Subversion Repositories openrisc_2011-10-31

/*

    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

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    FreeRTOS WEB site.

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*/

/*

Changes from V1.2.5

        +  Clear overrun errors in the Rx ISR.  Overrun errors prevent any further

           characters being received.

Changes from V2.0.0

        + Use portTickType in place of unsigned pdLONG for delay periods.

        + cQueueReieveFromISR() used in place of xQueueReceive() in ISR.

*/

/* BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER. */

/* Scheduler header files. */

#include "FreeRTOS.h"

#include "task.h"

#include "serial.h"

#include "queue.h"

/*

 * Prototypes for ISR's.  The PIC architecture means that these functions

 * have to be called from port.c.  The prototypes are not however included

 * in the header as the header is common to all ports.

 */

void vSerialTxISR( void );

void vSerialRxISR( void );

/* Hardware pin definitions. */

#define serTX_PIN       TRISCbits.TRISC6

#define serRX_PIN       TRISCbits.TRISC7

/* Bit/register definitions. */

#define serINPUT                                ( 1 )

#define serOUTPUT                               ( 0 )

#define serTX_ENABLE                    ( ( unsigned short ) 1 )

#define serRX_ENABLE                    ( ( unsigned short ) 1 )

#define serHIGH_SPEED                   ( ( unsigned short ) 1 )

#define serCONTINUOUS_RX                ( ( unsigned short ) 1 )

#define serCLEAR_OVERRUN                ( ( unsigned short ) 0 )

#define serINTERRUPT_ENABLED    ( ( unsigned short ) 1 )

#define serINTERRUPT_DISABLED   ( ( unsigned short ) 0 )

/* All ISR's use the PIC18 low priority interrupt. */

#define                                                 serLOW_PRIORITY ( 0 )

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

/* Queues to interface between comms API and interrupt routines. */

static xQueueHandle xRxedChars;

static xQueueHandle xCharsForTx;

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

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )

{

unsigned long ulBaud;

        /* Calculate the baud rate generator constant.

        SPBRG = ( (FOSC / Desired Baud Rate) / 16 ) - 1 */

        ulBaud = configCPU_CLOCK_HZ / ulWantedBaud;

        ulBaud /= ( unsigned long ) 16;

        ulBaud -= ( unsigned long ) 1;

        /* Create the queues used by the ISR's to interface to tasks. */

        xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );

        xCharsForTx = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( char ) );

        portENTER_CRITICAL();

        {

                /* Start with config registers cleared, so we can just set the wanted

                bits. */

                TXSTA = ( unsigned short ) 0;

                RCSTA = ( unsigned short ) 0;

                /* Set the baud rate generator using the above calculated constant. */

                SPBRG = ( unsigned char ) ulBaud;

                /* Setup the IO pins to enable the USART IO. */

                serTX_PIN = serOUTPUT;

                serRX_PIN = serINPUT;

                /* Set the serial interrupts to use the same priority as the tick. */

                IPR1bits.TXIP = serLOW_PRIORITY;

                IPR1bits.RCIP = serLOW_PRIORITY;

                /* Setup Tx configuration. */

                TXSTAbits.BRGH = serHIGH_SPEED;

                TXSTAbits.TXEN = serTX_ENABLE;

                /* Setup Rx configuration. */

                RCSTAbits.SPEN = serRX_ENABLE;

                RCSTAbits.CREN = serCONTINUOUS_RX;

                /* Enable the Rx interrupt now, the Tx interrupt will get enabled when

                we have data to send. */

                PIE1bits.RCIE = serINTERRUPT_ENABLED;

        }

        portEXIT_CRITICAL();

        /* Unlike other ports, this serial code does not allow for more than one

        com port.  We therefore don't return a pointer to a port structure and

        can     instead just return NULL. */

        return NULL;

}

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

xComPortHandle xSerialPortInit( eCOMPort ePort, eBaud eWantedBaud, eParity eWantedParity, eDataBits eWantedDataBits, eStopBits eWantedStopBits, unsigned portBASE_TYPE uxBufferLength )

{

        /* This is not implemented in this port.

        Use xSerialPortInitMinimal() instead. */

}

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

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

{

        /* 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;

        }

}

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

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

{

        /* Return false if after the block time there is no room on the Tx queue. */

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

        {

                return pdFAIL;

        }

        /* Turn interrupt on - ensure the compiler only generates a single

        instruction for this. */

        PIE1bits.TXIE = serINTERRUPT_ENABLED;

        return pdPASS;

}

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

void vSerialClose( xComPortHandle xPort )

{

        /* Not implemented for this port.

        To implement, turn off the interrupts and delete the memory

        allocated to the queues. */

}

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

#pragma interruptlow vSerialRxISR save=PRODH, PRODL, TABLAT, section(".tmpdata")

void vSerialRxISR( void )

{

char cChar;

portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

        /* Get the character and post it on the queue of Rxed characters.

        If the post causes a task to wake force a context switch as the woken task

        may have a higher priority than the task we have interrupted. */

        cChar = RCREG;

        /* Clear any overrun errors. */

        if( RCSTAbits.OERR )

        {

                RCSTAbits.CREN = serCLEAR_OVERRUN;

                RCSTAbits.CREN = serCONTINUOUS_RX;

        }

        xQueueSendFromISR( xRxedChars, ( const void * ) &cChar, &xHigherPriorityTaskWoken );

        if( xHigherPriorityTaskWoken )

        {

                taskYIELD();

        }

}

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

#pragma interruptlow vSerialTxISR save=PRODH, PRODL, TABLAT, section(".tmpdata")

void vSerialTxISR( void )

{

char cChar, cTaskWoken = pdFALSE;

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

        {

                /* Send the next character queued for Tx. */

                TXREG = cChar;

        }

        else

        {

                /* Queue empty, nothing to send. */

                PIE1bits.TXIE = serINTERRUPT_DISABLED;

        }

}