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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.

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    the terms of the GNU General Public License (version 2) as published by the

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*/

/*

        BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.

*/

/* Standard includes. */

#include <stdlib.h>

/* Scheduler includes. */

#include "FreeRTOS.h"

#include "queue.h"

/* Demo application includes. */

#include "serial.h"

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

/* Location of the COM0 registers. */

#define serCOM0                                                 ( ( AT91PS_USART ) AT91C_BASE_US0 )

/* Interrupt control macros. */

#define serINTERRUPT_LEVEL                              ( 5 )

#define vInterruptOn()                                  AT91F_US_EnableIt( serCOM0, AT91C_US_TXRDY | AT91C_US_RXRDY )

#define vInterruptOff()                                 AT91F_US_DisableIt( serCOM0, AT91C_US_TXRDY )

/* Misc constants. */

#define serINVALID_QUEUE                                ( ( xQueueHandle ) 0 )

#define serHANDLE                                               ( ( xComPortHandle ) 1 )

#define serNO_BLOCK                                             ( ( portTickType ) 0 )

#define serNO_TIMEGUARD                                 ( ( unsigned long ) 0 )

#define serNO_PERIPHERAL_B_SETUP                ( ( unsigned long ) 0 )

/* 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 = serHANDLE;

extern void ( vUART_ISR )( void );

        /* 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();

                {

                        /* Enable the USART clock. */

                        AT91F_PMC_EnablePeriphClock( AT91C_BASE_PMC, 1 << AT91C_ID_US0 );

                        AT91F_PIO_CfgPeriph( AT91C_BASE_PIOA, ( ( unsigned long ) AT91C_PA5_RXD0 ) | ( ( unsigned long ) AT91C_PA6_TXD0 ), serNO_PERIPHERAL_B_SETUP );

                        /* Set the required protocol. */

                        AT91F_US_Configure( serCOM0, configCPU_CLOCK_HZ, AT91C_US_ASYNC_MODE, ulWantedBaud, serNO_TIMEGUARD );

                        /* Enable Rx and Tx. */

                        serCOM0->US_CR = AT91C_US_RXEN | AT91C_US_TXEN;

                        /* Enable the Rx interrupts.  The Tx interrupts are not enabled

                        until there are characters to be transmitted. */

                AT91F_US_EnableIt( serCOM0, AT91C_US_RXRDY );

                        /* Enable the interrupts in the AIC. */

                        AT91F_AIC_ConfigureIt( AT91C_BASE_AIC, AT91C_ID_US0, serINTERRUPT_LEVEL, AT91C_AIC_SRCTYPE_INT_LEVEL_SENSITIVE, ( void (*)( void ) ) vSerialISREntry );

                        AT91F_AIC_EnableIt( AT91C_BASE_AIC, AT91C_ID_US0 );

                }

                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. */

        vInterruptOn();

        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 long ulStatus;

signed char cChar;

portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

        /* What caused the interrupt? */

        ulStatus = serCOM0->US_CSR &= serCOM0->US_IMR;

        if( ulStatus & AT91C_US_TXRDY )

        {

                /* 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. */

                        serCOM0->US_THR = cChar;

                }

                else

                {

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

                        vInterruptOff();

                }

        }

        if( ulStatus & AT91C_US_RXRDY )

        {

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

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

                characters. */

                cChar = serCOM0->US_RHR;

                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 AIC. */

        AT91C_BASE_AIC->AIC_EOICR = 0;

}