| /* |
| * 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 V2.6.0 |
| * |
| + 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 <stdlib.h> |
| #include <avr/interrupt.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 ) |
| |
| /* 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 /* if configUSE_PREEMPTION == 1 */ |
