path: root/drivers/usb/serial/sierra.c

/*
  USB Driver for Sierra Wireless

  Copyright (C) 2006, 2007  Kevin Lloyd <linux@sierrawireless.com>

  IMPORTANT DISCLAIMER: This driver is not commercially supported by
  Sierra Wireless. Use at your own risk.

  This driver is free software; you can redistribute it and/or modify
  it under the terms of Version 2 of the GNU General Public License as
  published by the Free Software Foundation.

  Portions based on the option driver by Matthias Urlichs <smurf@smurf.noris.de>
  Whom based his on the Keyspan driver by Hugh Blemings <hugh@blemings.org>
*/

#define DRIVER_VERSION "v.1.2.4b"
#define DRIVER_AUTHOR "Kevin Lloyd <linux@sierrawireless.com>"
#define DRIVER_DESC "USB Driver for Sierra Wireless USB modems"

#include <linux/kernel.h>
#include <linux/jiffies.h>
#include <linux/errno.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/usb/serial.h>

#define SWIMS_USB_REQUEST_SetMode	0x0B
#define SWIMS_USB_REQUEST_TYPE_SetMode	0x40
#define SWIMS_USB_INDEX_SetMode		0x0000
#define SWIMS_SET_MODE_Modem		0x0001

/* per port private data */
#define N_IN_URB	4
#define N_OUT_URB	4
#define IN_BUFLEN	4096

static int debug;

enum devicetype {
	DEVICE_3_PORT =		0,
	DEVICE_1_PORT =		1,
	DEVICE_INSTALLER =	2,
};

int sierra_set_power_state(struct usb_device *udev, __u16 swiState)
{
	int result;
	dev_dbg(&udev->dev, "%s", "SET POWER STATE");
	result = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
			0x00,			/* __u8 request      */
			0x40,			/* __u8 request type */
			swiState,		/* __u16 value       */
			0,			/* __u16 index       */
			NULL,			/* void *data        */
			0,			/* __u16 size 	     */
			USB_CTRL_SET_TIMEOUT);	/* int timeout 	     */
	return result;
}

int sierra_set_ms_mode(struct usb_device *udev, __u16 eSocMode)
{
	int result;
	dev_dbg(&udev->dev, "%s", "DEVICE MODE SWITCH");
	result = usb_control_msg(udev, usb_sndctrlpipe(udev, 0),
			SWIMS_USB_REQUEST_SetMode,	/* __u8 request      */
			SWIMS_USB_REQUEST_TYPE_SetMode,	/* __u8 request type */
			eSocMode,			/* __u16 value       */
			SWIMS_USB_INDEX_SetMode,	/* __u16 index       */
			NULL,				/* void *data        */
			0,				/* __u16 size 	     */
			USB_CTRL_SET_TIMEOUT);		/* int timeout       */
	return result;
}

int sierra_probe(struct usb_interface *iface, const struct usb_device_id *id)
{
	int result;
	struct usb_device *udev;

	udev = usb_get_dev(interface_to_usbdev(iface));

	/* Check if in installer mode */
	if (id->driver_info == DEVICE_INSTALLER) {
		dev_dbg(&udev->dev, "%s", "FOUND DEVICE(SW)\n");
		result = sierra_set_ms_mode(udev, SWIMS_SET_MODE_Modem);
		/*We do not want to bind to the device when in installer mode*/
		return -EIO;
	}

	return usb_serial_probe(iface, id);
}

static struct usb_device_id id_table [] = {
	{ USB_DEVICE(0x1199, 0x0017) },	/* Sierra Wireless EM5625 */
	{ USB_DEVICE(0x1199, 0x0018) },	/* Sierra Wireless MC5720 */
	{ USB_DEVICE(0x1199, 0x0218) },	/* Sierra Wireless MC5720 */
	{ USB_DEVICE(0x1199, 0x0020) },	/* Sierra Wireless MC5725 */
	{ USB_DEVICE(0x1199, 0x0019) },	/* Sierra Wireless AirCard 595 */
	{ USB_DEVICE(0x1199, 0x0120) },	/* Sierra Wireless AirCard 595U */
	{ USB_DEVICE(0x1199, 0x0021) },	/* Sierra Wireless AirCard 597E */
	{ USB_DEVICE(0x1199, 0x6802) },	/* Sierra Wireless MC8755 */
	{ USB_DEVICE(0x1199, 0x6804) },	/* Sierra Wireless MC8755 */
	{ USB_DEVICE(0x1199, 0x6803) },	/* Sierra Wireless MC8765 */
	{ USB_DEVICE(0x1199, 0x6812) },	/* Sierra Wireless MC8775 */
	{ USB_DEVICE(0x1199, 0x6820) },	/* Sierra Wireless AirCard 875 */

	{ USB_DEVICE(0x1199, 0x0112), .driver_info = DEVICE_1_PORT }, /* Sierra Wireless AirCard 580 */
	{ USB_DEVICE(0x0F3D, 0x0112), .driver_info = DEVICE_1_PORT }, /* Airprime/Sierra PC 5220 */

	{ USB_DEVICE(0x1199, 0x0FFF), .driver_info = DEVICE_INSTALLER},
	{ }
};
MODULE_DEVICE_TABLE(usb, id_table);

static struct usb_device_id id_table_1port [] = {
	{ USB_DEVICE(0x1199, 0x0112) }, /* Sierra Wireless AirCard 580 */
	{ USB_DEVICE(0x0F3D, 0x0112) }, /* AirPrime/Sierra PC 5220 */
	{ }
};

static struct usb_device_id id_table_3port [] = {
	/* CDMA Devices */
	{ USB_DEVICE(0x1199, 0x0017) },	/* Sierra Wireless EM5625 */
	{ USB_DEVICE(0x1199, 0x0018) },	/* Sierra Wireless MC5720 */
	{ USB_DEVICE(0x1199, 0x0218) },	/* Sierra Wireless MC5720 */
	{ USB_DEVICE(0x1199, 0x0020) },	/* Sierra Wireless MC5725 */
	{ USB_DEVICE(0x1199, 0x0019) },	/* Sierra Wireless AirCard 595 */
	{ USB_DEVICE(0x1199, 0x0120) },	/* Sierra Wireless AirCard 595U */
	{ USB_DEVICE(0x1199, 0x0021) },	/* Sierra Wireless AirCard 597E */

	/* GSM/UMTS Devices */
	{ USB_DEVICE(0x1199, 0x6802) },	/* Sierra Wireless MC8755 */
	{ USB_DEVICE(0x1199, 0x6804) },	/* Sierra Wireless MC8755 */
	{ USB_DEVICE(0x1199, 0x6803) },	/* Sierra Wireless MC8765 */
	{ USB_DEVICE(0x1199, 0x6812) },	/* Sierra Wireless MC8775 */
	{ USB_DEVICE(0x1199, 0x6820) },	/* Sierra Wireless AirCard 875 */
	{ }
};

static struct usb_driver sierra_driver = {
	.name       = "sierra",
	.probe      = sierra_probe,
	.disconnect = usb_serial_disconnect,
	.id_table   = id_table,
	.no_dynamic_id = 	1,
};


struct sierra_port_private {
	spinlock_t lock;	/* lock the structure */
	int outstanding_urbs;	/* number of out urbs in flight */

	/* Input endpoints and buffer for this port */
	struct urb *in_urbs[N_IN_URB];
	char in_buffer[N_IN_URB][IN_BUFLEN];

	/* Settings for the port */
	int rts_state;	/* Handshaking pins (outputs) */
	int dtr_state;
	int cts_state;	/* Handshaking pins (inputs) */
	int dsr_state;
	int dcd_state;
	int ri_state;
};

static int sierra_send_setup(struct usb_serial_port *port)
{
	struct usb_serial *serial = port->serial;
	struct sierra_port_private *portdata;

	dbg("%s", __FUNCTION__);

	portdata = usb_get_serial_port_data(port);

	if (port->tty) {
		int val = 0;
		if (portdata->dtr_state)
			val |= 0x01;
		if (portdata->rts_state)
			val |= 0x02;

		return usb_control_msg(serial->dev,
				usb_rcvctrlpipe(serial->dev, 0),
				0x22,0x21,val,0,NULL,0,USB_CTRL_SET_TIMEOUT);
	}

	return 0;
}

static void sierra_rx_throttle(struct usb_serial_port *port)
{
	dbg("%s", __FUNCTION__);
}

static void sierra_rx_unthrottle(struct usb_serial_port *port)
{
	dbg("%s", __FUNCTION__);
}

static void sierra_break_ctl(struct usb_serial_port *port, int break_state)
{
	/* Unfortunately, I don't know how to send a break */
	dbg("%s", __FUNCTION__);
}

static void sierra_set_termios(struct usb_serial_port *port,
			struct ktermios *old_termios)
{
	dbg("%s", __FUNCTION__);

	sierra_send_setup(port);
}

static int sierra_tiocmget(struct usb_serial_port *port, struct file *file)
{
	unsigned int value;
	struct sierra_port_private *portdata;

	portdata = usb_get_serial_port_data(port);

	value = ((portdata->rts_state) ? TIOCM_RTS : 0) |
		((portdata->dtr_state) ? TIOCM_DTR : 0) |
		((portdata->cts_state) ? TIOCM_CTS : 0) |
		((portdata->dsr_state) ? TIOCM_DSR : 0) |
		((portdata->dcd_state) ? TIOCM_CAR : 0) |
		((portdata->ri_state) ? TIOCM_RNG : 0);

	return value;
}

static int sierra_tiocmset(struct usb_serial_port *port, struct file *file,
			unsigned int set, unsigned int clear)
{
	struct sierra_port_private *portdata;

	portdata = usb_get_serial_port_data(port);

	if (set & TIOCM_RTS)
		portdata->rts_state = 1;
	if (set & TIOCM_DTR)
		portdata->dtr_state = 1;

	if (clear & TIOCM_RTS)
		portdata->rts_state = 0;
	if (clear & TIOCM_DTR)
		portdata->dtr_state = 0;
	return sierra_send_setup(port);
}

static int sierra_ioctl(struct usb_serial_port *port, struct file *file,
			unsigned int cmd, unsigned long arg)
{
	return -ENOIOCTLCMD;
}

static void sierra_outdat_callback(struct urb *urb)
{
	struct usb_serial_port *port = urb->context;
	struct sierra_port_private *portdata = usb_get_serial_port_data(port);
	int status = urb->status;
	unsigned long flags;

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

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

	if (status)
		dbg("%s - nonzero write bulk status received: %d",
		    __FUNCTION__, status);

	spin_lock_irqsave(&portdata->lock, flags);
	--portdata->outstanding_urbs;
	spin_unlock_irqrestore(&portdata->lock, flags);

	usb_serial_port_softint(port);
}

/* Write */
static int sierra_write(struct usb_serial_port *port,
			const unsigned char *buf, int count)
{
	struct sierra_port_private *portdata = usb_get_serial_port_data(port);
	struct usb_serial *serial = port->serial;
	unsigned long flags;
	unsigned char *buffer;
	struct urb *urb;
	int status;

	portdata = usb_get_serial_port_data(port);

	dbg("%s: write (%d chars)", __FUNCTION__, count);

	spin_lock_irqsave(&portdata->lock, flags);
	if (portdata->outstanding_urbs > N_OUT_URB) {
		spin_unlock_irqrestore(&portdata->lock, flags);
		dbg("%s - write limit hit\n", __FUNCTION__);
		return 0;
	}
	portdata->outstanding_urbs++;
	spin_unlock_irqrestore(&portdata->lock, flags);

	buffer = kmalloc(count, GFP_ATOMIC);
	if (!buffer) {
		dev_err(&port->dev, "out of memory\n");
		count = -ENOMEM;
		goto error_no_buffer;
	}

	urb = usb_alloc_urb(0, GFP_ATOMIC);
	if (!urb) {
		dev_err(&port->dev, "no more free urbs\n");
		count = -ENOMEM;
		goto error_no_urb;
	}

	memcpy(buffer, buf, count);

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

	usb_fill_bulk_urb(urb, serial->dev,
			  usb_sndbulkpipe(serial->dev,
					  port->bulk_out_endpointAddress),
			  buffer, count, sierra_outdat_callback, port);

	/* send it down the pipe */
	status = usb_submit_urb(urb, GFP_ATOMIC);
	if (status) {
		dev_err(&port->dev, "%s - usb_submit_urb(write bulk) failed "
			"with status = %d\n", __FUNCTION__, status);
		count = status;
		goto error;
	}

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

	return count;
error:
	usb_free_urb(urb);
error_no_urb:
	kfree(buffer);
error_no_buffer:
	spin_lock_irqsave(&portdata->lock, flags);
	--portdata->outstanding_urbs;
	spin_unlock_irqrestore(&portdata->lock, flags);
	return count;
}

static void sierra_indat_callback(struct urb *urb)
{
	int err;
	int endpoint;
	struct usb_serial_port *port;
	struct tty_struct *tty;
	unsigned char *data = urb->transfer_buffer;
	int status = urb->status;

	dbg("%s: %p", __FUNCTION__, urb);

	endpoint = usb_pipeendpoint(urb->pipe);
	port = (struct usb_serial_port *) urb->context;

	if (status) {
		dbg("%s: nonzero status: %d on endpoint %02x.",
		    __FUNCTION__, status, endpoint);
	} else {
		tty = port->tty;
		if (urb->actual_length) {
			tty_buffer_request_room(tty, urb->actual_length);
			tty_insert_flip_string(tty, data, urb->actual_length);
			tty_flip_buffer_push(tty);
		} else {
			dbg("%s: empty read urb received", __FUNCTION__);
		}

		/* Resubmit urb so we continue receiving */
		if (port->open_count && status != -ESHUTDOWN) {
			err = usb_submit_urb(urb, GFP_ATOMIC);
			if (err)
				dev_err(&port->dev, "resubmit read urb failed."
					"(%d)", err);
		}
	}
	return;
}

static void sierra_instat_callback(struct urb *urb)
{
	int err;
	int status = urb->status;
	struct usb_serial_port *port = (struct usb_serial_port *) urb->context;
	struct sierra_port_private *portdata = usb_get_serial_port_data(port);
	struct usb_serial *serial = port->serial;

	dbg("%s", __FUNCTION__);
	dbg("%s: urb %p port %p has data %p", __FUNCTION__,urb,port,portdata);

	if (status == 0) {
		struct usb_ctrlrequest *req_pkt =
				(struct usb_ctrlrequest *)urb->transfer_buffer;

		if (!req_pkt) {
			dbg("%s: NULL req_pkt\n", __FUNCTION__);
			return;
		}
		if ((req_pkt->bRequestType == 0xA1) &&
				(req_pkt->bRequest == 0x20)) {
			int old_dcd_state;
			unsigned char signals = *((unsigned char *)
					urb->transfer_buffer +
					sizeof(struct usb_ctrlrequest));

			dbg("%s: signal x%x", __FUNCTION__, signals);

			old_dcd_state = portdata->dcd_state;
			portdata->cts_state = 1;
			portdata->dcd_state = ((signals & 0x01) ? 1 : 0);
			portdata->dsr_state = ((signals & 0x02) ? 1 : 0);
			portdata->ri_state = ((signals & 0x08) ? 1 : 0);

			if (port->tty && !C_CLOCAL(port->tty) &&
					old_dcd_state && !portdata->dcd_state)
				tty_hangup(port->tty);
		} else {
			dbg("%s: type %x req %x", __FUNCTION__,
				req_pkt->bRequestType,req_pkt->bRequest);
		}
	} else
		dbg("%s: error %d", __FUNCTION__, status);

	/* Resubmit urb so we continue receiving IRQ data */
	if (status != -ESHUTDOWN) {
		urb->dev = serial->dev;
		err = usb_submit_urb(urb, GFP_ATOMIC);
		if (err)
			dbg("%s: resubmit intr urb failed. (%d)",
				__FUNCTION__, err);
	}
}

static int sierra_write_room(struct usb_serial_port *port)
{
	struct sierra_port_private *portdata = usb_get_serial_port_data(port);
	unsigned long flags;

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

	/* try to give a good number back based on if we have any free urbs at
	 * this point in time */
	spin_lock_irqsave(&portdata->lock, flags);
	if (portdata->outstanding_urbs > N_OUT_URB * 2 / 3) {
		spin_unlock_irqrestore(&portdata->lock, flags);
		dbg("%s - write limit hit\n", __FUNCTION__);
		return 0;
	}
	spin_unlock_irqrestore(&portdata->lock, flags);

	return 2048;
}

static int sierra_chars_in_buffer(struct usb_serial_port *port)
{
	dbg("%s - port %d", __FUNCTION__, port->number);

	/*
	 * We can't really account for how much data we
	 * have sent out, but hasn't made it through to the
	 * device as we can't see the backend here, so just
	 * tell the tty layer that everything is flushed.
	 */
	return 0;
}

static int sierra_open(struct usb_serial_port *port, struct file *filp)
{
	struct sierra_port_private *portdata;
	struct usb_serial *serial = port->serial;
	int i;
	struct urb *urb;
	int result;

	portdata = usb_get_serial_port_data(port);

	dbg("%s", __FUNCTION__);

	/* Set some sane defaults */
	portdata->rts_state = 1;
	portdata->dtr_state = 1;

	/* Reset low level data toggle and start reading from endpoints */
	for (i = 0; i < N_IN_URB; i++) {
		urb = portdata->in_urbs[i];
		if (!urb)
			continue;
		if (urb->dev != serial->dev) {
			dbg("%s: dev %p != %p", __FUNCTION__,
				urb->dev, serial->dev);
			continue;
		}

		/*
		 * make sure endpoint data toggle is synchronized with the
		 * device
		 */
		usb_clear_halt(urb->dev, urb->pipe);

		result = usb_submit_urb(urb, GFP_KERNEL);
		if (result) {
			dev_err(&port->dev, "submit urb %d failed (%d) %d",
				i, result, urb->transfer_buffer_length);
		}
	}

	port->tty->low_latency = 1;

	sierra_send_setup(port);

	/* start up the interrupt endpoint if we have one */
	if (port->interrupt_in_urb) {
		result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
		if (result)
			dev_err(&port->dev, "submit irq_in urb failed %d",
				result);
	}
	return 0;
}

static void sierra_close(struct usb_serial_port *port, struct file *filp)
{
	int i;
	struct usb_serial *serial = port->serial;
	struct sierra_port_private *portdata;

	dbg("%s", __FUNCTION__);
	portdata = usb_get_serial_port_data(port);

	portdata->rts_state = 0;
	portdata->dtr_state = 0;

	if (serial->dev) {
		sierra_send_setup(port);

		/* Stop reading/writing urbs */
		for (i = 0; i < N_IN_URB; i++)
			usb_kill_urb(portdata->in_urbs[i]);
	}

	usb_kill_urb(port->interrupt_in_urb);

	port->tty = NULL;
}

static int sierra_startup(struct usb_serial *serial)
{
	struct usb_serial_port *port;
	struct sierra_port_private *portdata;
	struct urb *urb;
	int i;
	int j;

	dbg("%s", __FUNCTION__);

	/*Set Device mode to D0 */
	sierra_set_power_state(serial->dev, 0x0000);

	/* Now setup per port private data */
	for (i = 0; i < serial->num_ports; i++) {
		port = serial->port[i];
		portdata = kzalloc(sizeof(*portdata), GFP_KERNEL);
		if (!portdata) {
			dbg("%s: kmalloc for sierra_port_private (%d) failed!.",
					__FUNCTION__, i);
			return -ENOMEM;
		}
		spin_lock_init(&portdata->lock);

		usb_set_serial_port_data(port, portdata);

		/* initialize the in urbs */
		for (j = 0; j < N_IN_URB; ++j) {
			urb = usb_alloc_urb(0, GFP_KERNEL);
			if (urb == NULL) {
				dbg("%s: alloc for in port failed.",
				    __FUNCTION__);
				continue;
			}
			/* Fill URB using supplied data. */
			usb_fill_bulk_urb(urb, serial->dev,
					  usb_rcvbulkpipe(serial->dev,
						port->bulk_in_endpointAddress),
					  portdata->in_buffer[j], IN_BUFLEN,
					  sierra_indat_callback, port);
			portdata->in_urbs[j] = urb;
		}
	}

	return 0;
}

static void sierra_shutdown(struct usb_serial *serial)
{
	int i, j;
	struct usb_serial_port *port;
	struct sierra_port_private *portdata;

	dbg("%s", __FUNCTION__);

	for (i = 0; i < serial->num_ports; ++i) {
		port = serial->port[i];
		if (!port)
			continue;
		portdata = usb_get_serial_port_data(port);
		if (!portdata)
			continue;

		for (j = 0; j < N_IN_URB; j++) {
			usb_kill_urb(portdata->in_urbs[j]);
			usb_free_urb(portdata->in_urbs[j]);
			portdata->in_urbs[j] = NULL;
		}
		kfree(portdata);
		usb_set_serial_port_data(port, NULL);
	}
}

static struct usb_serial_driver sierra_1port_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name =		"sierra1",
	},
	.description       = "Sierra USB modem (1 port)",
	.id_table          = id_table_1port,
	.usb_driver        = &sierra_driver,
	.num_interrupt_in  = NUM_DONT_CARE,
	.num_bulk_in       = 1,
	.num_bulk_out      = 1,
	.num_ports         = 1,
	.open              = sierra_open,
	.close             = sierra_close,
	.write             = sierra_write,
	.write_room        = sierra_write_room,
	.chars_in_buffer   = sierra_chars_in_buffer,
	.throttle          = sierra_rx_throttle,
	.unthrottle        = sierra_rx_unthrottle,
	.ioctl             = sierra_ioctl,
	.set_termios       = sierra_set_termios,
	.break_ctl         = sierra_break_ctl,
	.tiocmget          = sierra_tiocmget,
	.tiocmset          = sierra_tiocmset,
	.attach            = sierra_startup,
	.shutdown          = sierra_shutdown,
	.read_int_callback = sierra_instat_callback,
};

static struct usb_serial_driver sierra_3port_device = {
	.driver = {
		.owner =	THIS_MODULE,
		.name =		"sierra3",
	},
	.description       = "Sierra USB modem (3 port)",
	.id_table          = id_table_3port,
	.usb_driver        = &sierra_driver,
	.num_interrupt_in  = NUM_DONT_CARE,
	.num_bulk_in       = 3,
	.num_bulk_out      = 3,
	.num_ports         = 3,
	.open              = sierra_open,
	.close             = sierra_close,
	.write             = sierra_write,
	.write_room        = sierra_write_room,
	.chars_in_buffer   = sierra_chars_in_buffer,
	.throttle          = sierra_rx_throttle,
	.unthrottle        = sierra_rx_unthrottle,
	.ioctl             = sierra_ioctl,
	.set_termios       = sierra_set_termios,
	.break_ctl         = sierra_break_ctl,
	.tiocmget          = sierra_tiocmget,
	.tiocmset          = sierra_tiocmset,
	.attach            = sierra_startup,
	.shutdown          = sierra_shutdown,
	.read_int_callback = sierra_instat_callback,
};

/* Functions used by new usb-serial code. */
static int __init sierra_init(void)
{
	int retval;
	retval = usb_serial_register(&sierra_1port_device);
	if (retval)
		goto failed_1port_device_register;
	retval = usb_serial_register(&sierra_3port_device);
	if (retval)
		goto failed_3port_device_register;


	retval = usb_register(&sierra_driver);
	if (retval)
		goto failed_driver_register;

	info(DRIVER_DESC ": " DRIVER_VERSION);

	return 0;

failed_driver_register:
	usb_serial_deregister(&sierra_3port_device);
failed_3port_device_register:
	usb_serial_deregister(&sierra_1port_device);
failed_1port_device_register:
	return retval;
}

static void __exit sierra_exit(void)
{
	usb_deregister (&sierra_driver);
	usb_serial_deregister(&sierra_1port_device);
	usb_serial_deregister(&sierra_3port_device);
}

module_init(sierra_init);
module_exit(sierra_exit);

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

#ifdef CONFIG_USB_DEBUG
module_param(debug, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug, "Debug messages");
#endif