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/*

    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.

    ***************************************************************************

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    ***************************************************************************

    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under

    the terms of the GNU General Public License (version 2) as published by the

    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.

    ***NOTE*** The exception to the GPL is included to allow you to distribute

    a combined work that includes FreeRTOS without being obliged to provide the

    source code for proprietary components outside of the FreeRTOS kernel.

    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT

    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

    more details. You should have received a copy of the GNU General Public

    License and the FreeRTOS license exception along with FreeRTOS; if not it

    can be viewed here: http://www.freertos.org/a00114.html and also obtained

    by writing to Richard Barry, contact details for whom are available on the

    FreeRTOS WEB site.

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    http://www.FreeRTOS.org - Documentation, latest information, license and

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*/

/*-----------------------------------------------------------

 * Implementation of functions defined in portable.h for the OpenRISC port.

 *----------------------------------------------------------*/

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "task.h"

/* Processor constants. */

#include "port_spr_defs.h"

/* Jump buffer */

#include <setjmp.h>

static jmp_buf jmpbuf;

/* Tick Timer Interrupt handler */

void vTickHandler( void );

/* Setup the timer to generate the tick interrupts. */

static void prvSetupTimerInterrupt( void );

/* For writing into SPR. */

static inline void mtspr(unsigned long spr, unsigned long value) {

        asm("l.mtspr\t\t%0,%1,0": : "r" (spr), "r" (value));

}

/* For reading SPR. */

static inline unsigned long mfspr(unsigned long spr) {

        unsigned long value;

        asm("l.mfspr\t\t%0,%1,0" : "=r" (value) : "r" (spr));

        return value;

}

/*

 * naked attribute is ignored or32-elf-gcc 4.5.1-or32-1.0rc1

 * use assemble routines in portasm.S

 */

#if 0

void vPortDisableInterrupts( void ) __attribute__ ((__naked__))

{

        asm volatile (                                                          \

        "       @ get current SR                                \n\t"   \

        "       l.mfspr r3, r0, SPR_SR                  \n\t"   \

        "       l.addi  r4, r0, SPR_SR_TEE              \n\t"   \

        "       l.xori  r4, r4, 0xffffffff              \n\t"   \

        "       l.and   r3, r3, r4                              \n\t"   \

        "       l.addi  r4, r0, SPR_SR_IEE              \n\t"   \

        "       l.xori  r4, r4, 0xffffffff              \n\t"   \

        "       l.and   r3, r3, r4                              \n\t"   \

        "       @ update SR                                             \n\t"   \

        "       l.mtspr r0, r3, SPR_SR                  \n\t"   \

        );

}

void vPortEnableInterrupts( void ) __attribute__ ((__naked__))

{

        asm volatile (                                                          \

        "       @ get current SR                                \n\t"   \

        "       l.mfspr r3, r0, SPR_SR                  \n\t"   \

        "       @ enable Tick Timer Interrupt   \n\t"   \

        "       l.ori   r3, r3, SPR_SR_TEE              \n\t"   \

        "       @ enable External Interrupt             \n\t"   \

        "       l.ori   r3, r3, SPR_SR_IEE              \n\t"   \

        "       @ update SR                                             \n\t"   \

        "       l.mtspr r0, r3, SPR_SR                  \n\t"   \

        );

}

#endif

/*

 * Initialise the stack of a task to look exactly as if a call to

 * portSAVE_CONTEXT had been called.

 *

 * See header file for description.

 */

portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )

{

        unsigned portLONG uTaskSR = mfspr(SPR_ESR_BASE);

        uTaskSR &= ~SPR_SR_SM;                                  // User mode

        uTaskSR |= (SPR_SR_TEE | SPR_SR_IEE);   // Tick interrupt enable, All External interupt enable

        /* Setup the initial stack of the task.  The stack is set exactly as

        expected by the portRESTORE_CONTEXT() macro. */

        *(--pxTopOfStack) = (portSTACK_TYPE)pxCode;                     // SPR_EPCR_BASE(0)

        *(--pxTopOfStack) = (portSTACK_TYPE)uTaskSR;            // SPR_ESR_BASE(0) 

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000031;         // r31

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000030;         // r30

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000029;         // r29

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000028;         // r28

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000027;         // r27

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000026;         // r26

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000025;         // r25

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000024;         // r24

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000023;         // r23

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000022;         // r22

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000021;         // r21

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000020;         // r20

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000019;         // r19

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000018;         // r18

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000017;         // r17

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000016;         // r16

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000015;         // r15

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000014;         // r14

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000013;         // r13

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000012;         // r12

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000011;         // r11

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000010;         // r10

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000008;         // r8

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000007;         // r7

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000006;         // r6

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000005;         // r5

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000004;         // r4

        *(--pxTopOfStack) = (portSTACK_TYPE)pvParameters;       // task argument

        *(--pxTopOfStack) = (portSTACK_TYPE)0x00000002;         // r2

        *(--pxTopOfStack) = (portSTACK_TYPE)pxCode;                     // PC

        return pxTopOfStack;

}

portBASE_TYPE xPortStartScheduler( void )

{

        if(setjmp((void *)jmpbuf) == 0) {

                /* Start the timer that generates the tick ISR.  Interrupts are disabled

                here already. */

                prvSetupTimerInterrupt();

                /* Start the first task. */

                portRESTORE_CONTEXT();

                /* Should not get here! */

        } else {

                /* Retrun by vPortEndScheduler */

        }

        return 0;

}

void vPortEndScheduler( void )

{

        mtspr(SPR_SR, mfspr(SPR_SR) & (~SPR_SR_TEE));   // Tick stop

        longjmp((void *)jmpbuf, 1);                                             // return to xPortStartScheduler

}

/*

 * Setup the tick timer to generate the tick interrupts at the required frequency.

 */

static void prvSetupTimerInterrupt( void )

{

        const unsigned portLONG ulTickPeriod = configCPU_CLOCK_HZ / configTICK_RATE_HZ;

        // Disable tick timer exception recognition 

        mtspr(SPR_SR, mfspr(SPR_SR) & ~SPR_SR_TEE);

        // clears interrupt

        mtspr(SPR_TTMR, mfspr(SPR_TTMR) & ~(SPR_TTMR_IP));

        // Set period of one cycle, restartable mode 

        mtspr(SPR_TTMR, SPR_TTMR_IE | SPR_TTMR_RT | (ulTickPeriod & SPR_TTMR_PERIOD));

        // Reset counter 

        mtspr(SPR_TTCR, 0);

    // set OR1200 to accept exceptions

    mtspr(SPR_SR, mfspr(SPR_SR) | SPR_SR_TEE);

}

/*

 * naked attribute is ignored or32-elf-gcc 4.5.1-or32-1.0rc1

 * use assemble routines in portasm.S

 */

#if 0

void vTickHandler( void )

{

        // clears interrupt

        mtspr(SPR_TTMR, mfspr(SPR_TTMR) & ~(SPR_TTMR_IP));

        /* Increment the RTOS tick count, then look for the highest priority

           task that is ready to run. */

        vTaskIncrementTick();

        // The cooperative scheduler requires a normal simple Tick ISR to

        // simply increment the system tick.

#if configUSE_PREEMPTION == 0

        // nothing to do here

#else

        /* Save the context of the current task. */

        portSAVE_CONTEXT();

        /* Find the highest priority task that is ready to run. */

        vTaskSwitchContext();

        portRESTORE_CONTEXT();

#endif

}

#endif