mirror of
https://github.com/FreeRTOS/FreeRTOS-Kernel.git
synced 2025-11-04 11:09:01 +01:00
336 lines
13 KiB
C
336 lines
13 KiB
C
/*
|
|
* 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 */
|