sergiotarxz/nuttx
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity
d09bb13833
nuttx/drivers/serial/serial.c
Gregory Nutt d09bb13833 In case a thread is doing a blocking operation (e.g. read()) on a serial 
device, while it is being terminated by pthread_cancel(), then
uart_close() gets called, but the semaphore (dev->recv.sem in the above
example) is still blocked.

This means that once the serial device is opened next time, data will
arrive on the serial port (and driver interrupts handled as normal), but
the received characters never arrive in the reader thread.

This patch addresses the problem by re-initializing the semaphores on the
last uart_close() on the device.
2014-12-13 08:07:21 -06:00

1413 lines
38 KiB
C
Raw Blame History

/************************************************************************************
* drivers/serial/serial.c
*
* Copyright (C) 2007-2009, 2011-2013 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 <stdbool.h>
#include <unistd.h>
#include <semaphore.h>
#include <string.h>
#include <fcntl.h>
#include <poll.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <nuttx/fs/fs.h>
#include <nuttx/serial/serial.h>
#include <nuttx/fs/ioctl.h>
/************************************************************************************
* Definitions
************************************************************************************/
/* The architecture must provide up_putc for this driver */
#ifndef CONFIG_ARCH_LOWPUTC
# error "Architecture must provide up_putc() for this driver"
#endif
#define uart_putc(ch) up_putc(ch)
#define HALF_SECOND_MSEC 500
#define HALF_SECOND_USEC 500000L
/************************************************************************************
* Private Types
************************************************************************************/
/************************************************************************************
* Private Function Prototypes
************************************************************************************/
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);
#ifndef CONFIG_DISABLE_POLL
static int uart_poll(FAR struct file *filep, FAR struct pollfd *fds, bool setup);
#endif
/************************************************************************************
* Private Variables
************************************************************************************/
static const struct file_operations g_serialops =
{
uart_open, /* open */
uart_close, /* close */
uart_read, /* read */
uart_write, /* write */
0, /* seek */
uart_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, uart_poll /* poll */
#endif
};
/************************************************************************************
* Private Functions
************************************************************************************/
/************************************************************************************
* Name: sem_reinit
************************************************************************************/
static int sem_reinit(FAR sem_t *sem, int pshared, unsigned int value)
{
sem_destroy(sem);
return sem_init(sem, pshared, value);
}
/************************************************************************************
* Name: uart_takesem
************************************************************************************/
static int uart_takesem(FAR sem_t *sem, bool errout)
{
/* Loop, ignoring interrupts, until we have successfully acquired the semaphore */
while (sem_wait(sem) != OK)
{
/* The only case that an error should occur here is if the wait was awakened
* by a signal.
*/
ASSERT(get_errno() == EINTR);
/* When the signal is received, should we errout? Or should we just continue
* waiting until we have the semaphore?
*/
if (errout)
{
return -EINTR;
}
}
return OK;
}
/************************************************************************************
* Name: uart_givesem
************************************************************************************/
#define uart_givesem(sem) (void)sem_post(sem)
/****************************************************************************
* Name: uart_pollnotify
****************************************************************************/
#ifndef CONFIG_DISABLE_POLL
static void uart_pollnotify(FAR uart_dev_t *dev, pollevent_t eventset)
{
int i;
for (i = 0; i < CONFIG_SERIAL_NPOLLWAITERS; i++)
{
struct pollfd *fds = dev->fds[i];
if (fds)
{
#ifdef CONFIG_SERIAL_REMOVABLE
fds->revents |= ((fds->events | (POLLERR|POLLHUP)) & eventset);
#else
fds->revents |= (fds->events & eventset);
#endif
if (fds->revents != 0)
{
fvdbg("Report events: %02x\n", fds->revents);
sem_post(fds->sem);
}
}
}
}
#else
# define uart_pollnotify(dev,event)
#endif
/************************************************************************************
* 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 (;;)
{
if (nexthead != dev->xmit.tail)
{
dev->xmit.buffer[dev->xmit.head] = ch;
dev->xmit.head = nexthead;
return OK;
}
/* The buffer is full and no data is available now. Should be block,
* waiting for the hardware to remove some data from the TX
* buffer?
*/
else if (oktoblock)
{
/* Inform the interrupt level logic that we are waiting. This and
* the following steps must be atomic.
*/
flags = irqsave();
#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)
{
ret = -ENOTCONN;
}
else
#endif
{
/* 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.
*/
dev->xmitwaiting = true;
uart_enabletxint(dev);
ret = uart_takesem(&dev->xmitsem, true);
uart_disabletxint(dev);
}
irqrestore(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_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++;
/* If this is the console, then we should replace LF with CR-LF */
if (ch == '\n')
{
uart_putc('\r');
}
/* Output the character, using the low-level direct UART interfaces */
uart_putc(ch);
}
return ret;
}
/************************************************************************************
* 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 console 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() || getpid() == 0)
{
#ifdef CONFIG_SERIAL_REMOVABLE
/* If the removable device is no longer connected, refuse to write to
* the device.
*/
if (dev->disconnected)
{
return -ENOTCONN;
}
#endif
/* up_putc() will be used to generate the output in a busy-wait loop.
* up_putc() is only available for the console device.
*/
if (dev->isconsole)
{
irqstate_t flags = irqsave();
ret = uart_irqwrite(dev, buffer, buflen);
irqrestore(flags);
return ret;
}
else
{
return -EPERM;
}
}
/* Only one user can access dev->xmit.head at a time */
ret = (ssize_t)uart_takesem(&dev->xmit.sem, true);
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.sem because the
* disconnection event might have occurred while we were waiting for
* access to the transmit buffers.
*/
if (dev->disconnected)
{
uart_givesem(&dev->xmit.sem);
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;
#ifdef CONFIG_SERIAL_TERMIOS
/* Do output post-processing */
if (dev->tc_oflag & OPOST)
{
/* Mapping CR to NL? */
if ((ch == '\r') && (dev->tc_oflag & OCRNL))
{
ch = '\n';
}
/* Are we interested in newline processing? */
if ((ch == '\n') && (dev->tc_oflag & (ONLCR | ONLRET)))
{
ret = uart_putxmitchar(dev, '\r', oktoblock);
if (ret < 0)
{
nwritten = ret;
break;
}
}
/* Specifically not handled:
*
* OXTABS - primarily a full-screen terminal optimisation
* ONOEOT - Unix interoperability hack
* OLCUC - Not specified by POSIX
* ONOCR - low-speed interactive optimisation
*/
}
#else /* !CONFIG_SERIAL_TERMIOS */
/* If this is the console, convert \n -> \r\n */
if (dev->isconsole && ch == '\n')
{
ret = uart_putxmitchar(dev, '\r', oktoblock);
}
#endif
/* Put the character into the transmit buffer */
if (ret == OK)
{
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 < 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)
{
uart_enabletxint(dev);
}
uart_givesem(&dev->xmit.sem);
return nwritten;
}
/************************************************************************************
* 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;
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;
}
/************************************************************************************
* 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(filep, cmd, arg);
/* 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)
{
case FIONREAD:
{
int count;
irqstate_t state = irqsave();
/* Determine the number of bytes available in the 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);
}
irqrestore(state);
*(int *)arg = count;
ret = 0;
}
break;
case FIONWRITE:
{
int count;
irqstate_t state = irqsave();
/* Determine the number of bytes free in the 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;
}
irqrestore(state);
*(int *)arg = count;
ret = 0;
}
break;
}
}
#ifdef CONFIG_SERIAL_TERMIOS
/* Append any higher level TTY flags */
else if (ret == OK)
{
switch (cmd)
{
case TCGETS:
{
struct termios *termiosp = (struct termios*)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;
}
break;
case TCSETS:
{
struct termios *termiosp = (struct termios*)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;
}
break;
}
}
#endif
return ret;
}
/****************************************************************************
* Name: uart_poll
****************************************************************************/
#ifndef CONFIG_DISABLE_POLL
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 */
#if CONFIG_DEBUG
if (!dev || !fds)
{
return -ENODEV;
}
#endif
/* Are we setting up the poll? Or tearing it down? */
ret = uart_takesem(&dev->pollsem, true);
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;
(void)uart_takesem(&dev->xmit.sem, false);
ndx = dev->xmit.head + 1;
if (ndx >= dev->xmit.size)
{
ndx = 0;
}
if (ndx != dev->xmit.tail)
{
eventset |= (fds->events & POLLOUT);
}
uart_givesem(&dev->xmit.sem);
/* 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).
*/
(void)uart_takesem(&dev->recv.sem, false);
if (dev->recv.head != dev->recv.tail)
{
eventset |= (fds->events & POLLIN);
}
uart_givesem(&dev->recv.sem);
#ifdef CONFIG_SERIAL_REMOVABLE
/* Check if a removable device has been disconnected. */
if (dev->disconnected)
{
eventset |= (POLLERR|POLLHUP);
}
#endif
if (eventset)
{
uart_pollnotify(dev, eventset);
}
}
else if (fds->priv)
{
/* This is a request to tear down the poll. */
struct pollfd **slot = (struct pollfd **)fds->priv;
#ifdef CONFIG_DEBUG
if (!slot)
{
ret = -EIO;
goto errout;
}
#endif
/* Remove all memory of the poll setup */
*slot = NULL;
fds->priv = NULL;
}
errout:
uart_givesem(&dev->pollsem);
return ret;
}
#endif
/************************************************************************************
* 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.
*/
(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
*/
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;
}
/************************************************************************************
* 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 = uart_takesem(&dev->closesem, true);
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_sem;
}
#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_sem;
}
/* Check if this is the first time that the driver has been opened. */
if (tmp == 1)
{
irqstate_t flags = irqsave();
/* 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)
{
irqrestore(flags);
goto errout_with_sem;
}
}
/* 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)
{
uart_shutdown(dev);
irqrestore(flags);
goto errout_with_sem;
}
/* Mark the io buffers empty */
dev->xmit.head = 0;
dev->xmit.tail = 0;
dev->recv.head = 0;
dev->recv.tail = 0;
/* Initialise termios state */
#ifdef CONFIG_SERIAL_TERMIOS
dev->tc_iflag = 0;
if (dev->isconsole == true)
{
/* Enable \n -> \r\n translation for the console */
dev->tc_oflag = OPOST | ONLCR;
}
else
{
dev->tc_oflag = 0;
}
#endif
/* Enable the RX interrupt */
uart_enablerxint(dev);
irqrestore(flags);
}
/* Save the new open count on success */
dev->open_count = tmp;
errout_with_sem:
uart_givesem(&dev->closesem);
return ret;
}
/************************************************************************************
* Public Functions
************************************************************************************/
/************************************************************************************
* Name: uart_register
*
* Description:
* Register serial console and serial ports.
*
************************************************************************************/
int uart_register(FAR const char *path, FAR uart_dev_t *dev)
{
sem_init(&dev->xmit.sem, 0, 1);
sem_init(&dev->recv.sem, 0, 1);
sem_init(&dev->closesem, 0, 1);
sem_init(&dev->xmitsem, 0, 0);
sem_init(&dev->recvsem, 0, 0);
#ifndef CONFIG_DISABLE_POLL
sem_init(&dev->pollsem, 0, 1);
#endif
dbg("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)
{
/* Is there a thread waiting for read data? */
if (dev->recvwaiting)
{
/* Yes... wake it up */
dev->recvwaiting = false;
(void)sem_post(&dev->recvsem);
}
/* Notify all poll/select waiters that they can read from the recv buffer */
uart_pollnotify(dev, POLLIN);
}
/************************************************************************************
* 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)
{
/* Is there a thread waiting for space in xmit.buffer? */
if (dev->xmitwaiting)
{
/* Yes... wake it up */
dev->xmitwaiting = false;
(void)sem_post(&dev->xmitsem);
}
/* Notify all poll/select waiters that they can write to xmit buffer */
uart_pollnotify(dev, POLLOUT);
}
/************************************************************************************
* 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 = irqsave();
dev->disconnected = !connected;
if (!connected)
{
/* 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? */
if (dev->xmitwaiting)
{
/* Yes... wake it up */
dev->xmitwaiting = false;
(void)sem_post(&dev->xmitsem);
}
/* Is there a thread waiting for read data? */
if (dev->recvwaiting)
{
/* Yes... wake it up */
dev->recvwaiting = false;
(void)sem_post(&dev->recvsem);
}
/* Notify all poll/select waiters that a hangup occurred */
uart_pollnotify(dev, (POLLERR|POLLHUP));
}
irqrestore(flags);
}
#endif
Reference in New Issue View Git Blame Copy Permalink