FreeRTOS-Kernel/Demo/NiosII_CycloneIII_DBC3C40_GCC/RTOSDemo/serial.c

/*
    FreeRTOS V6.0.0 - Copyright (C) 2009 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
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*/

/* NOTE:  This is just a test file and not intended to be a generic 
COM driver. */

#include "altera_avalon_uart.h"
#include "altera_avalon_uart_regs.h"
#include "sys/alt_irq.h"

#include "FreeRTOS.h"
#include "queue.h"
#include "system.h"
#include "Serial.h"
/*---------------------------------------------------------------------------*/

#define serINVALID_QUEUE				( ( xQueueHandle ) 0 )
#define serNO_BLOCK						( ( portTickType ) 0 )
/*---------------------------------------------------------------------------*/

static xQueueHandle xRxedChars; 
static xQueueHandle xCharsForTx; 

alt_u32 uartControl;
/*---------------------------------------------------------------------------*/

static void vUARTInterruptHandler( void* context, alt_u32 id );
static void vUARTReceiveHandler( alt_u32 status );
static void vUARTTransmitHandler( alt_u32 status );
/*---------------------------------------------------------------------------*/

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
	/* 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();
		{
			uartControl = ALTERA_AVALON_UART_CONTROL_RTS_MSK | ALTERA_AVALON_UART_CONTROL_RRDY_MSK | ALTERA_AVALON_UART_CONTROL_DCTS_MSK;
			IOWR_ALTERA_AVALON_UART_CONTROL( UART_BASE, uartControl ); 
		  
		    /* register the interrupt handler */
			alt_irq_register ( UART_IRQ, NULL, vUARTInterruptHandler );
		}
		portEXIT_CRITICAL();
	}
	else
	{
		return ( xComPortHandle ) 0;
	}
    return ( xComPortHandle ) 1;
}
/*---------------------------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{
    /* Never used. */
}
/*---------------------------------------------------------------------------*/

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
	{
		uartControl |= ALTERA_AVALON_UART_CONTROL_RRDY_MSK;
		IOWR_ALTERA_AVALON_UART_CONTROL( UART_BASE, uartControl );
		return pdFALSE;
	}
}
/*---------------------------------------------------------------------------*/

signed portBASE_TYPE xSerialPutChar( xComPortHandle pxPort, signed char cOutChar, portTickType xBlockTime )
{
signed portBASE_TYPE lReturn = pdPASS;

	/* Place the character in the queue of characters to be transmitted. */
	if( xQueueSend( xCharsForTx, &cOutChar, xBlockTime ) == pdPASS )
	{
        /*Triggers an interrupt on every character or (down) when queue is full. */
        uartControl |= ALTERA_AVALON_UART_CONTROL_TRDY_MSK; 
        IOWR_ALTERA_AVALON_UART_CONTROL( UART_BASE, uartControl );
        lReturn = pdPASS;
    }
    else
    {	
		lReturn = pdFAIL;
	}
	return lReturn;
}
/*---------------------------------------------------------------------------*/

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++;
	}
}
/*-----------------------------------------------------------*/

static void vUARTInterruptHandler( void* context, alt_u32 id )
{
	alt_u32 status;

	/* Read the status register in order to determine the cause of the 
    interrupt. */
	status = IORD_ALTERA_AVALON_UART_STATUS( UART_BASE );
	
	/* Clear any error flags set at the device */
	IOWR_ALTERA_AVALON_UART_STATUS( UART_BASE, 0 );
	
	/* process a read irq */
	if ( status & ALTERA_AVALON_UART_STATUS_RRDY_MSK )
	{
		vUARTReceiveHandler( status );
	}
	
	/* process a write irq */
	if ( status & ( ALTERA_AVALON_UART_STATUS_TRDY_MSK  ) )
	{
		vUARTTransmitHandler( status );
	}
}
/*---------------------------------------------------------------------------*/

static void vUARTReceiveHandler( alt_u32 status )
{
signed char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

	/* If there was an error, discard the data */
	if ( status & ( ALTERA_AVALON_UART_STATUS_PE_MSK | ALTERA_AVALON_UART_STATUS_FE_MSK ) )
	{
        asm("break");
		return;
	}

	/* Transfer data from the device to the circular buffer */
	cChar = IORD_ALTERA_AVALON_UART_RXDATA( UART_BASE );
	if ( pdTRUE != xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken ) )
	{
		/* If the circular buffer was full, disable interrupts. Interrupts will 
        be re-enabled when data is removed from the buffer. */
		uartControl &= ~ALTERA_AVALON_UART_CONTROL_RRDY_MSK;
		IOWR_ALTERA_AVALON_UART_CONTROL( UART_BASE, uartControl );
	}
    
	portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );
}
/*---------------------------------------------------------------------------*/

static void vUARTTransmitHandler( alt_u32 status )
{
signed char cChar;
portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
	/* Transfer data if there is some ready to be transferred */
	if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
	{
		IOWR_ALTERA_AVALON_UART_TXDATA( UART_BASE, cChar );
    }
    else
    {
		uartControl &= ~ALTERA_AVALON_UART_CONTROL_TRDY_MSK;
    }
	
	IOWR_ALTERA_AVALON_UART_CONTROL( UART_BASE, uartControl );
    portEND_SWITCHING_ISR( xHigherPriorityTaskWoken );    
}    
/*---------------------------------------------------------------------------*/