/*
	FreeRTOS V5.4.2 - Copyright (C) 2009 Real Time Engineers Ltd.

	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.  
	Alternative commercial license and support terms are also available upon 
	request.  See the licensing section of http://www.FreeRTOS.org for full 
	license details.

	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.


	***************************************************************************
	*                                                                         *
	* Looking for a quick start?  Then check out the FreeRTOS eBook!          *
	* See http://www.FreeRTOS.org/Documentation for details                   *
	*                                                                         *
	***************************************************************************

	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
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*/

/*
	BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.

	*NOTE* - This file is designed to test some of the RTOS features - it is
	not intended to represent an efficient implementation!
*/

/* Standard includes. */
#include <stdlib.h>

/* Scheduler includes. */
#include "FreeRTOS.h"
#include "queue.h"

/* Demo application includes. */
#include "serial.h"


/* Hardware specifics. */
#define serRX_DATA_PIN		( 0x01 )
#define serTX_DATA_PIN		( 0x02 )
#define serCLOCK_Fxx_DIV_8		0x03
#define serUPWR		( 0x80 )
#define serUTXE		( 0x40 )
#define serURXE		( 0x20 )
#define serUCL		( 0x02 )
#define serLSB		( 0x10 )

/* Misc. */
#define serINVALID_QUEUE				( ( xQueueHandle ) 0 )
#define serHANDLE						( ( xComPortHandle ) 1 )
#define serNO_BLOCK						( ( portTickType ) 0 )

/*-----------------------------------------------------------*/

/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static xQueueHandle xRxedChars;
static xQueueHandle xCharsForTx;

/*-----------------------------------------------------------*/

/* Interrupt entry point written in the assembler file serialISR.s85. */
extern void vSerialISREntry( void );

/* Flag to indicate whether or not there are characters already queued to send. */
static volatile unsigned long ulTxInProgress = pdFALSE;

/*-----------------------------------------------------------*/

/*
 * See the serial2.h header file.
 */
xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
xComPortHandle xReturn = serHANDLE;
const unsigned portLONG ulFuclk = ( configCPU_CLOCK_HZ / 2 ) / 8UL;

	/* Create the queues used to hold Rx and Tx characters. */
	xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );
	xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed portCHAR ) );

	/* If the queues were created correctly then setup the serial port
	hardware. */
	if( ( xRxedChars != serINVALID_QUEUE ) && ( xCharsForTx != serINVALID_QUEUE ) )
	{
		portENTER_CRITICAL();
		{
			/* Set the UART0 Rx and Tx pins to their alternative function. */
			PMC3 |= ( serRX_DATA_PIN | serTX_DATA_PIN );
			PM3 &= ~( serTX_DATA_PIN );

			/* Setup clock for required baud. */			
			UD0CTL1 = serCLOCK_Fxx_DIV_8;
			UD0CTL2 = ulFuclk / ( 2 * ulWantedBaud );

			/* Enable, n81. */			
			UD0CTL0 = ( serUPWR | serUTXE | serURXE | serUCL | serLSB );
			
			/* Enable interrupts for both Rx and Tx. */
			UD0TIC  = 0x07;
			UD0RIC  = 0x07;
			
			ulTxInProgress = pdFALSE;
		}
		portEXIT_CRITICAL();
	}
	else
	{
		xReturn = ( xComPortHandle ) 0;
	}

	/* This demo file only supports a single port but we have to return
	something to comply with the standard demo header file. */
	return xReturn;
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )
{
	/* The port handle is not required as this driver only supports one port. */
	( void ) pxPort;

	/* Get the next character from the buffer.  Return false if no characters
	are available, or arrive before xBlockTime expires. */
	if( xQueueReceive( xRxedChars, pcRxedChar, xBlockTime ) )
	{
		return pdTRUE;
	}
	else
	{
		return pdFALSE;
	}
}
/*-----------------------------------------------------------*/

void vSerialPutString( xComPortHandle pxPort, const signed portCHAR * const pcString, unsigned portSHORT usStringLength )
{
signed portCHAR *pxNext;

	/* A couple of parameters that this port does not use. */
	( void ) usStringLength;
	( void ) pxPort;

	/* NOTE: This implementation does not handle the queue being full as no
	block time is used! */

	/* The port handle is not required as this driver only supports UART0. */
	( void ) pxPort;

	/* Send each character in the string, one at a time. */
	pxNext = ( signed portCHAR * ) pcString;
	while( *pxNext )
	{
		xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
		pxNext++;
	}
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )
{
portBASE_TYPE xReturn = pdPASS;

	portENTER_CRITICAL();
	{
		/* There are currently no characters queued up to send so write the
		character directly to the UART. */
		if( ulTxInProgress == pdFALSE )
		{
			UD0TX = cOutChar;
			ulTxInProgress = pdTRUE;
		}
		else
		{
			/* The UART is already busy so write the character to the Tx queue.
			The queue is drained from within the Tx interrupt. */
			if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )
			{
				xReturn = pdFAIL;
			}
		}
	}
	portEXIT_CRITICAL();
	
	return xReturn;
}
/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{
	/* Not supported as not required by the demo application. */
}
/*-----------------------------------------------------------*/

/* Tx interrupt handler.  This is called from the asm file wrapper. */
void vUARTTxISRHandler( void )
{
char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

	/* Are there any more characters queue to transmit? */
	if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
	{
		/* Send the next character. */
		UD0TX = cChar;
	}
	else
	{
		/* The UART is no longer active. */
		ulTxInProgress = pdFALSE;
	}
	
	/* If reading a character from the Rx queue caused a task to unblock, and
	the unblocked task has a priority higher than the currently running task,
	then xHigherPriorityTaskWoken will have been set to true and a context
	switch should occur now. */
	portYIELD_FROM_ISR( xHigherPriorityTaskWoken );
}
/*-----------------------------------------------------------*/

/* Rx interrupt handler.  This is called from the asm file wrapper. */
void vUARTRxISRHandler( void )
{
portCHAR cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

	/* Send the received character to the Rx queue. */
	cChar = UD0RX;
	xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
	
	/* If sending a character to the Tx queue caused a task to unblock, and
	the unblocked task has a priority higher than the currently running task,
	then xHigherPriorityTaskWoken will have been set to true and a context
	switch should occur now. */
	portYIELD_FROM_ISR( xHigherPriorityTaskWoken );	
}