ftdi_sio.c

標準的linux下rs-232驅動代碼,是2.6內核的.

	if (!buffer) {
		err("%s ran out of kernel memory for urb ...", __FUNCTION__);
		count = -ENOMEM;
		goto error_no_buffer;
	}

	urb = usb_alloc_urb(0, GFP_ATOMIC);
	if (!urb) {
		err("%s - no more free urbs", __FUNCTION__);
		count = -ENOMEM;
		goto error_no_urb;
	}

	/* Copy data */
	if (data_offset > 0) {
		/* Original sio requires control byte at start of each packet. */
		int user_pktsz = PKTSZ - data_offset;
		int todo = count;
		unsigned char *first_byte = buffer;
		const unsigned char *current_position = buf;

		while (todo > 0) {
			if (user_pktsz > todo) {
				user_pktsz = todo;
			}
			/* Write the control byte at the front of the packet*/
			*first_byte = 1 | ((user_pktsz) << 2);
			/* Copy data for packet */
			memcpy (first_byte + data_offset,
				current_position, user_pktsz);
			first_byte += user_pktsz + data_offset;
			current_position += user_pktsz;
			todo -= user_pktsz;
		}
	} else {
		/* No control byte required. */
		/* Copy in the data to send */
		memcpy (buffer, buf, count);
	}

	usb_serial_debug_data(debug, &port->dev, __FUNCTION__, transfer_size, buffer);

	/* fill the buffer and send it */
	usb_fill_bulk_urb(urb, port->serial->dev,
		      usb_sndbulkpipe(port->serial->dev, port->bulk_out_endpointAddress),
		      buffer, transfer_size,
		      ftdi_write_bulk_callback, port);

	status = usb_submit_urb(urb, GFP_ATOMIC);
	if (status) {
		err("%s - failed submitting write urb, error %d", __FUNCTION__, status);
		count = status;
		goto error;
	} else {
		spin_lock_irqsave(&priv->tx_lock, flags);
		priv->tx_outstanding_bytes += count;
		priv->tx_bytes += count;
		spin_unlock_irqrestore(&priv->tx_lock, flags);
	}

	/* we are done with this urb, so let the host driver
	 * really free it when it is finished with it */
	usb_free_urb(urb);

	dbg("%s write returning: %d", __FUNCTION__, count);
	return count;
error:
	usb_free_urb(urb);
error_no_urb:
	kfree (buffer);
error_no_buffer:
	spin_lock_irqsave(&priv->tx_lock, flags);
	priv->tx_outstanding_urbs--;
	spin_unlock_irqrestore(&priv->tx_lock, flags);
	return count;
} /* ftdi_write */


/* This function may get called when the device is closed */

static void ftdi_write_bulk_callback (struct urb *urb)
{
	unsigned long flags;
	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
	struct ftdi_private *priv;
	int data_offset;       /* will be 1 for the SIO and 0 otherwise */
	unsigned long countback;
	int status = urb->status;

	/* free up the transfer buffer, as usb_free_urb() does not do this */
	kfree (urb->transfer_buffer);

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

	if (status) {
		dbg("nonzero write bulk status received: %d", status);
		return;
	}

	priv = usb_get_serial_port_data(port);
	if (!priv) {
		dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
		return;
	}
	/* account for transferred data */
	countback = urb->actual_length;
	data_offset = priv->write_offset;
	if (data_offset > 0) {
		/* Subtract the control bytes */
		countback -= (data_offset * ((countback + (PKTSZ - 1)) / PKTSZ));
	}
	spin_lock_irqsave(&priv->tx_lock, flags);
	--priv->tx_outstanding_urbs;
	priv->tx_outstanding_bytes -= countback;
	spin_unlock_irqrestore(&priv->tx_lock, flags);

	usb_serial_port_softint(port);
} /* ftdi_write_bulk_callback */


static int ftdi_write_room( struct usb_serial_port *port )
{
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	int room;
	unsigned long flags;

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

	spin_lock_irqsave(&priv->tx_lock, flags);
	if (priv->tx_outstanding_urbs < URB_UPPER_LIMIT) {
		/*
		 * We really can take anything the user throws at us
		 * but let's pick a nice big number to tell the tty
		 * layer that we have lots of free space
		 */
		room = 2048;
	} else {
		room = 0;
	}
	spin_unlock_irqrestore(&priv->tx_lock, flags);
	return room;
} /* ftdi_write_room */


static int ftdi_chars_in_buffer (struct usb_serial_port *port)
{ /* ftdi_chars_in_buffer */
	struct ftdi_private *priv = usb_get_serial_port_data(port);
	int buffered;
	unsigned long flags;

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

	spin_lock_irqsave(&priv->tx_lock, flags);
	buffered = (int)priv->tx_outstanding_bytes;
	spin_unlock_irqrestore(&priv->tx_lock, flags);
	if (buffered < 0) {
		err("%s outstanding tx bytes is negative!", __FUNCTION__);
		buffered = 0;
	}
	return buffered;
} /* ftdi_chars_in_buffer */



static void ftdi_read_bulk_callback (struct urb *urb)
{ /* ftdi_read_bulk_callback */
	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
	struct tty_struct *tty;
	struct ftdi_private *priv;
	unsigned long countread;
	unsigned long flags;
	int status = urb->status;

	if (urb->number_of_packets > 0) {
		err("%s transfer_buffer_length %d actual_length %d number of packets %d",__FUNCTION__,
		    urb->transfer_buffer_length, urb->actual_length, urb->number_of_packets );
		err("%s transfer_flags %x ", __FUNCTION__,urb->transfer_flags );
	}

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

	if (port->open_count <= 0)
		return;

	tty = port->tty;
	if (!tty) {
		dbg("%s - bad tty pointer - exiting",__FUNCTION__);
		return;
	}

	priv = usb_get_serial_port_data(port);
	if (!priv) {
		dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
		return;
	}

	if (urb != port->read_urb) {
		err("%s - Not my urb!", __FUNCTION__);
	}

	if (status) {
		/* This will happen at close every time so it is a dbg not an err */
		dbg("(this is ok on close) nonzero read bulk status received: "
		    "%d", status);
		return;
	}

	/* count data bytes, but not status bytes */
	countread = urb->actual_length;
	countread -= 2 * ((countread + (PKTSZ - 1)) / PKTSZ);
	spin_lock_irqsave(&priv->rx_lock, flags);
	priv->rx_bytes += countread;
	spin_unlock_irqrestore(&priv->rx_lock, flags);

	ftdi_process_read(&priv->rx_work.work);

} /* ftdi_read_bulk_callback */


static void ftdi_process_read (struct work_struct *work)
{ /* ftdi_process_read */
	struct ftdi_private *priv =
		container_of(work, struct ftdi_private, rx_work.work);
	struct usb_serial_port *port = priv->port;
	struct urb *urb;
	struct tty_struct *tty;
	char error_flag;
	unsigned char *data;

	int i;
	int result;
	int need_flip;
	int packet_offset;
	unsigned long flags;

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

	if (port->open_count <= 0)
		return;

	tty = port->tty;
	if (!tty) {
		dbg("%s - bad tty pointer - exiting",__FUNCTION__);
		return;
	}

	priv = usb_get_serial_port_data(port);
	if (!priv) {
		dbg("%s - bad port private data pointer - exiting", __FUNCTION__);
		return;
	}

	urb = port->read_urb;
	if (!urb) {
		dbg("%s - bad read_urb pointer - exiting", __FUNCTION__);
		return;
	}

	data = urb->transfer_buffer;

	if (priv->rx_processed) {
		dbg("%s - already processed: %d bytes, %d remain", __FUNCTION__,
				priv->rx_processed,
				urb->actual_length - priv->rx_processed);
	} else {
		/* The first two bytes of every read packet are status */
		if (urb->actual_length > 2) {
			usb_serial_debug_data(debug, &port->dev, __FUNCTION__, urb->actual_length, data);
		} else {
			dbg("Status only: %03oo %03oo",data[0],data[1]);
		}
	}


	/* TO DO -- check for hung up line and handle appropriately: */
	/*   send hangup  */
	/* See acm.c - you do a tty_hangup  - eg tty_hangup(tty) */
	/* if CD is dropped and the line is not CLOCAL then we should hangup */

	need_flip = 0;
	for (packet_offset = priv->rx_processed; packet_offset < urb->actual_length; packet_offset += PKTSZ) {
		int length;

		/* Compare new line status to the old one, signal if different */
		/* N.B. packet may be processed more than once, but differences
		 * are only processed once.  */
		if (priv != NULL) {
			char new_status = data[packet_offset+0] & FTDI_STATUS_B0_MASK;
			if (new_status != priv->prev_status) {
				priv->diff_status |= new_status ^ priv->prev_status;
				wake_up_interruptible(&priv->delta_msr_wait);
				priv->prev_status = new_status;
			}
		}

		length = min(PKTSZ, urb->actual_length-packet_offset)-2;
		if (length < 0) {
			err("%s - bad packet length: %d", __FUNCTION__, length+2);
			length = 0;
		}

		if (priv->rx_flags & THROTTLED) {
			dbg("%s - throttled", __FUNCTION__);
			break;
		}
		if (tty_buffer_request_room(tty, length) < length) {
			/* break out & wait for throttling/unthrottling to happen */
			dbg("%s - receive room low", __FUNCTION__);
			break;
		}

		/* Handle errors and break */
		error_flag = TTY_NORMAL;
		/* Although the device uses a bitmask and hence can have multiple */
		/* errors on a packet - the order here sets the priority the */
		/* error is returned to the tty layer  */

		if ( data[packet_offset+1] & FTDI_RS_OE ) {
			error_flag = TTY_OVERRUN;
			dbg("OVERRRUN error");
		}
		if ( data[packet_offset+1] & FTDI_RS_BI ) {
			error_flag = TTY_BREAK;
			dbg("BREAK received");
		}
		if ( data[packet_offset+1] & FTDI_RS_PE ) {
			error_flag = TTY_PARITY;
			dbg("PARITY error");
		}
		if ( data[packet_offset+1] & FTDI_RS_FE ) {
			error_flag = TTY_FRAME;
			dbg("FRAMING error");
		}
		if (length > 0) {
			for (i = 2; i < length+2; i++) {
				/* Note that the error flag is duplicated for
				   every character received since we don't know
				   which character it applied to */
				tty_insert_flip_char(tty, data[packet_offset+i], error_flag);
			}
			need_flip = 1;
		}

#ifdef NOT_CORRECT_BUT_KEEPING_IT_FOR_NOW
		/* if a parity error is detected you get status packets forever
		   until a character is sent without a parity error.
		   This doesn't work well since the application receives a never
		   ending stream of bad data - even though new data hasn't been sent.
		   Therefore I (bill) have taken this out.
		   However - this might make sense for framing errors and so on
		   so I am leaving the code in for now.
		*/
		else {
			if (error_flag != TTY_NORMAL){
				dbg("error_flag is not normal");
				/* In this case it is just status - if that is an error send a bad character */
				if(tty->flip.count >= TTY_FLIPBUF_SIZE) {
					tty_flip_buffer_push(tty);
				}
				tty_insert_flip_char(tty, 0xff, error_flag);
				need_flip = 1;
			}
		}
#endif
	} /* "for(packet_offset=0..." */

	/* Low latency */
	if (need_flip) {
		tty_flip_buffer_push(tty);
	}

	if (packet_offset < urb->actual_length) {
		/* not completely processed - record progress */
		priv->rx_processed = packet_offset;
		dbg("%s - incomplete, %d bytes processed, %d remain",
				__FUNCTION__, packet_offset,
				urb->actual_length - packet_offset);
		/* check if we were throttled while processing */
		spin_lock_irqsave(&priv->rx_lock, flags);
		if (priv->rx_flags & THROTTLED) {
			priv->rx_flags |= ACTUALLY_THROTTLED;
			spin_unlock_irqrestore(&priv->rx_lock, flags);
			dbg("%s - deferring r