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jeremybenn |
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). Thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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***NOTE*** The exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*
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BASIC INTERRUPT DRIVEN SERIAL PORT DRIVER FOR UART0.
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This file contains all the serial port components that must be compiled
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to ARM mode. The components that can be compiled to either ARM or THUMB
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mode are contained in serial.c.
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*/
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/* Standard includes. */
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#include <stdlib.h>
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "queue.h"
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#include "task.h"
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/* Demo application includes. */
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#include "serial.h"
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/*-----------------------------------------------------------*/
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/* Constant to access the VIC. */
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#define serCLEAR_VIC_INTERRUPT ( ( unsigned long ) 0 )
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/* Constants to determine the ISR source. */
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#define serSOURCE_THRE ( ( unsigned char ) 0x02 )
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#define serSOURCE_RX_TIMEOUT ( ( unsigned char ) 0x0c )
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#define serSOURCE_ERROR ( ( unsigned char ) 0x06 )
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#define serSOURCE_RX ( ( unsigned char ) 0x04 )
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#define serINTERRUPT_SOURCE_MASK ( ( unsigned char ) 0x0f )
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/* Queues used to hold received characters, and characters waiting to be
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transmitted. */
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static xQueueHandle xRxedChars;
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static xQueueHandle xCharsForTx;
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static volatile long lTHREEmpty;
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/*-----------------------------------------------------------*/
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/*
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* The queues are created in serialISR.c as they are used from the ISR.
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* Obtain references to the queues and THRE Empty flag.
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*/
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void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars, xQueueHandle *pxCharsForTx, long volatile **pplTHREEmptyFlag );
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/* UART0 interrupt service routine entry point. */
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void vUART_ISR_Wrapper( void ) __attribute__ ((naked));
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/* UART0 interrupt service routine handler. */
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void vUART_ISR_Handler( void ) __attribute__ ((noinline));
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/*-----------------------------------------------------------*/
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void vSerialISRCreateQueues( unsigned portBASE_TYPE uxQueueLength, xQueueHandle *pxRxedChars,
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xQueueHandle *pxCharsForTx, long volatile **pplTHREEmptyFlag )
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{
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/* Create the queues used to hold Rx and Tx characters. */
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xRxedChars = xQueueCreate( uxQueueLength, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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xCharsForTx = xQueueCreate( uxQueueLength + 1, ( unsigned portBASE_TYPE ) sizeof( signed char ) );
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/* Pass back a reference to the queues so the serial API file can
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post/receive characters. */
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*pxRxedChars = xRxedChars;
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*pxCharsForTx = xCharsForTx;
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/* Initialise the THRE empty flag - and pass back a reference. */
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lTHREEmpty = ( long ) pdTRUE;
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*pplTHREEmptyFlag = &lTHREEmpty;
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}
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/*-----------------------------------------------------------*/
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void vUART_ISR_Wrapper( void )
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{
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/* Save the context of the interrupted task. */
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portSAVE_CONTEXT();
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/* Call the handler. This must be a separate function from the wrapper
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to ensure the correct stack frame is set up. */
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__asm volatile ("bl vUART_ISR_Handler");
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/* Restore the context of whichever task is going to run next. */
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portRESTORE_CONTEXT();
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}
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/*-----------------------------------------------------------*/
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void vUART_ISR_Handler( void )
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{
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signed char cChar;
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portBASE_TYPE xHigherPriorityTaskWoken = pdFALSE;
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/* What caused the interrupt? */
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switch( UART0_IIR & serINTERRUPT_SOURCE_MASK )
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{
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case serSOURCE_ERROR : /* Not handling this, but clear the interrupt. */
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cChar = UART0_LSR;
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break;
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case serSOURCE_THRE : /* The THRE is empty. If there is another
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character in the Tx queue, send it now. */
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if( xQueueReceiveFromISR( xCharsForTx, &cChar, &xHigherPriorityTaskWoken ) == pdTRUE )
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{
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UART0_THR = cChar;
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}
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else
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{
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/* There are no further characters
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queued to send so we can indicate
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that the THRE is available. */
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lTHREEmpty = pdTRUE;
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}
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break;
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case serSOURCE_RX_TIMEOUT :
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case serSOURCE_RX : /* A character was received. Place it in
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the queue of received characters. */
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cChar = UART0_RBR;
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xQueueSendFromISR( xRxedChars, &cChar, &xHigherPriorityTaskWoken );
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break;
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default : /* There is nothing to do, leave the ISR. */
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break;
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}
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if( xHigherPriorityTaskWoken )
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{
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portYIELD_FROM_ISR();
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}
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/* Clear the ISR in the VIC. */
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VICVectAddr = serCLEAR_VIC_INTERRUPT;
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}
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