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nuttx/drivers/serial/serialirq.c

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/************************************************************************************
* drivers/serial/serialirq.c
*
* Copyright (C) 2007-2009, 2011, 2015 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
************************************************************************************/
/************************************************************************************
* Included Files
************************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdint.h>
#include <semaphore.h>
#include <debug.h>
#include <nuttx/serial/serial.h>
/************************************************************************************
* Pre-processor Definitions
************************************************************************************/
/************************************************************************************
* Private Types
************************************************************************************/
/************************************************************************************
* Private Function Prototypes
************************************************************************************/
/************************************************************************************
* Private Variables
************************************************************************************/
/************************************************************************************
* Private Functions
************************************************************************************/
/************************************************************************************
* Name: uart_dorxflowcontrol
*
* Description:
* Handle RX flow control using watermark levels or not
*
************************************************************************************/
#ifdef CONFIG_SERIAL_IFLOWCONTROL
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
static inline bool uart_dorxflowcontrol(FAR uart_dev_t *dev,
FAR struct uart_buffer_s *rxbuf,
unsigned int watermark)
{
unsigned int nbuffered;
/* How many bytes are buffered */
if (rxbuf->head >= rxbuf->tail)
{
nbuffered = rxbuf->head - rxbuf->tail;
}
else
{
nbuffered = rxbuf->size - rxbuf->tail + rxbuf->head;
}
/* Is the level now above the watermark level that we need to report? */
if (nbuffered >= watermark)
{
/* Let the lower level driver know that the watermark level has been
* crossed. It will probably activate RX flow control.
*/
if (uart_rxflowcontrol(dev, nbuffered, true))
{
/* Low-level driver activated RX flow control, exit loop now. */
return true;
}
}
return false;
}
#else
static inline bool uart_dorxflowcontrol(FAR uart_dev_t *dev,
FAR struct uart_buffer_s *rxbuf,
bool is_full)
{
/* Check if RX buffer is full and allow serial low-level driver to pause
* processing. This allows proper utilization of hardware flow control.
*/
if (is_full)
{
if (uart_rxflowcontrol(dev, rxbuf->size, true))
{
/* Low-level driver activated RX flow control, exit loop now. */
return true;
}
}
return false;
}
#endif
#endif
/************************************************************************************
* Public Functions
************************************************************************************/
/************************************************************************************
* Name: uart_xmitchars_dma
*
* Description:
* Set up to transfer bytes from the TX circular buffer using DMA
*
************************************************************************************/
#ifdef CONFIG_SERIAL_DMA
void uart_xmitchars_dma(FAR uart_dev_t *dev)
{
FAR struct uart_dmaxfer_s *xfer = &dev->dmatx;
if (dev->xmit.head == dev->xmit.tail)
{
/* No data to transfer. */
return;
}
if (dev->xmit.tail < dev->xmit.head)
{
xfer->buffer = &dev->xmit.buffer[dev->xmit.tail];
xfer->length = dev->xmit.head - dev->xmit.tail;
xfer->nbuffer = NULL;
xfer->nlength = 0;
}
else
{
xfer->buffer = &dev->xmit.buffer[dev->xmit.tail];
xfer->length = dev->xmit.size - dev->xmit.tail;
xfer->nbuffer = dev->xmit.buffer;
xfer->nlength = dev->xmit.head;
}
uart_dmasend(dev);
}
#endif /* CONFIG_SERIAL_DMA */
/************************************************************************************
* Name: uart_xmitchars_done
*
* Description:
* Perform operations necessary at the complete of DMA including adjusting the
* TX circular buffer indices and waking up of any threads that may have been
* waiting for space to become available in the TX circular buffer.
*
************************************************************************************/
#ifdef CONFIG_SERIAL_DMA
void uart_xmitchars_done(FAR uart_dev_t *dev)
{
FAR struct uart_dmaxfer_s *xfer = &dev->dmatx;
size_t nbytes = xfer->nbytes;
struct uart_buffer_s *txbuf = &dev->xmit;
/* Move tail for nbytes. */
txbuf->tail = (txbuf->tail + nbytes) % txbuf->size;
xfer->nbytes = 0;
xfer->length = xfer->nlength = 0;
/* If any bytes were removed from the buffer, inform any waiters there there is
* space available.
*/
if (nbytes)
{
uart_datasent(dev);
}
}
#endif /* CONFIG_SERIAL_DMA */
/************************************************************************************
* Name: uart_recvchars_dma
*
* Description:
* Set up to receive bytes into the RX circular buffer using DMA
*
************************************************************************************/
#ifdef CONFIG_SERIAL_DMA
void uart_recvchars_dma(FAR uart_dev_t *dev)
{
FAR struct uart_dmaxfer_s *xfer = &dev->dmarx;
FAR struct uart_buffer_s *rxbuf = &dev->recv;
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
unsigned int watermark;
#endif
bool is_full;
int nexthead = rxbuf->head + 1;
if (nexthead >= rxbuf->size)
{
nexthead = 0;
}
is_full = nexthead == rxbuf->tail;
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
/* Pre-calcuate the watermark level that we will need to test against. */
watermark = (CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK * rxbuf->size) / 100;
#endif
#ifdef CONFIG_SERIAL_IFLOWCONTROL
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
if (uart_dorxflowcontrol(dev, rxbuf, watermark))
{
return;
}
#else
if (uart_dorxflowcontrol(dev, rxbuf, is_full))
{
return;
}
#endif
#endif
if (is_full)
{
/* If there is no free space in receive buffer we cannot start DMA
* transfer.
*/
return;
}
if (rxbuf->tail <= rxbuf->head)
{
xfer->buffer = &rxbuf->buffer[rxbuf->head];
xfer->nbuffer = rxbuf->buffer;
if (rxbuf->tail > 0)
{
xfer->length = rxbuf->size - rxbuf->head;
xfer->nlength = rxbuf->tail - 1;
}
else
{
xfer->length = rxbuf->size - rxbuf->head - 1;
xfer->nlength = 0;
}
}
else
{
xfer->buffer = &rxbuf->buffer[rxbuf->head];
xfer->length = rxbuf->tail - rxbuf->head - 1;
xfer->nbuffer = NULL;
xfer->nlength = 0;
}
uart_dmareceive(dev);
}
#endif /* CONFIG_SERIAL_DMA */
/************************************************************************************
* Name: uart_recvchars_done
*
* Description:
* Perform operations necessary at the complete of DMA including adjusting the
* RX circular buffer indices and waking up of any threads that may have been
* waiting for new data to become available in the RX circular buffer.
*
************************************************************************************/
#ifdef CONFIG_SERIAL_DMA
void uart_recvchars_done(FAR uart_dev_t *dev)
{
FAR struct uart_dmaxfer_s *xfer = &dev->dmarx;
FAR struct uart_buffer_s *rxbuf = &dev->recv;
size_t nbytes = xfer->nbytes;
/* Move head for nbytes. */
rxbuf->head = (rxbuf->head + nbytes) % rxbuf->size;
xfer->nbytes = 0;
xfer->length = xfer->nlength = 0;
/* If any bytes were added to the buffer, inform any waiters there is new
* incoming data available.
*/
if (nbytes)
{
uart_datareceived(dev);
}
}
#endif /* CONFIG_SERIAL_DMA */
/************************************************************************************
* Name: uart_xmitchars
*
* Description:
* This function is called from the UART interrupt handler when an interrupt
* is received indicating that there is more space in the transmit FIFO. This
* function will send characters from the tail of the xmit buffer while the driver
* write() logic adds data to the head of the xmit buffer.
*
************************************************************************************/
void uart_xmitchars(FAR uart_dev_t *dev)
{
uint16_t nbytes = 0;
/* Send while we still have data in the TX buffer & room in the fifo */
while (dev->xmit.head != dev->xmit.tail && uart_txready(dev))
{
/* Send the next byte */
uart_send(dev, dev->xmit.buffer[dev->xmit.tail]);
nbytes++;
/* Increment the tail index */
if (++(dev->xmit.tail) >= dev->xmit.size)
{
dev->xmit.tail = 0;
}
}
/* When all of the characters have been sent from the buffer disable the TX
* interrupt.
*
* Potential bug? If nbytes == 0 && (dev->xmit.head == dev->xmit.tail) &&
* dev->xmitwaiting == true, then disabling the TX interrupt will leave
* the uart_write() logic waiting to TX to complete with no TX interrupts.
* Can that happen?
*/
if (dev->xmit.head == dev->xmit.tail)
{
uart_disabletxint(dev);
}
/* If any bytes were removed from the buffer, inform any waiters there there is
* space available.
*/
if (nbytes)
{
uart_datasent(dev);
}
}
/************************************************************************************
* Name: uart_receivechars
*
* Description:
* This function is called from the UART interrupt handler when an interrupt
* is received indicating that are bytes available in the receive fifo. This
* function will add chars to head of receive buffer. Driver read() logic will
* take characters from the tail of the buffer.
*
************************************************************************************/
void uart_recvchars(FAR uart_dev_t *dev)
{
FAR struct uart_buffer_s *rxbuf = &dev->recv;
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
unsigned int watermark;
#endif
unsigned int status;
int nexthead = rxbuf->head + 1;
uint16_t nbytes = 0;
bool is_full;
if (nexthead >= rxbuf->size)
{
nexthead = 0;
}
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
/* Pre-calcuate the watermark level that we will need to test against. */
watermark = (CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK * rxbuf->size) / 100;
#endif
/* Loop putting characters into the receive buffer until there are no further
* characters to available.
*/
while (uart_rxavailable(dev))
{
is_full = (nexthead == rxbuf->tail);
char ch;
#ifdef CONFIG_SERIAL_IFLOWCONTROL
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
if (uart_dorxflowcontrol(dev, rxbuf, watermark))
{
break;
}
#else
if (uart_dorxflowcontrol(dev, rxbuf, is_full))
{
break;
}
#endif
#endif
ch = uart_receive(dev, &status);
/* If the RX buffer becomes full, then the serial data is discarded. This is
* necessary because on most serial hardware, you must read the data in order
* to clear the RX interrupt. An option on some hardware might be to simply
* disable RX interrupts until the RX buffer becomes non-FULL. However, that
* would probably just cause the overrun to occur in hardware (unless it has
* some large internal buffering).
*/
if (!is_full)
{
/* Add the character to the buffer */
rxbuf->buffer[rxbuf->head] = ch;
nbytes++;
/* Increment the head index */
rxbuf->head = nexthead;
if (++nexthead >= rxbuf->size)
{
nexthead = 0;
}
}
}
/* If any bytes were added to the buffer, inform any waiters there is new
* incoming data available.
*/
if (nbytes)
{
uart_datareceived(dev);
}
}
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