/****************************************************************************
* drivers/serial/serial_io.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifdef CONFIG_SMP
# include <nuttx/irq.h>
#endif
#include <assert.h>
#include <sys/types.h>
#include <stdint.h>
#include <debug.h>
#include <nuttx/signal.h>
#include <nuttx/serial/serial.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* 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;
#ifdef CONFIG_SMP
irqstate_t flags = enter_critical_section();
#endif
/* 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 that
* there is space available.
*/
if (nbytes)
{
uart_datasent(dev);
}
#ifdef CONFIG_SMP
leave_critical_section(flags);
#endif
}
/****************************************************************************
* Name: uart_recvchars
*
* 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;
#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP) || \
defined(CONFIG_TTY_FORCE_PANIC) || defined(CONFIG_TTY_LAUNCH)
int signo = 0;
#endif
uint16_t nbytes = 0;
if (nexthead >= rxbuf->size)
{
nexthead = 0;
}
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
/* Pre-calculate 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))
{
bool is_full = (nexthead == rxbuf->tail);
char ch;
#ifdef CONFIG_SERIAL_IFLOWCONTROL
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
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. */
break;
}
}
#else
/* 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. */
break;
}
}
#endif
#endif
/* Get this next character from the hardware */
ch = uart_receive(dev, &status);
#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP) || \
defined(CONFIG_TTY_FORCE_PANIC) || defined(CONFIG_TTY_LAUNCH)
signo = uart_check_special(dev, &ch, 1);
#endif
/* 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);
}
#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP) || \
defined(CONFIG_TTY_FORCE_PANIC) || defined(CONFIG_TTY_LAUNCH)
/* Send the signal if necessary */
if (signo != 0)
{
nxsig_kill(dev->pid, signo);
uart_reset_sem(dev);
}
#endif
}