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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

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*/

/*

        Changes from V2.4.0

                + Made serial ISR handling more complete and robust.

        Changes from V2.4.1

                + Split serial.c into serial.c and serialISR.c.  serial.c can be

                  compiled using ARM or THUMB modes.  serialISR.c must always be

                  compiled in ARM mode.

                + Another small change to cSerialPutChar().

        Changed from V2.5.1

                + In cSerialPutChar() an extra check is made to ensure the post to

                  the queue was successful if then attempting to retrieve the posted

                  character.

*/

/*

        BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.

        This file contains all the serial port components that can be compiled to

        either ARM or THUMB mode.  Components that must be compiled to ARM mode are

        contained in serialISR.c.

*/

/* Standard includes. */

#include <stdlib.h>

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "queue.h"

#include "task.h"

/* Demo application includes. */

#include "serial.h"

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

/* Constants to setup and access the UART. */

#define serDLAB                                                 ( ( unsigned char ) 0x80 )

#define serENABLE_INTERRUPTS                    ( ( unsigned char ) 0x03 )

#define serNO_PARITY                                    ( ( unsigned char ) 0x00 )

#define ser1_STOP_BIT                                   ( ( unsigned char ) 0x00 )

#define ser8_BIT_CHARS                                  ( ( unsigned char ) 0x03 )

#define serFIFO_ON                                              ( ( unsigned char ) 0x01 )

#define serCLEAR_FIFO                                   ( ( unsigned char ) 0x06 )

#define serWANTED_CLOCK_SCALING                 ( ( unsigned long ) 16 )

/* Constants to setup and access the VIC. */

#define serUART0_VIC_CHANNEL                    ( ( unsigned long ) 0x0006 )

#define serUART0_VIC_CHANNEL_BIT                ( ( unsigned long ) 0x0040 )

#define serUART0_VIC_ENABLE                             ( ( unsigned long ) 0x0020 )

#define serCLEAR_VIC_INTERRUPT                  ( ( unsigned long ) 0 )

#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;

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

/* Communication flag between the interrupt service routine and serial API. */

static volatile long *plTHREEmpty;

/*

 * The queues are created in serialISR.c as they are used from the ISR.

 * Obtain references to the queues and THRE Empty flag.

 */

extern void vSerialISRCreateQueues(     unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx, long volatile **pplTHREEmptyFlag );

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

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

unsigned long ulDivisor, ulWantedClock;

xComPortHandle xReturn = serHANDLE;

extern void ( vUART_ISR_Wrapper )( void );

        /* The queues are used in the serial ISR routine, so are created from

        serialISR.c (which is always compiled to ARM mode. */

        vSerialISRCreateQueues( uxQueueLength, &xRxedChars, &xCharsForTx, &plTHREEmpty );

        if(

                ( xRxedChars != serINVALID_QUEUE ) &&

                ( xCharsForTx != serINVALID_QUEUE ) &&

                ( ulWantedBaud != ( unsigned long ) 0 )

          )

        {

                portENTER_CRITICAL();

                {

                        /* Setup the baud rate:  Calculate the divisor value. */

                        ulWantedClock = ulWantedBaud * serWANTED_CLOCK_SCALING;

                        ulDivisor = configCPU_CLOCK_HZ / ulWantedClock;

                        /* Set the DLAB bit so we can access the divisor. */

                        UART0_LCR |= serDLAB;

                        /* Setup the divisor. */

                        UART0_DLL = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff );

                        ulDivisor >>= 8;

                        UART0_DLM = ( unsigned char ) ( ulDivisor & ( unsigned long ) 0xff );

                        /* Turn on the FIFO's and clear the buffers. */

                        UART0_FCR = ( serFIFO_ON | serCLEAR_FIFO );

                        /* Setup transmission format. */

                        UART0_LCR = serNO_PARITY | ser1_STOP_BIT | ser8_BIT_CHARS;

                        /* Setup the VIC for the UART. */

                        VICIntSelect &= ~( serUART0_VIC_CHANNEL_BIT );

                        VICIntEnable |= serUART0_VIC_CHANNEL_BIT;

                        VICVectAddr1 = ( long ) vUART_ISR_Wrapper;

                        VICVectCntl1 = serUART0_VIC_CHANNEL | serUART0_VIC_ENABLE;

                        /* Enable UART0 interrupts. */

                        UART0_IER |= serENABLE_INTERRUPTS;

                }

                portEXIT_CRITICAL();

        }

        else

        {

                xReturn = ( xComPortHandle ) 0;

        }

        return xReturn;

}

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

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

{

        /* The port handle is not required as this driver only supports UART0. */

        ( 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;

        /* 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;

        ( void ) usStringLength;

        /* 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 )

{

signed portBASE_TYPE xReturn;

        /* This demo driver only supports one port so the parameter is not used. */

        ( void ) pxPort;

        portENTER_CRITICAL();

        {

                /* Is there space to write directly to the UART? */

                if( *plTHREEmpty == ( long ) pdTRUE )

                {

                        /* We wrote the character directly to the UART, so was

                        successful. */

                        *plTHREEmpty = pdFALSE;

                        UART0_THR = cOutChar;

                        xReturn = pdPASS;

                }

                else

                {

                        /* We cannot write directly to the UART, so queue the character.

                        Block for a maximum of xBlockTime if there is no space in the

                        queue. */

                        xReturn = xQueueSend( xCharsForTx, &cOutChar, xBlockTime );

                        /* Depending on queue sizing and task prioritisation:  While we

                        were blocked waiting to post interrupts were not disabled.  It is

                        possible that the serial ISR has emptied the Tx queue, in which

                        case we need to start the Tx off again. */

                        if( ( *plTHREEmpty == ( long ) pdTRUE ) && ( xReturn == pdPASS ) )

                        {

                                xQueueReceive( xCharsForTx, &cOutChar, serNO_BLOCK );

                                *plTHREEmpty = pdFALSE;

                                UART0_THR = cOutChar;

                        }

                }

        }

        portEXIT_CRITICAL();

        return xReturn;

}

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

void vSerialClose( xComPortHandle xPort )

{

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

        ( void ) xPort;

}

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