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jeremybenn |
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). Thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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***NOTE*** The exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the OpenRISC port.
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*----------------------------------------------------------*/
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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/* Processor constants. */
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#include "port_spr_defs.h"
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/* Tick Timer Interrupt handler */
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void vTickHandler( void );
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/* Setup the timer to generate the tick interrupts. */
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static void prvSetupTimerInterrupt( void );
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/* For writing into SPR. */
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static inline void mtspr(unsigned long spr, unsigned long value) {
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asm("l.mtspr\t\t%0,%1,0": : "r" (spr), "r" (value));
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}
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/* For reading SPR. */
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static inline unsigned long mfspr(unsigned long spr) {
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unsigned long value;
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asm("l.mfspr\t\t%0,%1,0" : "=r" (value) : "r" (spr));
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return value;
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}
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/*
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* naked attribute is ignored or32-elf-gcc 4.5.1-or32-1.0rc1
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* use assemble routines in portasm.S
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*/
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#if 0
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void vPortDisableInterrupts( void ) __attribute__ ((__naked__))
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{
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asm volatile ( \
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" @ get current SR \n\t" \
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" l.mfspr r3, r0, SPR_SR \n\t" \
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" l.addi r4, r0, SPR_SR_TEE \n\t" \
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" l.xori r4, r4, 0xffffffff \n\t" \
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" l.and r3, r3, r4 \n\t" \
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" l.addi r4, r0, SPR_SR_IEE \n\t" \
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" l.xori r4, r4, 0xffffffff \n\t" \
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" l.and r3, r3, r4 \n\t" \
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" @ update SR \n\t" \
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" l.mtspr r0, r3, SPR_SR \n\t" \
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);
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}
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void vPortEnableInterrupts( void ) __attribute__ ((__naked__))
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{
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asm volatile ( \
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" @ get current SR \n\t" \
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" l.mfspr r3, r0, SPR_SR \n\t" \
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" @ enable Tick Timer Interrupt \n\t" \
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" l.ori r3, r3, SPR_SR_TEE \n\t" \
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" @ enable External Interrupt \n\t" \
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" l.ori r3, r3, SPR_SR_IEE \n\t" \
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" @ update SR \n\t" \
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" l.mtspr r0, r3, SPR_SR \n\t" \
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);
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}
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#endif
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/*
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* Initialise the stack of a task to look exactly as if a call to
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* portSAVE_CONTEXT had been called.
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*
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* See header file for description.
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*/
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portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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{
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unsigned portLONG uTaskSR = mfspr(SPR_ESR_BASE);
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uTaskSR &= ~SPR_SR_SM; // User mode
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uTaskSR |= (SPR_SR_TEE | SPR_SR_IEE); // Tick interrupt enable, All External interupt enable
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/* Setup the initial stack of the task. The stack is set exactly as
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expected by the portRESTORE_CONTEXT() macro. */
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*(--pxTopOfStack) = (portSTACK_TYPE)pxCode; // SPR_EPCR_BASE(0)
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*(--pxTopOfStack) = (portSTACK_TYPE)uTaskSR; // SPR_ESR_BASE(0)
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000031; // r31
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000030; // r30
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000029; // r29
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000028; // r28
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000027; // r27
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000026; // r26
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000025; // r25
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000024; // r24
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000023; // r23
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000022; // r22
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000021; // r21
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000020; // r20
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000019; // r19
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000018; // r18
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000017; // r17
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000016; // r16
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000015; // r15
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000014; // r14
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000013; // r13
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000012; // r12
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000011; // r11
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000010; // r10
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000008; // r8
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000007; // r7
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000006; // r6
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000005; // r5
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000004; // r4
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*(--pxTopOfStack) = (portSTACK_TYPE)pvParameters; // task argument
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*(--pxTopOfStack) = (portSTACK_TYPE)0x00000002; // r2
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*(--pxTopOfStack) = (portSTACK_TYPE)pxCode; // PC
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return pxTopOfStack;
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}
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portBASE_TYPE xPortStartScheduler( void )
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{
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/* Start the timer that generates the tick ISR. Interrupts are disabled
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here already. */
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prvSetupTimerInterrupt();
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/* Start the first task. */
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portRESTORE_CONTEXT();
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/* Should not get here! */
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return 0;
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}
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void vPortEndScheduler( void )
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{
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mtspr(SPR_SR, mfspr(SPR_SR) & (~SPR_SR_TEE)); // Tick stop
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}
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/*
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* Setup the tick timer to generate the tick interrupts at the required frequency.
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*/
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static void prvSetupTimerInterrupt( void )
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{
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const unsigned portLONG ulTickPeriod = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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// Disable tick timer exception recognition
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mtspr(SPR_SR, mfspr(SPR_SR) & ~SPR_SR_TEE);
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// clears interrupt
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mtspr(SPR_TTMR, mfspr(SPR_TTMR) & ~(SPR_TTMR_IP));
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// Set period of one cycle, restartable mode
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mtspr(SPR_TTMR, SPR_TTMR_IE | SPR_TTMR_RT | (ulTickPeriod & SPR_TTMR_PERIOD));
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// Reset counter
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mtspr(SPR_TTCR, 0);
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// set OR1200 to accept exceptions
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mtspr(SPR_SR, mfspr(SPR_SR) | SPR_SR_TEE);
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}
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#if 0
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void vTickHandler( void )
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{
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// clears interrupt
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mtspr(SPR_TTMR, mfspr(SPR_TTMR) & ~(SPR_TTMR_IP));
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/* Increment the RTOS tick count, then look for the highest priority
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task that is ready to run. */
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vTaskIncrementTick();
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// The cooperative scheduler requires a normal simple Tick ISR to
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// simply increment the system tick.
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#if configUSE_PREEMPTION == 0
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// nothing to do here
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#else
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/* Save the context of the current task. */
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portSAVE_CONTEXT();
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/* Find the highest priority task that is ready to run. */
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vTaskSwitchContext();
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portRESTORE_CONTEXT();
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#endif
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}
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#endif
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