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/*

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

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

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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.

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*/

/*

        BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.

*/

/* Library includes. */

#include "uart.h"

#include "gpio.h"

#include "eic.h"

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "queue.h"

/* Demo application includes. */

#include "serial.h"

#define UART0_Rx_Pin                                    ( 0x0001<< 8 )

#define UART0_Tx_Pin                                    ( 0x0001<< 9 )

#define serINVALID_QUEUE                                ( ( xQueueHandle ) 0 )

#define serNO_BLOCK                                             ( ( portTickType ) 0 )

/* Macros to turn on and off the Tx empty interrupt. */

#define serINTERRUPT_ON()                               UART0->IER |= UART_TxHalfEmpty

#define serINTERRUPT_OFF()                              UART0->IER &= ~UART_TxHalfEmpty

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

/* 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.s79. */

extern void vSerialISREntry( void );

/* The interrupt service routine - called from the assembly entry point. */

__arm void vSerialISR( void );

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

/*

 * See the serial2.h header file.

 */

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

xComPortHandle xReturn;

        /* 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();

                {

                        /* Setup the UART port pins. */

                        GPIO_Config( GPIO0, UART0_Tx_Pin, GPIO_AF_PP );

                        GPIO_Config( GPIO0, UART0_Rx_Pin, GPIO_IN_TRI_CMOS );

                        /* Configure the UART. */

                        UART_OnOffConfig( UART0, ENABLE );

                        UART_FifoConfig( UART0, DISABLE );

                        UART_FifoReset( UART0, UART_RxFIFO );

                        UART_FifoReset( UART0, UART_TxFIFO );

                        UART_LoopBackConfig(UART0, DISABLE );

                        UART_Config( UART0, ulWantedBaud, UART_NO_PARITY, UART_1_StopBits, UARTM_8D );

                        UART_RxConfig( UART0, ENABLE );

                        /* Configure the IEC for the UART interrupts. */

                        EIC_IRQChannelPriorityConfig( UART0_IRQChannel, 1 );

                        EIC_IRQChannelConfig( UART0_IRQChannel, ENABLE );

                        EIC_IRQConfig( ENABLE );

                        UART_ItConfig( UART0, UART_RxBufFull, ENABLE );

                }

                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, 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 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, portTickType xBlockTime )

{

        /* Place the character in the queue of characters to be transmitted. */

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

        {

                return pdFAIL;

        }

        /* Turn on the Tx interrupt so the ISR will remove the character from the

        queue and send it.   This does not need to be in a critical section as

        if the interrupt has already removed the character the next interrupt

        will simply turn off the Tx interrupt again. */

        serINTERRUPT_ON();

        return pdPASS;

}

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

void vSerialClose( xComPortHandle xPort )

{

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

}

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

/* Serial port ISR.  This can cause a context switch so is not defined as a

standard ISR using the __irq keyword.  Instead a wrapper function is defined

within serialISR.s79 which in turn calls this function.  See the port

documentation on the FreeRTOS.org website for more information. */

__arm void vSerialISR( void )

{

unsigned short usStatus;

signed char cChar;

portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

        /* What caused the interrupt? */

        usStatus = UART_FlagStatus( UART0 );

        if( usStatus & UART_TxHalfEmpty )

        {

                /* The interrupt was caused by the THR becoming empty.  Are there any

                more characters to transmit? */

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

                {

                        /* A character was retrieved from the queue so can be sent to the

                        THR now. */

                        UART0->TxBUFR = cChar;

                }

                else

                {

                        /* Queue empty, nothing to send so turn off the Tx interrupt. */

                        serINTERRUPT_OFF();

                }

        }

        if( usStatus &  UART_RxBufFull )

        {

                /* The interrupt was caused by a character being received.  Grab the

                character from the RHR and place it in the queue of received

                characters. */

                cChar = UART0->RxBUFR;

                xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );

        }

        /* If a task was woken by either a character being received or a character

        being transmitted then we may need to switch to another task. */

        portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );

        /* End the interrupt in the EIC. */

        portCLEAR_EIC();

}