FreeRTOS-Kernel/FreeRTOS/Demo/ARM7_AT91FR40008_GCC/serial/serial.c

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*/

/* 
	BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR USART0. 

	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"
#include "AT91R40008.h"
#include "usart.h"
#include "pio.h"
#include "aic.h"

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

/* Constants to setup and access the UART. */
#define portUSART0_AIC_CHANNEL	( ( unsigned long ) 2 )

#define serINVALID_QUEUE		( ( QueueHandle_t ) 0 )
#define serHANDLE				( ( xComPortHandle ) 1 )
#define serNO_BLOCK				( ( TickType_t ) 0 )

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

/* Queues used to hold received characters, and characters waiting to be
transmitted. */
static QueueHandle_t xRxedChars; 
static QueueHandle_t xCharsForTx; 

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

/* 
 * 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, QueueHandle_t *pxRxedChars, QueueHandle_t *pxCharsForTx );

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

xComPortHandle xSerialPortInitMinimal( unsigned long ulWantedBaud, unsigned portBASE_TYPE uxQueueLength )
{
unsigned long ulSpeed;
unsigned long ulCD;
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 );

	if( 
		( xRxedChars != serINVALID_QUEUE ) && 
		( xCharsForTx != serINVALID_QUEUE ) && 
		( ulWantedBaud != ( unsigned long ) 0 ) 
	  )
	{
		portENTER_CRITICAL();
		{
			/* Enable clock to USART0... */
			AT91C_BASE_PS->PS_PCER = AT91C_PS_US0;

			/* Disable all USART0 interrupt sources to begin... */
			AT91C_BASE_US0->US_IDR = 0xFFFFFFFF;

			/* Reset various status bits (just in case)... */
			AT91C_BASE_US0->US_CR = US_RSTSTA;

			AT91C_BASE_PIO->PIO_PDR = TXD0 | RXD0;  /* Enable RXD and TXD pins */
			AT91C_BASE_US0->US_CR = US_RSTRX | US_RSTTX | US_RXDIS | US_TXDIS;

			/* Clear Transmit and Receive Counters */
			AT91C_BASE_US0->US_RCR = 0;
			AT91C_BASE_US0->US_TCR = 0;

			/* Input clock to baud rate generator is MCK */
			ulSpeed = configCPU_CLOCK_HZ * 10;  
			ulSpeed = ulSpeed / 16;
			ulSpeed = ulSpeed / ulWantedBaud;
			
			/* compute the error */
			ulCD  = ulSpeed / 10;
			if ((ulSpeed - (ulCD * 10)) >= 5)
			ulCD++;

			/* Define the baud rate divisor register */
			AT91C_BASE_US0->US_BRGR = ulCD;

			/* Define the USART mode */
			AT91C_BASE_US0->US_MR = US_CLKS_MCK | US_CHRL_8 | US_PAR_NO | US_NBSTOP_1 | US_CHMODE_NORMAL;

			/* Write the Timeguard Register */
			AT91C_BASE_US0->US_TTGR = 0;

			/* Setup the interrupt for USART0.

			Store interrupt handler function address in USART0 vector register... */
			AT91C_BASE_AIC->AIC_SVR[ portUSART0_AIC_CHANNEL ] = (unsigned long)vUART_ISR_Wrapper;
			
			/* USART0 interrupt level-sensitive, priority 1... */
			AT91C_BASE_AIC->AIC_SMR[ portUSART0_AIC_CHANNEL ] = AIC_SRCTYPE_INT_LEVEL_SENSITIVE | 1;
			
			/* Clear some pending USART0 interrupts (just in case)... */
			AT91C_BASE_US0->US_CR = US_RSTSTA;

			/* Enable USART0 interrupt sources (but not Tx for now)... */
			AT91C_BASE_US0->US_IER = US_RXRDY;

			/* Enable USART0 interrupts in the AIC... */
			AT91C_BASE_AIC->AIC_IECR = ( 1 << portUSART0_AIC_CHANNEL );

			/* Enable receiver and transmitter... */
			AT91C_BASE_US0->US_CR = US_RXEN | US_TXEN;
		}
		portEXIT_CRITICAL();
	}
	else
	{
		xReturn = ( xComPortHandle ) 0;
	}

	return xReturn;
}
/*-----------------------------------------------------------*/

signed portBASE_TYPE xSerialGetChar( xComPortHandle pxPort, signed char *pcRxedChar, TickType_t 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, TickType_t xBlockTime )
{
	( void ) pxPort;

	/* 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. */
	AT91C_BASE_US0->US_IER = US_TXRDY;

	return pdPASS;
}
/*-----------------------------------------------------------*/

void vSerialClose( xComPortHandle xPort )
{
	/* Not supported as not required by the demo application. */
	( void ) xPort;
}
/*-----------------------------------------------------------*/