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/*
* FreeRTOS Kernel V10.3.0
* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
* http://www.FreeRTOS.org
* http://aws.amazon.com/freertos
*
* 1 tab == 4 spaces!
*/
/*
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 ( ( QueueHandle_t ) 0 )
#define serHANDLE ( ( xComPortHandle ) 1 )
#define serNO_BLOCK ( ( TickType_t ) 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 QueueHandle_t xRxedChars;
static QueueHandle_t 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, TickType_t 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, TickType_t 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;
}