/* * 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 * */ /* Scheduler includes. */ #include "FreeRTOS.h" #include "task.h" /*----------------------------------------------------------- * Implementation of functions defined in portable.h for the HCS12 port. *----------------------------------------------------------*/ /* * Configure a timer to generate the RTOS tick at the frequency specified * within FreeRTOSConfig.h. */ static void prvSetupTimerInterrupt( void ); /* Interrupt service routines have to be in non-banked memory - as does the * scheduler startup function. */ #pragma CODE_SEG __NEAR_SEG NON_BANKED /* Manual context switch function. This is the SWI ISR. */ void interrupt vPortYield( void ); /* Tick context switch function. This is the timer ISR. */ void interrupt vPortTickInterrupt( void ); /* Simply called by xPortStartScheduler(). xPortStartScheduler() does not * start the scheduler directly because the header file containing the * xPortStartScheduler() prototype is part of the common kernel code, and * therefore cannot use the CODE_SEG pragma. */ static BaseType_t xBankedStartScheduler( void ); #pragma CODE_SEG DEFAULT /* Calls to portENTER_CRITICAL() can be nested. When they are nested the * critical section should not be left (i.e. interrupts should not be re-enabled) * until the nesting depth reaches 0. This variable simply tracks the nesting * depth. Each task maintains it's own critical nesting depth variable so * uxCriticalNesting is saved and restored from the task stack during a context * switch. */ volatile UBaseType_t uxCriticalNesting = 0xff; /*-----------------------------------------------------------*/ /* * See header file for description. */ 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 can be uncommented to provide useful stack markers when debugging. * * pxTopOfStack = ( StackType_t ) 0x11; * pxTopOfStack--; * pxTopOfStack = ( StackType_t ) 0x22; * pxTopOfStack--; * pxTopOfStack = ( StackType_t ) 0x33; * pxTopOfStack--; */ /* Setup the initial stack of the task. The stack is set exactly as * expected by the portRESTORE_CONTEXT() macro. In this case the stack as * expected by the HCS12 RTI instruction. */ /* The address of the task function is placed in the stack byte at a time. */ *pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pxCode ) ) + 1 ); pxTopOfStack--; *pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pxCode ) ) + 0 ); pxTopOfStack--; /* Next are all the registers that form part of the task context. */ /* Y register */ *pxTopOfStack = ( StackType_t ) 0xff; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0xee; pxTopOfStack--; /* X register */ *pxTopOfStack = ( StackType_t ) 0xdd; pxTopOfStack--; *pxTopOfStack = ( StackType_t ) 0xcc; pxTopOfStack--; /* A register contains parameter high byte. */ *pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pvParameters ) ) + 0 ); pxTopOfStack--; /* B register contains parameter low byte. */ *pxTopOfStack = ( StackType_t ) *( ( ( StackType_t * ) ( &pvParameters ) ) + 1 ); pxTopOfStack--; /* CCR: Note that when the task starts interrupts will be enabled since * "I" bit of CCR is cleared */ *pxTopOfStack = ( StackType_t ) 0x00; pxTopOfStack--; #ifdef BANKED_MODEL /* The page of the task. */ *pxTopOfStack = ( StackType_t ) ( ( int ) pxCode ); pxTopOfStack--; #endif /* Finally the critical nesting depth is initialised with 0 (not within * a critical section). */ *pxTopOfStack = ( StackType_t ) 0x00; return pxTopOfStack; } /*-----------------------------------------------------------*/ void vPortEndScheduler( void ) { /* It is unlikely that the HCS12 port will get stopped. */ } /*-----------------------------------------------------------*/ static void prvSetupTimerInterrupt( void ) { TickTimer_SetFreqHz( configTICK_RATE_HZ ); TickTimer_Enable(); } /*-----------------------------------------------------------*/ BaseType_t xPortStartScheduler( void ) { /* xPortStartScheduler() does not start the scheduler directly because * the header file containing the xPortStartScheduler() prototype is part * of the common kernel code, and therefore cannot use the CODE_SEG pragma. * Instead it simply calls the locally defined xBankedStartScheduler() - * which does use the CODE_SEG pragma. */ return xBankedStartScheduler(); } /*-----------------------------------------------------------*/ #pragma CODE_SEG __NEAR_SEG NON_BANKED static BaseType_t xBankedStartScheduler( void ) { /* Configure the timer that will generate the RTOS tick. Interrupts are * disabled when this function is called. */ prvSetupTimerInterrupt(); /* Restore the context of the first task. */ portRESTORE_CONTEXT(); /* Simulate the end of an interrupt to start the scheduler off. */ __asm( "rti" ); /* Should not get here! */ return pdFALSE; } /*-----------------------------------------------------------*/ /* * Context switch functions. These are both interrupt service routines. */ /* * Manual context switch forced by calling portYIELD(). This is the SWI * handler. */ void interrupt vPortYield( void ) { portSAVE_CONTEXT(); vTaskSwitchContext(); portRESTORE_CONTEXT(); } /*-----------------------------------------------------------*/ /* * RTOS tick interrupt service routine. If the cooperative scheduler is * being used then this simply increments the tick count. If the * preemptive scheduler is being used a context switch can occur. */ void interrupt vPortTickInterrupt( void ) { #if configUSE_PREEMPTION == 1 { /* A context switch might happen so save the context. */ portSAVE_CONTEXT(); /* Increment the tick ... */ if( xTaskIncrementTick() != pdFALSE ) { vTaskSwitchContext(); } TFLG1 = 1; /* Restore the context of a task - which may be a different task * to that interrupted. */ portRESTORE_CONTEXT(); } #else /* if configUSE_PREEMPTION == 1 */ { xTaskIncrementTick(); TFLG1 = 1; } #endif /* if configUSE_PREEMPTION == 1 */ } #pragma CODE_SEG DEFAULT