io_edgeport.c

linux-2.6.15.6

		struct usb_serial_port *port0 = serial->port[0];
		
		/* not set up yet, so do it now */
		edge_serial->interrupt_in_buffer = port0->interrupt_in_buffer;
		edge_serial->interrupt_in_endpoint = port0->interrupt_in_endpointAddress;
		edge_serial->interrupt_read_urb = port0->interrupt_in_urb;
		edge_serial->bulk_in_buffer = port0->bulk_in_buffer;
		edge_serial->bulk_in_endpoint = port0->bulk_in_endpointAddress;
		edge_serial->read_urb = port0->read_urb;
		edge_serial->bulk_out_endpoint = port0->bulk_out_endpointAddress;
	
		/* set up our interrupt urb */
		usb_fill_int_urb(edge_serial->interrupt_read_urb,
				 serial->dev,
				 usb_rcvintpipe(serial->dev,
					        port0->interrupt_in_endpointAddress),
				 port0->interrupt_in_buffer,
				 edge_serial->interrupt_read_urb->transfer_buffer_length,
				 edge_interrupt_callback, edge_serial,
				 edge_serial->interrupt_read_urb->interval);
		
		/* set up our bulk in urb */
		usb_fill_bulk_urb(edge_serial->read_urb, serial->dev,
				  usb_rcvbulkpipe(serial->dev,
					  	  port0->bulk_in_endpointAddress),
				  port0->bulk_in_buffer,
				  edge_serial->read_urb->transfer_buffer_length,
				  edge_bulk_in_callback, edge_serial);
		edge_serial->read_in_progress = FALSE;

		/* start interrupt read for this edgeport
		 * this interrupt will continue as long as the edgeport is connected */
		response = usb_submit_urb (edge_serial->interrupt_read_urb, GFP_KERNEL);
		if (response) {
			dev_err(&port->dev, "%s - Error %d submitting control urb\n", __FUNCTION__, response);
		}
	}
	
	/* initialize our wait queues */
	init_waitqueue_head(&edge_port->wait_open);
	init_waitqueue_head(&edge_port->wait_chase);
	init_waitqueue_head(&edge_port->delta_msr_wait);
	init_waitqueue_head(&edge_port->wait_command);

	/* initialize our icount structure */
	memset (&(edge_port->icount), 0x00, sizeof(edge_port->icount));

	/* initialize our port settings */
	edge_port->txCredits            = 0;			/* Can't send any data yet */
	edge_port->shadowMCR            = MCR_MASTER_IE;	/* Must always set this bit to enable ints! */
	edge_port->chaseResponsePending = FALSE;

	/* send a open port command */
	edge_port->openPending = TRUE;
	edge_port->open        = FALSE;
	response = send_iosp_ext_cmd (edge_port, IOSP_CMD_OPEN_PORT, 0);

	if (response < 0) {
		dev_err(&port->dev, "%s - error sending open port command\n", __FUNCTION__);
		edge_port->openPending = FALSE;
		return -ENODEV;
	}

	/* now wait for the port to be completely opened */
	wait_event_timeout(edge_port->wait_open, (edge_port->openPending != TRUE), OPEN_TIMEOUT);

	if (edge_port->open == FALSE) {
		/* open timed out */
		dbg("%s - open timedout", __FUNCTION__);
		edge_port->openPending = FALSE;
		return -ENODEV;
	}

	/* create the txfifo */
	edge_port->txfifo.head	= 0;
	edge_port->txfifo.tail	= 0;
	edge_port->txfifo.count	= 0;
	edge_port->txfifo.size	= edge_port->maxTxCredits;
	edge_port->txfifo.fifo	= kmalloc (edge_port->maxTxCredits, GFP_KERNEL);

	if (!edge_port->txfifo.fifo) {
		dbg("%s - no memory", __FUNCTION__);
		edge_close (port, filp);
		return -ENOMEM;
	}

	/* Allocate a URB for the write */
	edge_port->write_urb = usb_alloc_urb (0, GFP_KERNEL);
	edge_port->write_in_progress = FALSE;

	if (!edge_port->write_urb) {
		dbg("%s - no memory", __FUNCTION__);
		edge_close (port, filp);
		return -ENOMEM;
	}

	dbg("%s(%d) - Initialize TX fifo to %d bytes", __FUNCTION__, port->number, edge_port->maxTxCredits);

	dbg("%s exited", __FUNCTION__);

	return 0;
}


/************************************************************************
 *
 * block_until_chase_response
 *
 *	This function will block the close until one of the following:
 *		1. Response to our Chase comes from Edgeport
 *		2. A timout of 10 seconds without activity has expired
 *		   (1K of Edgeport data @ 2400 baud ==> 4 sec to empty)
 *
 ************************************************************************/
static void block_until_chase_response(struct edgeport_port *edge_port)
{
	DEFINE_WAIT(wait);
	__u16 lastCredits;
	int timeout = 1*HZ;
	int loop = 10;

	while (1) {
		// Save Last credits
		lastCredits = edge_port->txCredits;

		// Did we get our Chase response
		if (edge_port->chaseResponsePending == FALSE) {
			dbg("%s - Got Chase Response", __FUNCTION__);

			// did we get all of our credit back?
			if (edge_port->txCredits == edge_port->maxTxCredits ) {
				dbg("%s - Got all credits", __FUNCTION__);
				return;
			}
		}

		// Block the thread for a while
		prepare_to_wait(&edge_port->wait_chase, &wait, TASK_UNINTERRUPTIBLE);
		schedule_timeout(timeout);
		finish_wait(&edge_port->wait_chase, &wait);

		if (lastCredits == edge_port->txCredits) {
			// No activity.. count down.
			loop--;
			if (loop == 0) {
				edge_port->chaseResponsePending = FALSE;
				dbg("%s - Chase TIMEOUT", __FUNCTION__);
				return;
			}
		} else {
			// Reset timout value back to 10 seconds
			dbg("%s - Last %d, Current %d", __FUNCTION__, lastCredits, edge_port->txCredits);
			loop = 10;
		}
	}
}


/************************************************************************
 *
 * block_until_tx_empty
 *
 *	This function will block the close until one of the following:
 *		1. TX count are 0
 *		2. The edgeport has stopped
 *		3. A timout of 3 seconds without activity has expired
 *
 ************************************************************************/
static void block_until_tx_empty (struct edgeport_port *edge_port)
{
	DEFINE_WAIT(wait);
	struct TxFifo *fifo = &edge_port->txfifo;
	__u32 lastCount;
	int timeout = HZ/10;
	int loop = 30;

	while (1) {
		// Save Last count
		lastCount = fifo->count;

		// Is the Edgeport Buffer empty?
		if (lastCount == 0) {
			dbg("%s - TX Buffer Empty", __FUNCTION__);
			return;
		}

		// Block the thread for a while
		prepare_to_wait (&edge_port->wait_chase, &wait, TASK_UNINTERRUPTIBLE);
		schedule_timeout(timeout);
		finish_wait(&edge_port->wait_chase, &wait);

		dbg("%s wait", __FUNCTION__);

		if (lastCount == fifo->count) {
			// No activity.. count down.
			loop--;
			if (loop == 0) {
				dbg("%s - TIMEOUT", __FUNCTION__);
				return;
			}
		} else {
			// Reset timout value back to seconds
			loop = 30;
		}
	}
}


/*****************************************************************************
 * edge_close
 *	this function is called by the tty driver when a port is closed
 *****************************************************************************/
static void edge_close (struct usb_serial_port *port, struct file * filp)
{
	struct edgeport_serial *edge_serial;
	struct edgeport_port *edge_port;
	int status;

	dbg("%s - port %d", __FUNCTION__, port->number);
			 
	edge_serial = usb_get_serial_data(port->serial);
	edge_port = usb_get_serial_port_data(port);
	if ((edge_serial == NULL) || (edge_port == NULL))
		return;
	
	// block until tx is empty
	block_until_tx_empty(edge_port);

	edge_port->closePending = TRUE;

	/* flush and chase */
	edge_port->chaseResponsePending = TRUE;

	dbg("%s - Sending IOSP_CMD_CHASE_PORT", __FUNCTION__);
	status = send_iosp_ext_cmd (edge_port, IOSP_CMD_CHASE_PORT, 0);
	if (status == 0) {
		// block until chase finished
		block_until_chase_response(edge_port);
	} else {
		edge_port->chaseResponsePending = FALSE;
	}

	/* close the port */
	dbg("%s - Sending IOSP_CMD_CLOSE_PORT", __FUNCTION__);
	send_iosp_ext_cmd (edge_port, IOSP_CMD_CLOSE_PORT, 0);

	//port->close = TRUE;
	edge_port->closePending = FALSE;
	edge_port->open = FALSE;
	edge_port->openPending = FALSE;

	if (edge_port->write_urb) {
		usb_kill_urb(edge_port->write_urb);
	}

	if (edge_port->write_urb) {
		/* if this urb had a transfer buffer already (old transfer) free it */
		kfree(edge_port->write_urb->transfer_buffer);
		usb_free_urb(edge_port->write_urb);
		edge_port->write_urb = NULL;
	}
	kfree(edge_port->txfifo.fifo);
	edge_port->txfifo.fifo = NULL;

	dbg("%s exited", __FUNCTION__);
}   

/*****************************************************************************
 * SerialWrite
 *	this function is called by the tty driver when data should be written to
 *	the port.
 *	If successful, we return the number of bytes written, otherwise we return
 *	a negative error number.
 *****************************************************************************/
static int edge_write (struct usb_serial_port *port, const unsigned char *data, int count)
{
	struct edgeport_port *edge_port = usb_get_serial_port_data(port);
	struct TxFifo *fifo;
	int copySize;
	int bytesleft;
	int firsthalf;
	int secondhalf;
	unsigned long flags;

	dbg("%s - port %d", __FUNCTION__, port->number);

	if (edge_port == NULL)
		return -ENODEV;

	// get a pointer to the Tx fifo
	fifo = &edge_port->txfifo;

	spin_lock_irqsave(&edge_port->ep_lock, flags);

	// calculate number of bytes to put in fifo
	copySize = min ((unsigned int)count, (edge_port->txCredits - fifo->count));

	dbg("%s(%d) of %d byte(s) Fifo room  %d -- will copy %d bytes", __FUNCTION__, 
	    port->number, count, edge_port->txCredits - fifo->count, copySize);

	/* catch writes of 0 bytes which the tty driver likes to give us, and when txCredits is empty */
	if (copySize == 0) {
		dbg("%s - copySize = Zero", __FUNCTION__);
		goto finish_write;
	}

	// queue the data	
	// since we can never overflow the buffer we do not have to check for full condition

	// the copy is done is two parts -- first fill to the end of the buffer
	// then copy the reset from the start of the buffer 

	bytesleft = fifo->size - fifo->head;
	firsthalf = min (bytesleft, copySize);
	dbg("%s - copy %d bytes of %d into fifo ", __FUNCTION__, firsthalf, bytesleft);

	/* now copy our data */
	memcpy(&fifo->fifo[fifo->head], data, firsthalf);
	usb_serial_debug_data(debug, &port->dev, __FUNCTION__, firsthalf, &fifo->fifo[fifo->head]);

	// update the index and size
	fifo->head  += firsthalf;
	fifo->count += firsthalf;

	// wrap the index
	if (fifo->head == fifo->size) {
		fifo->head = 0;
	}

	secondhalf = copySize-firsthalf;

	if (secondhalf) {
		dbg("%s - copy rest of data %d", __FUNCTION__, secondhalf);
		memcpy(&fifo->fifo[fifo->head], &data[firsthalf], secondhalf);
		usb_serial_debug_data(debug, &port->dev, __FUNCTION__, secondhalf, &fifo->fifo[fifo->head]);
		// update the index and size
		fifo->count += secondhalf;
		fifo->head  += secondhalf;
		// No need to check for wrap since we can not get to end of fifo in this part
	}

finish_write:
	spin_unlock_irqrestore(&edge_port->ep_lock, flags);

	send_more_port_data((struct edgeport_serial *)usb_get_serial_data(port->serial), edge_port);

	dbg("%s wrote %d byte(s) TxCredits %d, Fifo %d", __FUNCTION__, copySize, edge_port->txCredits, fifo->count);

	return copySize;   
}


/************************************************************************
 *
 * send_more_port_data()
 *
 *	This routine attempts to write additional UART transmit data
 *	to a port over the USB bulk pipe. It is called (1) when new
 *	data has been written to a port's TxBuffer from higher layers
 *	(2) when the peripheral sends us additional TxCredits indicating
 *	that it can accept more	Tx data for a given port; and (3) when
 *	a bulk write completes successfully and we want to see if we
 *	can transmit more.
 *
 ************************************************************************/
static void send_more_port_data(struct edgeport_serial *edge_serial, struct edgeport_port *edge_port)
{
	struct TxFifo	*fifo = &edge_port->txfifo;
	struct urb	*urb;
	unsigned char	*buffer;
	int		status;
	int		count;
	int		bytesleft;
	int		firsthalf;
	int		secondhalf;
	unsigned long	flags;

	dbg("%s(%d)", __FUNCTION__, edge_port->port->number);

	spin_lock_irqsave(&edge_port->ep_lock, flags);

	if (edge_port->write_in_progress ||
	    !edge_port->open             ||
	    (fifo->count == 0)) {
		dbg("%s(%d) EXIT - fifo %d, PendingWrite = %d", __FUNCTION__, edge_port->port->number, fifo->count, edge_port->write_in_progress);
		goto exit_send;
	}

	// since the amount of data in the fifo will always fit into the
	// edgeport buffer we do not need to check the write length

	//	Do we have enough credits for this port to make it worthwhile
	//	to bother queueing a write. If it's too small, say a few bytes,
	//	it's better to wait for more credits so we can do a larger
	//	write.