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;
}
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 */
ret = can_xmit(dev);
/* Are there any threads waiting for space in the TX FIFO? */
if (ret == OK && dev->cd_ntxwaiters > 0)
{
/* Yes.. Inform them that new xmit space is available */
ret = sem_post(&dev->cd_xmit.tx_sem);
}
}
return ret;
}
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)
{
/* We have the response... copy the data to the user's buffer */
memcpy(&msg->cm_hdr, hdr, sizeof(struct can_hdr_s));
for (i = 0, dest = msg->cm_data; i < hdr->ch_dlc; 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)
{
/* Add the new, decoded CAN message at the tail of the FIFO */
memcpy(&fifo->rx_buffer[fifo->rx_tail].cm_hdr, hdr, sizeof(struct can_hdr_s));
for (i = 0, dest = fifo->rx_buffer[fifo->rx_tail].cm_data; i < hdr->ch_dlc; 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;
}