| /* |
| * FreeRTOS Kernel <DEVELOPMENT BRANCH> |
| * 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 <stdlib.h> |
| #include <signal.h> |
| |
| /* 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 */ |
