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/*

	FreeRTOS.org V4.2.1 - Copyright (C) 2003-2007 Richard Barry.

	This file is part of the FreeRTOS.org distribution.

	FreeRTOS.org 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.org 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.org; 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.org, 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.

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

	See http://www.FreeRTOS.org for documentation, latest information, license 

	and contact details.  Please ensure to read the configuration and relevant 

	port sections of the online documentation.

	Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along

	with commercial development and support options.

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

*/

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

 * Implementation of functions defined in portable.h for the ARM7 port.

 *

 * Components that can be compiled to either ARM or THUMB mode are

 * contained in this file.  The ISR routines, which can only be compiled

 * to ARM mode are contained in portISR.c.

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

/*

	Changes from V2.5.2

	+ ulCriticalNesting is now saved as part of the task context, as is 

	  therefore added to the initial task stack during pxPortInitialiseStack.

*/

/* Standard includes. */

#include <stdlib.h>

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "task.h"

/* Processor constants. */

#include "AT91SAM7.h"

#include "lib_AT91SAM7.h"

/* Constants required to setup the task context. */

#define portINITIAL_SPSR				( ( portSTACK_TYPE ) 0x1f )	/* System mode, ARM mode, interrupts enabled. */

#define portTHUMB_MODE_BIT				( ( portSTACK_TYPE ) 0x20 )

#define portINSTRUCTION_SIZE			( ( portSTACK_TYPE ) 4 )

#define portNO_CRITICAL_SECTION_NESTING	( ( portSTACK_TYPE ) 0 )

/* Constants required to setup the tick ISR. */

#define portENABLE_TIMER			( ( unsigned portCHAR ) 0x01 )

#define portPRESCALE_VALUE			0x00

#define portINTERRUPT_ON_MATCH		( ( unsigned portLONG ) 0x01 )

#define portRESET_COUNT_ON_MATCH	( ( unsigned portLONG ) 0x02 )

/* Constants required to setup the PIT. */

#define portPIT_CLOCK_DIVISOR			( ( unsigned portLONG ) 16 )

#define portPIT_COUNTER_VALUE			( ( ( configCPU_CLOCK_HZ / portPIT_CLOCK_DIVISOR ) / 1000UL ) * portTICK_RATE_MS )

#define portINT_LEVEL_SENSITIVE  0

#define portPIT_ENABLE      	( ( unsigned portSHORT ) 0x1 << 24 )

#define portPIT_INT_ENABLE     	( ( unsigned portSHORT ) 0x1 << 25 )

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

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

static void prvSetupTimerInterrupt (void);

/* 

 * The scheduler can only be started from ARM mode, so 

 * vPortISRStartFirstSTask() is defined in portISR.c. 

 */

extern void vPortISRStartFirstTask (void);

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

/* 

 * 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)

{

  portSTACK_TYPE *pxOriginalTOS;

  pxOriginalTOS = pxTopOfStack;

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

     expected by the portRESTORE_CONTEXT() macro. */

  /* First on the stack is the return address - which in this case is the

     start of the task.  The offset is added to make the return address appear

     as it would within an IRQ ISR. */

  *pxTopOfStack = (portSTACK_TYPE) pxCode + portINSTRUCTION_SIZE;

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0xaaaaaaaa;	/* R14 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) pxOriginalTOS;	/* Stack used when task starts goes in R13. */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x12121212;	/* R12 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x11111111;	/* R11 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x10101010;	/* R10 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x09090909;	/* R9 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x08080808;	/* R8 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x07070707;	/* R7 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x06060606;	/* R6 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x05050505;	/* R5 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x04040404;	/* R4 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x03030303;	/* R3 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x02020202;	/* R2 */

  pxTopOfStack--;

  *pxTopOfStack = (portSTACK_TYPE) 0x01010101;	/* R1 */

  pxTopOfStack--;

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

     R0. */

  *pxTopOfStack = (portSTACK_TYPE) pvParameters;	/* R0 */

  pxTopOfStack--;

  /* The last thing onto the stack is the status register, which is set for

     system mode, with interrupts enabled. */

  *pxTopOfStack = (portSTACK_TYPE) portINITIAL_SPSR;

#ifdef THUMB_INTERWORK

  {

    /* We want the task to start in thumb mode. */

    *pxTopOfStack |= portTHUMB_MODE_BIT;

  }

#endif

  pxTopOfStack--;

  /* Some optimisation levels use the stack differently to others.  This 

     means the interrupt flags cannot always be stored on the stack and will

     instead be stored in a variable, which is then saved as part of the

     tasks context. */

  *pxTopOfStack = portNO_CRITICAL_SECTION_NESTING;

  return pxTopOfStack;

}

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

portBASE_TYPE

xPortStartScheduler (void)

{

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

     here already. */

  prvSetupTimerInterrupt ();

  /* Start the first task. */

  vPortISRStartFirstTask ();

  /* Should not get here! */

  return 0;

}

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

void

vPortEndScheduler (void)

{

  /* It is unlikely that the ARM port will require this function as there

     is nothing to return to.  */

}

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

/*

 * Setup the timer 0 to generate the tick interrupts at the required frequency.

 */

static void

prvSetupTimerInterrupt (void)

{

  AT91PS_PITC pxPIT = AT91C_BASE_PITC;

  /* Setup the AIC for PIT interrupts.  The interrupt routine chosen depends

     on whether the preemptive or cooperative scheduler is being used. */

#if configUSE_PREEMPTION == 0

  extern void (vNonPreemptiveTick) (void);

  AT91F_AIC_ConfigureIt (AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST,

			 portINT_LEVEL_SENSITIVE,

			 (void (*)(void)) vNonPreemptiveTick);

#else

  extern void (vPreemptiveTick) (void);

  AT91F_AIC_ConfigureIt (AT91C_ID_SYS, AT91C_AIC_PRIOR_HIGHEST,

			 portINT_LEVEL_SENSITIVE,

			 (void (*)(void)) vPreemptiveTick);

#endif

  /* Configure the PIT period. */

  pxPIT->PITC_PIMR =

    portPIT_ENABLE | portPIT_INT_ENABLE | portPIT_COUNTER_VALUE;

  /* Enable the interrupt.  Global interrupts are disables at this point so 

     this is safe. */

  AT91C_BASE_AIC->AIC_IECR = 0x1 << AT91C_ID_SYS;

}

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