257 lines
7.3 KiB
C
257 lines
7.3 KiB
C
/****************************************************************************
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* drivers/serial/serial_io.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#ifdef CONFIG_SMP
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# include <nuttx/irq.h>
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#endif
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#include <assert.h>
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#include <sys/types.h>
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#include <stdint.h>
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#include <debug.h>
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#include <nuttx/signal.h>
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#include <nuttx/serial/serial.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: uart_xmitchars
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*
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* Description:
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* This function is called from the UART interrupt handler when an
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* interrupt is received indicating that there is more space in the
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* transmit FIFO. This function will send characters from the tail of
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* the xmit buffer while the driver write() logic adds data to the head
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* of the xmit buffer.
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*
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****************************************************************************/
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void uart_xmitchars(FAR uart_dev_t *dev)
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{
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uint16_t nbytes = 0;
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#ifdef CONFIG_SMP
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irqstate_t flags = enter_critical_section();
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#endif
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/* Send while we still have data in the TX buffer & room in the fifo */
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while (dev->xmit.head != dev->xmit.tail && uart_txready(dev))
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{
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/* Send the next byte */
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uart_send(dev, dev->xmit.buffer[dev->xmit.tail]);
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nbytes++;
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/* Increment the tail index */
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if (++(dev->xmit.tail) >= dev->xmit.size)
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{
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dev->xmit.tail = 0;
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}
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}
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/* When all of the characters have been sent from the buffer disable the TX
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* interrupt.
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*
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* Potential bug? If nbytes == 0 && (dev->xmit.head == dev->xmit.tail) &&
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* dev->xmitwaiting == true, then disabling the TX interrupt will leave
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* the uart_write() logic waiting to TX to complete with no TX interrupts.
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* Can that happen?
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*/
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if (dev->xmit.head == dev->xmit.tail)
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{
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uart_disabletxint(dev);
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}
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/* If any bytes were removed from the buffer, inform any waiters that
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* there is space available.
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*/
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if (nbytes)
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{
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uart_datasent(dev);
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}
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#ifdef CONFIG_SMP
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leave_critical_section(flags);
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#endif
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}
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/****************************************************************************
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* Name: uart_receivechars
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*
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* Description:
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* This function is called from the UART interrupt handler when an
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* interrupt is received indicating that are bytes available in the
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* receive FIFO. This function will add chars to head of receive buffer.
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* Driver read() logic will take characters from the tail of the buffer.
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*
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****************************************************************************/
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void uart_recvchars(FAR uart_dev_t *dev)
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{
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FAR struct uart_buffer_s *rxbuf = &dev->recv;
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#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
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unsigned int watermark;
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#endif
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unsigned int status;
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int nexthead = rxbuf->head + 1;
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#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP) || \
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defined(CONFIG_TTY_FORCE_PANIC) || defined(CONFIG_TTY_LAUNCH)
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int signo = 0;
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#endif
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uint16_t nbytes = 0;
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if (nexthead >= rxbuf->size)
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{
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nexthead = 0;
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}
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#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
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/* Pre-calculate the watermark level that we will need to test against. */
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watermark = (CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK * rxbuf->size) /
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100;
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#endif
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/* Loop putting characters into the receive buffer until there are no
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* further characters to available.
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*/
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while (uart_rxavailable(dev))
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{
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bool is_full = (nexthead == rxbuf->tail);
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char ch;
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#ifdef CONFIG_SERIAL_IFLOWCONTROL
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#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
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unsigned int nbuffered;
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/* How many bytes are buffered */
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if (rxbuf->head >= rxbuf->tail)
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{
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nbuffered = rxbuf->head - rxbuf->tail;
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}
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else
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{
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nbuffered = rxbuf->size - rxbuf->tail + rxbuf->head;
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}
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/* Is the level now above the watermark level that we need to report? */
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if (nbuffered >= watermark)
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{
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/* Let the lower level driver know that the watermark level has
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* been crossed. It will probably activate RX flow control.
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*/
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if (uart_rxflowcontrol(dev, nbuffered, true))
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{
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/* Low-level driver activated RX flow control, exit loop now. */
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break;
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}
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}
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#else
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/* Check if RX buffer is full and allow serial low-level driver to
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* pause processing. This allows proper utilization of hardware flow
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* control.
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*/
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if (is_full)
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{
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if (uart_rxflowcontrol(dev, rxbuf->size, true))
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{
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/* Low-level driver activated RX flow control, exit loop now. */
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break;
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}
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}
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#endif
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#endif
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/* Get this next character from the hardware */
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ch = uart_receive(dev, &status);
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#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP) || \
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defined(CONFIG_TTY_FORCE_PANIC) || defined(CONFIG_TTY_LAUNCH)
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signo = uart_check_special(dev, &ch, 1);
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#endif
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/* If the RX buffer becomes full, then the serial data is discarded.
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* This is necessary because on most serial hardware, you must read
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* the data in order to clear the RX interrupt. An option on some
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* hardware might be to simply disable RX interrupts until the RX
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* buffer becomes non-FULL. However, that would probably just cause
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* the overrun to occur in hardware (unless it has some large internal
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* buffering).
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*/
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if (!is_full)
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{
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/* Add the character to the buffer */
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rxbuf->buffer[rxbuf->head] = ch;
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nbytes++;
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/* Increment the head index */
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rxbuf->head = nexthead;
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if (++nexthead >= rxbuf->size)
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{
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nexthead = 0;
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}
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}
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}
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/* If any bytes were added to the buffer, inform any waiters there is new
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* incoming data available.
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*/
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if (nbytes)
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{
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uart_datareceived(dev);
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}
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#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP) || \
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defined(CONFIG_TTY_FORCE_PANIC) || defined(CONFIG_TTY_LAUNCH)
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/* Send the signal if necessary */
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if (signo != 0)
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{
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nxsig_kill(dev->pid, signo);
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uart_reset_sem(dev);
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}
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#endif
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}
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