drivers/usb/misc/usblcd.c - kernel/msm-4.9 - Gitiles

 /*****************************************************************************
  *                          USBLCD Kernel Driver                             *
  *                            Version 1.05                                   *
  *             (C) 2005 Georges Toth <g.toth@e-biz.lu>                       *
  *                                                                           *
  *     This file is licensed under the GPL. See COPYING in the package.      *
  * Based on usb-skeleton.c 2.0 by Greg Kroah-Hartman (greg@kroah.com)        *
  *                                                                           *
  *                                                                           *
  * 28.02.05 Complete rewrite of the original usblcd.c driver,                *
  *          based on usb_skeleton.c.                                         *
  *          This new driver allows more than one USB-LCD to be connected     *
  *          and controlled, at once                                          *
  *****************************************************************************/
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/errno.h>
 #include <asm/uaccess.h>
 #include <linux/usb.h>

 #define DRIVER_VERSION "USBLCD Driver Version 1.05"

 #define USBLCD_MINOR		144

 #define IOCTL_GET_HARD_VERSION	1
 #define IOCTL_GET_DRV_VERSION	2


 static struct usb_device_id id_table [] = {
 	{ .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
 	{ },
 };
 MODULE_DEVICE_TABLE (usb, id_table);


 struct usb_lcd {
 	struct usb_device *	udev;			/* init: probe_lcd */
 	struct usb_interface *  interface;		/* the interface for this device */
 	unsigned char *         bulk_in_buffer;		/* the buffer to receive data */
 	size_t			bulk_in_size;		/* the size of the receive buffer */
 	__u8			bulk_in_endpointAddr;	/* the address of the bulk in endpoint */
 	__u8			bulk_out_endpointAddr;	/* the address of the bulk out endpoint */
 	struct kref		kref;
 	struct semaphore	limit_sem;		/* to stop writes at full throttle from
 							 * using up all RAM */
 };
 #define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)

 #define USB_LCD_CONCURRENT_WRITES	5

 static struct usb_driver lcd_driver;
 static DEFINE_MUTEX(usb_lcd_open_mutex);


 static void lcd_delete(struct kref *kref)
 {
 	struct usb_lcd *dev = to_lcd_dev(kref);

 	usb_put_dev(dev->udev);
 	kfree (dev->bulk_in_buffer);
 	kfree (dev);
 }


 static int lcd_open(struct inode *inode, struct file *file)
 {
 	struct usb_lcd *dev;
 	struct usb_interface *interface;
 	int subminor;
 	int retval = 0;

 	subminor = iminor(inode);

 	mutex_lock(&usb_lcd_open_mutex);
 	interface = usb_find_interface(&lcd_driver, subminor);
 	if (!interface) {
 		err ("USBLCD: %s - error, can't find device for minor %d",
 		     __FUNCTION__, subminor);
 		retval = -ENODEV;
 		goto exit;
 	}

 	dev = usb_get_intfdata(interface);
 	if (!dev) {
 		retval = -ENODEV;
 		goto exit;
 	}

 	/* increment our usage count for the device */
 	kref_get(&dev->kref);

 	/* save our object in the file's private structure */
 	file->private_data = dev;

 exit:
 	mutex_unlock(&usb_lcd_open_mutex);
 	return retval;
 }

 static int lcd_release(struct inode *inode, struct file *file)
 {
 	struct usb_lcd *dev;

 	dev = (struct usb_lcd *)file->private_data;
 	if (dev == NULL)
 		return -ENODEV;

 	/* decrement the count on our device */
 	kref_put(&dev->kref, lcd_delete);
 	return 0;
 }

 static ssize_t lcd_read(struct file *file, char __user * buffer, size_t count, loff_t *ppos)
 {
 	struct usb_lcd *dev;
 	int retval = 0;
 	int bytes_read;

 	dev = (struct usb_lcd *)file->private_data;

 	/* do a blocking bulk read to get data from the device */
 	retval = usb_bulk_msg(dev->udev,
 			      usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
 			      dev->bulk_in_buffer,
 			      min(dev->bulk_in_size, count),
 			      &bytes_read, 10000);

 	/* if the read was successful, copy the data to userspace */
 	if (!retval) {
 		if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
 			retval = -EFAULT;
 		else
 			retval = bytes_read;
 	}

 	return retval;
 }

 static int lcd_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
 {
 	struct usb_lcd *dev;
 	u16 bcdDevice;
 	char buf[30];

 	dev = (struct usb_lcd *)file->private_data;
 	if (dev == NULL)
 		return -ENODEV;

 	switch (cmd) {
 	case IOCTL_GET_HARD_VERSION:
 		bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
 		sprintf(buf,"%1d%1d.%1d%1d",
 			(bcdDevice & 0xF000)>>12,
 			(bcdDevice & 0xF00)>>8,
 			(bcdDevice & 0xF0)>>4,
 			(bcdDevice & 0xF));
 		if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
 			return -EFAULT;
 		break;
 	case IOCTL_GET_DRV_VERSION:
 		sprintf(buf,DRIVER_VERSION);
 		if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
 			return -EFAULT;
 		break;
 	default:
 		return -ENOTTY;
 		break;
 	}

 	return 0;
 }

 static void lcd_write_bulk_callback(struct urb *urb)
 {
 	struct usb_lcd *dev;

 	dev = (struct usb_lcd *)urb->context;

 	/* sync/async unlink faults aren't errors */
 	if (urb->status &&
 	    !(urb->status == -ENOENT ||
 	      urb->status == -ECONNRESET ||
               urb->status == -ESHUTDOWN)) {
 		dbg("USBLCD: %s - nonzero write bulk status received: %d",
 		    __FUNCTION__, urb->status);
 	}

 	/* free up our allocated buffer */
 	usb_buffer_free(urb->dev, urb->transfer_buffer_length,
 			urb->transfer_buffer, urb->transfer_dma);
 	up(&dev->limit_sem);
 }

 static ssize_t lcd_write(struct file *file, const char __user * user_buffer, size_t count, loff_t *ppos)
 {
 	struct usb_lcd *dev;
         int retval = 0, r;
 	struct urb *urb = NULL;
 	char *buf = NULL;

 	dev = (struct usb_lcd *)file->private_data;

 	/* verify that we actually have some data to write */
 	if (count == 0)
 		goto exit;

 	r = down_interruptible(&dev->limit_sem);
 	if (r < 0)
 		return -EINTR;

 	/* create a urb, and a buffer for it, and copy the data to the urb */
 	urb = usb_alloc_urb(0, GFP_KERNEL);
 	if (!urb) {
 		retval = -ENOMEM;
 		goto err_no_buf;
 	}

 	buf = usb_buffer_alloc(dev->udev, count, GFP_KERNEL, &urb->transfer_dma);
 	if (!buf) {
 		retval = -ENOMEM;
 		goto error;
 	}

 	if (copy_from_user(buf, user_buffer, count)) {
 		retval = -EFAULT;
 		goto error;
 	}

 	/* initialize the urb properly */
 	usb_fill_bulk_urb(urb, dev->udev,
 			  usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
 			  buf, count, lcd_write_bulk_callback, dev);
 	urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;

 	/* send the data out the bulk port */
 	retval = usb_submit_urb(urb, GFP_KERNEL);
 	if (retval) {
 		err("USBLCD: %s - failed submitting write urb, error %d", __FUNCTION__, retval);
 		goto error;
 	}

 	/* release our reference to this urb, the USB core will eventually free it entirely */
 	usb_free_urb(urb);

 exit:
 	return count;

 error:
 	usb_buffer_free(dev->udev, count, buf, urb->transfer_dma);
 	usb_free_urb(urb);
 err_no_buf:
 	up(&dev->limit_sem);
 	return retval;
 }

 static const struct file_operations lcd_fops = {
         .owner =        THIS_MODULE,
         .read =         lcd_read,
         .write =        lcd_write,
         .open =         lcd_open,
 	.ioctl =        lcd_ioctl,
         .release =      lcd_release,
 };

 /*
  * usb class driver info in order to get a minor number from the usb core,
  * and to have the device registered with the driver core
  */
 static struct usb_class_driver lcd_class = {
         .name =         "lcd%d",
         .fops =         &lcd_fops,
         .minor_base =   USBLCD_MINOR,
 };

 static int lcd_probe(struct usb_interface *interface, const struct usb_device_id *id)
 {
 	struct usb_lcd *dev = NULL;
 	struct usb_host_interface *iface_desc;
 	struct usb_endpoint_descriptor *endpoint;
 	size_t buffer_size;
 	int i;
 	int retval = -ENOMEM;

 	/* allocate memory for our device state and initialize it */
 	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 	if (dev == NULL) {
 		err("Out of memory");
 		goto error;
 	}
 	kref_init(&dev->kref);
 	sema_init(&dev->limit_sem, USB_LCD_CONCURRENT_WRITES);

 	dev->udev = usb_get_dev(interface_to_usbdev(interface));
 	dev->interface = interface;

 	if (le16_to_cpu(dev->udev->descriptor.idProduct) != 0x0001) {
 		warn(KERN_INFO "USBLCD model not supported.");
 		return -ENODEV;
 	}

 	/* set up the endpoint information */
 	/* use only the first bulk-in and bulk-out endpoints */
 	iface_desc = interface->cur_altsetting;
 	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
 		endpoint = &iface_desc->endpoint[i].desc;

 		if (!dev->bulk_in_endpointAddr &&
 		    usb_endpoint_is_bulk_in(endpoint)) {
 			/* we found a bulk in endpoint */
 			buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
 			dev->bulk_in_size = buffer_size;
 			dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
 			dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
 			if (!dev->bulk_in_buffer) {
 				err("Could not allocate bulk_in_buffer");
 				goto error;
 			}
 		}

 		if (!dev->bulk_out_endpointAddr &&
 		    usb_endpoint_is_bulk_out(endpoint)) {
 			/* we found a bulk out endpoint */
 			dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
 		}
 	}
 	if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
 		err("Could not find both bulk-in and bulk-out endpoints");
 		goto error;
 	}

 	/* save our data pointer in this interface device */
 	usb_set_intfdata(interface, dev);

 	/* we can register the device now, as it is ready */
 	retval = usb_register_dev(interface, &lcd_class);
 	if (retval) {
 		/* something prevented us from registering this driver */
 		err("Not able to get a minor for this device.");
 		usb_set_intfdata(interface, NULL);
 		goto error;
 	}

 	i = le16_to_cpu(dev->udev->descriptor.bcdDevice);

 	info("USBLCD Version %1d%1d.%1d%1d found at address %d",
 		(i & 0xF000)>>12,(i & 0xF00)>>8,(i & 0xF0)>>4,(i & 0xF),
 		dev->udev->devnum);

 	/* let the user know what node this device is now attached to */
 	info("USB LCD device now attached to USBLCD-%d", interface->minor);
 	return 0;

 error:
 	if (dev)
 		kref_put(&dev->kref, lcd_delete);
 	return retval;
 }

 static void lcd_disconnect(struct usb_interface *interface)
 {
 	struct usb_lcd *dev;
         int minor = interface->minor;

         /* prevent skel_open() from racing skel_disconnect() */
         mutex_lock(&usb_lcd_open_mutex);

         dev = usb_get_intfdata(interface);
         usb_set_intfdata(interface, NULL);

         /* give back our minor */
         usb_deregister_dev(interface, &lcd_class);

 	mutex_unlock(&usb_lcd_open_mutex);

 	/* decrement our usage count */
 	kref_put(&dev->kref, lcd_delete);

 	info("USB LCD #%d now disconnected", minor);
 }

 static struct usb_driver lcd_driver = {
 	.name =		"usblcd",
 	.probe =	lcd_probe,
 	.disconnect =	lcd_disconnect,
 	.id_table =	id_table,
 };

 static int __init usb_lcd_init(void)
 {
 	int result;

 	result = usb_register(&lcd_driver);
 	if (result)
 		err("usb_register failed. Error number %d", result);

 	return result;
 }


 static void __exit usb_lcd_exit(void)
 {
 	usb_deregister(&lcd_driver);
 }

 module_init(usb_lcd_init);
 module_exit(usb_lcd_exit);

 MODULE_AUTHOR("Georges Toth <g.toth@e-biz.lu>");
 MODULE_DESCRIPTION(DRIVER_VERSION);
 MODULE_LICENSE("GPL");
	/*****************************************************************************
	* USBLCD Kernel Driver *
	* Version 1.05 *
	* (C) 2005 Georges Toth <g.toth@e-biz.lu> *
	* *
	* This file is licensed under the GPL. See COPYING in the package. *
	* Based on usb-skeleton.c 2.0 by Greg Kroah-Hartman (greg@kroah.com) *
	* *
	* *
	* 28.02.05 Complete rewrite of the original usblcd.c driver, *
	* based on usb_skeleton.c. *
	* This new driver allows more than one USB-LCD to be connected *
	* and controlled, at once *
	*****************************************************************************/
	#include <linux/module.h>
	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/slab.h>
	#include <linux/errno.h>
	#include <asm/uaccess.h>
	#include <linux/usb.h>

	#define DRIVER_VERSION "USBLCD Driver Version 1.05"

	#define USBLCD_MINOR 144

	#define IOCTL_GET_HARD_VERSION 1
	#define IOCTL_GET_DRV_VERSION 2


	static struct usb_device_id id_table [] = {
	{ .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
	{ },
	};
	MODULE_DEVICE_TABLE (usb, id_table);


	struct usb_lcd {
	struct usb_device * udev; /* init: probe_lcd */
	struct usb_interface * interface; /* the interface for this device */
	unsigned char * bulk_in_buffer; /* the buffer to receive data */
	size_t bulk_in_size; /* the size of the receive buffer */
	__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
	__u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
	struct kref kref;
	struct semaphore limit_sem; /* to stop writes at full throttle from
	* using up all RAM */
	};
	#define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)

	#define USB_LCD_CONCURRENT_WRITES 5

	static struct usb_driver lcd_driver;
	static DEFINE_MUTEX(usb_lcd_open_mutex);


	static void lcd_delete(struct kref *kref)
	{
	struct usb_lcd *dev = to_lcd_dev(kref);

	usb_put_dev(dev->udev);
	kfree (dev->bulk_in_buffer);
	kfree (dev);
	}


	static int lcd_open(struct inode inode, struct file file)
	{
	struct usb_lcd *dev;
	struct usb_interface *interface;
	int subminor;
	int retval = 0;

	subminor = iminor(inode);

	mutex_lock(&usb_lcd_open_mutex);
	interface = usb_find_interface(&lcd_driver, subminor);
	if (!interface) {
	err ("USBLCD: %s - error, can't find device for minor %d",
	__FUNCTION__, subminor);
	retval = -ENODEV;
	goto exit;
	}

	dev = usb_get_intfdata(interface);
	if (!dev) {
	retval = -ENODEV;
	goto exit;
	}

	/* increment our usage count for the device */
	kref_get(&dev->kref);

	/* save our object in the file's private structure */
	file->private_data = dev;

	exit:
	mutex_unlock(&usb_lcd_open_mutex);
	return retval;
	}

	static int lcd_release(struct inode inode, struct file file)
	{
	struct usb_lcd *dev;

	dev = (struct usb_lcd *)file->private_data;
	if (dev == NULL)
	return -ENODEV;

	/* decrement the count on our device */
	kref_put(&dev->kref, lcd_delete);
	return 0;
	}

	static ssize_t lcd_read(struct file file, char __user buffer, size_t count, loff_t *ppos)
	{
	struct usb_lcd *dev;
	int retval = 0;
	int bytes_read;

	dev = (struct usb_lcd *)file->private_data;

	/* do a blocking bulk read to get data from the device */
	retval = usb_bulk_msg(dev->udev,
	usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
	dev->bulk_in_buffer,
	min(dev->bulk_in_size, count),
	&bytes_read, 10000);

	/* if the read was successful, copy the data to userspace */
	if (!retval) {
	if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
	retval = -EFAULT;
	else
	retval = bytes_read;
	}

	return retval;
	}

	static int lcd_ioctl(struct inode inode, struct file file, unsigned int cmd, unsigned long arg)
	{
	struct usb_lcd *dev;
	u16 bcdDevice;
	char buf[30];

	dev = (struct usb_lcd *)file->private_data;
	if (dev == NULL)
	return -ENODEV;

	switch (cmd) {
	case IOCTL_GET_HARD_VERSION:
	bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
	sprintf(buf,"%1d%1d.%1d%1d",
	(bcdDevice & 0xF000)>>12,
	(bcdDevice & 0xF00)>>8,
	(bcdDevice & 0xF0)>>4,
	(bcdDevice & 0xF));
	if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
	return -EFAULT;
	break;
	case IOCTL_GET_DRV_VERSION:
	sprintf(buf,DRIVER_VERSION);
	if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
	return -EFAULT;
	break;
	default:
	return -ENOTTY;
	break;
	}

	return 0;
	}

	static void lcd_write_bulk_callback(struct urb *urb)
	{
	struct usb_lcd *dev;

	dev = (struct usb_lcd *)urb->context;

	/* sync/async unlink faults aren't errors */
	if (urb->status &&
	!(urb->status == -ENOENT \|\|
	urb->status == -ECONNRESET \|\|
	urb->status == -ESHUTDOWN)) {
	dbg("USBLCD: %s - nonzero write bulk status received: %d",
	__FUNCTION__, urb->status);
	}

	/* free up our allocated buffer */
	usb_buffer_free(urb->dev, urb->transfer_buffer_length,
	urb->transfer_buffer, urb->transfer_dma);
	up(&dev->limit_sem);
	}

	static ssize_t lcd_write(struct file file, const char __user user_buffer, size_t count, loff_t *ppos)
	{
	struct usb_lcd *dev;
	int retval = 0, r;
	struct urb *urb = NULL;
	char *buf = NULL;

	dev = (struct usb_lcd *)file->private_data;

	/* verify that we actually have some data to write */
	if (count == 0)
	goto exit;

	r = down_interruptible(&dev->limit_sem);
	if (r < 0)
	return -EINTR;

	/* create a urb, and a buffer for it, and copy the data to the urb */
	urb = usb_alloc_urb(0, GFP_KERNEL);
	if (!urb) {
	retval = -ENOMEM;
	goto err_no_buf;
	}

	buf = usb_buffer_alloc(dev->udev, count, GFP_KERNEL, &urb->transfer_dma);
	if (!buf) {
	retval = -ENOMEM;
	goto error;
	}

	if (copy_from_user(buf, user_buffer, count)) {
	retval = -EFAULT;
	goto error;
	}

	/* initialize the urb properly */
	usb_fill_bulk_urb(urb, dev->udev,
	usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
	buf, count, lcd_write_bulk_callback, dev);
	urb->transfer_flags \|= URB_NO_TRANSFER_DMA_MAP;

	/* send the data out the bulk port */
	retval = usb_submit_urb(urb, GFP_KERNEL);
	if (retval) {
	err("USBLCD: %s - failed submitting write urb, error %d", __FUNCTION__, retval);
	goto error;
	}

	/* release our reference to this urb, the USB core will eventually free it entirely */
	usb_free_urb(urb);

	exit:
	return count;

	error:
	usb_buffer_free(dev->udev, count, buf, urb->transfer_dma);
	usb_free_urb(urb);
	err_no_buf:
	up(&dev->limit_sem);
	return retval;
	}

	static const struct file_operations lcd_fops = {
	.owner = THIS_MODULE,
	.read = lcd_read,
	.write = lcd_write,
	.open = lcd_open,
	.ioctl = lcd_ioctl,
	.release = lcd_release,
	};

	/*
	* usb class driver info in order to get a minor number from the usb core,
	* and to have the device registered with the driver core
	*/
	static struct usb_class_driver lcd_class = {
	.name = "lcd%d",
	.fops = &lcd_fops,
	.minor_base = USBLCD_MINOR,
	};

	static int lcd_probe(struct usb_interface interface, const struct usb_device_id id)
	{
	struct usb_lcd *dev = NULL;
	struct usb_host_interface *iface_desc;
	struct usb_endpoint_descriptor *endpoint;
	size_t buffer_size;
	int i;
	int retval = -ENOMEM;

	/* allocate memory for our device state and initialize it */
	dev = kzalloc(sizeof(*dev), GFP_KERNEL);
	if (dev == NULL) {
	err("Out of memory");
	goto error;
	}
	kref_init(&dev->kref);
	sema_init(&dev->limit_sem, USB_LCD_CONCURRENT_WRITES);

	dev->udev = usb_get_dev(interface_to_usbdev(interface));
	dev->interface = interface;

	if (le16_to_cpu(dev->udev->descriptor.idProduct) != 0x0001) {
	warn(KERN_INFO "USBLCD model not supported.");
	return -ENODEV;
	}

	/* set up the endpoint information */
	/* use only the first bulk-in and bulk-out endpoints */
	iface_desc = interface->cur_altsetting;
	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
	endpoint = &iface_desc->endpoint[i].desc;

	if (!dev->bulk_in_endpointAddr &&
	usb_endpoint_is_bulk_in(endpoint)) {
	/* we found a bulk in endpoint */
	buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
	dev->bulk_in_size = buffer_size;
	dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
	dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
	if (!dev->bulk_in_buffer) {
	err("Could not allocate bulk_in_buffer");
	goto error;
	}
	}

	if (!dev->bulk_out_endpointAddr &&
	usb_endpoint_is_bulk_out(endpoint)) {
	/* we found a bulk out endpoint */
	dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
	}
	}
	if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
	err("Could not find both bulk-in and bulk-out endpoints");
	goto error;
	}

	/* save our data pointer in this interface device */
	usb_set_intfdata(interface, dev);

	/* we can register the device now, as it is ready */
	retval = usb_register_dev(interface, &lcd_class);
	if (retval) {
	/* something prevented us from registering this driver */
	err("Not able to get a minor for this device.");
	usb_set_intfdata(interface, NULL);
	goto error;
	}

	i = le16_to_cpu(dev->udev->descriptor.bcdDevice);

	info("USBLCD Version %1d%1d.%1d%1d found at address %d",
	(i & 0xF000)>>12,(i & 0xF00)>>8,(i & 0xF0)>>4,(i & 0xF),
	dev->udev->devnum);

	/* let the user know what node this device is now attached to */
	info("USB LCD device now attached to USBLCD-%d", interface->minor);
	return 0;

	error:
	if (dev)
	kref_put(&dev->kref, lcd_delete);
	return retval;
	}

	static void lcd_disconnect(struct usb_interface *interface)
	{
	struct usb_lcd *dev;
	int minor = interface->minor;

	/* prevent skel_open() from racing skel_disconnect() */
	mutex_lock(&usb_lcd_open_mutex);

	dev = usb_get_intfdata(interface);
	usb_set_intfdata(interface, NULL);

	/* give back our minor */
	usb_deregister_dev(interface, &lcd_class);

	mutex_unlock(&usb_lcd_open_mutex);

	/* decrement our usage count */
	kref_put(&dev->kref, lcd_delete);

	info("USB LCD #%d now disconnected", minor);
	}

	static struct usb_driver lcd_driver = {
	.name = "usblcd",
	.probe = lcd_probe,
	.disconnect = lcd_disconnect,
	.id_table = id_table,
	};

	static int __init usb_lcd_init(void)
	{
	int result;

	result = usb_register(&lcd_driver);
	if (result)
	err("usb_register failed. Error number %d", result);

	return result;
	}


	static void __exit usb_lcd_exit(void)
	{
	usb_deregister(&lcd_driver);
	}

	module_init(usb_lcd_init);
	module_exit(usb_lcd_exit);

	MODULE_AUTHOR("Georges Toth <g.toth@e-biz.lu>");
	MODULE_DESCRIPTION(DRIVER_VERSION);
	MODULE_LICENSE("GPL");