/****************************************************************************
* drivers/can/can.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 <sys/types.h>
#include <inttypes.h>
#include <stdint.h>
#include <stdbool.h>
#include <unistd.h>
#include <string.h>
#include <time.h>
#include <fcntl.h>
#include <assert.h>
#include <poll.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <nuttx/clock.h>
#include <nuttx/signal.h>
#include <nuttx/fs/fs.h>
#include <nuttx/can/can.h>
#include <nuttx/kmalloc.h>
#ifdef CONFIG_CAN_TXREADY
# include <nuttx/wqueue.h>
#endif
#include <nuttx/irq.h>
#ifdef CONFIG_CAN
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
#ifdef CONFIG_CAN_TXREADY
# if !defined(CONFIG_SCHED_WORKQUEUE)
# error Work queue support required in this configuration
# undef CONFIG_CAN_TXREADY
# undef CONFIG_CAN_TXREADY_LOPRI
# undef CONFIG_CAN_TXREADY_HIPRI
# elif defined(CONFIG_CAN_TXREADY_LOPRI)
# undef CONFIG_CAN_TXREADY_HIPRI
# ifdef CONFIG_SCHED_LPWORK
# define CANWORK LPWORK
# else
# error Low priority work queue support required in this configuration
# undef CONFIG_CAN_TXREADY
# undef CONFIG_CAN_TXREADY_LOPRI
# endif
# elif defined(CONFIG_CAN_TXREADY_HIPRI)
# ifdef CONFIG_SCHED_HPWORK
# define CANWORK HPWORK
# else
# error High priority work queue support required in this configuration
# undef CONFIG_CAN_TXREADY
# undef CONFIG_CAN_TXREADY_HIPRI
# endif
# else
# error No work queue selection
# undef CONFIG_CAN_TXREADY
# endif
#endif
/* Timing Definitions *******************************************************/
#define HALF_SECOND_MSEC 500
#define HALF_SECOND_USEC 500000L
/****************************************************************************
* 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
#ifdef CONFIG_CAN_TXREADY
static void can_txready_work(FAR void *arg);
#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 file *filep,
FAR struct canioc_rtr_s *rtr);
static int can_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
static int can_poll(FAR struct file *filep,
FAR struct pollfd *fds,
bool setup);
/****************************************************************************
* Private Data
****************************************************************************/
static const struct file_operations g_canops =
{
can_open, /* open */
can_close, /* close */
can_read, /* read */
can_write, /* write */
NULL, /* seek */
can_ioctl, /* ioctl */
NULL, /* mmap */
NULL, /* truncate */
can_poll /* poll */
};
/****************************************************************************
* 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 Parameters:
* 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 Parameters:
* 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_txready_work
*
* Description:
* This function performs deferred processing from can_txready. See the
* description of can_txready below for additional information.
*
****************************************************************************/
#ifdef CONFIG_CAN_TXREADY
static void can_txready_work(FAR void *arg)
{
FAR struct can_dev_s *dev = (FAR struct can_dev_s *)arg;
irqstate_t flags;
int ret;
caninfo("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. The following operations must
* be performed with interrupt disabled.
*/
flags = enter_critical_section();
if (dev->cd_xmit.tx_head != dev->cd_xmit.tx_tail)
{
/* Send the next message in the FIFO. */
ret = can_xmit(dev);
/* If the message was successfully queued in the H/W FIFO, then
* can_txdone() should have been called. If the S/W FIFO were
* full before then there should now be free space in the S/W FIFO.
*/
if (ret >= 0)
{
/* 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 */
nxsem_post(&dev->cd_xmit.tx_sem);
}
}
}
leave_critical_section(flags);
}
#endif
static FAR struct can_reader_s *init_can_reader(FAR struct file *filep)
{
FAR struct can_reader_s *reader = kmm_zalloc(sizeof(struct can_reader_s));
DEBUGASSERT(reader != NULL);
reader->fifo.rx_head = 0;
reader->fifo.rx_tail = 0;
nxsem_init(&reader->fifo.rx_sem, 0, 0);
filep->f_priv = reader;
return reader;
}
/****************************************************************************
* 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;
irqstate_t flags;
int ret;
/* If the port is the middle of closing, wait until the close is finished */
ret = nxmutex_lock(&dev->cd_closelock);
if (ret < 0)
{
return ret;
}
/* If this is the first time that the driver has been opened
* for this device, then perform hardware initialization.
*/
caninfo("ocount: %u\n", dev->cd_crefs);
if (dev->cd_crefs >= 255)
{
/* Limit to no more than 255 opens */
ret = -EMFILE;
goto errout;
}
else
{
flags = enter_critical_section();
if (dev->cd_crefs == 0)
{
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;
/* Finally, Enable the CAN RX interrupt */
dev_rxint(dev, true);
}
}
if (ret == OK)
{
dev->cd_crefs++;
/* Update the reader list only if driver was open for reading */
if ((filep->f_oflags & O_RDOK) != 0)
{
list_add_head(&dev->cd_readers,
(FAR struct list_node *)init_can_reader(filep));
}
}
leave_critical_section(flags);
}
errout:
nxmutex_unlock(&dev->cd_closelock);
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;
FAR struct list_node *node;
FAR struct list_node *tmp;
int ret;
#ifdef CONFIG_DEBUG_CAN_INFO
caninfo("ocount: %u\n", dev->cd_crefs);
#endif
ret = nxmutex_lock(&dev->cd_closelock);
if (ret < 0)
{
return ret;
}
list_for_every_safe(&dev->cd_readers, node, tmp)
{
if (((FAR struct can_reader_s *)node) ==
((FAR struct can_reader_s *)filep->f_priv))
{
list_delete(node);
kmm_free(node);
break;
}
}
filep->f_priv = NULL;
dev->cd_crefs--;
/* De-initialize the driver if there are no more readers */
if (dev->cd_crefs > 0)
{
goto errout;
}
/* 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)
{
nxsig_usleep(HALF_SECOND_USEC);
}
/* And wait for the TX hardware FIFO to drain */
while (!dev_txempty(dev))
{
nxsig_usleep(HALF_SECOND_USEC);
}
/* Free the IRQ and disable the CAN device */
flags = enter_critical_section(); /* Disable interrupts */
dev_shutdown(dev); /* Disable the CAN */
leave_critical_section(flags);
errout:
nxmutex_unlock(&dev->cd_closelock);
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 can_reader_s *reader;
FAR struct can_rxfifo_s *fifo;
size_t nread;
irqstate_t flags;
int ret = 0;
#ifdef CONFIG_CAN_ERRORS
FAR struct inode *inode = filep->f_inode;
FAR struct can_dev_s *dev = inode->i_private;
#endif
caninfo("buflen: %zu\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))
{
DEBUGASSERT(filep->f_priv != NULL);
reader = (FAR struct can_reader_s *)filep->f_priv;
fifo = &reader->fifo;
/* Interrupts must be disabled while accessing the cd_recv FIFO */
flags = enter_critical_section();
#ifdef CONFIG_CAN_ERRORS
/* Check for reader fifo overflow */
if (fifo->rx_overflow)
{
dev->cd_error |= CAN_ERROR5_RXOVERFLOW;
fifo->rx_overflow = false;
}
/* Check for internal errors */
if (dev->cd_error != 0)
{
FAR struct can_msg_s *msg;
/* Detected an internal driver error. Generate a
* CAN_ERROR_MESSAGE
*/
if (buflen < CAN_MSGLEN(CAN_ERROR_DLC))
{
goto return_with_irqdisabled;
}
msg = (FAR struct can_msg_s *)buffer;
msg->cm_hdr.ch_id = CAN_ERROR_INTERNAL;
msg->cm_hdr.ch_dlc = CAN_ERROR_DLC;
msg->cm_hdr.ch_rtr = 0;
msg->cm_hdr.ch_error = 1;
#ifdef CONFIG_CAN_EXTID
msg->cm_hdr.ch_extid = 0;
#endif
msg->cm_hdr.ch_unused = 0;
memset(&(msg->cm_data), 0, CAN_ERROR_DLC);
msg->cm_data[5] = dev->cd_error;
/* Reset the error flag */
dev->cd_error = 0;
ret = CAN_MSGLEN(CAN_ERROR_DLC);
goto return_with_irqdisabled;
}
#endif /* CONFIG_CAN_ERRORS */
if ((filep->f_oflags & O_NONBLOCK) != 0)
{
ret = nxsem_trywait(&fifo->rx_sem);
}
else
{
ret = nxsem_wait(&fifo->rx_sem);
}
if (ret < 0)
{
goto return_with_irqdisabled;
}
if (fifo->rx_head == fifo->rx_tail)
{
canerr("RX FIFO sem posted but FIFO is empty.\n");
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 = &fifo->rx_buffer[fifo->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 (++fifo->rx_head >= CONFIG_CAN_FIFOSIZE)
{
fifo->rx_head = 0;
}
}
while (fifo->rx_head != fifo->rx_tail);
if (fifo->rx_head != fifo->rx_tail)
{
/* The user's buffer was too small, so some messages remain in the
* FIFO. Post the semaphore so future calls to poll() or read()
* don't block.
*/
nxsem_post(&fifo->rx_sem);
}
/* Return the number of bytes that were read. */
ret = nread;
return_with_irqdisabled:
leave_critical_section(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;
caninfo("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);
#ifndef CONFIG_CAN_TXREADY
/* We can disable CAN TX interrupts -- unless there is a H/W FIFO. In
* that case, TX interrupts must stay enabled until the H/W FIFO is
* fully emptied.
*/
dev_txint(dev, false);
#endif
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 < 0)
{
canerr("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;
caninfo("buflen: %zu\n", buflen);
/* Interrupts must disabled throughout the following */
flags = enter_critical_section();
/* 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 (((ssize_t)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) != 0)
{
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 */
DEBUGASSERT(dev->cd_ntxwaiters < 255);
dev->cd_ntxwaiters++;
ret = nxsem_wait(&fifo->tx_sem);
dev->cd_ntxwaiters--;
if (ret < 0)
{
goto return_with_irqdisabled;
}
/* 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 off the XMIT sequence.
*/
if (inactive)
{
can_xmit(dev);
}
/* Return the number of bytes that were sent */
ret = nsent;
return_with_irqdisabled:
leave_critical_section(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 file *filep,
FAR struct canioc_rtr_s *request)
{
FAR struct can_dev_s *dev = filep->f_inode->i_private;
FAR struct can_rtrwait_s *wait = NULL;
irqstate_t flags;
int i;
int sval;
int ret = -ENOMEM;
/* Disable interrupts through this operation */
flags = enter_critical_section();
/* 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];
ret = nxsem_get_value(&tmp->cr_sem, &sval);
if (ret < 0)
{
continue;
}
if (sval == 0)
{
/* No one is waiting on RTR transaction; take it. */
tmp->cr_msg = request->ci_msg;
dev->cd_npendrtr++;
wait = tmp;
break;
}
}
if (wait)
{
/* Send the remote transmission request with the "old method" unless
* the lower-half driver indicates otherwise.
*/
if (dev->cd_ops->co_remoterequest != NULL)
{
if (request->ci_msg->cm_hdr.ch_id < CAN_MAX_STDMSGID
#ifdef CONFIG_CAN_EXTID
&& !request->ci_msg->cm_hdr.ch_extid
#endif
)
{
ret = dev_remoterequest(dev,
(uint16_t)(request->ci_msg->cm_hdr.ch_id));
}
else
{
ret = -EINVAL;
}
}
else
{
#ifdef CONFIG_CAN_USE_RTR
/* Temporarily set the RTR bit, then send the remote transmission
* request message with the lower-half driver's regular function.
*/
request->ci_msg->cm_hdr.ch_rtr = 1;
ret = can_write(filep,
(const char *) request->ci_msg,
CAN_MSGLEN(request->ci_msg->cm_hdr.ch_dlc));
request->ci_msg->cm_hdr.ch_rtr = 0;
#else
canerr("Error: Driver needs CONFIG_CAN_USE_RTR.\n");
ret = -ENOSYS;
#endif
}
if (ret >= 0)
{
/* Then wait for the response */
ret = nxsem_tickwait(&wait->cr_sem,
SEC2TICK(request->ci_timeout.tv_sec) +
NSEC2TICK(request->ci_timeout.tv_nsec));
}
}
leave_critical_section(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;
FAR struct can_reader_s *reader = filep->f_priv;
int ret = OK;
caninfo("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(filep,
(FAR struct canioc_rtr_s *)((uintptr_t)arg));
}
break;
/* CANIOC_IFLUSH: Flush data received but not read. No argument. */
case CANIOC_IFLUSH:
{
reader->fifo.rx_head = 0;
reader->fifo.rx_tail = 0;
/* invoke lower half ioctl */
ret = dev_ioctl(dev, cmd, arg);
}
break;
/* CANIOC_OFLUSH: Flush data written but not transmitted. No argument */
case CANIOC_OFLUSH:
{
dev->cd_xmit.tx_head = 0;
dev->cd_xmit.tx_queue = 0;
dev->cd_xmit.tx_tail = 0;
/* invoke lower half ioctl */
ret = dev_ioctl(dev, cmd, arg);
}
break;
/* CANIOC_IOFLUSH: Flush data received but not read and data written
* but not yet transmitted
*/
case CANIOC_IOFLUSH:
{
dev->cd_xmit.tx_head = 0;
dev->cd_xmit.tx_queue = 0;
dev->cd_xmit.tx_tail = 0;
reader->fifo.rx_head = 0;
reader->fifo.rx_tail = 0;
/* invoke lower half ioctl */
ret = dev_ioctl(dev, cmd, arg);
}
break;
/* FIONWRITE: Return the number of CAN messages in the send queue */
case FIONWRITE:
{
*(uint8_t *)arg = dev->cd_xmit.tx_tail;
}
break;
/* FIONREAD: Return the number of CAN messages in the receive FIFO */
case FIONREAD:
{
*(uint8_t *)arg = reader->fifo.rx_tail;
}
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;
}
/****************************************************************************
* Name: can_poll
****************************************************************************/
static int can_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup)
{
FAR struct inode *inode = (FAR struct inode *)filep->f_inode;
FAR struct can_dev_s *dev = inode->i_private;
FAR struct can_reader_s *reader = NULL;
pollevent_t eventset;
int ndx;
int sval;
irqstate_t flags;
int ret;
int i;
/* Some sanity checking */
#ifdef CONFIG_DEBUG_FEATURES
if (dev == NULL || fds == NULL)
{
return -ENODEV;
}
#endif
/* Ensure exclusive access to FIFO indices - don't want can_receive or
* can_read changing them in the middle of the comparison
*/
flags = enter_critical_section();
DEBUGASSERT(filep->f_priv != NULL);
reader = (FAR struct can_reader_s *)filep->f_priv;
/* Get exclusive access to the poll structures */
ret = nxmutex_lock(&dev->cd_polllock);
if (ret < 0)
{
/* A signal received while waiting for access to the poll data
* will abort the operation
*/
goto return_with_irqdisabled;
}
/* Are we setting up the poll? Or tearing it down? */
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_CAN_NPOLLWAITERS; i++)
{
/* Find an available slot */
if (dev->cd_fds[i] == NULL)
{
/* Bind the poll structure and this slot */
dev->cd_fds[i] = fds;
fds->priv = &dev->cd_fds[i];
break;
}
}
if (i >= CONFIG_CAN_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 cd_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;
DEBUGASSERT(dev->cd_ntxwaiters < 255);
dev->cd_ntxwaiters++;
do
{
ret = nxsem_wait(&dev->cd_xmit.tx_sem);
}
while (ret < 0);
dev->cd_ntxwaiters--;
ndx = dev->cd_xmit.tx_tail + 1;
if (ndx >= CONFIG_CAN_FIFOSIZE)
{
ndx = 0;
}
if (ndx != dev->cd_xmit.tx_head)
{
eventset |= POLLOUT;
}
nxsem_post(&dev->cd_xmit.tx_sem);
/* Check whether there are messages in the RX FIFO. */
ret = nxsem_get_value(&reader->fifo.rx_sem, &sval);
if (ret < 0)
{
DEBUGPANIC();
goto return_with_irqdisabled;
}
else if (sval > 0)
{
if (reader->fifo.rx_head != reader->fifo.rx_tail)
{
/* No need to wait, just notify the application immediately */
eventset |= POLLIN;
}
else
{
canerr("RX FIFO sem not locked but FIFO is empty.\n");
}
}
poll_notify(&fds, 1, 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 == NULL)
{
ret = -EIO;
goto errout;
}
#endif
/* Remove all memory of the poll setup */
*slot = NULL;
fds->priv = NULL;
}
errout:
nxmutex_unlock(&dev->cd_polllock);
return_with_irqdisabled:
leave_critical_section(flags);
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_crefs = 0;
dev->cd_npendrtr = 0;
dev->cd_ntxwaiters = 0;
#ifdef CONFIG_CAN_ERRORS
dev->cd_error = 0;
#endif
list_initialize(&dev->cd_readers);
/* Initialize semaphores */
nxsem_init(&dev->cd_xmit.tx_sem, 0, 1);
nxmutex_init(&dev->cd_closelock);
nxmutex_init(&dev->cd_polllock);
for (i = 0; i < CONFIG_CAN_NPENDINGRTR; i++)
{
/* Initialize wait semaphores. These semaphores are used for signaling
* and should not have priority inheritance enabled.
*/
nxsem_init(&dev->cd_rtr[i].cr_sem, 0, 0);
}
/* Initialize/reset the CAN hardware */
dev_reset(dev);
/* Register the CAN device */
caninfo("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
*
* Input Parameters:
* dev - CAN driver state structure
* hdr - CAN message header
* data - CAN message data (if DLC > 0)
*
* Returned Value:
* OK on success; a negated errno on failure.
*
* 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;
FAR uint8_t *dest;
FAR struct list_node *node;
FAR struct list_node *tmp;
int nexttail;
int errcode = -ENOMEM;
int i;
int j;
int sval;
int ret;
caninfo("ID: %" PRId32 " DLC: %d\n", (uint32_t)hdr->ch_id, hdr->ch_dlc);
/* Check if adding this new message would over-run the drivers ability to
* enqueue read data.
*/
/* 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 *wait = &dev->cd_rtr[i];
FAR struct can_msg_s *waitmsg = wait->cr_msg;
/* Check if the entry is in use and whether the ID matches */
ret = nxsem_get_value(&wait->cr_sem, &sval);
if (ret < 0)
{
continue;
}
else if (sval < 0
#ifdef CONFIG_CAN_ERRORS
&& hdr->ch_error == false
#endif
#ifdef CONFIG_CAN_EXTID
&& waitmsg->cm_hdr.ch_extid == hdr->ch_extid
#endif
&& waitmsg->cm_hdr.ch_id == hdr->ch_id)
{
int nbytes;
/* We have the response... copy the data to the user's buffer */
memcpy(&waitmsg->cm_hdr, hdr, sizeof(struct can_hdr_s));
nbytes = can_dlc2bytes(hdr->ch_dlc);
for (j = 0, dest = waitmsg->cm_data; j < nbytes; j++)
{
*dest++ = *data++;
}
dev->cd_npendrtr--;
/* Restart the waiting thread and mark the entry unused */
nxsem_post(&wait->cr_sem);
}
}
}
list_for_every_safe(&dev->cd_readers, node, tmp)
{
FAR struct can_reader_s *reader = (FAR struct can_reader_s *)node;
fifo = &reader->fifo;
nexttail = fifo->rx_tail + 1;
if (nexttail >= CONFIG_CAN_FIFOSIZE)
{
nexttail = 0;
}
/* 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);
memcpy(fifo->rx_buffer[fifo->rx_tail].cm_data, data, nbytes);
/* Increment the tail of the circular buffer */
fifo->rx_tail = nexttail;
/* Notify all poll/select waiters that they can read from the
* cd_recv buffer
*/
poll_notify(dev->cd_fds, CONFIG_CAN_NPOLLWAITERS, POLLIN);
sval = 0;
if (nxsem_get_value(&fifo->rx_sem, &sval) < 0)
{
DEBUGPANIC();
#ifdef CONFIG_CAN_ERRORS
/* Report unspecified error */
dev->cd_error |= CAN_ERROR5_UNSPEC;
#endif
return -EINVAL;
}
/* Unlock the binary semaphore, waking up can_read if it is
* blocked. If can_read were not blocked, we would not be
* executing this because interrupts would be disabled.
*/
if (sval <= 0)
{
nxsem_post(&fifo->rx_sem);
}
errcode = OK;
}
#ifdef CONFIG_CAN_ERRORS
else
{
/* Report rx overflow error */
fifo->rx_overflow = true;
}
#endif
}
return errcode;
}
/****************************************************************************
* Name: can_txdone
*
* Description:
* Called when the hardware has processed the outgoing TX message. This
* normally means that the CAN messages was sent out on the wire. But
* if the CAN hardware supports a H/W TX FIFO, then this call may mean
* only that the CAN message has been added to the H/W FIFO. In either
* case, the upper-half CAN driver can remove the outgoing message from
* the S/W FIFO and discard it.
*
* This function may be called in different contexts, depending upon the
* nature of the underlying CAN hardware.
*
* 1. No H/W TX FIFO (CONFIG_CAN_TXREADY not defined)
*
* This function is only called from the CAN interrupt handler at the
* completion of a send operation.
*
* can_write() -> can_xmit() -> dev_send()
* CAN interrupt -> can_txdone()
*
* If the CAN hardware is busy, then the call to dev_send() will
* fail, the S/W TX FIFO will accumulate outgoing messages, and the
* thread calling can_write() may eventually block waiting for space in
* the S/W TX FIFO.
*
* When the CAN hardware completes the transfer and processes the
* CAN interrupt, the call to can_txdone() will make space in the S/W
* TX FIFO and will awaken the waiting can_write() thread.
*
* 2a. H/W TX FIFO (CONFIG_CAN_TXREADY=y) and S/W TX FIFO not full
*
* This function will be called back from dev_send() immediately when a
* new CAN message is added to H/W TX FIFO:
*
* can_write() -> can_xmit() -> dev_send() -> can_txdone()
*
* When the H/W TX FIFO becomes full, dev_send() will fail and
* can_txdone() will not be called. In this case the S/W TX FIFO will
* accumulate outgoing messages, and the thread calling can_write() may
* eventually block waiting for space in the S/W TX FIFO.
*
* 2b. H/W TX FIFO (CONFIG_CAN_TXREADY=y) and S/W TX FIFO full
*
* In this case, the thread calling can_write() is blocked waiting for
* space in the S/W TX FIFO. can_txdone() will be called, indirectly,
* from can_txready_work() running on the thread of the work queue.
*
* CAN interrupt -> can_txready() -> Schedule can_txready_work()
* can_txready_work() -> can_xmit() -> dev_send() -> can_txdone()
*
* The call dev_send() should not fail in this case and the subsequent
* call to can_txdone() will make space in the S/W TX FIFO and will
* awaken the waiting thread.
*
* Input Parameters:
* dev - The specific CAN device
* hdr - The 16-bit CAN header
* data - An array contain the CAN data.
*
* Returned Value:
* OK on success; a negated errno on failure.
*
* Assumptions:
* Interrupts are disabled. This is required by can_xmit() which is called
* by this function. Interrupts are explicitly disabled when called
* through can_write(). Interrupts are expected be disabled when called
* from the CAN interrupt handler.
*
****************************************************************************/
int can_txdone(FAR struct can_dev_s *dev)
{
int ret = -ENOENT;
caninfo("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)
{
/* The tx_queue index is incremented each time can_xmit() queues
* the transmission. When can_txdone() is called, the tx_queue
* index should always have been advanced beyond the current tx_head
* index.
*/
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 */
can_xmit(dev);
/* Notify all poll/select waiters that they can write to the cd_xmit
* buffer
*/
poll_notify(dev->cd_fds, CONFIG_CAN_NPOLLWAITERS, POLLOUT);
/* 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 = nxsem_post(&dev->cd_xmit.tx_sem);
}
else
{
ret = OK;
}
}
return ret;
}
/****************************************************************************
* Name: can_txready
*
* Description:
* Called from the CAN interrupt handler at the completion of a send
* operation. This interface is needed only for CAN hardware that
* supports queueing of outgoing messages in a H/W FIFO.
*
* The CAN upper half driver also supports a queue of output messages in a
* S/W FIFO. Messages are added to that queue when when can_write() is
* called and removed from the queue in can_txdone() when each TX message
* is complete.
*
* After each message is added to the S/W FIFO, the CAN upper half driver
* will attempt to send the message by calling into the lower half driver.
* That send will not be performed if the lower half driver is busy, i.e.,
* if dev_txready() returns false. In that case, the number of messages in
* the S/W FIFO can grow. If the S/W FIFO becomes full, then can_write()
* will wait for space in the S/W FIFO.
*
* If the CAN hardware does not support a H/W FIFO then busy means that
* the hardware is actively sending the message and is guaranteed to
* become non-busy (i.e, dev_txready()) when the send transfer completes
* and can_txdone() is called. So the call to can_txdone() means that the
* transfer has completed and also that the hardware is ready to accept
* another transfer.
*
* If the CAN hardware supports a H/W FIFO, can_txdone() is not called
* when the transfer is complete, but rather when the transfer is queued in
* the H/W FIFO. When the H/W FIFO becomes full, then dev_txready() will
* report false and the number of queued messages in the S/W FIFO will
* grow.
*
* There is no mechanism in this case to inform the upper half driver when
* the hardware is again available, when there is again space in the H/W
* FIFO. can_txdone() will not be called again. If the S/W FIFO becomes
* full, then the upper half driver will wait for space to become
* available, but there is no event to awaken it and the driver will hang.
*
* Enabling this feature adds support for the can_txready() interface.
* This function is called from the lower half driver's CAN interrupt
* handler each time a TX transfer completes. This is a sure indication
* that the H/W FIFO is no longer full. can_txready() will then awaken
* the can_write() logic and the hang condition is avoided.
*
* Input Parameters:
* dev - The specific CAN device
*
* Returned Value:
* OK on success; a negated errno on failure.
*
* Assumptions:
* Interrupts are disabled. This function may execute in the context of
* and interrupt handler.
*
****************************************************************************/
#ifdef CONFIG_CAN_TXREADY
int can_txready(FAR struct can_dev_s *dev)
{
int ret = -ENOENT;
caninfo("xmit head: %d queue: %d tail: %d waiters: %d\n",
dev->cd_xmit.tx_head, dev->cd_xmit.tx_queue, dev->cd_xmit.tx_tail,
dev->cd_ntxwaiters);
/* Verify that the xmit FIFO is not empty. This is safe because interrupts
* are always disabled when calling into can_xmit(); this cannot collide
* with ongoing activity from can_write().
*/
if (dev->cd_xmit.tx_head != dev->cd_xmit.tx_tail)
{
/* Is work already scheduled? */
if (work_available(&dev->cd_work))
{
/* Yes... schedule to perform can_txready() work on the worker
* thread. Although data structures are protected by disabling
* interrupts, the can_xmit() operations may involve semaphore
* operations and, hence, should not be done at the interrupt
* level.
*/
ret = work_queue(CANWORK, &dev->cd_work, can_txready_work, dev, 0);
}
else
{
ret = -EBUSY;
}
}
else
{
/* There should not be any threads waiting for space in the S/W TX
* FIFO is it is empty. However, an assertion would fire in certain
* race conditions, i.e, when all waiters have been awakened but
* have not yet had a chance to decrement cd_ntxwaiters.
*/
#if 0 /* REVISIT */
/* When the H/W FIFO has been emptied, we can disable further TX
* interrupts.
*
* REVISIT: The fact that the S/W FIFO is empty does not mean that
* the H/W FIFO is also empty. If we really want this to work this
* way, then we would probably need and additional parameter to tell
* us if the H/W FIFO is empty.
*/
dev_txint(dev, false);
#endif
}
return ret;
}
#endif /* CONFIG_CAN_TXREADY */
#endif /* CONFIG_CAN */