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/*

    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.

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

    *                                                                         *

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    *                                                                         *

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

    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.

    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 and the FreeRTOS license exception along with FreeRTOS; if not it

    can be viewed here: http://www.freertos.org/a00114.html and also obtained

    by writing to Richard Barry, contact details for whom are available on the

    FreeRTOS WEB site.

    1 tab == 4 spaces!

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*/

/*

        BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART

*/

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "queue.h"

#include "task.h"

/* Demo application includes. */

#include "serial.h"

/* Library includes. */

#include "xparameters.h"

#include "xuartlite.h"

#include "xuartlite_l.h"

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

/* Queues used to hold received characters, and characters waiting to be

transmitted. */

static xQueueHandle xRxedChars;

static xQueueHandle xCharsForTx;

/* Structure that maintains information on the UART being used. */

static XUartLite xUART;

/*

 * Sample UART interrupt handler.  Note this is used to demonstrate the kernel

 * features and test the port - it is not intended to represent an efficient

 * implementation.

 */

static void vSerialISR( XUartLite *pxUART );

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

xComPortHandle xSerialPortInitMinimal( unsigned portLONG ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

        /* NOTE: The baud rate used by this driver is determined by the hardware

        parameterization of the UART Lite peripheral, and the baud value passed to

        this function has no effect. */

        ( void ) ulWantedBaud;

        /* 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 ) );

        /* Only initialise the UART if the queues were created correctly. */

        if( ( xRxedChars != NULL ) && ( xCharsForTx != NULL ) )

        {

                XUartLite_Initialize( &xUART, XPAR_RS232_UART_DEVICE_ID );

                XUartLite_ResetFifos( &xUART );

                XUartLite_DisableInterrupt( &xUART );

                if( xPortInstallInterruptHandler( XPAR_XPS_INTC_0_RS232_UART_INTERRUPT_INTR, ( XInterruptHandler )vSerialISR, (void *)&xUART ) == pdPASS )

                {

                        /* xPortInstallInterruptHandler() could fail if

                        vPortSetupInterruptController() has not been called prior to this

                        function. */

                        XUartLite_EnableInterrupt( &xUART );

                }

        }

        /* There is only one port so the handle is not used. */

        return ( xComPortHandle ) 0;

}

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

signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed portCHAR *pcRxedChar, portTickType xBlockTime )

{

        /* The port handle is not required as this driver only supports one UART. */

        ( 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;

        }

}

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

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed portCHAR cOutChar, portTickType xBlockTime )

{

portBASE_TYPE xReturn = pdTRUE;

        /* Just to remove compiler warning. */

        ( void ) pxPort;

        portENTER_CRITICAL();

        {

                /* If the UART FIFO is full we can block posting the new data on the

                Tx queue. */

                if( XUartLite_mIsTransmitFull( XPAR_RS232_UART_BASEADDR ) )

                {

                        if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )

                        {

                                xReturn = pdFAIL;

                        }

                }

                /* Otherwise, if there is data already in the queue we should add the

                new data to the back of the queue to ensure the sequencing is

                maintained. */

                else if( uxQueueMessagesWaiting( xCharsForTx ) )

                {

                        if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) != pdPASS )

                        {

                                xReturn = pdFAIL;

                        }

                }

                /* If the UART FIFO is not full and there is no data already in the

                queue we can write directly to the FIFO without disrupting the

                sequence. */

                else

                {

                        XIo_Out32( XPAR_RS232_UART_BASEADDR + XUL_TX_FIFO_OFFSET, cOutChar );

                }

        }

        portEXIT_CRITICAL();

        return xReturn;

}

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

void vSerialClose( xComPortHandle xPort )

{

        /* Not supported as not required by the demo application. */

        ( void ) xPort;

}

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

static void vSerialISR( XUartLite *pxUART )

{

unsigned portLONG ulISRStatus;

portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE, lDidSomething;

portCHAR cChar;

        /* Just to remove compiler warning. */

        ( void ) pxUART;

        do

        {

                lDidSomething = pdFALSE;

                ulISRStatus = XIo_In32( XPAR_RS232_UART_BASEADDR + XUL_STATUS_REG_OFFSET );

                if( ( ulISRStatus & XUL_SR_RX_FIFO_VALID_DATA ) != 0 )

                {

                        /* A character is available - place it in the queue of received

                        characters.  This might wake a task that was blocked waiting for

                        data. */

                        cChar = ( portCHAR ) XIo_In32( XPAR_RS232_UART_BASEADDR + XUL_RX_FIFO_OFFSET );

                        xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );

                        lDidSomething = pdTRUE;

                }

                if( ( ulISRStatus & XUL_SR_TX_FIFO_EMPTY ) != 0 )

                {

                        /* There is space in the FIFO - if there are any characters queue for

                        transmission they can be sent to the UART now.  This might unblock a

                        task that was waiting for space to become available on the Tx queue. */

                        if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )

                        {

                                XIo_Out32( XPAR_RS232_UART_BASEADDR + XUL_TX_FIFO_OFFSET, cChar );

                                lDidSomething = pdTRUE;

                        }

                }

        } while( lDidSomething == pdTRUE );

        /* If we woke any tasks we may require a context switch. */

        if( xHigherPriorityTaskWoken )

        {

                portYIELD_FROM_ISR();

        }

}