/* | |
* 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 | |
* | |
*/ | |
#include <stdlib.h> | |
#include "FreeRTOS.h" | |
#include "task.h" | |
/*----------------------------------------------------------- | |
* Implementation of functions defined in portable.h for the AVR/IAR port. | |
*----------------------------------------------------------*/ | |
/* Start tasks with interrupts enables. */ | |
#define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x80 ) | |
/* Hardware constants for timer 1. */ | |
#define portCLEAR_COUNTER_ON_MATCH ( ( uint8_t ) 0x08 ) | |
#define portPRESCALE_64 ( ( uint8_t ) 0x03 ) | |
#define portCLOCK_PRESCALER ( ( uint32_t ) 64 ) | |
#define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( uint8_t ) 0x10 ) | |
/* The number of bytes used on the hardware stack by the task start address. */ | |
#define portBYTES_USED_BY_RETURN_ADDRESS ( 2 ) | |
/*-----------------------------------------------------------*/ | |
/* Stores the critical section nesting. This must not be initialised to 0. | |
It will be initialised when a task starts. */ | |
#define portNO_CRITICAL_NESTING ( ( UBaseType_t ) 0 ) | |
UBaseType_t uxCriticalNesting = 0x50; | |
/* | |
* Perform hardware setup to enable ticks from timer 1, compare match A. | |
*/ | |
static void prvSetupTimerInterrupt( void ); | |
/* | |
* The IAR compiler does not have full support for inline assembler, so | |
* these are defined in the portmacro assembler file. | |
*/ | |
extern void vPortYieldFromTick( void ); | |
extern void vPortStart( void ); | |
/*-----------------------------------------------------------*/ | |
/* | |
* See header file for description. | |
*/ | |
StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters ) | |
{ | |
uint16_t usAddress; | |
StackType_t *pxTopOfHardwareStack; | |
/* Place a few bytes of known values on the bottom of the stack. | |
This is just useful for debugging. */ | |
*pxTopOfStack = 0x11; | |
pxTopOfStack--; | |
*pxTopOfStack = 0x22; | |
pxTopOfStack--; | |
*pxTopOfStack = 0x33; | |
pxTopOfStack--; | |
/* Remember where the top of the hardware stack is - this is required | |
below. */ | |
pxTopOfHardwareStack = pxTopOfStack; | |
/* Simulate how the stack would look after a call to vPortYield(). */ | |
/*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */ | |
/* The IAR compiler requires two stacks per task. First there is the | |
hardware call stack which uses the AVR stack pointer. Second there is the | |
software stack (local variables, parameter passing, etc.) which uses the | |
AVR Y register. | |
This function places both stacks within the memory block passed in as the | |
first parameter. The hardware stack is placed at the bottom of the memory | |
block. A gap is then left for the hardware stack to grow. Next the software | |
stack is placed. The amount of space between the software and hardware | |
stacks is defined by configCALL_STACK_SIZE. | |
The first part of the stack is the hardware stack. Place the start | |
address of the task on the hardware stack. */ | |
usAddress = ( uint16_t ) pxCode; | |
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
pxTopOfStack--; | |
usAddress >>= 8; | |
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
pxTopOfStack--; | |
/* Leave enough space for the hardware stack before starting the software | |
stack. The '- 2' is because we have already used two spaces for the | |
address of the start of the task. */ | |
pxTopOfStack -= ( configCALL_STACK_SIZE - 2 ); | |
/* Next simulate the stack as if after a call to portSAVE_CONTEXT(). | |
portSAVE_CONTEXT places the flags on the stack immediately after r0 | |
to ensure the interrupts get disabled as soon as possible, and so ensuring | |
the stack use is minimal should a context switch interrupt occur. */ | |
*pxTopOfStack = ( StackType_t ) 0x00; /* R0 */ | |
pxTopOfStack--; | |
*pxTopOfStack = portFLAGS_INT_ENABLED; | |
pxTopOfStack--; | |
/* Next place the address of the hardware stack. This is required so | |
the AVR stack pointer can be restored to point to the hardware stack. */ | |
pxTopOfHardwareStack -= portBYTES_USED_BY_RETURN_ADDRESS; | |
usAddress = ( uint16_t ) pxTopOfHardwareStack; | |
/* SPL */ | |
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
pxTopOfStack--; | |
/* SPH */ | |
usAddress >>= 8; | |
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
pxTopOfStack--; | |
/* Now the remaining registers. */ | |
*pxTopOfStack = ( StackType_t ) 0x01; /* R1 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x02; /* R2 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x03; /* R3 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x04; /* R4 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x05; /* R5 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x06; /* R6 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x07; /* R7 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x08; /* R8 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x09; /* R9 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x10; /* R10 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x11; /* R11 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x12; /* R12 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x13; /* R13 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x14; /* R14 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x15; /* R15 */ | |
pxTopOfStack--; | |
/* Place the parameter on the stack in the expected location. */ | |
usAddress = ( uint16_t ) pvParameters; | |
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
pxTopOfStack--; | |
usAddress >>= 8; | |
*pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x18; /* R18 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x19; /* R19 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x20; /* R20 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x21; /* R21 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x22; /* R22 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x23; /* R23 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x24; /* R24 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x25; /* R25 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x26; /* R26 X */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x27; /* R27 */ | |
pxTopOfStack--; | |
/* The Y register is not stored as it is used as the software stack and | |
gets saved into the task control block. */ | |
*pxTopOfStack = ( StackType_t ) 0x30; /* R30 Z */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( StackType_t ) 0x031; /* R31 */ | |
pxTopOfStack--; | |
*pxTopOfStack = portNO_CRITICAL_NESTING; /* Critical nesting is zero when the task starts. */ | |
/*lint +e950 +e611 +e923 */ | |
return pxTopOfStack; | |
} | |
/*-----------------------------------------------------------*/ | |
BaseType_t xPortStartScheduler( void ) | |
{ | |
/* Setup the hardware to generate the tick. */ | |
prvSetupTimerInterrupt(); | |
/* Restore the context of the first task that is going to run. | |
Normally we would just call portRESTORE_CONTEXT() here, but as the IAR | |
compiler does not fully support inline assembler we have to make a call.*/ | |
vPortStart(); | |
/* Should not get here! */ | |
return pdTRUE; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEndScheduler( void ) | |
{ | |
/* It is unlikely that the AVR port will get stopped. If required simply | |
disable the tick interrupt here. */ | |
} | |
/*-----------------------------------------------------------*/ | |
/* | |
* Setup timer 1 compare match A to generate a tick interrupt. | |
*/ | |
static void prvSetupTimerInterrupt( void ) | |
{ | |
uint32_t ulCompareMatch; | |
uint8_t ucHighByte, ucLowByte; | |
/* Using 16bit timer 1 to generate the tick. Correct fuses must be | |
selected for the configCPU_CLOCK_HZ clock. */ | |
ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ; | |
/* We only have 16 bits so have to scale to get our required tick rate. */ | |
ulCompareMatch /= portCLOCK_PRESCALER; | |
/* Adjust for correct value. */ | |
ulCompareMatch -= ( uint32_t ) 1; | |
/* Setup compare match value for compare match A. Interrupts are disabled | |
before this is called so we need not worry here. */ | |
ucLowByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff ); | |
ulCompareMatch >>= 8; | |
ucHighByte = ( uint8_t ) ( ulCompareMatch & ( uint32_t ) 0xff ); | |
OCR1AH = ucHighByte; | |
OCR1AL = ucLowByte; | |
/* Setup clock source and compare match behaviour. */ | |
ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64; | |
TCCR1B = ucLowByte; | |
/* Enable the interrupt - this is okay as interrupt are currently globally | |
disabled. */ | |
TIMSK |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE; | |
} | |
/*-----------------------------------------------------------*/ | |
#if configUSE_PREEMPTION == 1 | |
/* | |
* Tick ISR for preemptive scheduler. We can use a __task attribute as | |
* the context is saved at the start of vPortYieldFromTick(). The tick | |
* count is incremented after the context is saved. | |
*/ | |
__task void SIG_OUTPUT_COMPARE1A( void ) | |
{ | |
vPortYieldFromTick(); | |
asm( "reti" ); | |
} | |
#else | |
/* | |
* 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(); | |
* | |
* THE INTERRUPT VECTOR IS POPULATED IN portmacro.s90. DO NOT INSTALL | |
* IT HERE USING THE USUAL PRAGMA. | |
*/ | |
__interrupt void SIG_OUTPUT_COMPARE1A( void ) | |
{ | |
xTaskIncrementTick(); | |
} | |
#endif | |
/*-----------------------------------------------------------*/ | |
void vPortEnterCritical( void ) | |
{ | |
portDISABLE_INTERRUPTS(); | |
uxCriticalNesting++; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortExitCritical( void ) | |
{ | |
uxCriticalNesting--; | |
if( uxCriticalNesting == portNO_CRITICAL_NESTING ) | |
{ | |
portENABLE_INTERRUPTS(); | |
} | |
} | |