/*
    FreeRTOS V9.0.0rc2 - Copyright (C) 2016 Real Time Engineers Ltd.
    All rights reserved

    VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.

    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 modification 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.  Full license text is available on the following
    link: http://www.freertos.org/a00114.html

    ***************************************************************************
     *                                                                       *
     *    FreeRTOS provides completely free yet professionally developed,    *
     *    robust, strictly quality controlled, supported, and cross          *
     *    platform software that is more than just the market leader, it     *
     *    is the industry's de facto standard.                               *
     *                                                                       *
     *    Help yourself get started quickly while simultaneously helping     *
     *    to support the FreeRTOS project by purchasing a FreeRTOS           *
     *    tutorial book, reference manual, or both:                          *
     *    http://www.FreeRTOS.org/Documentation                              *
     *                                                                       *
    ***************************************************************************

    http://www.FreeRTOS.org/FAQHelp.html - Having a problem?  Start by reading
    the FAQ page "My application does not run, what could be wrong?".  Have you
    defined configASSERT()?

    http://www.FreeRTOS.org/support - In return for receiving this top quality
    embedded software for free we request you assist our global community by
    participating in the support forum.

    http://www.FreeRTOS.org/training - Investing in training allows your team to
    be as productive as possible as early as possible.  Now you can receive
    FreeRTOS training directly from Richard Barry, CEO of Real Time Engineers
    Ltd, and the world's leading authority on the world's leading RTOS.

    http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
    including FreeRTOS+Trace - an indispensable productivity tool, a DOS
    compatible FAT file system, and our tiny thread aware UDP/IP stack.

    http://www.FreeRTOS.org/labs - Where new FreeRTOS products go to incubate.
    Come and try FreeRTOS+TCP, our new open source TCP/IP stack for FreeRTOS.

    http://www.OpenRTOS.com - Real Time Engineers ltd. license FreeRTOS to High
    Integrity Systems ltd. to sell under the OpenRTOS brand.  Low cost OpenRTOS
    licenses offer ticketed support, indemnification and commercial middleware.

    http://www.SafeRTOS.com - High Integrity Systems also provide a safety
    engineered and independently SIL3 certified version for use in safety and
    mission critical applications that require provable dependability.

    1 tab == 4 spaces!
*/

/*
	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				( ( QueueHandle_t ) 0 )
#define serHANDLE						( ( xComPortHandle ) 1 )
#define serNO_BLOCK						( ( TickType_t ) 0 )

/*-----------------------------------------------------------*/

/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static QueueHandle_t xRxedChars;
static QueueHandle_t 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 long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
xComPortHandle xReturn = serHANDLE;
const unsigned long ulFuclk = ( configCPU_CLOCK_HZ / 2 ) / 8UL;

	/* Create the queues used to hold Rx and Tx characters. */
	xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
	xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );

	/* 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 char *pcRxedChar, TickType_t 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 char * const pcString, unsigned short usStringLength )
{
signed char *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 char * ) pcString;
	while( *pxNext )
	{
		xSerialPutChar( pxPort, *pxNext, serNO_BLOCK );
		pxNext++;
	}
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, TickType_t 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 )
{
char 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 );	
}