/* * 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 * */ #include #include "porthardware.h" #include "FreeRTOS.h" #include "task.h" /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the AVR port. *----------------------------------------------------------*/ /* Start tasks with interrupts enables. */ #define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x80 ) /*-----------------------------------------------------------*/ #define portBYTES_USED_BY_RETURN_ADDRESS 2 #define portNO_CRITICAL_NESTING ( ( UBaseType_t ) 0 ) /* Stores the critical section nesting. This must not be initialised to 0. * It will be initialised when a task starts. */ UBaseType_t uxCriticalNesting = 0x50; /* * Setup timer to generate a tick interrupt. */ 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; /* 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. */ /* 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; 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--; *pxTopOfStack = ( StackType_t ) 0x00; /* RAMPZ */ 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 ) { /* vPortEndScheduler is not implemented in this port. */ } /*-----------------------------------------------------------*/ /* * Setup timer to generate a tick interrupt. */ static void prvSetupTimerInterrupt( void ) { TICK_init(); } /*-----------------------------------------------------------*/ #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. */ __task void TICK_INT( 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(); */ __interrupt void TICK_INT( void ) { /* Clear tick interrupt flag. */ INT_FLAGS = INT_MASK; xTaskIncrementTick(); } #endif /* if configUSE_PREEMPTION == 1 */ /*-----------------------------------------------------------*/ void vPortEnterCritical( void ) { portDISABLE_INTERRUPTS(); uxCriticalNesting++; } /*-----------------------------------------------------------*/ void vPortExitCritical( void ) { uxCriticalNesting--; if( uxCriticalNesting == portNO_CRITICAL_NESTING ) { portENABLE_INTERRUPTS(); } }