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nuttx/drivers/serial/serial.c
chao an 6be363ff35 drivers/serial: fix race condition in multi-thread write 
if multiple threads are doing serial read/write at the same time,
the driver will only wake up one of the thread, which will cause
other threads fail to be woken up in time and cause blocking

Signed-off-by: chao an <anchao@xiaomi.com>
2023-05-17 07:56:08 +02:00

2049 lines
56 KiB
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/****************************************************************************
* drivers/serial/serial.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>
#include <ctype.h>
#include <sys/types.h>
#include <sys/param.h>
#include <stdint.h>
#include <stdbool.h>
#include <time.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <spawn.h>
#include <nuttx/irq.h>
#include <nuttx/ascii.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#include <nuttx/sched.h>
#include <nuttx/signal.h>
#include <nuttx/fs/fs.h>
#include <nuttx/cancelpt.h>
#include <nuttx/serial/serial.h>
#include <nuttx/fs/ioctl.h>
#include <nuttx/power/pm.h>
#include <nuttx/wqueue.h>
#include <nuttx/kthread.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Check watermark levels */
#if defined(CONFIG_SERIAL_IFLOWCONTROL) && \
defined(CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS)
# if CONFIG_SERIAL_IFLOWCONTROL_LOWER_WATERMARK < 1
# warning CONFIG_SERIAL_IFLOWCONTROL_LOWER_WATERMARK too small
# endif
# if CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK > 99
# warning CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK too large
# endif
# if CONFIG_SERIAL_IFLOWCONTROL_LOWER_WATERMARK >= CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK
# warning CONFIG_SERIAL_IFLOWCONTROL_LOWER_WATERMARK too large
# warning Must be less than CONFIG_SERIAL_IFLOWCONTROL_UPPER_WATERMARK
# endif
#endif
/* Timing */
#define POLL_DELAY_USEC 1000
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* Write support */
static int uart_putxmitchar(FAR uart_dev_t *dev, int ch,
bool oktoblock);
static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
FAR const char *buffer,
size_t buflen);
static int uart_tcdrain(FAR uart_dev_t *dev,
bool cancelable, clock_t timeout);
static int uart_tcsendbreak(FAR uart_dev_t *dev,
FAR struct file *filep,
unsigned int ms);
/* Character driver methods */
static int uart_open(FAR struct file *filep);
static int uart_close(FAR struct file *filep);
static ssize_t uart_read(FAR struct file *filep,
FAR char *buffer, size_t buflen);
static ssize_t uart_write(FAR struct file *filep,
FAR const char *buffer,
size_t buflen);
static int uart_ioctl(FAR struct file *filep,
int cmd, unsigned long arg);
static int uart_poll(FAR struct file *filep,
FAR struct pollfd *fds, bool setup);
/****************************************************************************
* Public Function Prototypes
****************************************************************************/
#ifdef CONFIG_TTY_LAUNCH_ENTRY
/* Lanch program entry, this must be supplied by the application. */
int CONFIG_TTY_LAUNCH_ENTRYPOINT(int argc, char *argv[]);
#endif
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_serialops =
{
uart_open, /* open */
uart_close, /* close */
uart_read, /* read */
uart_write, /* write */
NULL, /* seek */
uart_ioctl, /* ioctl */
NULL, /* mmap */
NULL, /* truncate */
uart_poll /* poll */
};
#ifdef CONFIG_TTY_LAUNCH
static struct work_s g_serial_work;
#endif
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: uart_putxmitchar
****************************************************************************/
static int uart_putxmitchar(FAR uart_dev_t *dev, int ch, bool oktoblock)
{
irqstate_t flags;
int nexthead;
int ret;
/* Increment to see what the next head pointer will be.
* We need to use the "next" head pointer to determine when the circular
* buffer would overrun
*/
nexthead = dev->xmit.head + 1;
if (nexthead >= dev->xmit.size)
{
nexthead = 0;
}
/* Loop until we are able to add the character to the TX buffer. */
for (; ; )
{
/* Check if the TX buffer is full */
if (nexthead != dev->xmit.tail)
{
/* No.. not full. Add the character to the TX buffer and return. */
dev->xmit.buffer[dev->xmit.head] = ch;
dev->xmit.head = nexthead;
return OK;
}
/* The TX buffer is full. Should be block, waiting for the hardware
* to remove some data from the TX buffer?
*/
else if (oktoblock)
{
/* The following steps must be atomic with respect to serial
* interrupt handling.
*/
flags = enter_critical_section();
/* Check again... In certain race conditions an interrupt may
* have occurred between the test at the top of the loop and
* entering the critical section and the TX buffer may no longer
* be full.
*
* NOTE: On certain devices, such as USB CDC/ACM, the entire TX
* buffer may have been emptied in this race condition. In that
* case, the logic would hang below waiting for space in the TX
* buffer without this test.
*/
if (nexthead != dev->xmit.tail)
{
ret = OK;
}
#ifdef CONFIG_SERIAL_REMOVABLE
/* Check if the removable device is no longer connected while we
* have interrupts off. We do not want the transition to occur
* as a race condition before we begin the wait.
*/
else if (dev->disconnected)
{
ret = -ENOTCONN;
}
#endif
else
{
/* Wait for some characters to be sent from the buffer with
* the TX interrupt enabled. When the TX interrupt is enabled,
* uart_xmitchars() should execute and remove some of the data
* from the TX buffer.
*
* NOTE that interrupts will be re-enabled while we wait for
* the semaphore.
*/
#ifdef CONFIG_SERIAL_TXDMA
uart_dmatxavail(dev);
#endif
uart_enabletxint(dev);
ret = nxsem_wait(&dev->xmitsem);
uart_disabletxint(dev);
}
leave_critical_section(flags);
#ifdef CONFIG_SERIAL_REMOVABLE
/* Check if the removable device was disconnected while we were
* waiting.
*/
if (dev->disconnected)
{
return -ENOTCONN;
}
#endif
/* Check if we were awakened by signal. */
if (ret < 0)
{
/* A signal received while waiting for the xmit buffer to
* become non-full will abort the transfer.
*/
return -EINTR;
}
}
/* The caller has request that we not block for data. So return the
* EAGAIN error to signal this situation.
*/
else
{
return -EAGAIN;
}
}
/* We won't get here. Some compilers may complain that this code is
* unreachable.
*/
return OK;
}
/****************************************************************************
* Name: uart_putc
****************************************************************************/
static inline void uart_putc(FAR uart_dev_t *dev, int ch)
{
while (!uart_txready(dev))
{
}
uart_send(dev, ch);
}
/****************************************************************************
* Name: uart_irqwrite
****************************************************************************/
static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
FAR const char *buffer,
size_t buflen)
{
ssize_t ret = buflen;
/* Force each character through the low level interface */
for (; buflen; buflen--)
{
int ch = *buffer++;
/* Do output post-processing */
if ((dev->tc_oflag & OPOST) != 0)
{
/* Mapping CR to NL? */
if ((ch == '\r') && (dev->tc_oflag & OCRNL) != 0)
{
ch = '\n';
}
/* Are we interested in newline processing? */
if ((ch == '\n') && (dev->tc_oflag & (ONLCR | ONLRET)) != 0)
{
uart_putc(dev, '\r');
}
}
/* Output the character, using the low-level direct UART interfaces */
uart_putc(dev, ch);
}
return ret;
}
/****************************************************************************
* Name: uart_tcdrain
*
* Description:
* Block further TX input.
* Wait until all data has been transferred from the TX buffer and
* until the hardware TX FIFOs are empty.
*
****************************************************************************/
static int uart_tcdrain(FAR uart_dev_t *dev,
bool cancelable, clock_t timeout)
{
int ret;
/* tcdrain is a cancellation point */
if (cancelable && enter_cancellation_point())
{
#ifdef CONFIG_CANCELLATION_POINTS
/* If there is a pending cancellation, then do not perform
* the wait. Exit now with ECANCELED.
*/
leave_cancellation_point();
return -ECANCELED;
#endif
}
/* Get exclusive access to the to dev->tmit. We cannot permit new data to
* be written while we are trying to flush the old data.
*
* A signal received while waiting for access to the xmit.head will abort
* the operation with EINTR.
*/
ret = nxmutex_lock(&dev->xmit.lock);
if (ret >= 0)
{
irqstate_t flags;
clock_t start;
/* Trigger emission to flush the contents of the tx buffer */
flags = enter_critical_section();
#ifdef CONFIG_SERIAL_REMOVABLE
/* Check if the removable device is no longer connected while we have
* interrupts off. We do not want the transition to occur as a race
* condition before we begin the wait.
*/
if (dev->disconnected)
{
dev->xmit.tail = dev->xmit.head; /* Drop the buffered TX data */
ret = -ENOTCONN;
}
else
#endif
{
/* Continue waiting while the TX buffer is not empty.
*
* NOTE: There is no timeout on the following loop. In
* situations were this loop could hang (with hardware flow
* control, as an example), the caller should call
* tcflush() first to discard this buffered Tx data.
*/
ret = OK;
while (ret >= 0 && dev->xmit.head != dev->xmit.tail)
{
/* Wait for some characters to be sent from the buffer with
* the TX interrupt enabled. When the TX interrupt is
* enabled, uart_xmitchars() should execute and remove some
* of the data from the TX buffer. We may have to wait several
* times for the TX buffer to be entirely emptied.
*
* NOTE that interrupts will be re-enabled while we wait for
* the semaphore.
*/
#ifdef CONFIG_SERIAL_TXDMA
uart_dmatxavail(dev);
#endif
uart_enabletxint(dev);
ret = nxsem_wait(&dev->xmitsem);
uart_disabletxint(dev);
}
}
leave_critical_section(flags);
/* The TX buffer is empty (or an error occurred). But there still may
* be data in the UART TX FIFO. We get no asynchronous indication of
* this event, so we have to do a busy wait poll.
*/
/* Set up for the timeout
*
* REVISIT: This is a kludge. The correct fix would be add an
* interface to the lower half driver so that the tcflush() operation
* all also cause the lower half driver to clear and reset the Tx FIFO.
*/
start = clock_systime_ticks();
if (ret >= 0)
{
while (!uart_txempty(dev))
{
clock_t elapsed;
nxsig_usleep(POLL_DELAY_USEC);
/* Check for a timeout */
elapsed = clock_systime_ticks() - start;
if (elapsed >= timeout)
{
nxmutex_unlock(&dev->xmit.lock);
return -ETIMEDOUT;
}
}
}
nxmutex_unlock(&dev->xmit.lock);
}
if (cancelable)
{
leave_cancellation_point();
}
return ret;
}
/****************************************************************************
* Name: uart_tcsendbreak
*
* Description:
* Request a serial line Break by calling the lower half driver's
* BSD-compatible Break IOCTLs TIOCSBRK and TIOCCBRK, with a sleep of the
* specified duration between them.
*
* Input Parameters:
* dev - Serial device.
* filep - Required for issuing lower half driver IOCTL call.
* ms - If non-zero, duration of the Break in milliseconds; if
* zero, duration is 400 milliseconds.
*
* Returned Value:
* 0 on success or a negated errno value on failure.
*
****************************************************************************/
static int uart_tcsendbreak(FAR uart_dev_t *dev, FAR struct file *filep,
unsigned int ms)
{
int ret;
/* tcsendbreak is a cancellation point */
if (enter_cancellation_point())
{
#ifdef CONFIG_CANCELLATION_POINTS
/* If there is a pending cancellation, then do not perform
* the wait. Exit now with ECANCELED.
*/
leave_cancellation_point();
return -ECANCELED;
#endif
}
/* REVISIT: Do we need to perform the equivalent of tcdrain() before
* beginning the Break to avoid corrupting the transmit data? If so, note
* that just calling uart_tcdrain() here would create a race condition,
* since new transmit data could be written after uart_tcdrain() returns
* but before we re-acquire the dev->xmit.lock here. Therefore, we would
* need to refactor the functional portion of uart_tcdrain() to a separate
* function and call it from both uart_tcdrain() and uart_tcsendbreak()
* in critical section and with xmit lock already held.
*/
if (dev->ops->ioctl)
{
ret = nxmutex_lock(&dev->xmit.lock);
if (ret >= 0)
{
/* Request lower half driver to start the Break */
ret = dev->ops->ioctl(filep, TIOCSBRK, 0);
if (ret >= 0)
{
/* Wait 400 ms or the requested Break duration */
nxsig_usleep((ms == 0) ? 400000 : ms * 1000);
/* Request lower half driver to end the Break */
ret = dev->ops->ioctl(filep, TIOCCBRK, 0);
}
}
nxmutex_unlock(&dev->xmit.lock);
}
else
{
/* With no lower half IOCTL, we cannot request Break at all. */
ret = -ENOTTY;
}
leave_cancellation_point();
return ret;
}
/****************************************************************************
* Name: uart_open
*
* Description:
* This routine is called whenever a serial port is opened.
*
****************************************************************************/
static int uart_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
uint8_t tmp;
int ret;
/* If the port is the middle of closing, wait until the close is finished.
* If a signal is received while we are waiting, then return EINTR.
*/
ret = nxmutex_lock(&dev->closelock);
if (ret < 0)
{
/* A signal received while waiting for the last close operation. */
return ret;
}
#ifdef CONFIG_SERIAL_REMOVABLE
/* If the removable device is no longer connected, refuse to open the
* device. We check this after obtaining the close semaphore because
* we might have been waiting when the device was disconnected.
*/
if (dev->disconnected)
{
ret = -ENOTCONN;
goto errout_with_lock;
}
#endif
/* Start up serial port */
/* Increment the count of references to the device. */
tmp = dev->open_count + 1;
if (tmp == 0)
{
/* More than 255 opens; uint8_t overflows to zero */
ret = -EMFILE;
goto errout_with_lock;
}
/* Check if this is the first time that the driver has been opened. */
if (tmp == 1)
{
irqstate_t flags = enter_critical_section();
/* If this is the console, then the UART has already been
* initialized.
*/
if (!dev->isconsole)
{
/* Perform one time hardware initialization */
ret = uart_setup(dev);
if (ret < 0)
{
leave_critical_section(flags);
goto errout_with_lock;
}
}
/* In any event, we do have to configure for interrupt driven mode of
* operation. Attach the hardware IRQ(s). Hmm.. should shutdown() the
* the device in the rare case that uart_attach() fails, tmp==1, and
* this is not the console.
*/
ret = uart_attach(dev);
if (ret < 0)
{
if (!dev->isconsole)
{
uart_shutdown(dev);
}
leave_critical_section(flags);
goto errout_with_lock;
}
#ifdef CONFIG_SERIAL_RXDMA
/* Notify DMA that there is free space in the RX buffer */
uart_dmarxfree(dev);
#endif
/* Enable the RX interrupt */
uart_enablerxint(dev);
leave_critical_section(flags);
}
/* Save the new open count on success */
dev->open_count = tmp;
errout_with_lock:
nxmutex_unlock(&dev->closelock);
return ret;
}
/****************************************************************************
* Name: uart_close
*
* Description:
* This routine is called when the serial port gets closed.
* It waits for the last remaining data to be sent.
*
****************************************************************************/
static int uart_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
irqstate_t flags;
/* Get exclusive access to the close semaphore (to synchronize open/close
* operations.
* NOTE: that we do not let this wait be interrupted by a signal.
* Technically, we should, but almost no one every checks the return value
* from close() so we avoid a potential memory leak by ignoring signals in
* this case.
*/
nxmutex_lock(&dev->closelock);
if (dev->open_count > 1)
{
dev->open_count--;
nxmutex_unlock(&dev->closelock);
return OK;
}
/* There are no more references to the port */
dev->open_count = 0;
/* Stop accepting input */
uart_disablerxint(dev);
/* Prevent blocking if the device is opened with O_NONBLOCK */
if ((filep->f_oflags & O_NONBLOCK) == 0)
{
/* Now we wait for the transmit buffer(s) to clear */
uart_tcdrain(dev, false, 4 * TICK_PER_SEC);
}
/* Free the IRQ and disable the UART */
flags = enter_critical_section(); /* Disable interrupts */
uart_detach(dev); /* Detach interrupts */
if (!dev->isconsole) /* Check for the serial console UART */
{
uart_shutdown(dev); /* Disable the UART */
}
leave_critical_section(flags);
/* Wake up read and poll functions */
uart_datareceived(dev);
/* We need to re-initialize the semaphores if this is the last close
* of the device, as the close might be caused by pthread_cancel() of
* a thread currently blocking on any of them.
*/
uart_reset_sem(dev);
nxmutex_unlock(&dev->closelock);
return OK;
}
/****************************************************************************
* Name: uart_read
****************************************************************************/
static ssize_t uart_read(FAR struct file *filep,
FAR char *buffer, size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
FAR struct uart_buffer_s *rxbuf = &dev->recv;
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
unsigned int nbuffered;
unsigned int watermark;
#endif
irqstate_t flags;
ssize_t recvd = 0;
bool echoed = false;
int16_t tail;
char ch;
int ret;
/* Only one user can access rxbuf->tail at a time */
ret = nxmutex_lock(&dev->recv.lock);
if (ret < 0)
{
/* A signal received while waiting for access to the recv.tail will
* abort the transfer. After the transfer has started, we are
* committed and signals will be ignored.
*/
return ret;
}
/* Loop while we still have data to copy to the receive buffer.
* we add data to the head of the buffer; uart_xmitchars takes the
* data from the end of the buffer.
*/
while ((size_t)recvd < buflen)
{
#ifdef CONFIG_SERIAL_REMOVABLE
/* If the removable device is no longer connected, refuse to read any
* further from the device.
*/
if (dev->disconnected)
{
if (recvd == 0)
{
recvd = -ENOTCONN;
}
break;
}
#endif
/* Check if there is more data to return in the circular buffer.
* NOTE: Rx interrupt handling logic may asynchronously increment
* the head index but must not modify the tail index. The tail
* index is only modified in this function. Therefore, no
* special handshaking is required here.
*
* The head and tail pointers are 16-bit values. The only time that
* the following could be unsafe is if the CPU made two non-atomic
* 8-bit accesses to obtain the 16-bit head index.
*/
tail = rxbuf->tail;
if (rxbuf->head != tail)
{
/* Take the next character from the tail of the buffer */
ch = rxbuf->buffer[tail];
/* Increment the tail index. Most operations are done using the
* local variable 'tail' so that the final rxbuf->tail update
* is atomic.
*/
if (++tail >= rxbuf->size)
{
tail = 0;
}
rxbuf->tail = tail;
/* Do input processing if any is enabled */
if (dev->tc_iflag & (INLCR | IGNCR | ICRNL))
{
/* \n -> \r or \r -> \n translation? */
if ((ch == '\n') && (dev->tc_iflag & INLCR))
{
ch = '\r';
}
else if ((ch == '\r') && (dev->tc_iflag & ICRNL))
{
ch = '\n';
}
/* Discarding \r ? */
if ((ch == '\r') & (dev->tc_iflag & IGNCR))
{
continue;
}
}
/* Specifically not handled:
*
* All of the local modes; echo, line editing, etc.
* Anything to do with break or parity errors.
* ISTRIP - we should be 8-bit clean.
* IUCLC - Not Posix
* IXON/OXOFF - no xon/xoff flow control.
*/
/* Store the received character */
*buffer++ = ch;
recvd++;
if (dev->tc_lflag & ECHO)
{
/* Check for the beginning of a VT100 escape sequence, 3 byte */
if (ch == ASCII_ESC)
{
/* Mark that we should skip 2 more bytes */
dev->escape = 2;
continue;
}
else if (dev->escape == 2 && ch != ASCII_LBRACKET)
{
/* It's not an <esc>[x 3 byte sequence, show it */
dev->escape = 0;
}
/* Echo if the character is not a control byte */
if ((!iscntrl(ch & 0xff) || (ch == '\n')) && dev->escape == 0)
{
if (ch == '\n')
{
uart_putxmitchar(dev, '\r', true);
}
uart_putxmitchar(dev, ch, true);
/* Mark the tx buffer have echoed content here,
* to avoid the tx buffer is empty such as special escape
* sequence received, but enable the tx interrupt.
*/
echoed = true;
}
/* Skipping character count down */
if (dev->escape > 0)
{
dev->escape--;
}
}
}
#ifdef CONFIG_DEV_SERIAL_FULLBLOCKS
/* No... then we would have to wait to get receive more data.
* If the user has specified the O_NONBLOCK option, then just
* return what we have.
*/
else if ((filep->f_oflags & O_NONBLOCK) != 0)
{
/* If nothing was transferred, then return the -EAGAIN
* error (not zero which means end of file).
*/
if (recvd < 1)
{
recvd = -EAGAIN;
}
break;
}
#else
/* No... the circular buffer is empty. Have we returned anything
* to the caller?
*/
else if (recvd > 0)
{
/* Yes.. break out of the loop and return the number of bytes
* received up to the wait condition.
*/
break;
}
else if (filep->f_inode == 0)
{
/* File has been closed.
* Descriptor is not valid.
*/
recvd = -EBADFD;
break;
}
/* No... then we would have to wait to get receive some data.
* If the user has specified the O_NONBLOCK option, then do not
* wait.
*/
else if ((filep->f_oflags & O_NONBLOCK) != 0)
{
/* Break out of the loop returning -EAGAIN */
recvd = -EAGAIN;
break;
}
#endif
/* Otherwise we are going to have to wait for data to arrive */
else
{
/* Disable all interrupts and test again... */
flags = enter_critical_section();
/* Disable Rx interrupts and test again... */
uart_disablerxint(dev);
/* If the Rx ring buffer still empty? Bytes may have been added
* between the last time that we checked and when we disabled
* interrupts.
*/
if (rxbuf->head == rxbuf->tail)
{
/* Yes.. the buffer is still empty. We will need to wait for
* additional data to be received.
*/
#ifdef CONFIG_SERIAL_RXDMA
/* Notify DMA that there is free space in the RX buffer */
uart_dmarxfree(dev);
#endif
/* Wait with the RX interrupt re-enabled. All interrupts are
* disabled briefly to assure that the following operations
* are atomic.
*/
/* Re-enable UART Rx interrupts */
uart_enablerxint(dev);
/* Check again if the RX buffer is empty. The UART driver
* might have buffered data received between disabling the
* RX interrupt and entering the critical section. Some
* drivers (looking at you, cdcacm...) will push the buffer
* to the receive queue during uart_enablerxint().
* Just continue processing the RX queue if this happens.
*/
if (rxbuf->head != rxbuf->tail)
{
leave_critical_section(flags);
continue;
}
#ifdef CONFIG_SERIAL_REMOVABLE
/* Check again if the removable device is still connected
* while we have interrupts off. We do not want the transition
* to occur as a race condition before we begin the wait.
*/
if (dev->disconnected)
{
ret = -ENOTCONN;
}
else
#endif
{
/* Now wait with the Rx interrupt enabled. NuttX will
* automatically re-enable global interrupts when this
* thread goes to sleep.
*/
#ifdef CONFIG_SERIAL_TERMIOS
dev->minrecv = MIN(buflen - recvd, dev->minread - recvd);
if (dev->timeout)
{
ret = nxsem_tickwait(&dev->recvsem,
DSEC2TICK(dev->timeout));
}
else
#endif
{
ret = nxsem_wait(&dev->recvsem);
}
}
leave_critical_section(flags);
/* Was a signal received while waiting for data to be
* received? Was a removable device disconnected while
* we were waiting?
*/
#ifdef CONFIG_SERIAL_REMOVABLE
if (ret < 0 || dev->disconnected)
#else
if (ret < 0)
#endif
{
/* POSIX requires that we return after a signal is
* received.
* If some bytes were read, we need to return the
* number of bytes read; if no bytes were read, we
* need to return -1 with the errno set correctly.
*/
if (recvd == 0)
{
/* No bytes were read, return -EINTR
* (the VFS layer will set the errno value
* appropriately).
*/
#ifdef CONFIG_SERIAL_REMOVABLE
recvd = dev->disconnected ? -ENOTCONN : ret;
#else
recvd = ret;
#endif
}
break;
}
}
else
{
/* No... the ring buffer is no longer empty. Just re-enable Rx
* interrupts and accept the new data on the next time through
* the loop.
*/
leave_critical_section(flags);
uart_enablerxint(dev);
}
}
}
if (echoed)
{
#ifdef CONFIG_SERIAL_TXDMA
uart_dmatxavail(dev);
#endif
uart_enabletxint(dev);
}
#ifdef CONFIG_SERIAL_RXDMA
/* Notify DMA that there is free space in the RX buffer */
flags = enter_critical_section();
uart_dmarxfree(dev);
leave_critical_section(flags);
#endif
/* RX interrupt could be disabled by RX buffer overflow. Enable it now. */
uart_enablerxint(dev);
#ifdef CONFIG_SERIAL_IFLOWCONTROL
#ifdef CONFIG_SERIAL_IFLOWCONTROL_WATERMARKS
/* How many bytes are now buffered */
rxbuf = &dev->recv;
if (rxbuf->head >= rxbuf->tail)
{
nbuffered = rxbuf->head - rxbuf->tail;
}
else
{
nbuffered = rxbuf->size - rxbuf->tail + rxbuf->head;
}
/* Is the level now below the watermark level that we need to report? */
watermark = (CONFIG_SERIAL_IFLOWCONTROL_LOWER_WATERMARK *
rxbuf->size) / 100;
if (nbuffered <= watermark)
{
/* Let the lower level driver know that the watermark level has been
* crossed. It will probably deactivate RX flow control.
*/
uart_rxflowcontrol(dev, nbuffered, false);
}
#else
/* Is the RX buffer empty? */
if (rxbuf->head == rxbuf->tail)
{
/* Deactivate RX flow control. */
uart_rxflowcontrol(dev, 0, false);
}
#endif
#endif
nxmutex_unlock(&dev->recv.lock);
return recvd;
}
/****************************************************************************
* Name: uart_write
****************************************************************************/
static ssize_t uart_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
ssize_t nwritten = buflen;
bool oktoblock;
int ret;
char ch;
/* We may receive serial writes through this path from interrupt handlers
* and from debug output in the IDLE task! In these cases, we will need to
* do things a little differently.
*/
if (up_interrupt_context() || sched_idletask())
{
irqstate_t flags;
#ifdef CONFIG_SERIAL_REMOVABLE
/* If the removable device is no longer connected, refuse to write to
* the device.
*/
if (dev->disconnected)
{
return -ENOTCONN;
}
#endif
flags = enter_critical_section();
ret = uart_irqwrite(dev, buffer, buflen);
leave_critical_section(flags);
return ret;
}
/* Only one user can access dev->xmit.head at a time */
ret = nxmutex_lock(&dev->xmit.lock);
if (ret < 0)
{
/* A signal received while waiting for access to the xmit.head will
* abort the transfer. After the transfer has started, we are
* committed and signals will be ignored.
*/
return ret;
}
#ifdef CONFIG_SERIAL_REMOVABLE
/* If the removable device is no longer connected, refuse to write to the
* device. This check occurs after taking the xmit.lock because the
* disconnection event might have occurred while we were waiting for
* access to the transmit buffers.
*/
if (dev->disconnected)
{
nxmutex_unlock(&dev->xmit.lock);
return -ENOTCONN;
}
#endif
/* Can the following loop block, waiting for space in the TX
* buffer?
*/
oktoblock = ((filep->f_oflags & O_NONBLOCK) == 0);
/* Loop while we still have data to copy to the transmit buffer.
* we add data to the head of the buffer; uart_xmitchars takes the
* data from the end of the buffer.
*/
uart_disabletxint(dev);
for (; buflen; buflen--)
{
ch = *buffer++;
ret = OK;
/* Do output post-processing */
if ((dev->tc_oflag & OPOST) != 0)
{
/* Mapping CR to NL? */
if ((ch == '\r') && (dev->tc_oflag & OCRNL) != 0)
{
ch = '\n';
}
/* Are we interested in newline processing? */
if ((ch == '\n') && (dev->tc_oflag & (ONLCR | ONLRET)) != 0)
{
ret = uart_putxmitchar(dev, '\r', oktoblock);
}
/* Specifically not handled:
*
* OXTABS - primarily a full-screen terminal optimization
* ONOEOT - Unix interoperability hack
* OLCUC - Not specified by POSIX
* ONOCR - low-speed interactive optimization
*/
}
/* Put the character into the transmit buffer */
if (ret >= 0)
{
ret = uart_putxmitchar(dev, ch, oktoblock);
}
/* uart_putxmitchar() might return an error under one of two
* conditions: (1) The wait for buffer space might have been
* interrupted by a signal (ret should be -EINTR), (2) if
* CONFIG_SERIAL_REMOVABLE is defined, then uart_putxmitchar()
* might also return if the serial device was disconnected
* (with -ENOTCONN), or (3) if O_NONBLOCK is specified, then
* then uart_putxmitchar() might return -EAGAIN if the output
* TX buffer is full.
*/
if (ret < 0)
{
/* POSIX requires that we return -1 and errno set if no data was
* transferred. Otherwise, we return the number of bytes in the
* interrupted transfer.
*/
if (buflen < (size_t)nwritten)
{
/* Some data was transferred. Return the number of bytes that
* were successfully transferred.
*/
nwritten -= buflen;
}
else
{
/* No data was transferred. Return the negated errno value.
* The VFS layer will set the errno value appropriately).
*/
nwritten = ret;
}
break;
}
}
if (dev->xmit.head != dev->xmit.tail)
{
#ifdef CONFIG_SERIAL_TXDMA
uart_dmatxavail(dev);
#endif
uart_enabletxint(dev);
}
nxmutex_unlock(&dev->xmit.lock);
return nwritten;
}
/****************************************************************************
* Name: uart_ioctl
****************************************************************************/
static int uart_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
/* Handle TTY-level IOCTLs here */
/* Let low-level driver handle the call first */
int ret = dev->ops->ioctl ? dev->ops->ioctl(filep, cmd, arg) : -ENOTTY;
/* The device ioctl() handler returns -ENOTTY when it doesn't know
* how to handle the command. Check if we can handle it here.
*/
if (ret == -ENOTTY)
{
switch (cmd)
{
/* Get the number of bytes that may be read from the RX buffer
* (without waiting)
*/
case FIONREAD:
{
int count;
irqstate_t flags = enter_critical_section();
/* Determine the number of bytes available in the RX buffer */
if (dev->recv.tail <= dev->recv.head)
{
count = dev->recv.head - dev->recv.tail;
}
else
{
count = dev->recv.size - (dev->recv.tail - dev->recv.head);
}
leave_critical_section(flags);
*(FAR int *)((uintptr_t)arg) = count;
ret = 0;
}
break;
/* Get the number of bytes that have been written to the TX
* buffer.
*/
case FIONWRITE:
{
int count;
irqstate_t flags = enter_critical_section();
/* Determine the number of bytes waiting in the TX buffer */
if (dev->xmit.tail <= dev->xmit.head)
{
count = dev->xmit.head - dev->xmit.tail;
}
else
{
count = dev->xmit.size - (dev->xmit.tail - dev->xmit.head);
}
leave_critical_section(flags);
*(FAR int *)((uintptr_t)arg) = count;
ret = 0;
}
break;
/* Get the number of free bytes in the TX buffer */
case FIONSPACE:
{
int count;
irqstate_t flags = enter_critical_section();
/* Determine the number of bytes free in the TX buffer */
if (dev->xmit.head < dev->xmit.tail)
{
count = dev->xmit.tail - dev->xmit.head - 1;
}
else
{
count = dev->xmit.size -
(dev->xmit.head - dev->xmit.tail) - 1;
}
leave_critical_section(flags);
*(FAR int *)((uintptr_t)arg) = count;
ret = 0;
}
break;
case TCFLSH:
{
/* Empty the tx/rx buffers */
irqstate_t flags = enter_critical_section();
if (arg == TCIFLUSH || arg == TCIOFLUSH)
{
dev->recv.tail = dev->recv.head;
#ifdef CONFIG_SERIAL_IFLOWCONTROL
/* De-activate RX flow control. */
uart_rxflowcontrol(dev, 0, false);
#endif
}
if (arg == TCOFLUSH || arg == TCIOFLUSH)
{
dev->xmit.tail = dev->xmit.head;
/* Inform any waiters there there is space available. */
uart_datasent(dev);
}
leave_critical_section(flags);
ret = 0;
}
break;
case TCDRN:
{
ret = uart_tcdrain(dev, true, 10 * TICK_PER_SEC);
}
break;
case TCSBRK:
{
/* Non-standard Break specifies duration in milliseconds */
ret = uart_tcsendbreak(dev, filep, arg);
}
break;
case TCSBRKP:
{
/* POSIX Break specifies duration in units of 100ms */
ret = uart_tcsendbreak(dev, filep, arg * 100);
}
break;
#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP)
/* Make the controlling terminal of the calling process */
case TIOCSCTTY:
{
/* Save the PID of the recipient of the SIGINT signal. */
if ((int)arg < 0 || dev->pid >= 0)
{
ret = -EINVAL;
}
else
{
dev->pid = (pid_t)arg;
ret = 0;
}
}
break;
case TIOCNOTTY:
{
dev->pid = INVALID_PROCESS_ID;
ret = 0;
}
break;
#endif
}
}
/* Append any higher level TTY flags */
if (ret == OK || ret == -ENOTTY)
{
switch (cmd)
{
case TCGETS:
{
FAR struct termios *termiosp = (FAR struct termios *)
(uintptr_t)arg;
if (!termiosp)
{
ret = -EINVAL;
break;
}
/* And update with flags from this layer */
termiosp->c_iflag = dev->tc_iflag;
termiosp->c_oflag = dev->tc_oflag;
termiosp->c_lflag = dev->tc_lflag;
#ifdef CONFIG_SERIAL_TERMIOS
termiosp->c_cc[VTIME] = dev->timeout;
termiosp->c_cc[VMIN] = dev->minread;
#endif
ret = 0;
}
break;
case TCSETS:
{
FAR struct termios *termiosp = (FAR struct termios *)
(uintptr_t)arg;
if (!termiosp)
{
ret = -EINVAL;
break;
}
/* Update the flags we keep at this layer */
dev->tc_iflag = termiosp->c_iflag;
dev->tc_oflag = termiosp->c_oflag;
dev->tc_lflag = termiosp->c_lflag;
#ifdef CONFIG_SERIAL_TERMIOS
dev->timeout = termiosp->c_cc[VTIME];
dev->minread = termiosp->c_cc[VMIN];
#endif
ret = 0;
}
break;
}
}
return ret;
}
/****************************************************************************
* Name: uart_poll
****************************************************************************/
static int uart_poll(FAR struct file *filep,
FAR struct pollfd *fds, bool setup)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
pollevent_t eventset;
int ndx;
int ret;
int i;
/* Some sanity checking */
#ifdef CONFIG_DEBUG_FEATURES
if (dev == NULL || fds == NULL)
{
return -ENODEV;
}
#endif
/* Are we setting up the poll? Or tearing it down? */
ret = nxmutex_lock(&dev->polllock);
if (ret < 0)
{
/* A signal received while waiting for access to the poll data
* will abort the operation.
*/
return ret;
}
if (setup)
{
/* This is a request to set up the poll. Find an available
* slot for the poll structure reference
*/
for (i = 0; i < CONFIG_SERIAL_NPOLLWAITERS; i++)
{
/* Find an available slot */
if (!dev->fds[i])
{
/* Bind the poll structure and this slot */
dev->fds[i] = fds;
fds->priv = &dev->fds[i];
break;
}
}
if (i >= CONFIG_SERIAL_NPOLLWAITERS)
{
fds->priv = NULL;
ret = -EBUSY;
goto errout;
}
/* Should we immediately notify on any of the requested events?
* First, check if the xmit buffer is full.
*
* Get exclusive access to the xmit buffer indices.
* NOTE: that we do not let this wait be interrupted by a signal
* (we probably should, but that would be a little awkward).
*/
eventset = 0;
nxmutex_lock(&dev->xmit.lock);
ndx = dev->xmit.head + 1;
if (ndx >= dev->xmit.size)
{
ndx = 0;
}
if (ndx != dev->xmit.tail)
{
eventset |= POLLOUT;
}
nxmutex_unlock(&dev->xmit.lock);
/* Check if the receive buffer is empty.
*
* Get exclusive access to the recv buffer indices.
* NOTE: that we do not let this wait be interrupted by a signal
* (we probably should, but that would be a little awkward).
*/
nxmutex_lock(&dev->recv.lock);
if (dev->recv.head != dev->recv.tail)
{
eventset |= POLLIN;
}
nxmutex_unlock(&dev->recv.lock);
#ifdef CONFIG_SERIAL_REMOVABLE
/* Check if a removable device has been disconnected. */
if (dev->disconnected)
{
eventset |= (POLLERR | POLLHUP);
}
#endif
poll_notify(dev->fds, CONFIG_SERIAL_NPOLLWAITERS, eventset);
}
else if (fds->priv != NULL)
{
/* This is a request to tear down the poll. */
FAR struct pollfd **slot = (FAR struct pollfd **)fds->priv;
#ifdef CONFIG_DEBUG_FEATURES
if (!slot)
{
ret = -EIO;
goto errout;
}
#endif
/* Remove all memory of the poll setup */
*slot = NULL;
fds->priv = NULL;
}
errout:
nxmutex_unlock(&dev->polllock);
return ret;
}
/****************************************************************************
* Name: uart_nxsched_foreach_cb
****************************************************************************/
#ifdef CONFIG_TTY_LAUNCH
static void uart_launch_foreach(FAR struct tcb_s *tcb, FAR void *arg)
{
#ifdef CONFIG_TTY_LAUNCH_ENTRY
if (!strcmp(tcb->name, CONFIG_TTY_LAUNCH_ENTRYNAME))
#else
if (!strcmp(tcb->name, CONFIG_TTY_LAUNCH_FILEPATH))
#endif
{
*(int *)arg = 1;
}
}
static void uart_launch_worker(void *arg)
{
#ifdef CONFIG_TTY_LAUNCH_ARGS
FAR char *const argv[] =
{
CONFIG_TTY_LAUNCH_ARGS,
NULL,
};
#else
FAR char *const *argv = NULL;
#endif
int found = 0;
nxsched_foreach(uart_launch_foreach, &found);
if (!found)
{
posix_spawnattr_t attr;
posix_spawnattr_init(&attr);
attr.priority = CONFIG_TTY_LAUNCH_PRIORITY;
attr.stacksize = CONFIG_TTY_LAUNCH_STACKSIZE;
#ifdef CONFIG_TTY_LAUNCH_ENTRY
task_spawn(CONFIG_TTY_LAUNCH_ENTRYNAME,
CONFIG_TTY_LAUNCH_ENTRYPOINT,
NULL, &attr, argv, NULL);
#else
exec_spawn(CONFIG_TTY_LAUNCH_FILEPATH,
argv, NULL, NULL, 0, NULL, &attr);
#endif
posix_spawnattr_destroy(&attr);
}
}
static void uart_launch(void)
{
work_queue(HPWORK, &g_serial_work, uart_launch_worker, NULL, 0);
}
#endif
static void uart_wakeup(FAR sem_t *sem)
{
int sval;
if (nxsem_get_value(sem, &sval) != OK)
{
return;
}
/* Yes... wake up all waiting threads */
while (sval++ < 1)
{
nxsem_post(sem);
}
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: uart_register
*
* Description:
* Register serial console and serial ports.
*
****************************************************************************/
int uart_register(FAR const char *path, FAR uart_dev_t *dev)
{
#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP)
/* Initialize of the task that will receive SIGINT signals. */
dev->pid = INVALID_PROCESS_ID;
#endif
/* If this UART is a serial console */
if (dev->isconsole)
{
/* Enable signals and echo by default */
dev->tc_lflag |= ISIG | ECHO;
/* Enable \n -> \r\n translation for the console */
dev->tc_oflag = OPOST | ONLCR;
/* Convert CR to LF by default for console */
dev->tc_iflag |= ICRNL;
/* Clear escape counter */
dev->escape = 0;
}
/* Initialize mutex & semaphores */
nxmutex_init(&dev->xmit.lock);
nxmutex_init(&dev->recv.lock);
nxmutex_init(&dev->closelock);
nxsem_init(&dev->xmitsem, 0, 0);
nxsem_init(&dev->recvsem, 0, 0);
nxmutex_init(&dev->polllock);
#ifdef CONFIG_SERIAL_TERMIOS
dev->timeout = 0;
dev->minread = 1;
#endif
/* Register the serial driver */
sinfo("Registering %s\n", path);
return register_driver(path, &g_serialops, 0666, dev);
}
/****************************************************************************
* Name: uart_datareceived
*
* Description:
* This function is called from uart_recvchars when new serial data is
* place in the driver's circular buffer. This function will wake-up any
* stalled read() operations that are waiting for incoming data.
*
****************************************************************************/
void uart_datareceived(FAR uart_dev_t *dev)
{
/* Notify all poll/select waiters that they can read from the recv buffer */
poll_notify(dev->fds, CONFIG_SERIAL_NPOLLWAITERS, POLLIN);
/* Is there a thread waiting for read data? */
uart_wakeup(&dev->recvsem);
#if defined(CONFIG_PM) && defined(CONFIG_SERIAL_CONSOLE)
/* Call pm_activity when characters are received on the console device */
if (dev->isconsole)
{
pm_activity(CONFIG_SERIAL_PM_ACTIVITY_DOMAIN,
CONFIG_SERIAL_PM_ACTIVITY_PRIORITY);
}
#endif
}
/****************************************************************************
* Name: uart_datasent
*
* Description:
* This function is called from uart_xmitchars after serial data has been
* sent, freeing up some space in the driver's circular buffer. This
* function will wake-up any stalled write() operations that was waiting
* for space to buffer outgoing data.
*
****************************************************************************/
void uart_datasent(FAR uart_dev_t *dev)
{
/* Notify all poll/select waiters that they can write to xmit buffer */
poll_notify(dev->fds, CONFIG_SERIAL_NPOLLWAITERS, POLLOUT);
/* Is there a thread waiting for space in xmit.buffer? */
uart_wakeup(&dev->xmitsem);
}
/****************************************************************************
* Name: uart_connected
*
* Description:
* Serial devices (like USB serial) can be removed.
* In that case, the "upper half" serial driver must be informed that there
* is no longer a valid serial channel associated with the driver.
*
* In this case, the driver will terminate all pending transfers wint
* ENOTCONN and will refuse all further transactions while the "lower half"
* is disconnected.
* The driver will continue to be registered, but will be in an unusable
* state.
*
* Conversely, the "upper half" serial driver needs to know when the serial
* device is reconnected so that it can resume normal operations.
*
* Assumptions/Limitations:
* This function may be called from an interrupt handler.
*
****************************************************************************/
#ifdef CONFIG_SERIAL_REMOVABLE
void uart_connected(FAR uart_dev_t *dev, bool connected)
{
irqstate_t flags;
/* Is the device disconnected? Interrupts are disabled because this
* function may be called from interrupt handling logic.
*/
flags = enter_critical_section();
dev->disconnected = !connected;
if (!connected)
{
/* Notify all poll/select waiters that a hangup occurred */
poll_notify(dev->fds, CONFIG_SERIAL_NPOLLWAITERS, POLLERR | POLLHUP);
/* Yes.. wake up all waiting threads. Each thread should detect the
* disconnection and return the ENOTCONN error.
*/
/* Is there a thread waiting for space in xmit.buffer? */
uart_wakeup(&dev->xmitsem);
/* Is there a thread waiting for read data? */
uart_wakeup(&dev->recvsem);
}
leave_critical_section(flags);
}
#endif
/****************************************************************************
* Name: uart_reset_sem
*
* Description:
* This function is called when need reset uart semaphore, this may used in
* kill one process, but this process was reading/writing with the
* semaphore.
*
****************************************************************************/
void uart_reset_sem(FAR uart_dev_t *dev)
{
nxsem_reset(&dev->xmitsem, 0);
nxsem_reset(&dev->recvsem, 0);
nxmutex_reset(&dev->xmit.lock);
nxmutex_reset(&dev->recv.lock);
nxmutex_reset(&dev->polllock);
}
/****************************************************************************
* Name: uart_check_special
*
* Description:
* Check if the SIGINT or SIGTSTP character is in the contiguous Rx DMA
* buffer region. The first signal associated with the first such
* character is returned.
*
* If there multiple such characters in the buffer, only the signal
* associated with the first is returned (this a bug!)
*
* Returned Value:
* 0 if a signal-related character does not appear in the. Otherwise,
* SIGKILL or SIGTSTP may be returned to indicate the appropriate signal
* action.
*
****************************************************************************/
#if defined(CONFIG_TTY_SIGINT) || defined(CONFIG_TTY_SIGTSTP) || \
defined(CONFIG_TTY_FORCE_PANIC) || defined(CONFIG_TTY_LAUNCH)
int uart_check_special(FAR uart_dev_t *dev, const char *buf, size_t size)
{
size_t i;
if ((dev->tc_lflag & ISIG) == 0)
{
return 0;
}
for (i = 0; i < size; i++)
{
#ifdef CONFIG_TTY_FORCE_PANIC
if (buf[i] == CONFIG_TTY_FORCE_PANIC_CHAR)
{
PANIC();
return 0;
}
#endif
#ifdef CONFIG_TTY_LAUNCH
if (buf[i] == CONFIG_TTY_LAUNCH_CHAR)
{
uart_launch();
return 0;
}
#endif
#ifdef CONFIG_TTY_SIGINT
if (dev->pid > 0 && buf[i] == CONFIG_TTY_SIGINT_CHAR)
{
return SIGINT;
}
#endif
#ifdef CONFIG_TTY_SIGTSTP
if (dev->pid > 0 && buf[i] == CONFIG_TTY_SIGTSTP_CHAR)
{
return SIGTSTP;
}
#endif
}
return 0;
}
#endif
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