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nuttx/drivers/can.c
Gregory Nutt cf14f8d1b5 drivers/: Fixes to spacing and alignement
2015-10-10 10:41:00 -06:00

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/****************************************************************************
* drivers/can.c
*
* Copyright (C) 2008-2009, 2011-2012, 2014-2015 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 <string.h>
#include <semaphore.h>
#include <fcntl.h>
#include <assert.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/fs/fs.h>
#include <nuttx/arch.h>
#include <nuttx/can.h>
#include <arch/irq.h>
#ifdef CONFIG_CAN
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Debug ********************************************************************/
/* Non-standard debug that may be enabled just for testing CAN */
#ifdef CONFIG_DEBUG_CAN
# define candbg dbg
# define canvdbg vdbg
# define canlldbg lldbg
# define canllvdbg llvdbg
#else
# define candbg(x...)
# define canvdbg(x...)
# define canlldbg(x...)
# define canllvdbg(x...)
#endif
/* Timing Definitions *******************************************************/
#define HALF_SECOND_MSEC 500
#define HALF_SECOND_USEC 500000L
/****************************************************************************
* Private Type Definitions
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/* CAN helpers */
static uint8_t can_dlc2bytes(uint8_t dlc);
#if 0 /* Not used */
static uint8_t can_bytes2dlc(uint8_t nbytes);
#endif
/* Character driver methods */
static int can_open(FAR struct file *filep);
static int can_close(FAR struct file *filep);
static ssize_t can_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static int can_xmit(FAR struct can_dev_s *dev);
static ssize_t can_write(FAR struct file *filep,
FAR const char *buffer, size_t buflen);
static inline ssize_t can_rtrread(FAR struct can_dev_s *dev,
FAR struct canioc_rtr_s *rtr);
static int can_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_canops =
{
can_open, /* open */
can_close, /* close */
can_read, /* read */
can_write, /* write */
0, /* seek */
can_ioctl /* ioctl */
#ifndef CONFIG_DISABLE_POLL
, 0 /* poll */
#endif
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, 0 /* unlink */
#endif
};
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: can_dlc2bytes
*
* Description:
* In the CAN FD format, the coding of the DLC differs from the standard
* CAN format. The DLC codes 0 to 8 have the same coding as in standard
* CAN. But the codes 9 to 15 all imply a data field of 8 bytes with
* standard CAN. In CAN FD mode, the values 9 to 15 are encoded to values
* in the range 12 to 64.
*
* Input Parameter:
* dlc - the DLC value to convert to a byte count
*
* Returned Value:
* The number of bytes corresponding to the DLC value.
*
****************************************************************************/
static uint8_t can_dlc2bytes(uint8_t dlc)
{
if (dlc > 8)
{
#ifdef CONFIG_CAN_FD
switch (dlc)
{
case 9:
return 12;
case 10:
return 16;
case 11:
return 20;
case 12:
return 24;
case 13:
return 32;
case 14:
return 48;
default:
case 15:
return 64;
}
#else
return 8;
#endif
}
return dlc;
}
/****************************************************************************
* Name: can_bytes2dlc
*
* Description:
* In the CAN FD format, the coding of the DLC differs from the standard
* CAN format. The DLC codes 0 to 8 have the same coding as in standard
* CAN. But the codes 9 to 15 all imply a data field of 8 bytes with
* standard CAN. In CAN FD mode, the values 9 to 15 are encoded to values
* in the range 12 to 64.
*
* Input Parameter:
* nbytes - the byte count to convert to a DLC value
*
* Returned Value:
* The encoded DLC value corresponding to at least that number of bytes.
*
****************************************************************************/
#if 0 /* Not used */
static uint8_t can_bytes2dlc(FAR struct sam_can_s *priv, uint8_t nbytes)
{
if (nbytes <= 8)
{
return nbytes;
}
#ifdef CONFIG_CAN_FD
else if (nbytes <= 12)
{
return 9;
}
else if (nbytes <= 16)
{
return 10;
}
else if (nbytes <= 20)
{
return 11;
}
else if (nbytes <= 24)
{
return 12;
}
else if (nbytes <= 32)
{
return 13;
}
else if (nbytes <= 48)
{
return 14;
}
else /* if (nbytes <= 64) */
{
return 15;
}
#else
else
{
return 8;
}
#endif
}
#endif
/****************************************************************************
* Name: can_open
*
* Description:
* This function is called whenever the CAN device is opened.
*
****************************************************************************/
static int can_open(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct can_dev_s *dev = inode->i_private;
uint8_t tmp;
int ret = OK;
canvdbg("ocount: %d\n", dev->cd_ocount);
/* If the port is the middle of closing, wait until the close is finished */
if (sem_wait(&dev->cd_closesem) != OK)
{
ret = -get_errno();
}
else
{
/* Increment the count of references to the device. If this is the first
* time that the driver has been opened for this device, then initialize
* the device.
*/
tmp = dev->cd_ocount + 1;
if (tmp == 0)
{
/* More than 255 opens; uint8_t overflows to zero */
ret = -EMFILE;
}
else
{
/* Check if this is the first time that the driver has been opened. */
if (tmp == 1)
{
/* Yes.. perform one time hardware initialization. */
irqstate_t flags = irqsave();
ret = dev_setup(dev);
if (ret == OK)
{
/* Mark the FIFOs empty */
dev->cd_xmit.tx_head = 0;
dev->cd_xmit.tx_queue = 0;
dev->cd_xmit.tx_tail = 0;
dev->cd_recv.rx_head = 0;
dev->cd_recv.rx_tail = 0;
/* Finally, Enable the CAN RX interrupt */
dev_rxint(dev, true);
/* Save the new open count only on success */
dev->cd_ocount = 1;
}
irqrestore(flags);
}
else
{
/* Save the incremented open count */
dev->cd_ocount = tmp;
}
}
sem_post(&dev->cd_closesem);
}
return ret;
}
/****************************************************************************
* Name: can_close
*
* Description:
* This routine is called when the CAN device is closed.
* It waits for the last remaining data to be sent.
*
****************************************************************************/
static int can_close(FAR struct file *filep)
{
FAR struct inode *inode = filep->f_inode;
FAR struct can_dev_s *dev = inode->i_private;
irqstate_t flags;
int ret = OK;
canvdbg("ocount: %d\n", dev->cd_ocount);
if (sem_wait(&dev->cd_closesem) != OK)
{
ret = -get_errno();
}
else
{
/* Decrement the references to the driver. If the reference count will
* decrement to 0, then uninitialize the driver.
*/
if (dev->cd_ocount > 1)
{
dev->cd_ocount--;
sem_post(&dev->cd_closesem);
}
else
{
/* There are no more references to the port */
dev->cd_ocount = 0;
/* Stop accepting input */
dev_rxint(dev, false);
/* Now we wait for the transmit FIFO to clear */
while (dev->cd_xmit.tx_head != dev->cd_xmit.tx_tail)
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* And wait for the TX hardware FIFO to drain */
while (!dev_txempty(dev))
{
#ifndef CONFIG_DISABLE_SIGNALS
usleep(HALF_SECOND_USEC);
#else
up_mdelay(HALF_SECOND_MSEC);
#endif
}
/* Free the IRQ and disable the CAN device */
flags = irqsave(); /* Disable interrupts */
dev_shutdown(dev); /* Disable the CAN */
irqrestore(flags);
sem_post(&dev->cd_closesem);
}
}
return ret;
}
/****************************************************************************
* Name: can_read
*
* Description:
* Read standard CAN messages
*
****************************************************************************/
static ssize_t can_read(FAR struct file *filep, FAR char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct can_dev_s *dev = inode->i_private;
size_t nread;
irqstate_t flags;
int ret = 0;
canvdbg("buflen: %d\n", buflen);
/* The caller must provide enough memory to catch the smallest possible
* message. This is not a system error condition, but we won't permit
* it, Hence we return 0.
*/
if (buflen >= CAN_MSGLEN(0))
{
/* Interrupts must be disabled while accessing the cd_recv FIFO */
flags = irqsave();
while (dev->cd_recv.rx_head == dev->cd_recv.rx_tail)
{
/* The receive FIFO is empty -- was non-blocking mode selected? */
if (filep->f_oflags & O_NONBLOCK)
{
ret = -EAGAIN;
goto return_with_irqdisabled;
}
/* Wait for a message to be received */
dev->cd_nrxwaiters++;
do
{
ret = sem_wait(&dev->cd_recv.rx_sem);
}
while (ret >= 0 && dev->cd_recv.rx_head == dev->cd_recv.rx_tail);
dev->cd_nrxwaiters--;
if (ret < 0)
{
ret = -get_errno();
goto return_with_irqdisabled;
}
}
/* The cd_recv FIFO is not empty. Copy all buffered data that will fit
* in the user buffer.
*/
nread = 0;
do
{
/* Will the next message in the FIFO fit into the user buffer? */
FAR struct can_msg_s *msg = &dev->cd_recv.rx_buffer[dev->cd_recv.rx_head];
int nbytes = can_dlc2bytes(msg->cm_hdr.ch_dlc);
int msglen = CAN_MSGLEN(nbytes);
if (nread + msglen > buflen)
{
break;
}
/* Copy the message to the user buffer */
memcpy(&buffer[nread], msg, msglen);
nread += msglen;
/* Increment the head of the circular message buffer */
if (++dev->cd_recv.rx_head >= CONFIG_CAN_FIFOSIZE)
{
dev->cd_recv.rx_head = 0;
}
}
while (dev->cd_recv.rx_head != dev->cd_recv.rx_tail);
/* All on the messages have bee transferred. Return the number of bytes
* that were read.
*/
ret = nread;
return_with_irqdisabled:
irqrestore(flags);
}
return ret;
}
/****************************************************************************
* Name: can_xmit
*
* Description:
* Send the message at the head of the cd_xmit FIFO
*
* Assumptions:
* Called with interrupts disabled
*
****************************************************************************/
static int can_xmit(FAR struct can_dev_s *dev)
{
int tmpndx;
int ret = -EBUSY;
canllvdbg("xmit head: %d queue: %d tail: %d\n",
dev->cd_xmit.tx_head, dev->cd_xmit.tx_queue, dev->cd_xmit.tx_tail);
/* If there is nothing to send, then just disable interrupts and return */
if (dev->cd_xmit.tx_head == dev->cd_xmit.tx_tail)
{
DEBUGASSERT(dev->cd_xmit.tx_queue == dev->cd_xmit.tx_head);
dev_txint(dev, false);
return -EIO;
}
/* Check if we have already queued all of the data in the TX fifo.
*
* tx_tail: Incremented in can_write each time a message is queued in the FIFO
* tx_head: Incremented in can_txdone each time a message completes
* tx_queue: Incremented each time that a message is sent to the hardware.
*
* Logically (ignoring buffer wrap-around): tx_head <= tx_queue <= tx_tail
* tx_head == tx_queue == tx_tail means that the FIFO is empty
* tx_head < tx_queue == tx_tail means that all data has been queued, but
* we are still waiting for transmissions to complete.
*/
while (dev->cd_xmit.tx_queue != dev->cd_xmit.tx_tail && dev_txready(dev))
{
/* No.. The FIFO should not be empty in this case */
DEBUGASSERT(dev->cd_xmit.tx_head != dev->cd_xmit.tx_tail);
/* Increment the FIFO queue index before sending (because dev_send()
* might call can_txdone().
*/
tmpndx = dev->cd_xmit.tx_queue;
if (++dev->cd_xmit.tx_queue >= CONFIG_CAN_FIFOSIZE)
{
dev->cd_xmit.tx_queue = 0;
}
/* Send the next message at the FIFO queue index */
ret = dev_send(dev, &dev->cd_xmit.tx_buffer[tmpndx]);
if (ret != OK)
{
candbg("dev_send failed: %d\n", ret);
break;
}
}
/* Make sure that TX interrupts are enabled */
dev_txint(dev, true);
return ret;
}
/****************************************************************************
* Name: can_write
****************************************************************************/
static ssize_t can_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR struct can_dev_s *dev = inode->i_private;
FAR struct can_txfifo_s *fifo = &dev->cd_xmit;
FAR struct can_msg_s *msg;
bool inactive;
ssize_t nsent = 0;
irqstate_t flags;
int nexttail;
int nbytes;
int msglen;
int ret = 0;
canvdbg("buflen: %d\n", buflen);
/* Interrupts must disabled throughout the following */
flags = irqsave();
/* Check if the TX is inactive when we started. In certain race conditions,
* there may be a pending interrupt to kick things back off, but we will
* be sure here that there is not. That the hardware is IDLE and will
* need to be kick-started.
*/
inactive = dev_txempty(dev);
/* Add the messages to the FIFO. Ignore any trailing messages that are
* shorter than the minimum.
*/
while ((buflen - nsent) >= CAN_MSGLEN(0))
{
/* Check if adding this new message would over-run the drivers ability
* to enqueue xmit data.
*/
nexttail = fifo->tx_tail + 1;
if (nexttail >= CONFIG_CAN_FIFOSIZE)
{
nexttail = 0;
}
/* If the XMIT FIFO becomes full, then wait for space to become available */
while (nexttail == fifo->tx_head)
{
/* The transmit FIFO is full -- was non-blocking mode selected? */
if (filep->f_oflags & O_NONBLOCK)
{
if (nsent == 0)
{
ret = -EAGAIN;
}
else
{
ret = nsent;
}
goto return_with_irqdisabled;
}
/* If the TX hardware was inactive when we started, then we will have
* start the XMIT sequence generate the TX done interrupts needed
* to clear the FIFO.
*/
if (inactive)
{
can_xmit(dev);
}
/* Wait for a message to be sent */
do
{
DEBUGASSERT(dev->cd_ntxwaiters < 255);
dev->cd_ntxwaiters++;
ret = sem_wait(&fifo->tx_sem);
dev->cd_ntxwaiters--;
if (ret < 0 && get_errno() != EINTR)
{
ret = -get_errno();
goto return_with_irqdisabled;
}
}
while (ret < 0);
/* Re-check the FIFO state */
inactive = dev_txempty(dev);
}
/* We get here if there is space at the end of the FIFO. Add the new
* CAN message at the tail of the FIFO.
*/
msg = (FAR struct can_msg_s *)&buffer[nsent];
nbytes = can_dlc2bytes(msg->cm_hdr.ch_dlc);
msglen = CAN_MSGLEN(nbytes);
memcpy(&fifo->tx_buffer[fifo->tx_tail], msg, msglen);
/* Increment the tail of the circular buffer */
fifo->tx_tail = nexttail;
/* Increment the number of bytes that were sent */
nsent += msglen;
}
/* We get here after all messages have been added to the FIFO. Check if
* we need to kick of the XMIT sequence.
*/
if (inactive)
{
can_xmit(dev);
}
/* Return the number of bytes that were sent */
ret = nsent;
return_with_irqdisabled:
irqrestore(flags);
return ret;
}
/****************************************************************************
* Name: can_rtrread
*
* Description:
* Read RTR messages. The RTR message is a special message -- it is an
* outgoing message that says "Please re-transmit the message with the
* same identifier as this message. So the RTR read is really a
* send-wait-receive operation.
*
****************************************************************************/
static inline ssize_t can_rtrread(FAR struct can_dev_s *dev,
FAR struct canioc_rtr_s *rtr)
{
FAR struct can_rtrwait_s *wait = NULL;
irqstate_t flags;
int i;
int ret = -ENOMEM;
/* Disable interrupts through this operation */
flags = irqsave();
/* Find an available slot in the pending RTR list */
for (i = 0; i < CONFIG_CAN_NPENDINGRTR; i++)
{
FAR struct can_rtrwait_s *tmp = &dev->cd_rtr[i];
if (!rtr->ci_msg)
{
tmp->cr_id = rtr->ci_id;
tmp->cr_msg = rtr->ci_msg;
dev->cd_npendrtr++;
wait = tmp;
break;
}
}
if (wait)
{
/* Send the remote transmission request */
ret = dev_remoterequest(dev, wait->cr_id);
if (ret == OK)
{
/* Then wait for the response */
ret = sem_wait(&wait->cr_sem);
}
}
irqrestore(flags);
return ret;
}
/****************************************************************************
* Name: can_ioctl
****************************************************************************/
static int can_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
{
FAR struct inode *inode = filep->f_inode;
FAR struct can_dev_s *dev = inode->i_private;
int ret = OK;
canvdbg("cmd: %d arg: %ld\n", cmd, arg);
/* Handle built-in ioctl commands */
switch (cmd)
{
/* CANIOC_RTR: Send the remote transmission request and wait for the
* response. Argument is a reference to struct canioc_rtr_s
* (casting to uintptr_t first eliminates complaints on some
* architectures where the sizeof long is different from the size of
* a pointer).
*/
case CANIOC_RTR:
ret = can_rtrread(dev, (FAR struct canioc_rtr_s *)((uintptr_t)arg));
break;
/* Not a "built-in" ioctl command.. perhaps it is unique to this
* lower-half, device driver.
*/
default:
ret = dev_ioctl(dev, cmd, arg);
break;
}
return ret;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: can_register
*
* Description:
* Register serial console and serial ports.
*
****************************************************************************/
int can_register(FAR const char *path, FAR struct can_dev_s *dev)
{
int i;
/* Initialize the CAN device structure */
dev->cd_ocount = 0;
dev->cd_ntxwaiters = 0;
dev->cd_nrxwaiters = 0;
dev->cd_npendrtr = 0;
sem_init(&dev->cd_xmit.tx_sem, 0, 0);
sem_init(&dev->cd_recv.rx_sem, 0, 0);
sem_init(&dev->cd_closesem, 0, 1);
for (i = 0; i < CONFIG_CAN_NPENDINGRTR; i++)
{
sem_init(&dev->cd_rtr[i].cr_sem, 0, 0);
dev->cd_rtr[i].cr_msg = NULL;
}
/* Initialize/reset the CAN hardware */
dev_reset(dev);
/* Register the CAN device */
canvdbg("Registering %s\n", path);
return register_driver(path, &g_canops, 0666, dev);
}
/****************************************************************************
* Name: can_receive
*
* Description:
* Called from the CAN interrupt handler when new read data is available
*
* Parameters:
* dev - CAN driver state structure
* hdr - CAN message header
* data - CAN message data (if DLC > 0)
*
* Assumptions:
* CAN interrupts are disabled.
*
****************************************************************************/
int can_receive(FAR struct can_dev_s *dev, FAR struct can_hdr_s *hdr,
FAR uint8_t *data)
{
FAR struct can_rxfifo_s *fifo = &dev->cd_recv;
FAR uint8_t *dest;
int nexttail;
int err = -ENOMEM;
int i;
canllvdbg("ID: %d DLC: %d\n", hdr->ch_id, hdr->ch_dlc);
/* Check if adding this new message would over-run the drivers ability to
* enqueue read data.
*/
nexttail = fifo->rx_tail + 1;
if (nexttail >= CONFIG_CAN_FIFOSIZE)
{
nexttail = 0;
}
/* First, check if this response matches any RTR response that we may be
* waiting for.
*/
if (dev->cd_npendrtr > 0)
{
/* There are pending RTR requests -- search the lists of requests
* and see any any matches this new message.
*/
for (i = 0; i < CONFIG_CAN_NPENDINGRTR; i++)
{
FAR struct can_rtrwait_s *rtr = &dev->cd_rtr[i];
FAR struct can_msg_s *msg = rtr->cr_msg;
/* Check if the entry is valid and if the ID matches. A valid
* entry has a non-NULL receiving address
*/
if (msg && hdr->ch_id == rtr->cr_id)
{
int nbytes;
/* We have the response... copy the data to the user's buffer */
memcpy(&msg->cm_hdr, hdr, sizeof(struct can_hdr_s));
nbytes = can_dlc2bytes(hdr->ch_dlc);
for (i = 0, dest = msg->cm_data; i < nbytes; i++)
{
*dest++ = *data++;
}
/* Mark the entry unused */
rtr->cr_msg = NULL;
dev->cd_npendrtr--;
/* And restart the waiting thread */
sem_post(&rtr->cr_sem);
}
}
}
/* Refuse the new data if the FIFO is full */
if (nexttail != fifo->rx_head)
{
int nbytes;
/* Add the new, decoded CAN message at the tail of the FIFO.
*
* REVISIT: In the CAN FD format, the coding of the DLC differs from
* the standard CAN format. The DLC codes 0 to 8 have the same coding
* as in standard CAN, the codes 9 to 15, which in standard CAN all
* code a data field of 8 bytes, are encoded:
*
* 9->12, 10->16, 11->20, 12->24, 13->32, 14->48, 15->64
*/
memcpy(&fifo->rx_buffer[fifo->rx_tail].cm_hdr, hdr, sizeof(struct can_hdr_s));
nbytes = can_dlc2bytes(hdr->ch_dlc);
for (i = 0, dest = fifo->rx_buffer[fifo->rx_tail].cm_data; i < nbytes; i++)
{
*dest++ = *data++;
}
/* Increment the tail of the circular buffer */
fifo->rx_tail = nexttail;
/* The increment the counting semaphore. The maximum value should be
* CONFIG_CAN_FIFOSIZE -- one possible count for each allocated
* message buffer.
*/
if (dev->cd_nrxwaiters > 0)
{
sem_post(&fifo->rx_sem);
}
err = OK;
}
return err;
}
/****************************************************************************
* Name: can_txdone
*
* Description:
* Called from the CAN interrupt handler at the completion of a send
* operation.
*
* Parameters:
* dev - The specific CAN device
* hdr - The 16-bit CAN header
* data - An array contain the CAN data.
*
* Return:
* OK on success; a negated errno on failure.
*
****************************************************************************/
int can_txdone(FAR struct can_dev_s *dev)
{
int ret = -ENOENT;
canllvdbg("xmit head: %d queue: %d tail: %d\n",
dev->cd_xmit.tx_head, dev->cd_xmit.tx_queue, dev->cd_xmit.tx_tail);
/* Verify that the xmit FIFO is not empty */
if (dev->cd_xmit.tx_head != dev->cd_xmit.tx_tail)
{
DEBUGASSERT(dev->cd_xmit.tx_head != dev->cd_xmit.tx_queue);
/* Remove the message at the head of the xmit FIFO */
if (++dev->cd_xmit.tx_head >= CONFIG_CAN_FIFOSIZE)
{
dev->cd_xmit.tx_head = 0;
}
/* Send the next message in the FIFO */
(void)can_xmit(dev);
/* Are there any threads waiting for space in the TX FIFO? */
if (dev->cd_ntxwaiters > 0)
{
/* Yes.. Inform them that new xmit space is available */
ret = sem_post(&dev->cd_xmit.tx_sem);
}
else
{
ret = OK;
}
}
return ret;
}
#endif /* CONFIG_CAN */
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