port.c

FreeRTOS is a portable, open source, mini Real Time Kernel - a free to download and royalty free RTO

/*This file has been prepared for Doxygen automatic documentation generation.*/
/*! \file *********************************************************************
 *
 * \brief FreeRTOS port source for AVR32 UC3.
 *
 * - Compiler:           GNU GCC for AVR32
 * - Supported devices:  All AVR32 devices can be used.
 * - AppNote:
 *
 * \author               Atmel Corporation: http://www.atmel.com \n
 *                       Support and FAQ: http://support.atmel.no/
 *
 *****************************************************************************/

/*
	FreeRTOS.org V5.2.0 - Copyright (C) 2003-2009 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 (version 2) as published
	by the Free Software Foundation and modified by the FreeRTOS exception.

	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 is included to allow you 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.


	***************************************************************************
	*                                                                         *
	* 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.                                                              *
	*                                                                         *
	***************************************************************************

	1 tab == 4 spaces!

	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.

	http://www.OpenRTOS.com - Commercial support, development, porting,
	licensing and training services.
*/


/* Standard includes. */
#include <sys/cpu.h>
#include <sys/usart.h>
#include <malloc.h>

/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"

/* AVR32 UC3 includes. */
#include <avr32/io.h>
#include "gpio.h"
#if( configTICK_USE_TC==1 )
	#include "tc.h"
#endif


/* Constants required to setup the task context. */
#define portINITIAL_SR            ( ( portSTACK_TYPE ) 0x00400000 ) /* AVR32 : [M2:M0]=001 I1M=0 I0M=0, GM=0 */
#define portINSTRUCTION_SIZE      ( ( portSTACK_TYPE ) 0 )

/* Each task maintains its own critical nesting variable. */
#define portNO_CRITICAL_NESTING   ( ( unsigned portLONG ) 0 )
volatile unsigned portLONG ulCriticalNesting = 9999UL;

#if( configTICK_USE_TC==0 )
	static void prvScheduleNextTick( void );
#else
	static void prvClearTcInt( void );
#endif

/* Setup the timer to generate the tick interrupts. */
static void prvSetupTimerInterrupt( void );

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

/*
 * Low-level initialization routine called during startup, before the main
 * function.
 * This version comes in replacement to the default one provided by Newlib.
 * Newlib's _init_startup only calls init_exceptions, but Newlib's exception
 * vectors are not compatible with the SCALL management in the current FreeRTOS
 * port. More low-level initializations are besides added here.
 */
void _init_startup(void)
{
	/* Import the Exception Vector Base Address. */
	extern void _evba;

	#if configHEAP_INIT
		extern void __heap_start__;
		extern void __heap_end__;
		portBASE_TYPE *pxMem;
	#endif

	/* Load the Exception Vector Base Address in the corresponding system register. */
	Set_system_register( AVR32_EVBA, ( int ) &_evba );

	/* Enable exceptions. */
	ENABLE_ALL_EXCEPTIONS();

	/* Initialize interrupt handling. */
	INTC_init_interrupts();

	#if configHEAP_INIT

		/* Initialize the heap used by malloc. */
		for( pxMem = &__heap_start__; pxMem < ( portBASE_TYPE * )&__heap_end__; )
		{
			*pxMem++ = 0xA5A5A5A5;
		}

	#endif

	/* Give the used CPU clock frequency to Newlib, so it can work properly. */
	set_cpu_hz( configCPU_CLOCK_HZ );

	/* Code section present if and only if the debug trace is activated. */
	#if configDBG
	{
		static const gpio_map_t DBG_USART_GPIO_MAP =
		{
			{ configDBG_USART_RX_PIN, configDBG_USART_RX_FUNCTION },
			{ configDBG_USART_TX_PIN, configDBG_USART_TX_FUNCTION }
		};

		/* Initialize the USART used for the debug trace with the configured parameters. */
		set_usart_base( ( void * ) configDBG_USART );
		gpio_enable_module( DBG_USART_GPIO_MAP,
		                    sizeof( DBG_USART_GPIO_MAP ) / sizeof( DBG_USART_GPIO_MAP[0] ) );
		usart_init( configDBG_USART_BAUDRATE );
	}
	#endif
}
/*-----------------------------------------------------------*/

/*
 * malloc, realloc and free are meant to be called through respectively
 * pvPortMalloc, pvPortRealloc and vPortFree.
 * The latter functions call the former ones from within sections where tasks
 * are suspended, so the latter functions are task-safe. __malloc_lock and
 * __malloc_unlock use the same mechanism to also keep the former functions
 * task-safe as they may be called directly from Newlib's functions.
 * However, all these functions are interrupt-unsafe and SHALL THEREFORE NOT BE
 * CALLED FROM WITHIN AN INTERRUPT, because __malloc_lock and __malloc_unlock do
 * not call portENTER_CRITICAL and portEXIT_CRITICAL in order not to disable
 * interrupts during memory allocation management as this may be a very time-
 * consuming process.
 */

/*
 * Lock routine called by Newlib on malloc / realloc / free entry to guarantee a
 * safe section as memory allocation management uses global data.
 * See the aforementioned details.
 */
void __malloc_lock(struct _reent *ptr)
{
	vTaskSuspendAll();
}

/*
 * Unlock routine called by Newlib on malloc / realloc / free exit to guarantee
 * a safe section as memory allocation management uses global data.
 * See the aforementioned details.
 */
void __malloc_unlock(struct _reent *ptr)
{
	xTaskResumeAll();
}
/*-----------------------------------------------------------*/

/* Added as there is no such function in FreeRTOS. */
void *pvPortRealloc( void *pv, size_t xWantedSize )
{
void *pvReturn;

	vTaskSuspendAll();
	{
		pvReturn = realloc( pv, xWantedSize );
	}
	xTaskResumeAll();

	return pvReturn;
}
/*-----------------------------------------------------------*/

/* The cooperative scheduler requires a normal IRQ service routine to
simply increment the system tick. */
/* The preemptive scheduler is defined as "naked" as the full context is saved
on entry as part of the context switch. */
__attribute__((__naked__)) static void vTick( void )
{
	/* Save the context of the interrupted task. */
	portSAVE_CONTEXT_OS_INT();

	#if( configTICK_USE_TC==1 )
		/* Clear the interrupt flag. */
		prvClearTcInt();
	#else
		/* Schedule the COUNT&COMPARE match interrupt in (configCPU_CLOCK_HZ/configTICK_RATE_HZ)
		clock cycles from now. */
		prvScheduleNextTick();
	#endif