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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

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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"

/* Library includes. */

#include "usart/usart.h"

#include "pmc/pmc.h"

#include "irq/irq.h"

#include "pio/pio.h"

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

/* Interrupt control macros. */

#define serINTERRUPT_LEVEL                              ( 5 )

#define vInterruptOn()                                  BOARD_USART_BASE->US_IER = ( AT91C_US_TXRDY | AT91C_US_RXRDY )

#define vInterruptOff()                                 BOARD_USART_BASE->US_IDR = 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;

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

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

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 );

const Pin xUSART_Pins[] = { BOARD_PIN_USART_RXD, BOARD_PIN_USART_TXD };

        /* 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 peripheral clock in the PMC. */

                        PMC_EnablePeripheral( BOARD_ID_USART );

                        /* Configure the USART. */

                        USART_Configure( BOARD_USART_BASE, AT91C_US_CHRL_8_BITS | AT91C_US_PAR_NONE | AT91C_US_NBSTOP_1_BIT, ulWantedBaud, configCPU_CLOCK_HZ );

                        /* Configure the interrupt.  Note the pre-emption priority is set

                        in bits [8:15] of the priority value passed as the parameter. */

                        IRQ_ConfigureIT( BOARD_ID_USART, ( configMAX_SYSCALL_INTERRUPT_PRIORITY << 8 ), vSerialISR );

                        IRQ_EnableIT( BOARD_ID_USART );

                        /* Enable receiver & transmitter. */

                        USART_SetTransmitterEnabled( BOARD_USART_BASE, pdTRUE );

                        USART_SetReceiverEnabled( BOARD_USART_BASE, pdTRUE );

                        /* Configure IO for USART use. */

                        PIO_Configure( xUSART_Pins, PIO_LISTSIZE( xUSART_Pins ) );

                }

                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. */

}

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

void vSerialISR( void )

{

unsigned long ulStatus;

signed char cChar;

portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;

        /* What caused the interrupt? */

        ulStatus = BOARD_USART_BASE->US_CSR &= BOARD_USART_BASE->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. */

                        BOARD_USART_BASE->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 = BOARD_USART_BASE->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 );

}