/* * FreeRTOS Kernel V10.4.6 * 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 V2.6.0 + AVR port - Replaced the inb() and outb() functions with direct memory access. This allows the port to be built with the 20050414 build of WinAVR. */ #include #include #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 ) /* 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 ) /*-----------------------------------------------------------*/ /* 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; /*-----------------------------------------------------------*/ /* * Macro to save all the general purpose registers, the save the stack pointer * into the TCB. * * The first thing we do is save the flags then disable interrupts. This is to * guard our stack against having a context switch interrupt after we have already * pushed the registers onto the stack - causing the 32 registers to be on the * stack twice. * * r1 is set to zero as the compiler expects it to be thus, however some * of the math routines make use of R1. * * The interrupts will have been disabled during the call to portSAVE_CONTEXT() * so we need not worry about reading/writing to the stack pointer. */ #define portSAVE_CONTEXT() \ asm volatile ( "push r0 \n\t" \ "in r0, __SREG__ \n\t" \ "cli \n\t" \ "push r0 \n\t" \ "push r1 \n\t" \ "clr r1 \n\t" \ "push r2 \n\t" \ "push r3 \n\t" \ "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" \ "push r16 \n\t" \ "push r17 \n\t" \ "push r18 \n\t" \ "push r19 \n\t" \ "push r20 \n\t" \ "push r21 \n\t" \ "push r22 \n\t" \ "push r23 \n\t" \ "push r24 \n\t" \ "push r25 \n\t" \ "push r26 \n\t" \ "push r27 \n\t" \ "push r28 \n\t" \ "push r29 \n\t" \ "push r30 \n\t" \ "push r31 \n\t" \ "lds r26, pxCurrentTCB \n\t" \ "lds r27, pxCurrentTCB + 1 \n\t" \ "in r0, 0x3d \n\t" \ "st x+, r0 \n\t" \ "in r0, 0x3e \n\t" \ "st x+, r0 \n\t" \ ); /* * Opposite to portSAVE_CONTEXT(). Interrupts will have been disabled during * the context save so we can write to the stack pointer. */ #define portRESTORE_CONTEXT() \ asm volatile ( "lds r26, pxCurrentTCB \n\t" \ "lds r27, pxCurrentTCB + 1 \n\t" \ "ld r28, x+ \n\t" \ "out __SP_L__, r28 \n\t" \ "ld r29, x+ \n\t" \ "out __SP_H__, r29 \n\t" \ "pop r31 \n\t" \ "pop r30 \n\t" \ "pop r29 \n\t" \ "pop r28 \n\t" \ "pop r27 \n\t" \ "pop r26 \n\t" \ "pop r25 \n\t" \ "pop r24 \n\t" \ "pop r23 \n\t" \ "pop r22 \n\t" \ "pop r21 \n\t" \ "pop r20 \n\t" \ "pop r19 \n\t" \ "pop r18 \n\t" \ "pop r17 \n\t" \ "pop r16 \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" \ "pop r3 \n\t" \ "pop r2 \n\t" \ "pop r1 \n\t" \ "pop r0 \n\t" \ "out __SREG__, r0 \n\t" \ "pop r0 \n\t" \ ); /*-----------------------------------------------------------*/ /* * Perform hardware setup to enable ticks from timer 1, compare match A. */ static void prvSetupTimerInterrupt( void ); /*-----------------------------------------------------------*/ /* * See header file for description. */ StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters ) { uint16_t usAddress; /* 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--; /* Simulate how the stack would look after a call to vPortYield() generated by the compiler. */ /*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */ /* The start of the task code will be popped off the stack last, so place it on first. */ usAddress = ( uint16_t ) pxCode; *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); pxTopOfStack--; usAddress >>= 8; *pxTopOfStack = ( StackType_t ) ( usAddress & ( uint16_t ) 0x00ff ); pxTopOfStack--; /* 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--; /* Now the remaining registers. The compiler expects R1 to be 0. */ *pxTopOfStack = ( StackType_t ) 0x00; /* 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--; *pxTopOfStack = ( StackType_t ) 0x16; /* R16 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x17; /* R17 */ 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--; /* 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 ) 0x26; /* R26 X */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x27; /* R27 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x28; /* R28 Y */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x29; /* R29 */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x30; /* R30 Z */ pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0x031; /* R31 */ pxTopOfStack--; /*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. */ portRESTORE_CONTEXT(); /* Simulate a function call end as generated by the compiler. We will now jump to the start of the task the context of which we have just restored. */ asm volatile ( "ret" ); /* 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. */ } /*-----------------------------------------------------------*/ /* * Manual context switch. The first thing we do is save the registers so we * can use a naked attribute. */ void vPortYield( void ) __attribute__ ( ( naked ) ); void vPortYield( void ) { portSAVE_CONTEXT(); vTaskSwitchContext(); portRESTORE_CONTEXT(); asm volatile ( "ret" ); } /*-----------------------------------------------------------*/ /* * Context switch function used by the tick. This must be identical to * vPortYield() from the call to vTaskSwitchContext() onwards. The only * difference from vPortYield() is the tick count is incremented as the * call comes from the tick ISR. */ void vPortYieldFromTick( void ) __attribute__ ( ( naked ) ); void vPortYieldFromTick( void ) { portSAVE_CONTEXT(); if( xTaskIncrementTick() != pdFALSE ) { vTaskSwitchContext(); } portRESTORE_CONTEXT(); asm volatile ( "ret" ); } /*-----------------------------------------------------------*/ /* * 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. */ ucLowByte = TIMSK; ucLowByte |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE; TIMSK = ucLowByte; } /*-----------------------------------------------------------*/ #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. */ void TIMER1_COMPA_vect( void ) __attribute__ ( ( signal, naked ) ); void TIMER1_COMPA_vect( void ) { vPortYieldFromTick(); asm volatile ( "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(); */ void TIMER1_COMPA_vect( void ) __attribute__ ( ( signal ) ); void TIMER1_COMPA_vect( void ) { xTaskIncrementTick(); } #endif