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;
uart_takesem(&dev->closesem);
if (dev->open_count > 1)
{
dev->open_count--;
uart_givesem(&dev->closesem);
return OK;
}
/* There are no more references to the port */
dev->open_count = 0;
/* Stop accepting input */
uart_disablerxint(dev);
/* Now we wait for the transmit buffer to clear */
while (dev->xmit.head != dev->xmit.tail)
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* And wait for the TX fifo to drain */
while (!uart_txempty(dev))
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* Free the IRQ and disable the UART */
flags = irqsave(); /* Disable interrupts */
uart_detach(dev); /* Detach interrupts */
if (!dev->isconsole) /* Check for the serial console UART */
{
uart_shutdown(dev); /* Disable the UART */
}
irqrestore(flags);
uart_givesem(&dev->closesem);
return OK;
}
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;
irqstate_t flags;
ssize_t recvd = 0;
int16_t tail;
/* Only one user can be accessing dev->recv.tail at once */
uart_takesem(&dev->recv.sem);
/* 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 (recvd < buflen)
{
/* Check if there is more data to return in the circular buffer.
* NOTE: Rx interrupt handling logic may aynchronously 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 = dev->recv.tail;
if (dev->recv.head != tail)
{
/* Take the next character from the tail of the buffer */
*buffer++ = dev->recv.buffer[tail];
recvd++;
/* Increment the tail index. Most operations are done using the
* local variable 'tail' so that the final dev->recv.tail update
* is atomic.
*/
if (++tail >= dev->recv.size)
{
tail = 0;
}
dev->recv.tail = tail;
}
#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)
{
/* 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;
}
/* 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)
{
/* 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 Rx interrupts and test again... */
uart_disablerxint(dev);
/* If the Rx ring buffer still empty? Bytes may have been addded
* between the last time that we checked and when we disabled Rx
* interrupts.
*/
if (dev->recv.head == dev->recv.tail)
{
/* Yes.. the buffer is still empty. Wait for some characters
* to be received into the buffer with the RX interrupt re-
* enabled. All interrupts are disabled briefly to assure
* that the following operations are atomic.
*/
flags = irqsave();
dev->recvwaiting = true;
uart_enablerxint(dev);
/* Now wait with the Rx interrupt re-enabled. NuttX will
* automatically re-enable global interrupts when this
* thread goes to sleep.
*/
uart_takesem(&dev->recvsem);
irqrestore(flags);
}
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.
*/
uart_enablerxint(dev);
}
}
}
uart_givesem(&dev->recv.sem);
return recvd;
}
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;
irqstate_t flags;
ssize_t recvd = 0;
int16_t tail;
int ret;
char ch;
/* Only one user can access dev->recv.tail at a time */
ret = uart_takesem(&dev->recv.sem, true);
if (ret < 0)
{
/* A signal received while waiting for access to the recv.tail will avort
* 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 (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 aynchronously 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 = dev->recv.tail;
if (dev->recv.head != tail)
{
/* Take the next character from the tail of the buffer */
ch = dev->recv.buffer[tail];
/* Increment the tail index. Most operations are done using the
* local variable 'tail' so that the final dev->recv.tail update
* is atomic.
*/
if (++tail >= dev->recv.size)
{
tail = 0;
}
dev->recv.tail = tail;
#ifdef CONFIG_SERIAL_TERMIOS
/* 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.
*/
#endif
/* Store the received character */
*buffer++ = ch;
recvd++;
}
#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;
}
/* 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 Rx interrupts and test again... */
uart_disablerxint(dev);
/* If the Rx ring buffer still empty? Bytes may have been addded
* between the last time that we checked and when we disabled Rx
* interrupts.
*/
if (dev->recv.head == dev->recv.tail)
{
/* Yes.. the buffer is still empty. Wait for some characters
* to be received into the buffer with the RX interrupt re-
* enabled. All interrupts are disabled briefly to assure
* that the following operations are atomic.
*/
flags = irqsave();
uart_enablerxint(dev);
#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 re-enabled. NuttX will
* automatically re-enable global interrupts when this
* thread goes to sleep.
*/
dev->recvwaiting = true;
ret = uart_takesem(&dev->recvsem, true);
}
irqrestore(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 : -EINTR;
#else
recvd = -EINTR;
#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.
*/
uart_enablerxint(dev);
}
}
}
#ifdef CONFIG_SERIAL_IFLOWCONTROL
if (dev->recv.head == dev->recv.tail)
{
/* We might leave Rx interrupt disabled if full recv buffer was read
* empty. Enable Rx interrupt to make sure that more input is received.
*/
uart_enablerxint(dev);
}
#endif
uart_givesem(&dev->recv.sem);
return recvd;
}
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.
*/
(void)uart_takesem(&dev->closesem, false);
if (dev->open_count > 1)
{
dev->open_count--;
uart_givesem(&dev->closesem);
return OK;
}
/* There are no more references to the port */
dev->open_count = 0;
/* Stop accepting input */
uart_disablerxint(dev);
/* Now we wait for the transmit buffer to clear */
while (dev->xmit.head != dev->xmit.tail)
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* And wait for the TX fifo to drain */
while (!uart_txempty(dev))
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* Free the IRQ and disable the UART */
flags = irqsave(); /* Disable interrupts */
uart_detach(dev); /* Detach interrupts */
if (!dev->isconsole) /* Check for the serial console UART */
{
uart_shutdown(dev); /* Disable the UART */
}
irqrestore(flags);
uart_givesem(&dev->closesem);
return OK;
}
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.
*/
(void)uart_takesem(&dev->closesem, false);
if (dev->open_count > 1)
{
dev->open_count--;
uart_givesem(&dev->closesem);
return OK;
}
/* There are no more references to the port */
dev->open_count = 0;
/* Stop accepting input */
uart_disablerxint(dev);
/* Now we wait for the transmit buffer to clear */
while (dev->xmit.head != dev->xmit.tail)
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* And wait for the TX fifo to drain */
while (!uart_txempty(dev))
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* Free the IRQ and disable the UART */
flags = irqsave(); /* Disable interrupts */
uart_detach(dev); /* Detach interrupts */
if (!dev->isconsole) /* Check for the serial console UART */
{
uart_shutdown(dev); /* Disable the UART */
}
irqrestore(flags);
/* 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.
*
* REVISIT: This logic *only* works in the case where the cancelled
* thread had the only reference to the serial driver. If there other
* references, then the this logic will not be executed and the
* semaphore count will still be incorrect.
*/
sem_reinit(&dev->xmitsem, 0, 0);
sem_reinit(&dev->recvsem, 0, 0);
sem_reinit(&dev->xmit.sem, 0, 1);
sem_reinit(&dev->recv.sem, 0, 1);
#ifndef CONFIG_DISABLE_POLL
sem_reinit(&dev->pollsem, 0, 1);
#endif
uart_givesem(&dev->closesem);
return OK;
}
