FreeRTOS/Source/portable/GCC/MCF5235/port.c

/*
    FreeRTOS V4.1.1 - Copyright (C) 2003-2006 Richard Barry.
    MCF5235 Port - Copyright (C) 2006 Christian Walter.

    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** as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    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
    along with FreeRTOS; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    A special exception to the GPL can be applied should you wish to distribute
    a combined work that includes FreeRTOS, without being obliged to provide
    the source code for any proprietary components.  See the licensing section
    of http://www.FreeRTOS.org for full details of how and when the exception
    can be applied.

    ***************************************************************************
    ***************************************************************************
    *                                                                         *
    * Get the FreeRTOS eBook!  See http://www.FreeRTOS.org/Documentation      *
	*                                                                         *
	* This is a concise, step by step, 'hands on' guide that describes both   *
	* general multitasking concepts and FreeRTOS specifics. It presents and   *
	* explains numerous examples that are written using the FreeRTOS API.     *
	* Full source code for all the examples is provided in an accompanying    *
	* .zip file.                                                              *
    *                                                                         *
    ***************************************************************************
    ***************************************************************************

	Please ensure to read the configuration and relevant port sections of the
	online documentation.

	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.

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*/

#include <stdlib.h>

#include "FreeRTOS.h"
#include "FreeRTOSConfig.h"
#include "task.h"

/* ------------------------ Types ----------------------------------------- */
typedef volatile uint32_t vuint32;
typedef volatile uint16_t vuint16;
typedef volatile uint8_t vuint8;

/* ------------------------ Defines --------------------------------------- */
#define portVECTOR_TABLE                __RAMVEC
#define portVECTOR_SYSCALL              ( 32 + portTRAP_YIELD )
#define portVECTOR_TIMER                ( 64 + 36 )

#define MCF_PIT_PRESCALER               512UL
#define MCF_PIT_TIMER_TICKS             ( FSYS_2 / MCF_PIT_PRESCALER )
#define MCF_PIT_MODULUS_REGISTER(freq)  ( MCF_PIT_TIMER_TICKS / ( freq ) - 1UL)

#define MCF_PIT_PMR0                    ( *( vuint16 * )( void * )( &__IPSBAR[ 0x150002 ] ) )
#define MCF_PIT_PCSR0                   ( *( vuint16 * )( void * )( &__IPSBAR[ 0x150000 ] ) )
#define MCF_PIT_PCSR_PRE(x)             ( ( ( x ) & 0x000F ) << 8 )
#define MCF_PIT_PCSR_EN                 ( 0x0001 )
#define MCF_PIT_PCSR_RLD                ( 0x0002 )
#define MCF_PIT_PCSR_PIF                ( 0x0004 )
#define MCF_PIT_PCSR_PIE                ( 0x0008 )
#define MCF_PIT_PCSR_OVW                ( 0x0010 )
#define MCF_INTC0_ICR36                 ( *( vuint8 * )( void * )( &__IPSBAR[ 0x000C64 ] ) )
#define MCF_INTC0_IMRH                  ( *( vuint32 * )( void * )( &__IPSBAR[ 0x000C08 ] ) )
#define MCF_INTC0_IMRH_INT_MASK36       ( 0x00000010 )
#define MCF_INTC0_IMRH_MASKALL          ( 0x00000001 )
#define MCF_INTC0_ICRn_IP(x)            ( ( ( x ) & 0x07 ) << 0 )
#define MCF_INTC0_ICRn_IL(x)            ( ( ( x ) & 0x07 ) << 3 )

#define portNO_CRITICAL_NESTING         ( ( uint32_t ) 0 )
#define portINITIAL_CRITICAL_NESTING    ( ( uint32_t ) 10 )

/* ------------------------ Static variables ------------------------------ */
volatile uint32_t              ulCriticalNesting = portINITIAL_CRITICAL_NESTING;

/* ------------------------ Static functions ------------------------------ */
#if configUSE_PREEMPTION == 0
static void prvPortPreemptiveTick ( void ) __attribute__ ((interrupt_handler));
#else
static void prvPortPreemptiveTick ( void );
#endif

/* ------------------------ Start implementation -------------------------- */

StackType_t *
pxPortInitialiseStack( StackType_t * pxTopOfStack, TaskFunction_t pxCode,
                       void *pvParameters )
{
    /* Place the parameter on the stack in the expected location. */
    *pxTopOfStack = ( StackType_t ) pvParameters;
    pxTopOfStack--;

    /* Place dummy return address on stack. Tasks should never terminate so
     * we can set this to anything. */
    *pxTopOfStack = ( StackType_t ) 0;
    pxTopOfStack--;

    /* Create a Motorola Coldfire exception stack frame. First comes the return
     * address. */
    *pxTopOfStack = ( StackType_t ) pxCode;
    pxTopOfStack--;

    /* Format, fault-status, vector number for exception stack frame. Task
     * run in supervisor mode. */
    *pxTopOfStack = 0x40002000UL | ( portVECTOR_SYSCALL + 32 ) << 18;
    pxTopOfStack--;

    /* Set the initial critical section nesting counter to zero. This value
     * is used to restore the value of ulCriticalNesting. */
    *pxTopOfStack = 0;
    *pxTopOfStack--;

    *pxTopOfStack = ( StackType_t ) 0xA6;    /* A6 / FP */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xA5;    /* A5 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xA4;    /* A4 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xA3;    /* A3 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xA2;    /* A2 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xA1;    /* A1 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xA0;    /* A0 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD7;    /* D7 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD6;    /* D6 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD5;    /* D5 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD4;    /* D4 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD3;    /* D3 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD2;    /* D2 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD1;    /* D1 */
    pxTopOfStack--;
    *pxTopOfStack = ( StackType_t ) 0xD0;    /* D0 */

    return pxTopOfStack;
}

/*
 * Called by portYIELD() or taskYIELD() to manually force a context switch.
 */
static void
prvPortYield( void )
{
    asm volatile ( "move.w  #0x2700, %sr\n\t" );
#if _GCC_USES_FP == 1
    asm volatile ( "unlk %fp\n\t" );
#endif
     /* Perform the context switch.  First save the context of the current task. */
    portSAVE_CONTEXT(  );

    /* Find the highest priority task that is ready to run. */
    vTaskSwitchContext(  );

    /* Restore the context of the new task. */
    portRESTORE_CONTEXT(  );
}

#if configUSE_PREEMPTION == 0
/*
 * The ISR used for the scheduler tick depends on whether the cooperative or
 * the preemptive scheduler is being used.
 */
static void
prvPortPreemptiveTick ( void )
{
    /* The cooperative scheduler requires a normal IRQ service routine to
     * simply increment the system tick.
     */

    xTaskIncrementTick();
    MCF_PIT_PCSR0 |= MCF_PIT_PCSR_PIF;
}

#else

static void
prvPortPreemptiveTick( void )
{
    asm volatile ( "move.w  #0x2700, %sr\n\t" );
#if _GCC_USES_FP == 1
    asm volatile ( "unlk %fp\n\t" );
#endif
    portSAVE_CONTEXT(  );
    MCF_PIT_PCSR0 |= MCF_PIT_PCSR_PIF;
    if( xTaskIncrementTick() != pdFALSE )
	{
		vTaskSwitchContext(  );
	}
    portRESTORE_CONTEXT(  );
}
#endif

void
vPortEnterCritical()
{
    /* FIXME: We should store the old IPL here - How are we supposed to do
     * this.
     */
    ( void )portSET_IPL( portIPL_MAX );

    /* Now interrupts are disabled ulCriticalNesting can be accessed
     * directly.  Increment ulCriticalNesting to keep a count of how many times
     * portENTER_CRITICAL() has been called. */
    ulCriticalNesting++;
}

void
vPortExitCritical()
{
    if( ulCriticalNesting > portNO_CRITICAL_NESTING )
    {
        /* Decrement the nesting count as we are leaving a critical section. */
        ulCriticalNesting--;

        /* If the nesting level has reached zero then interrupts should be
        re-enabled. */
        if( ulCriticalNesting == portNO_CRITICAL_NESTING )
        {
            ( void )portSET_IPL( 0 );
        }
    }
}

BaseType_t
xPortStartScheduler( void )
{
    extern void     ( *portVECTOR_TABLE[  ] ) (  );

    /* Add entry in vector table for yield system call. */
    portVECTOR_TABLE[ portVECTOR_SYSCALL ] = prvPortYield;
    /* Add entry in vector table for periodic timer. */
    portVECTOR_TABLE[ portVECTOR_TIMER ] = prvPortPreemptiveTick;

    /* Configure the timer for the system clock. */
    if ( configTICK_RATE_HZ > 0)
    {
        /* Configure prescaler */
        MCF_PIT_PCSR0 = MCF_PIT_PCSR_PRE( 0x9 ) | MCF_PIT_PCSR_RLD | MCF_PIT_PCSR_OVW;
        /* Initialize the periodic timer interrupt. */
        MCF_PIT_PMR0 = MCF_PIT_MODULUS_REGISTER( configTICK_RATE_HZ );
        /* Configure interrupt priority and level and unmask interrupt. */
        MCF_INTC0_ICR36 = MCF_INTC0_ICRn_IL( 0x1 ) | MCF_INTC0_ICRn_IP( 0x1 );
        MCF_INTC0_IMRH &= ~( MCF_INTC0_IMRH_INT_MASK36 | MCF_INTC0_IMRH_MASKALL );
        /* Enable interrupts */
        MCF_PIT_PCSR0 |= MCF_PIT_PCSR_PIE | MCF_PIT_PCSR_EN | MCF_PIT_PCSR_PIF;
    }

    /* Restore the context of the first task that is going to run. */
    portRESTORE_CONTEXT(  );

    /* Should not get here. */
    return pdTRUE;
}

void
vPortEndScheduler( void )
{
}