Subversion Repositories openrisc_2011-10-31

/*

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

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

    *                                                                         *

    * If you are:                                                             *

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    *    + New to FreeRTOS,                                                   *

    *    + Wanting to learn FreeRTOS or multitasking in general quickly       *

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    *                                                                         *

    * then take a look at the FreeRTOS books - available as PDF or paperback  *

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    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *

    *                  http://www.FreeRTOS.org/Documentation                  *

    *                                                                         *

    * A pdf reference manual is also available.  Both are usually delivered   *

    * to your inbox within 20 minutes to two hours when purchased between 8am *

    * and 8pm GMT (although please allow up to 24 hours in case of            *

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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.

    1 tab == 4 spaces!

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

    contact details.

    http://www.SafeRTOS.com - A version that is certified for use in safety

    critical systems.

    http://www.OpenRTOS.com - Commercial support, development, porting,

    licensing and training services.

*/

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "task.h"

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

 * Implementation of functions defined in portable.h for the MSP430 port.

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

/* Constants required for hardware setup.  The tick ISR runs off the ACLK,

not the MCLK. */

#define portACLK_FREQUENCY_HZ                   ( ( portTickType ) 32768 )

#define portINITIAL_CRITICAL_NESTING    ( ( unsigned short ) 10 )

#define portFLAGS_INT_ENABLED                   ( ( portSTACK_TYPE ) 0x08 )

/* We require the address of the pxCurrentTCB variable, but don't want to know

any details of its type. */

typedef void tskTCB;

extern volatile tskTCB * volatile pxCurrentTCB;

/* Each task maintains a count of the critical section nesting depth.  Each

time a critical section is entered the count is incremented.  Each time a

critical section is exited the count is decremented - with interrupts only

being re-enabled if the count is zero.

usCriticalNesting will get set to zero when the scheduler starts, but must

not be initialised to zero as this will cause problems during the startup

sequence. */

volatile unsigned short usCriticalNesting = portINITIAL_CRITICAL_NESTING;

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

/*

 * Sets up the periodic ISR used for the RTOS tick.  This uses timer 0, but

 * could have alternatively used the watchdog timer or timer 1.

 */

void vPortSetupTimerInterrupt( void );

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

/*

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

 * portSAVE_CONTEXT had been called.

 *

 * See the header file portable.h.

 */

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

{

        /*

                Place a few bytes of known values on the bottom of the stack.

                This is just useful for debugging and can be included if required.

                *pxTopOfStack = ( portSTACK_TYPE ) 0x1111;

                pxTopOfStack--;

                *pxTopOfStack = ( portSTACK_TYPE ) 0x2222;

                pxTopOfStack--;

                *pxTopOfStack = ( portSTACK_TYPE ) 0x3333;

                pxTopOfStack--;

        */

        /* The msp430 automatically pushes the PC then SR onto the stack before

        executing an ISR.  We want the stack to look just as if this has happened

        so place a pointer to the start of the task on the stack first - followed

        by the flags we want the task to use when it starts up. */

        *pxTopOfStack = ( portSTACK_TYPE ) pxCode;

        pxTopOfStack--;

        *pxTopOfStack = portFLAGS_INT_ENABLED;

        pxTopOfStack--;

        /* Next the general purpose registers. */

        *pxTopOfStack = ( portSTACK_TYPE ) 0x4444;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0x5555;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0x6666;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0x7777;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0x8888;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0x9999;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0xaaaa;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0xbbbb;

        pxTopOfStack--;

        /* When the task starts is will expect to find the function parameter in

        R15. */

        *pxTopOfStack = ( portSTACK_TYPE ) pvParameters;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0xdddd;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0xeeee;

        pxTopOfStack--;

        *pxTopOfStack = ( portSTACK_TYPE ) 0xffff;

        pxTopOfStack--;

        /* A variable is used to keep track of the critical section nesting.

        This variable has to be stored as part of the task context and is

        initially set to zero. */

        *pxTopOfStack = ( portSTACK_TYPE ) portNO_CRITICAL_SECTION_NESTING;

        /* Return a pointer to the top of the stack we have generated so this can

        be stored in the task control block for the task. */

        return pxTopOfStack;

}

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

void vPortEndScheduler( void )

{

        /* It is unlikely that the MSP430 port will get stopped.  If required simply

        disable the tick interrupt here. */

}

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

/*

 * Hardware initialisation to generate the RTOS tick.  This uses timer 0

 * but could alternatively use the watchdog timer or timer 1.

 */

void vPortSetupTimerInterrupt( void )

{

        /* Ensure the timer is stopped. */

        TACTL = 0;

        /* Run the timer of the ACLK. */

        TACTL = TASSEL_1;

        /* Clear everything to start with. */

        TACTL |= TACLR;

        /* Set the compare match value according to the tick rate we want. */

        TACCR0 = portACLK_FREQUENCY_HZ / configTICK_RATE_HZ;

        /* Enable the interrupts. */

        TACCTL0 = CCIE;

        /* Start up clean. */

        TACTL |= TACLR;

        /* Up mode. */

        TACTL |= MC_1;

}

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