ( ( TickType_t ) 32768 ) #define portINITIAL_CRITICAL_NESTING ( ( uint16_t ) 10 ) #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x08 ) /* We require the address of the pxCurrentTCB variable, but don't want to know * any details of its type. */ typedef void TCB_t; extern volatile TCB_t * volatile pxCurrentTCB; /* Most ports implement critical sections by placing the interrupt flags on * the stack before disabling interrupts. Exiting the critical section is then * simply a case of popping the flags from the stack. As mspgcc does not use * a frame pointer this cannot be done as modifying the stack will clobber all * the stack variables. Instead each task maintains a count of the critical * section nesting depth. Each time a critical section is entered the count is * incremented. Each time a critical section is left the count is decremented - * with interrupts only being re-enabled if the count is zero. * * usCriticalNesting will get set to zero when the scheduler starts, but must * not be initialised to zero as this will cause problems during the startup * sequence. */ volatile uint16_t usCriticalNesting = portINITIAL_CRITICAL_NESTING; /*-----------------------------------------------------------*/ /* * Macro to save a task context to the task stack. This simply pushes all the * general purpose msp430 registers onto the stack, followed by the * usCriticalNesting value used by the task. Finally the resultant stack * pointer value is saved into the task control block so it can be retrieved * the next time the task executes. */ #define portSAVE_CONTEXT() \ asm volatile ( "push r4 \n\t" \ "push r5 \n\t" \ "push r6 \n\t" \ "push r7 \n\t" \ "push r8 \n\t" \ "push r9 \n\t" \ "push r10 \n\t" \ "push r11 \n\t" \ "push r12 \n\t" \ "push r13 \n\t" \ "push r14 \n\t" \ "push r15 \n\t" \ "mov.w usCriticalNesting, r14 \n\t" \ "push r14 \n\t" \ "mov.w pxCurrentTCB, r12 \n\t" \ "mov.w r1, @r12 \n\t" \ ); /* * Macro to restore a task context from the task stack. This is effectively * the reverse of portSAVE_CONTEXT(). First the stack pointer value is * loaded from the task control block. Next the value for usCriticalNesting * used by the task is retrieved from the stack - followed by the value of all * the general purpose msp430 registers. * * The bic instruction ensures there are no low power bits set in the status * register that is about to be popped from the stack. */ #define portRESTORE_CONTEXT() \ asm volatile ( "mov.w pxCurrentTCB, r12 \n\t" \ "mov.w @r12, r1 \n\t" \ "pop r15 \n\t" \ "mov.w r15, usCriticalNesting \n\t" \ "pop r15 \n\t" \ "pop r14 \n\t" \ "pop r13 \n\t" \ "pop r12 \n\t" \ "pop r11 \n\t" \ "pop r10 \n\t" \ "pop r9 \n\t" \ "pop r8 \n\t" \ "pop r7 \n\t" \ "pop r6 \n\t" \ "pop r5 \n\t" \ "pop r4 \n\t" \ "bic #(0xf0),0(r1) \n\t" \ "reti \n\t" \ ); /*-----------------------------------------------------------*/ /* * Sets up the periodic ISR used for the RTOS tick. This uses timer 0, but * could have alternatively used the watchdog timer or timer 1. */ static void prvSetupTimerInterrupt( void ); /*-----------------------------------------------------------*/ /* * Initialise the stack of a task to look exactly as if a call to * portSAVE_CONTEXT had been called. * * See the header file portable.h. */ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack, TaskFunction_t pxCode, void * pvParameters ) { /* * Place a few bytes of known values on the bottom of the stack. * This is just useful for debugging and can be included if required. * * pxTopOfStack = ( StackType_t ) 0x1111; * pxTopOfStack--; * pxTopOfStack = ( StackType_t ) 0x2222; * pxTopOfStack--; * pxTopOfStack = ( StackType_t ) 0x3333; * pxTopOfStack--; */ /* The msp430 automatically pushes the PC then SR onto the stack before * executing an ISR. We want the stack to look just as if this has happened * so place a pointer to the start of the task on the stack first - followed * by the flags we want the task to use when it starts up. */ *pxTopOfStack = ( StackType_t ) pxCode; pxTopOfStack--; *pxTopOfStack = portFLAGS_INT_ENABLED; pxTopOfStack--; /* Next the general purpose registers. */ *pxTopOfStack = ( StackType_t ) 0x4444; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x5555; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x6666; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x7777; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x8888; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x9999; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0xaaaa; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0xbbbb; pxTopOfStack--; #ifdef __MSPGCC__ *pxTopOfStack = ( StackType_t ) 0xcccc; #else /* The MSP430 EABI expects the function parameter in R12. */ *pxTopOfStack = ( StackType_t ) pvParameters; #endif pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0xdddd; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0xeeee; pxTopOfStack--; #ifdef __MSPGCC__ /* The mspgcc ABI expects the function parameter in R15. */ *pxTopOfStack = ( StackType_t ) pvParameters; #else *pxTopOfStack = ( StackType_t ) 0xffff; #endif pxTopOfStack--; /* The code generated by the mspgcc compiler does not maintain separate * stack and frame pointers. The portENTER_CRITICAL macro cannot therefore * use the stack as per other ports. Instead a variable is used to keep * track of the critical section nesting. This variable has to be stored * as part of the task context and is initially set to zero. */ *pxTopOfStack = ( StackType_t ) portNO_CRITICAL_SECTION_NESTING; /* Return a pointer to the top of the stack we have generated so this can * be stored in the task control block for the task. */ return pxTopOfStack; } /*-----------------------------------------------------------*/ BaseType_t xPortStartScheduler( void ) { /* Setup the hardware to generate the tick. Interrupts are disabled when * this function is called. */ prvSetupTimerInterrupt(); /* Restore the context of the first task that is going to run. */ portRESTORE_CONTEXT(); /* Should not get here as the tasks are now running! */ return pdTRUE; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* It is unlikely that the MSP430 port will get stopped. If required simply * disable the tick interrupt here. */ } /*-----------------------------------------------------------*/ /* * Manual context switch called by portYIELD or taskYIELD. * * The first thing we do is save the registers so we can use a naked attribute. */ void vPortYield( void ) __attribute__( ( naked ) ); void vPortYield( void ) { /* We want the stack of the task being saved to look exactly as if the task * was saved during a pre-emptive RTOS tick ISR. Before calling an ISR the * msp430 places the status register onto the stack. As this is a function * call and not an ISR we have to do this manually. */ asm volatile ( "push r2" ); _DINT(); /* Save the context of the current task. */ portSAVE_CONTEXT(); /* Switch to the highest priority task that is ready to run. */ vTaskSwitchContext(); /* Restore the context of the new task. */ portRESTORE_CONTEXT(); } /*-----------------------------------------------------------*/ /* * Hardware initialisation to generate the RTOS tick. This uses timer 0 * but could alternatively use the watchdog timer or timer 1. */ static void prvSetupTimerInterrupt( void ) { /* Ensure the timer is stopped. */ TACTL = 0; /* Run the timer of the ACLK. */ TACTL = TASSEL_1; /* Clear everything to start with. */ TACTL |= TACLR; /* Set the compare match value according to the tick rate we want. */ TACCR0 = portACLK_FREQUENCY_HZ / configTICK_RATE_HZ; /* Enable the interrupts. */ TACCTL0 = CCIE; /* Start up clean. */ TACTL |= TACLR; /* Up mode. */ TACTL |= MC_1; } /*-----------------------------------------------------------*/ /* * The interrupt service routine used depends on whether the pre-emptive * scheduler is being used or not. */ #if configUSE_PREEMPTION == 1 /* * Tick ISR for preemptive scheduler. We can use a naked attribute as * the context is saved at the start of vPortYieldFromTick(). The tick * count is incremented after the context is saved. */ interrupt( TIMERA0_VECTOR ) void prvTickISR( void ) __attribute__( ( naked ) ); interrupt( TIMERA0_VECTOR ) void prvTickISR( void ) { /* Save the context of the interrupted task. */ portSAVE_CONTEXT(); /* Increment the tick count then switch to the highest priority task * that is ready to run. */ if( xTaskIncrementTick() != pdFALSE ) { vTaskSwitchContext(); } /* Restore the context of the new task. */ portRESTORE_CONTEXT(); } #else /* if configUSE_PREEMPTION == 1 */ /* * Tick ISR for the cooperative scheduler. All this does is increment the * tick count. We don't need to switch context, this can only be done by * manual calls to taskYIELD(); */ interrupt( TIMERA0_VECTOR ) void prvTickISR( void ); interrupt( TIMERA0_VECTOR ) void prvTickISR( void ) { xTaskIncrementTick(); } #endif /* if configUSE_PREEMPTION == 1 */