empeg.c

讲述linux的初始化过程

			urb->transfer_buffer,
			transfer_size,
			empeg_write_bulk_callback,
			port);

		urb->transfer_flags |= USB_QUEUE_BULK;

		/* send it down the pipe */
		status = usb_submit_urb(urb);
		if (status)
			dbg(__FUNCTION__ " - usb_submit_urb(write bulk) failed with status = %d", status);

		current_position += transfer_size;
		bytes_sent += transfer_size;
		count -= transfer_size;
		bytes_out += transfer_size;

	}

exit:
	return bytes_sent;

} 


static void empeg_write_bulk_callback (struct urb *urb)
{
	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;

	if (port_paranoia_check (port, __FUNCTION__))
		return;

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

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

	queue_task(&port->tqueue, &tq_immediate);
	mark_bh(IMMEDIATE_BH);

	return;

}


static void empeg_read_bulk_callback (struct urb *urb)
{
	struct usb_serial_port *port = (struct usb_serial_port *)urb->context;
	struct usb_serial *serial = get_usb_serial (port, __FUNCTION__);
	struct tty_struct *tty;
	unsigned char *data = urb->transfer_buffer;
	int i;
	int result;

	if (port_paranoia_check (port, __FUNCTION__))
		return;

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

	if (!serial) {
		dbg(__FUNCTION__ " - bad serial pointer, exiting");
		return;
	}

	if (urb->status) {
		dbg(__FUNCTION__ " - nonzero read bulk status received: %d", urb->status);
		return;
	}

	usb_serial_debug_data (__FILE__, __FUNCTION__, urb->actual_length, data);

	tty = port->tty;

	if (urb->actual_length) {
		for (i = 0; i < urb->actual_length ; ++i) {
			/* gb - 2000/11/13
			 * If we insert too many characters we'll overflow the buffer.
			 * This means we'll lose bytes - Decidedly bad.
			 */
			if(tty->flip.count >= TTY_FLIPBUF_SIZE) {
				tty_flip_buffer_push(tty);
				}
			/* gb - 2000/11/13
			 * This doesn't push the data through unless tty->low_latency is set.
			 */
			tty_insert_flip_char(tty, data[i], 0);
		}
		/* gb - 2000/11/13
		 * Goes straight through instead of scheduling - if tty->low_latency is set.
		 */
		tty_flip_buffer_push(tty);
		bytes_in += urb->actual_length;
	}

	/* Continue trying to always read  */
	FILL_BULK_URB(
		port->read_urb,
		serial->dev, 
		usb_rcvbulkpipe(serial->dev,
			port->bulk_in_endpointAddress),
		port->read_urb->transfer_buffer,
		port->read_urb->transfer_buffer_length,
		empeg_read_bulk_callback,
		port);

	port->read_urb->transfer_flags |= USB_QUEUE_BULK;

	result = usb_submit_urb(port->read_urb);

	if (result)
		err(__FUNCTION__ " - failed resubmitting read urb, error %d", result);

	return;

}


static void empeg_throttle (struct usb_serial_port *port)
{
	unsigned long flags;

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

	spin_lock_irqsave (&port->port_lock, flags);

	usb_unlink_urb (port->read_urb);

	spin_unlock_irqrestore (&port->port_lock, flags);

	return;

}


static void empeg_unthrottle (struct usb_serial_port *port)
{
	unsigned long flags;
	int result;

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

	spin_lock_irqsave (&port->port_lock, flags);

	port->read_urb->dev = port->serial->dev;

	result = usb_submit_urb(port->read_urb);

	if (result)
		err(__FUNCTION__ " - failed submitting read urb, error %d", result);

	spin_unlock_irqrestore (&port->port_lock, flags);

	return;

}


static int  empeg_startup (struct usb_serial *serial)
{

	dbg(__FUNCTION__);

	dbg(__FUNCTION__ " - Set config to 1");
	usb_set_configuration (serial->dev, 1);

	/* continue on with initialization */
	return 0;

}


static void empeg_shutdown (struct usb_serial *serial)
{
	int i;

	dbg (__FUNCTION__);

	/* stop reads and writes on all ports */
	for (i=0; i < serial->num_ports; ++i) {
		while (serial->port[i].open_count > 0) {
			empeg_close (&serial->port[i], NULL);
		}
	}

}


static int empeg_ioctl (struct usb_serial_port *port, struct file * file, unsigned int cmd, unsigned long arg)
{
	dbg(__FUNCTION__ " - port %d, cmd 0x%.4x", port->number, cmd);

	return -ENOIOCTLCMD;
}


/* This function is all nice and good, but we don't change anything based on it :) */
static void empeg_set_termios (struct usb_serial_port *port, struct termios *old_termios)
{
	unsigned int cflag = port->tty->termios->c_cflag;

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

	/* check that they really want us to change something */
	if (old_termios) {
		if ((cflag == old_termios->c_cflag) &&
		    (RELEVANT_IFLAG(port->tty->termios->c_iflag) == RELEVANT_IFLAG(old_termios->c_iflag))) {
			dbg(__FUNCTION__ " - nothing to change...");
			return;
		}
	}

	if ((!port->tty) || (!port->tty->termios)) {
		dbg(__FUNCTION__" - no tty structures");
		return;
	}

	/* get the byte size */
	switch (cflag & CSIZE) {
		case CS5:	dbg(__FUNCTION__ " - data bits = 5");   break;
		case CS6:	dbg(__FUNCTION__ " - data bits = 6");   break;
		case CS7:	dbg(__FUNCTION__ " - data bits = 7");   break;
		default:
		case CS8:	dbg(__FUNCTION__ " - data bits = 8");   break;
	}

	/* determine the parity */
	if (cflag & PARENB)
		if (cflag & PARODD)
			dbg(__FUNCTION__ " - parity = odd");
		else
			dbg(__FUNCTION__ " - parity = even");
	else
		dbg(__FUNCTION__ " - parity = none");

	/* figure out the stop bits requested */
	if (cflag & CSTOPB)
		dbg(__FUNCTION__ " - stop bits = 2");
	else
		dbg(__FUNCTION__ " - stop bits = 1");

	/* figure out the flow control settings */
	if (cflag & CRTSCTS)
		dbg(__FUNCTION__ " - RTS/CTS is enabled");
	else
		dbg(__FUNCTION__ " - RTS/CTS is disabled");

	/* determine software flow control */
	if (I_IXOFF(port->tty))
		dbg(__FUNCTION__ " - XON/XOFF is enabled, XON = %2x, XOFF = %2x", START_CHAR(port->tty), STOP_CHAR(port->tty));
	else
		dbg(__FUNCTION__ " - XON/XOFF is disabled");

	/* get the baud rate wanted */
	dbg(__FUNCTION__ " - baud rate = %d", tty_get_baud_rate(port->tty));

	return;

}


static int __init empeg_init (void)
{
	struct urb *urb;
	int i;

	usb_serial_register (&empeg_device);

	/* create our write urb pool and transfer buffers */ 
	spin_lock_init (&write_urb_pool_lock);
	for (i = 0; i < NUM_URBS; ++i) {
		urb = usb_alloc_urb(0);
		write_urb_pool[i] = urb;
		if (urb == NULL) {
			err("No more urbs???");
			continue;
		}

		urb->transfer_buffer = NULL;
		urb->transfer_buffer = kmalloc (URB_TRANSFER_BUFFER_SIZE, GFP_KERNEL);
		if (!urb->transfer_buffer) {
			err (__FUNCTION__ " - out of memory for urb buffers.");
			continue;
		}
	}

	return 0;

}


static void __exit empeg_exit (void)
{
	int i;
	unsigned long flags;

	usb_serial_deregister (&empeg_device);

	spin_lock_irqsave (&write_urb_pool_lock, flags);

	for (i = 0; i < NUM_URBS; ++i) {
		if (write_urb_pool[i]) {
			/* FIXME - uncomment the following usb_unlink_urb call when
			 * the host controllers get fixed to set urb->dev = NULL after
			 * the urb is finished.  Otherwise this call oopses. */
			/* usb_unlink_urb(write_urb_pool[i]); */
			if (write_urb_pool[i]->transfer_buffer)
				kfree(write_urb_pool[i]->transfer_buffer);
			usb_free_urb (write_urb_pool[i]);
		}
	}

	spin_unlock_irqrestore (&write_urb_pool_lock, flags);

}


module_init(empeg_init);
module_exit(empeg_exit);

MODULE_AUTHOR("Gary Brubaker <[e-mail]>");
MODULE_DESCRIPTION("USB Empeg Mark I/II Driver");