if (!ACM_READY(acm))
		return -EINVAL;

	return -ENOIOCTLCMD;
}

static __u32 acm_tty_speed[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600,
	1200, 1800, 2400, 4800, 9600, 19200, 38400,
	57600, 115200, 230400, 460800, 500000, 576000,
	921600, 1000000, 1152000, 1500000, 2000000,
	2500000, 3000000, 3500000, 4000000
};

static __u8 acm_tty_size[] = {
	5, 6, 7, 8
};

static void acm_tty_set_termios(struct tty_struct *tty, struct termios *termios_old)
{
	struct acm *acm = tty->driver_data;
	struct termios *termios = tty->termios;
	struct acm_line newline;
	int newctrl = acm->ctrlout;

	if (!ACM_READY(acm))
		return;

	newline.speed = cpu_to_le32p(acm_tty_speed +
		(termios->c_cflag & CBAUD & ~CBAUDEX) + (termios->c_cflag & CBAUDEX ? 15 : 0));
	newline.stopbits = termios->c_cflag & CSTOPB ? 2 : 0;
	newline.parity = termios->c_cflag & PARENB ?
		(termios->c_cflag & PARODD ? 1 : 2) + (termios->c_cflag & CMSPAR ? 2 : 0) : 0;
	newline.databits = acm_tty_size[(termios->c_cflag & CSIZE) >> 4];

	acm->clocal = ((termios->c_cflag & CLOCAL) != 0);

	if (!newline.speed) {
		newline.speed = acm->line.speed;
		newctrl &= ~ACM_CTRL_DTR;
	} else  newctrl |=  ACM_CTRL_DTR;

	if (newctrl != acm->ctrlout)
		acm_set_control(acm, acm->ctrlout = newctrl);

	if (memcmp(&acm->line, &newline, sizeof(struct acm_line))) {
		memcpy(&acm->line, &newline, sizeof(struct acm_line));
		dbg("set line: %d %d %d %d", newline.speed, newline.stopbits, newline.parity, newline.databits);
		acm_set_line(acm, &acm->line);
	}
}

/*
 * USB probe and disconnect routines.
 */

static int acm_probe (struct usb_interface *intf,
		      const struct usb_device_id *id)
{
	struct union_desc *union_header = NULL;
	char *buffer = intf->altsetting->extra;
	int buflen = intf->altsetting->extralen;
	struct usb_interface *control_interface;
	struct usb_interface *data_interface;
	struct usb_endpoint_descriptor *epctrl;
	struct usb_endpoint_descriptor *epread;
	struct usb_endpoint_descriptor *epwrite;
	struct usb_device *usb_dev = interface_to_usbdev(intf);
	struct acm *acm;
	int minor;
	int ctrlsize,readsize;
	u8 *buf;
	u8 ac_management_function = 0;
	u8 call_management_function = 0;
	int call_interface_num = -1;
	int data_interface_num;
	unsigned long quirks;

	/* handle quirks deadly to normal probing*/
	quirks = (unsigned long)id->driver_info;
	if (quirks == NO_UNION_NORMAL) {
		data_interface = usb_ifnum_to_if(usb_dev, 1);
		control_interface = usb_ifnum_to_if(usb_dev, 0);
		goto skip_normal_probe;
	}
	
	/* normal probing*/
	if (!buffer) {
		err("Wierd descriptor references\n");
		return -EINVAL;
	}

	if (!buflen) {
		if (intf->cur_altsetting->endpoint->extralen && intf->cur_altsetting->endpoint->extra) {
			dev_dbg(&intf->dev,"Seeking extra descriptors on endpoint\n");
			buflen = intf->cur_altsetting->endpoint->extralen;
			buffer = intf->cur_altsetting->endpoint->extra;
		} else {
			err("Zero length descriptor references\n");
			return -EINVAL;
		}
	}

	while (buflen > 0) {
		if (buffer [1] != USB_DT_CS_INTERFACE) {
			err("skipping garbage\n");
			goto next_desc;
		}

		switch (buffer [2]) {
			case CDC_UNION_TYPE: /* we've found it */
				if (union_header) {
					err("More than one union descriptor, skipping ...");
					goto next_desc;
				}
				union_header = (struct union_desc *)buffer;
				break;
			case CDC_COUNTRY_TYPE: /* maybe somehow export */
				break; /* for now we ignore it */
			case CDC_HEADER_TYPE: /* maybe check version */ 
				break; /* for now we ignore it */ 
			case CDC_AC_MANAGEMENT_TYPE:
				ac_management_function = buffer[3];
				break;
			case CDC_CALL_MANAGEMENT_TYPE:
				call_management_function = buffer[3];
				call_interface_num = buffer[4];
				if ((call_management_function & 3) != 3)
					err("This device cannot do calls on its own. It is no modem.");
				break;
				
			default:
				err("Ignoring extra header, type %d, length %d", buffer[2], buffer[0]);
				break;
			}
next_desc:
		buflen -= buffer[0];
		buffer += buffer[0];
	}

	if (!union_header) {
		if (call_interface_num > 0) {
			dev_dbg(&intf->dev,"No union descriptor, using call management descriptor\n");
			data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = call_interface_num));
			control_interface = intf;
		} else {
			dev_dbg(&intf->dev,"No union descriptor, giving up\n");
			return -ENODEV;
		}
	} else {
		control_interface = usb_ifnum_to_if(usb_dev, union_header->bMasterInterface0);
		data_interface = usb_ifnum_to_if(usb_dev, (data_interface_num = union_header->bSlaveInterface0));
		if (!control_interface || !data_interface) {
			dev_dbg(&intf->dev,"no interfaces\n");
			return -ENODEV;
		}
	}
	
	if (data_interface_num != call_interface_num)
		dev_dbg(&intf->dev,"Seperate call control interface. That is not fully supported.\n");

skip_normal_probe:

	/*workaround for switched interfaces */
	if (data_interface->cur_altsetting->desc.bInterfaceClass != CDC_DATA_INTERFACE_TYPE) {
		if (control_interface->cur_altsetting->desc.bInterfaceClass == CDC_DATA_INTERFACE_TYPE) {
			struct usb_interface *t;
			dev_dbg(&intf->dev,"Your device has switched interfaces.\n");

			t = control_interface;
			control_interface = data_interface;
			data_interface = t;
		} else {
			return -EINVAL;
		}
	}
	
	if (usb_interface_claimed(data_interface)) { /* valid in this context */
		dev_dbg(&intf->dev,"The data interface isn't available\n");
		return -EBUSY;
	}


	if (data_interface->cur_altsetting->desc.bNumEndpoints < 2)
		return -EINVAL;

	epctrl = &control_interface->cur_altsetting->endpoint[0].desc;
	epread = &data_interface->cur_altsetting->endpoint[0].desc;
	epwrite = &data_interface->cur_altsetting->endpoint[1].desc;


	/* workaround for switched endpoints */
	if ((epread->bEndpointAddress & USB_DIR_IN) != USB_DIR_IN) {
		/* descriptors are swapped */
		struct usb_endpoint_descriptor *t;
		dev_dbg(&intf->dev,"The data interface has switched endpoints\n");
		
		t = epread;
		epread = epwrite;
		epwrite = t;
	}
	dbg("interfaces are valid");
	for (minor = 0; minor < ACM_TTY_MINORS && acm_table[minor]; minor++);

	if (minor == ACM_TTY_MINORS) {
		err("no more free acm devices");
		return -ENODEV;
	}

	if (!(acm = kmalloc(sizeof(struct acm), GFP_KERNEL))) {
		dev_dbg(&intf->dev, "out of memory (acm kmalloc)\n");
		goto alloc_fail;
	}
	memset(acm, 0, sizeof(struct acm));

	ctrlsize = le16_to_cpu(epctrl->wMaxPacketSize);
	readsize = le16_to_cpu(epread->wMaxPacketSize);
	acm->writesize = le16_to_cpu(epwrite->wMaxPacketSize);
	acm->control = control_interface;
	acm->data = data_interface;
	acm->minor = minor;
	acm->dev = usb_dev;
	acm->ctrl_caps = ac_management_function;
	acm->ctrlsize = ctrlsize;
	acm->readsize = readsize;
	acm->bh.func = acm_rx_tasklet;
	acm->bh.data = (unsigned long) acm;
	INIT_WORK(&acm->work, acm_softint, acm);
	spin_lock_init(&acm->throttle_lock);
	acm->ready_for_write = 1;

	buf = usb_buffer_alloc(usb_dev, ctrlsize, GFP_KERNEL, &acm->ctrl_dma);
	if (!buf) {
		dev_dbg(&intf->dev, "out of memory (ctrl buffer alloc)\n");
		goto alloc_fail2;
	}
	acm->ctrl_buffer = buf;

	buf = usb_buffer_alloc(usb_dev, readsize, GFP_KERNEL, &acm->read_dma);
	if (!buf) {
		dev_dbg(&intf->dev, "out of memory (read buffer alloc)\n");
		goto alloc_fail3;
	}
	acm->read_buffer = buf;

	buf = usb_buffer_alloc(usb_dev, acm->writesize, GFP_KERNEL, &acm->write_dma);
	if (!buf) {
		dev_dbg(&intf->dev, "out of memory (write buffer alloc)\n");
		goto alloc_fail4;
	}
	acm->write_buffer = buf;	

	acm->ctrlurb = usb_alloc_urb(0, GFP_KERNEL);
	if (!acm->ctrlurb) {
		dev_dbg(&intf->dev, "out of memory (ctrlurb kmalloc)\n");
		goto alloc_fail5;
	}
	acm->readurb = usb_alloc_urb(0, GFP_KERNEL);
	if (!acm->readurb) {
		dev_dbg(&intf->dev, "out of memory (readurb kmalloc)\n");
		goto alloc_fail6;
	}
	acm->writeurb = usb_alloc_urb(0, GFP_KERNEL);
	if (!acm->writeurb) {
		dev_dbg(&intf->dev, "out of memory (writeurb kmalloc)\n");
		goto alloc_fail7;
	}

	usb_fill_int_urb(acm->ctrlurb, usb_dev, usb_rcvintpipe(usb_dev, epctrl->bEndpointAddress),
			 acm->ctrl_buffer, ctrlsize, acm_ctrl_irq, acm, epctrl->bInterval);
	acm->ctrlurb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
	acm->ctrlurb->transfer_dma = acm->ctrl_dma;

	usb_fill_bulk_urb(acm->readurb, usb_dev, usb_rcvbulkpipe(usb_dev, epread->bEndpointAddress),
			  acm->read_buffer, readsize, acm_read_bulk, acm);
	acm->readurb->transfer_flags |= URB_NO_FSBR | URB_NO_TRANSFER_DMA_MAP;
	acm->readurb->transfer_dma = acm->read_dma;

	usb_fill_bulk_urb(acm->writeurb, usb_dev, usb_sndbulkpipe(usb_dev, epwrite->bEndpointAddress),
			  acm->write_buffer, acm->writesize, acm_write_bulk, acm);
	acm->writeurb->transfer_flags |= URB_NO_FSBR | URB_NO_TRANSFER_DMA_MAP;
	acm->writeurb->transfer_dma = acm->write_dma;

	dev_info(&intf->dev, "ttyACM%d: USB ACM device\n", minor);

	acm_set_control(acm, acm->ctrlout);

	acm->line.speed = cpu_to_le32(9600);
	acm->line.databits = 8;
	acm_set_line(acm, &acm->line);

	usb_driver_claim_interface(&acm_driver, data_interface, acm);

	tty_register_device(acm_tty_driver, minor, &intf->dev);

	acm_table[minor] = acm;
	usb_set_intfdata (intf, acm);
	return 0;

alloc_fail7:
	usb_free_urb(acm->readurb);
alloc_fail6:
	usb_free_urb(acm->ctrlurb);
alloc_fail5:
	usb_buffer_free(usb_dev, acm->writesize, acm->write_buffer, acm->write_dma);
alloc_fail4:
	usb_buffer_free(usb_dev, readsize, acm->read_buffer, acm->read_dma);
alloc_fail3:
	usb_buffer_free(usb_dev, ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);
alloc_fail2:
	kfree(acm);
alloc_fail:
	return -ENOMEM;
}

static void acm_disconnect(struct usb_interface *intf)
{
	struct acm *acm = usb_get_intfdata (intf);
	struct usb_device *usb_dev = interface_to_usbdev(intf);

	if (!acm || !acm->dev) {
		dbg("disconnect on nonexisting interface");
		return;
	}

	down(&open_sem);
	acm->dev = NULL;
	usb_set_intfdata (intf, NULL);

	usb_kill_urb(acm->ctrlurb);
	usb_kill_urb(acm->readurb);
	usb_kill_urb(acm->writeurb);

	flush_scheduled_work(); /* wait for acm_softint */

	usb_buffer_free(usb_dev, acm->writesize, acm->write_buffer, acm->write_dma);
	usb_buffer_free(usb_dev, acm->readsize, acm->read_buffer, acm->read_dma);
	usb_buffer_free(usb_dev, acm->ctrlsize, acm->ctrl_buffer, acm->ctrl_dma);

	usb_driver_release_interface(&acm_driver, acm->data);

	if (!acm->used) {
		tty_unregister_device(acm_tty_driver, acm->minor);
		acm_table[acm->minor] = NULL;
		usb_free_urb(acm->ctrlurb);
		usb_free_urb(acm->readurb);
		usb_free_urb(acm->writeurb);
		kfree(acm);
		up(&open_sem);
		return;
	}

	up(&open_sem);

	if (acm->tty)
		tty_hangup(acm->tty);
}

/*
 * USB driver structure.
 */

static struct usb_device_id acm_ids[] = {
	/* quirky and broken devices */
	{ USB_DEVICE(0x0870, 0x0001), /* Metricom GS Modem */
	.driver_info = NO_UNION_NORMAL, /* has no union descriptor */
	},
	/* control interfaces with various AT-command sets */
	{ USB_INTERFACE_INFO(USB_CLASS_COMM, 2, 1) },
	{ USB_INTERFACE_INFO(USB_CLASS_COMM, 2, 2) },
	{ USB_INTERFACE_INFO(USB_CLASS_COMM, 2, 3) },
	{ USB_INTERFACE_INFO(USB_CLASS_COMM, 2, 4) },
	{ USB_INTERFACE_INFO(USB_CLASS_COMM, 2, 5) },
	{ USB_INTERFACE_INFO(USB_CLASS_COMM, 2, 6) },

	/* NOTE:  COMM/2/0xff is likely MSFT RNDIS ... NOT a modem!! */
	{ }
};

MODULE_DEVICE_TABLE (usb, acm_ids);

static struct usb_driver acm_driver = {
	.owner =	THIS_MODULE,
	.name =		"cdc_acm",
	.probe =	acm_probe,
	.disconnect =	acm_disconnect,
	.id_table =	acm_ids,
};

/*
 * TTY driver structures.
 */

static struct tty_operations acm_ops = {
	.open =			acm_tty_open,
	.close =		acm_tty_close,
	.write =		acm_tty_write,
	.write_room =		acm_tty_write_room,
	.ioctl =		acm_tty_ioctl,
	.throttle =		acm_tty_throttle,
	.unthrottle =		acm_tty_unthrottle,
	.chars_in_buffer =	acm_tty_chars_in_buffer,
	.break_ctl =		acm_tty_break_ctl,
	.set_termios =		acm_tty_set_termios,
	.tiocmget =		acm_tty_tiocmget,
	.tiocmset =		acm_tty_tiocmset,
};

/*
 * Init / exit.
 */

static int __init acm_init(void)
{
	int retval;
	acm_tty_driver = alloc_tty_driver(ACM_TTY_MINORS);
	if (!acm_tty_driver)
		return -ENOMEM;
	acm_tty_driver->owner = THIS_MODULE,
	acm_tty_driver->driver_name = "acm",
	acm_tty_driver->name = "ttyACM",
	acm_tty_driver->devfs_name = "usb/acm/",
	acm_tty_driver->major = ACM_TTY_MAJOR,
	acm_tty_driver->minor_start = 0,
	acm_tty_driver->type = TTY_DRIVER_TYPE_SERIAL,
	acm_tty_driver->subtype = SERIAL_TYPE_NORMAL,
	acm_tty_driver->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_NO_DEVFS,
	acm_tty_driver->init_termios = tty_std_termios;
	acm_tty_driver->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
	tty_set_operations(acm_tty_driver, &acm_ops);

	retval = tty_register_driver(acm_tty_driver);
	if (retval) {
		put_tty_driver(acm_tty_driver);
		return retval;
	}

	retval = usb_register(&acm_driver);
	if (retval) {
		tty_unregister_driver(acm_tty_driver);
		put_tty_driver(acm_tty_driver);
		return retval;
	}

	info(DRIVER_VERSION ":" DRIVER_DESC);

	return 0;
}

static void __exit acm_exit(void)
{
	usb_deregister(&acm_driver);
	tty_unregister_driver(acm_tty_driver);
	put_tty_driver(acm_tty_driver);
}

module_init(acm_init);
module_exit(acm_exit);

MODULE_AUTHOR( DRIVER_AUTHOR );
MODULE_DESCRIPTION( DRIVER_DESC );
MODULE_LICENSE("GPL");