text: // SPDX-License-Identifier: GPL-2.0-or-later
  /*
   *  Copyright (c) 2001 Paul Stewart
   *  Copyright (c) 2001 Vojtech Pavlik
   *
   *  HID char devices, giving access to raw HID device events.
   */
  
  /*
   *
   * Should you need to contact me, the author, you can do so either by
   * e-mail - mail your message to Paul Stewart <stewart@wetlogic.net>
   */
  
  #include <linux/poll.h>
  #include <linux/slab.h>
  #include <linux/sched/signal.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/input.h>
  #include <linux/usb.h>
  #include <linux/hid.h>
  #include <linux/hiddev.h>
  #include <linux/compat.h>
  #include <linux/vmalloc.h>
  #include <linux/nospec.h>
  #include "usbhid.h"
  
  #ifdef CONFIG_USB_DYNAMIC_MINORS
  #define HIDDEV_MINOR_BASE	0
  #define HIDDEV_MINORS		256
  #else
  #define HIDDEV_MINOR_BASE	96
  #define HIDDEV_MINORS		16
  #endif
  #define HIDDEV_BUFFER_SIZE	2048
  
  struct hiddev_list {
  	struct hiddev_usage_ref buffer[HIDDEV_BUFFER_SIZE];
  	int head;
  	int tail;
  	unsigned flags;
  	struct fasync_struct *fasync;
  	struct hiddev *hiddev;
  	struct list_head node;
  	struct mutex thread_lock;
  };
  
  /*
   * Find a report, given the report's type and ID.  The ID can be specified
   * indirectly by REPORT_ID_FIRST (which returns the first report of the given
   * type) or by (REPORT_ID_NEXT | old_id), which returns the next report of the
   * given type which follows old_id.
   */
  static struct hid_report *
  hiddev_lookup_report(struct hid_device *hid, struct hiddev_report_info *rinfo)
  {
  	unsigned int flags = rinfo->report_id & ~HID_REPORT_ID_MASK;
  	unsigned int rid = rinfo->report_id & HID_REPORT_ID_MASK;
  	struct hid_report_enum *report_enum;
  	struct hid_report *report;
  	struct list_head *list;
  
  	if (rinfo->report_type < HID_REPORT_TYPE_MIN ||
  	    rinfo->report_type > HID_REPORT_TYPE_MAX)
  		return NULL;
  
  	report_enum = hid->report_enum +
  		(rinfo->report_type - HID_REPORT_TYPE_MIN);
  
  	switch (flags) {
  	case 0: /* Nothing to do -- report_id is already set correctly */
  		break;
  
  	case HID_REPORT_ID_FIRST:
  		if (list_empty(&report_enum->report_list))
  			return NULL;
  
  		list = report_enum->report_list.next;
  		report = list_entry(list, struct hid_report, list);
  		rinfo->report_id = report->id;
  		break;
  
  	case HID_REPORT_ID_NEXT:
  		report = report_enum->report_id_hash[rid];
  		if (!report)
  			return NULL;
  
  		list = report->list.next;
  		if (list == &report_enum->report_list)
  			return NULL;
  
  		report = list_entry(list, struct hid_report, list);
  		rinfo->report_id = report->id;
  		break;
  
  	default:
  		return NULL;
  	}
  
  	return report_enum->report_id_hash[rinfo->report_id];
  }
  
  /*
   * Perform an exhaustive search of the report table for a usage, given its
   * type and usage id.
   */
  static struct hid_field *
  hiddev_lookup_usage(struct hid_device *hid, struct hiddev_usage_ref *uref)
  {
  	int i, j;
  	struct hid_report *report;
  	struct hid_report_enum *report_enum;
  	struct hid_field *field;
  
  	if (uref->report_type < HID_REPORT_TYPE_MIN ||
  	    uref->report_type > HID_REPORT_TYPE_MAX)
  		return NULL;
  
  	report_enum = hid->report_enum +
  		(uref->report_type - HID_REPORT_TYPE_MIN);
  
  	list_for_each_entry(report, &report_enum->report_list, list) {
  		for (i = 0; i < report->maxfield; i++) {
  			field = report->field[i];
  			for (j = 0; j < field->maxusage; j++) {
  				if (field->usage[j].hid == uref->usage_code) {
  					uref->report_id = report->id;
  					uref->field_index = i;
  					uref->usage_index = j;
  					return field;
  				}
  			}
  		}
  	}
  
  	return NULL;
  }
  
  static void hiddev_send_event(struct hid_device *hid,
  			      struct hiddev_usage_ref *uref)
  {
  	struct hiddev *hiddev = hid->hiddev;
  	struct hiddev_list *list;
  	unsigned long flags;
  
  	spin_lock_irqsave(&hiddev->list_lock, flags);
  	list_for_each_entry(list, &hiddev->list, node) {
  		if (uref->field_index != HID_FIELD_INDEX_NONE ||
  		    (list->flags & HIDDEV_FLAG_REPORT) != 0) {
  			list->buffer[list->head] = *uref;
  			list->head = (list->head + 1) &
  				(HIDDEV_BUFFER_SIZE - 1);
  			kill_fasync(&list->fasync, SIGIO, POLL_IN);
  		}
  	}
  	spin_unlock_irqrestore(&hiddev->list_lock, flags);
  
  	wake_up_interruptible(&hiddev->wait);
  }
  
  /*
   * This is where hid.c calls into hiddev to pass an event that occurred over
   * the interrupt pipe
   */
  void hiddev_hid_event(struct hid_device *hid, struct hid_field *field,
  		      struct hid_usage *usage, __s32 value)
  {
  	unsigned type = field->report_type;
  	struct hiddev_usage_ref uref;
  
  	uref.report_type =
  	  (type == HID_INPUT_REPORT) ? HID_REPORT_TYPE_INPUT :
  	  ((type == HID_OUTPUT_REPORT) ? HID_REPORT_TYPE_OUTPUT :
  	   ((type == HID_FEATURE_REPORT) ? HID_REPORT_TYPE_FEATURE : 0));
  	uref.report_id = field->report->id;
  	uref.field_index = field->index;
  	uref.usage_index = (usage - field->usage);
  	uref.usage_code = usage->hid;
  	uref.value = value;
  
  	hiddev_send_event(hid, &uref);
  }
  EXPORT_SYMBOL_GPL(hiddev_hid_event);
  
  void hiddev_report_event(struct hid_device *hid, struct hid_report *report)
  {
  	unsigned type = report->type;
  	struct hiddev_usage_ref uref;
  
  	memset(&uref, 0, sizeof(uref));
  	uref.report_type =
  	  (type == HID_INPUT_REPORT) ? HID_REPORT_TYPE_INPUT :
  	  ((type == HID_OUTPUT_REPORT) ? HID_REPORT_TYPE_OUTPUT :
  	   ((type == HID_FEATURE_REPORT) ? HID_REPORT_TYPE_FEATURE : 0));
  	uref.report_id = report->id;
  	uref.field_index = HID_FIELD_INDEX_NONE;
  
  	hiddev_send_event(hid, &uref);
  }
  
  /*
   * fasync file op
   */
  static int hiddev_fasync(int fd, struct file *file, int on)
  {
  	struct hiddev_list *list = file->private_data;
  
  	return fasync_helper(fd, file, on, &list->fasync);
  }
  
  
  /*
   * release file op
   */
  static int hiddev_release(struct inode * inode, struct file * file)
  {
  	struct hiddev_list *list = file->private_data;
  	unsigned long flags;
  
  	spin_lock_irqsave(&list->hiddev->list_lock, flags);
  	list_del(&list->node);
  	spin_unlock_irqrestore(&list->hiddev->list_lock, flags);
  
  	mutex_lock(&list->hiddev->existancelock);
  	if (!--list->hiddev->open) {
  		if (list->hiddev->exist) {
  			hid_hw_close(list->hiddev->hid);
  			hid_hw_power(list->hiddev->hid, PM_HINT_NORMAL);
  		} else {
  			mutex_unlock(&list->hiddev->existancelock);
  			kfree(list->hiddev);
  			vfree(list);
  			return 0;
  		}
  	}
  
  	mutex_unlock(&list->hiddev->existancelock);
  	vfree(list);
  
  	return 0;
  }
  
  static int __hiddev_open(struct hiddev *hiddev, struct file *file)
  {
  	struct hiddev_list *list;
  	int error;
  
  	lockdep_assert_held(&hiddev->existancelock);
  
  	list = vzalloc(sizeof(*list));
  	if (!list)
  		return -ENOMEM;
  
  	mutex_init(&list->thread_lock);
  	list->hiddev = hiddev;
  
  	if (!hiddev->open++) {
  		error = hid_hw_power(hiddev->hid, PM_HINT_FULLON);
  		if (error < 0)
  			goto err_drop_count;
  
  		error = hid_hw_open(hiddev->hid);
  		if (error < 0)
  			goto err_normal_power;
  	}
  
  	spin_lock_irq(&hiddev->list_lock);
  	list_add_tail(&list->node, &hiddev->list);
  	spin_unlock_irq(&hiddev->list_lock);
  
  	file->private_data = list;
  
  	return 0;
  
  err_normal_power:
  	hid_hw_power(hiddev->hid, PM_HINT_NORMAL);
  err_drop_count:
  	hiddev->open--;
  	vfree(list);
  	return error;
  }
  
  /*
   * open file op
   */
  static int hiddev_open(struct inode *inode, struct file *file)
  {
  	struct usb_interface *intf;
  	struct hid_device *hid;
  	struct hiddev *hiddev;
  	int res;
  
  	intf = usbhid_find_interface(iminor(inode));
  	if (!intf)
  		return -ENODEV;
  
  	hid = usb_get_intfdata(intf);
  	hiddev = hid->hiddev;
  
  	mutex_lock(&hiddev->existancelock);
  	res = hiddev->exist ? __hiddev_open(hiddev, file) : -ENODEV;
  	mutex_unlock(&hiddev->existancelock);
  
  	return res;
  }
  
  /*
   * "write" file op
   */
  static ssize_t hiddev_write(struct file * file, const char __user * buffer, size_t count, loff_t *ppos)
  {
  	return -EINVAL;
  }
  
  /*
   * "read" file op
   */
  static ssize_t hiddev_read(struct file * file, char __user * buffer, size_t count, loff_t *ppos)
  {
  	DEFINE_WAIT(wait);
  	struct hiddev_list *list = file->private_data;
  	int event_size;
  	int retval;
  
  	event_size = ((list->flags & HIDDEV_FLAG_UREF) != 0) ?
  		sizeof(struct hiddev_usage_ref) : sizeof(struct hiddev_event);
  
  	if (count < event_size)
  		return 0;
  
  	/* lock against other threads */
  	retval = mutex_lock_interruptible(&list->thread_lock);
  	if (retval)
  		return -ERESTARTSYS;
  
  	while (retval == 0) {
  		if (list->head == list->tail) {
  			prepare_to_wait(&list->hiddev->wait, &wait, TASK_INTERRUPTIBLE);
  
  			while (list->head == list->tail) {
  				if (signal_pending(current)) {
  					retval = -ERESTARTSYS;
  					break;
  				}
  				if (!list->hiddev->exist) {
  					retval = -EIO;
  					break;
  				}
  				if (file->f_flags & O_NONBLOCK) {
  					retval = -EAGAIN;
  					break;
  				}
  
  				/* let O_NONBLOCK tasks run */
  				mutex_unlock(&list->thread_lock);
  				schedule();
  				if (mutex_lock_interruptible(&list->thread_lock)) {
  					finish_wait(&list->hiddev->wait, &wait);
  					return -EINTR;
  				}
  				set_current_state(TASK_INTERRUPTIBLE);
  			}
  			finish_wait(&list->hiddev->wait, &wait);
  
  		}
  
  		if (retval) {
  			mutex_unlock(&list->thread_lock);
  			return retval;
  		}
  
  
  		while (list->head != list->tail &&
  		       retval + event_size <= count) {
  			if ((list->flags & HIDDEV_FLAG_UREF) == 0) {
  				if (list->buffer[list->tail].field_index != HID_FIELD_INDEX_NONE) {
  					struct hiddev_event event;
  
  					event.hid = list->buffer[list->tail].usage_code;
  					event.value = list->buffer[list->tail].value;
  					if (copy_to_user(buffer + retval, &event, sizeof(struct hiddev_event))) {
  						mutex_unlock(&list->thread_lock);
  						return -EFAULT;
  					}
  					retval += sizeof(struct hiddev_event);
  				}
  			} else {
  				if (list->buffer[list->tail].field_index != HID_FIELD_INDEX_NONE ||
  				    (list->flags & HIDDEV_FLAG_REPORT) != 0) {
  
  					if (copy_to_user(buffer + retval, list->buffer + list->tail, sizeof(struct hiddev_usage_ref))) {
  						mutex_unlock(&list->thread_lock);
  						return -EFAULT;
  					}
  					retval += sizeof(struct hiddev_usage_ref);
  				}
  			}
  			list->tail = (list->tail + 1) & (HIDDEV_BUFFER_SIZE - 1);
  		}
  
  	}
  	mutex_unlock(&list->thread_lock);
  
  	return retval;
  }
  
  /*
   * "poll" file op
   * No kernel lock - fine
   */
  static __poll_t hiddev_poll(struct file *file, poll_table *wait)
  {
  	struct hiddev_list *list = file->private_data;
  
  	poll_wait(file, &list->hiddev->wait, wait);
  	if (list->head != list->tail)
  		return EPOLLIN | EPOLLRDNORM | EPOLLOUT;
  	if (!list->hiddev->exist)
  		return EPOLLERR | EPOLLHUP;
  	return 0;
  }
  
  /*
   * "ioctl" file op
   */
  static noinline int hiddev_ioctl_usage(struct hiddev *hiddev, unsigned int cmd, void __user *user_arg)
  {
  	struct hid_device *hid = hiddev->hid;
  	struct hiddev_report_info rinfo;
  	struct hiddev_usage_ref_multi *uref_multi = NULL;
  	struct hiddev_usage_ref *uref;
  	struct hid_report *report;
  	struct hid_field *field;
  	int i;
  
  	uref_multi = kmalloc(sizeof(struct hiddev_usage_ref_multi), GFP_KERNEL);
  	if (!uref_multi)
  		return -ENOMEM;
  	uref = &uref_multi->uref;
  	if (cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) {
  		if (copy_from_user(uref_multi, user_arg,
  				   sizeof(*uref_multi)))
  			goto fault;
  	} else {
  		if (copy_from_user(uref, user_arg, sizeof(*uref)))
  			goto fault;
  	}
  
  	switch (cmd) {
  	case HIDIOCGUCODE:
  		rinfo.report_type = uref->report_type;
  		rinfo.report_id = uref->report_id;
  		if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
  			goto inval;
  
  		if (uref->field_index >= report->maxfield)
  			goto inval;
  		uref->field_index = array_index_nospec(uref->field_index,
  						       report->maxfield);
  
  		field = report->field[uref->field_index];
  		if (uref->usage_index >= field->maxusage)
  			goto inval;
  		uref->usage_index = array_index_nospec(uref->usage_index,
  						       field->maxusage);
  
  		uref->usage_code = field->usage[uref->usage_index].hid;
  
  		if (copy_to_user(user_arg, uref, sizeof(*uref)))
  			goto fault;
  
  		goto goodreturn;
  
  	default:
  		if (cmd != HIDIOCGUSAGE &&
  		    cmd != HIDIOCGUSAGES &&
  		    uref->report_type == HID_REPORT_TYPE_INPUT)
  			goto inval;
  
  		if (uref->report_id == HID_REPORT_ID_UNKNOWN) {
  			field = hiddev_lookup_usage(hid, uref);
  			if (field == NULL)
  				goto inval;
  		} else {
  			rinfo.report_type = uref->report_type;
  			rinfo.report_id = uref->report_id;
  			if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
  				goto inval;
  
  			if (uref->field_index >= report->maxfield)
  				goto inval;
  			uref->field_index = array_index_nospec(uref->field_index,
  							       report->maxfield);
  
  			field = report->field[uref->field_index];
  
  			if (cmd == HIDIOCGCOLLECTIONINDEX) {
  				if (uref->usage_index >= field->maxusage)
  					goto inval;
  				uref->usage_index =
  					array_index_nospec(uref->usage_index,
  							   field->maxusage);
  			} else if (uref->usage_index >= field->report_count)
  				goto inval;
  		}
  
  		if (cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) {
  			if (uref_multi->num_values > HID_MAX_MULTI_USAGES ||
  			    uref->usage_index + uref_multi->num_values >
  			    field->report_count)
  				goto inval;
  
  			uref->usage_index =
  				array_index_nospec(uref->usage_index,
  						   field->report_count -
  						   uref_multi->num_values);
  		}
  
  		switch (cmd) {
  		case HIDIOCGUSAGE:
  			uref->value = field->value[uref->usage_index];
  			if (copy_to_user(user_arg, uref, sizeof(*uref)))
  				goto fault;
  			goto goodreturn;
  
  		case HIDIOCSUSAGE:
  			field->value[uref->usage_index] = uref->value;
  			goto goodreturn;
  
  		case HIDIOCGCOLLECTIONINDEX:
  			i = field->usage[uref->usage_index].collection_index;
  			kfree(uref_multi);
  			return i;
  		case HIDIOCGUSAGES:
  			for (i = 0; i < uref_multi->num_values; i++)
  				uref_multi->values[i] =
  				    field->value[uref->usage_index + i];
  			if (copy_to_user(user_arg, uref_multi,
  					 sizeof(*uref_multi)))
  				goto fault;
  			goto goodreturn;
  		case HIDIOCSUSAGES:
  			for (i = 0; i < uref_multi->num_values; i++)
  				field->value[uref->usage_index + i] =
  				    uref_multi->values[i];
  			goto goodreturn;
  		}
  
  goodreturn:
  		kfree(uref_multi);
  		return 0;
  fault:
  		kfree(uref_multi);
  		return -EFAULT;
  inval:
  		kfree(uref_multi);
  		return -EINVAL;
  	}
  }
  
  static noinline int hiddev_ioctl_string(struct hiddev *hiddev, unsigned int cmd, void __user *user_arg)
  {
  	struct hid_device *hid = hiddev->hid;
  	struct usb_device *dev = hid_to_usb_dev(hid);
  	int idx, len;
  	char *buf;
  
  	if (get_user(idx, (int __user *)user_arg))
  		return -EFAULT;
  
  	if ((buf = kmalloc(HID_STRING_SIZE, GFP_KERNEL)) == NULL)
  		return -ENOMEM;
  
  	if ((len = usb_string(dev, idx, buf, HID_STRING_SIZE-1)) < 0) {
  		kfree(buf);
  		return -EINVAL;
  	}
  
  	if (copy_to_user(user_arg+sizeof(int), buf, len+1)) {
  		kfree(buf);
  		return -EFAULT;
  	}
  
  	kfree(buf);
  
  	return len;
  }
  
  static long hiddev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {
  	struct hiddev_list *list = file->private_data;
  	struct hiddev *hiddev = list->hiddev;
  	struct hid_device *hid;
  	struct hiddev_collection_info cinfo;
  	struct hiddev_report_info rinfo;
  	struct hiddev_field_info finfo;
  	struct hiddev_devinfo dinfo;
  	struct hid_report *report;
  	struct hid_field *field;
  	void __user *user_arg = (void __user *)arg;
  	int i, r = -EINVAL;
  
  	/* Called without BKL by compat methods so no BKL taken */
  
  	mutex_lock(&hiddev->existancelock);
  	if (!hiddev->exist) {
  		r = -ENODEV;
  		goto ret_unlock;
  	}
  
  	hid = hiddev->hid;
  
  	switch (cmd) {
  
  	case HIDIOCGVERSION:
  		r = put_user(HID_VERSION, (int __user *)arg) ?
  			-EFAULT : 0;
  		break;
  
  	case HIDIOCAPPLICATION:
  		if (arg >= hid->maxapplication)
  			break;
  
  		for (i = 0; i < hid->maxcollection; i++)
  			if (hid->collection[i].type ==
  			    HID_COLLECTION_APPLICATION && arg-- == 0)
  				break;
  
  		if (i < hid->maxcollection)
  			r = hid->collection[i].usage;
  		break;
  
  	case HIDIOCGDEVINFO:
  		{
  			struct usb_device *dev = hid_to_usb_dev(hid);
  			struct usbhid_device *usbhid = hid->driver_data;
  
  			memset(&dinfo, 0, sizeof(dinfo));
  
  			dinfo.bustype = BUS_USB;
  			dinfo.busnum = dev->bus->busnum;
  			dinfo.devnum = dev->devnum;
  			dinfo.ifnum = usbhid->ifnum;
  			dinfo.vendor = le16_to_cpu(dev->descriptor.idVendor);
  			dinfo.product = le16_to_cpu(dev->descriptor.idProduct);
  			dinfo.version = le16_to_cpu(dev->descriptor.bcdDevice);
  			dinfo.num_applications = hid->maxapplication;
  
  			r = copy_to_user(user_arg, &dinfo, sizeof(dinfo)) ?
  				-EFAULT : 0;
  			break;
  		}
  
  	case HIDIOCGFLAG:
  		r = put_user(list->flags, (int __user *)arg) ?
  			-EFAULT : 0;
  		break;
  
  	case HIDIOCSFLAG:
  		{
  			int newflags;
  
  			if (get_user(newflags, (int __user *)arg)) {
  				r = -EFAULT;
  				break;
  			}
  
  			if ((newflags & ~HIDDEV_FLAGS) != 0 ||
  			    ((newflags & HIDDEV_FLAG_REPORT) != 0 &&
  			     (newflags & HIDDEV_FLAG_UREF) == 0))
  				break;
  
  			list->flags = newflags;
  
  			r = 0;
  			break;
  		}
  
  	case HIDIOCGSTRING:
  		r = hiddev_ioctl_string(hiddev, cmd, user_arg);
  		break;
  
  	case HIDIOCINITREPORT:
  		usbhid_init_reports(hid);
  		hiddev->initialized = true;
  		r = 0;
  		break;
  
  	case HIDIOCGREPORT:
  		if (copy_from_user(&rinfo, user_arg, sizeof(rinfo))) {
  			r = -EFAULT;
  			break;
  		}
  
  		if (rinfo.report_type == HID_REPORT_TYPE_OUTPUT)
  			break;
  
  		report = hiddev_lookup_report(hid, &rinfo);
  		if (report == NULL)
  			break;
  
  		hid_hw_request(hid, report, HID_REQ_GET_REPORT);
  		hid_hw_wait(hid);
  
  		r = 0;
  		break;
  
  	case HIDIOCSREPORT:
  		if (copy_from_user(&rinfo, user_arg, sizeof(rinfo))) {
  			r = -EFAULT;
  			break;
  		}
  
  		if (rinfo.report_type == HID_REPORT_TYPE_INPUT)
  			break;
  
  		report = hiddev_lookup_report(hid, &rinfo);
  		if (report == NULL)
  			break;
  
  		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
  		hid_hw_wait(hid);
  
  		r = 0;
  		break;
  
  	case HIDIOCGREPORTINFO:
  		if (copy_from_user(&rinfo, user_arg, sizeof(rinfo))) {
  			r = -EFAULT;
  			break;
  		}
  
  		report = hiddev_lookup_report(hid, &rinfo);
  		if (report == NULL)
  			break;
  
  		rinfo.num_fields = report->maxfield;
  
  		r = copy_to_user(user_arg, &rinfo, sizeof(rinfo)) ?
  			-EFAULT : 0;
  		break;
  
  	case HIDIOCGFIELDINFO:
  		if (copy_from_user(&finfo, user_arg, sizeof(finfo))) {
  			r = -EFAULT;
  			break;
  		}
  
  		rinfo.report_type = finfo.report_type;
  		rinfo.report_id = finfo.report_id;
  
  		report = hiddev_lookup_report(hid, &rinfo);
  		if (report == NULL)
  			break;
  
  		if (finfo.field_index >= report->maxfield)
  			break;
  		finfo.field_index = array_index_nospec(finfo.field_index,
  						       report->maxfield);
  
  		field = report->field[finfo.field_index];
  		memset(&finfo, 0, sizeof(finfo));
  		finfo.report_type = rinfo.report_type;
  		finfo.report_id = rinfo.report_id;
  		finfo.field_index = field->report_count - 1;
  		finfo.maxusage = field->maxusage;
  		finfo.flags = field->flags;
  		finfo.physical = field->physical;
  		finfo.logical = field->logical;
  		finfo.application = field->application;
  		finfo.logical_minimum = field->logical_minimum;
  		finfo.logical_maximum = field->logical_maximum;
  		finfo.physical_minimum = field->physical_minimum;
  		finfo.physical_maximum = field->physical_maximum;
  		finfo.unit_exponent = field->unit_exponent;
  		finfo.unit = field->unit;
  
  		r = copy_to_user(user_arg, &finfo, sizeof(finfo)) ?
  			-EFAULT : 0;
  		break;
  
  	case HIDIOCGUCODE:
  		/* fall through */
  	case HIDIOCGUSAGE:
  	case HIDIOCSUSAGE:
  	case HIDIOCGUSAGES:
  	case HIDIOCSUSAGES:
  	case HIDIOCGCOLLECTIONINDEX:
  		if (!hiddev->initialized) {
  			usbhid_init_reports(hid);
  			hiddev->initialized = true;
  		}
  		r = hiddev_ioctl_usage(hiddev, cmd, user_arg);
  		break;
  
  	case HIDIOCGCOLLECTIONINFO:
  		if (copy_from_user(&cinfo, user_arg, sizeof(cinfo))) {
  			r = -EFAULT;
  			break;
  		}
  
  		if (cinfo.index >= hid->maxcollection)
  			break;
  		cinfo.index = array_index_nospec(cinfo.index,
  						 hid->maxcollection);
  
  		cinfo.type = hid->collection[cinfo.index].type;
  		cinfo.usage = hid->collection[cinfo.index].usage;
  		cinfo.level = hid->collection[cinfo.index].level;
  
  		r = copy_to_user(user_arg, &cinfo, sizeof(cinfo)) ?
  			-EFAULT : 0;
  		break;
  
  	default:
  		if (_IOC_TYPE(cmd) != 'H' || _IOC_DIR(cmd) != _IOC_READ)
  			break;
  
  		if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGNAME(0))) {
  			int len = strlen(hid->name) + 1;
  			if (len > _IOC_SIZE(cmd))
  				 len = _IOC_SIZE(cmd);
  			r = copy_to_user(user_arg, hid->name, len) ?
  				-EFAULT : len;
  			break;
  		}
  
  		if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGPHYS(0))) {
  			int len = strlen(hid->phys) + 1;
  			if (len > _IOC_SIZE(cmd))
  				len = _IOC_SIZE(cmd);
  			r = copy_to_user(user_arg, hid->phys, len) ?
  				-EFAULT : len;
  			break;
  		}
  	}
  
  ret_unlock:
  	mutex_unlock(&hiddev->existancelock);
  	return r;
  }
  
  #ifdef CONFIG_COMPAT
  static long hiddev_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {
  	return hiddev_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
  }
  #endif
  
  static const struct file_operations hiddev_fops = {
  	.owner =	THIS_MODULE,
  	.read =		hiddev_read,
  	.write =	hiddev_write,
  	.poll =		hiddev_poll,
  	.open =		hiddev_open,
  	.release =	hiddev_release,
  	.unlocked_ioctl =	hiddev_ioctl,
  	.fasync =	hiddev_fasync,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl	= hiddev_compat_ioctl,
  #endif
  	.llseek		= noop_llseek,
  };
  
  static char *hiddev_devnode(struct device *dev, umode_t *mode)
  {
  	return kasprintf(GFP_KERNEL, "usb/%s", dev_name(dev));
  }
  
  static struct usb_class_driver hiddev_class = {
  	.name =		"hiddev%d",
  	.devnode =	hiddev_devnode,
  	.fops =		&hiddev_fops,
  	.minor_base =	HIDDEV_MINOR_BASE,
  };
  
  /*
   * This is where hid.c calls us to connect a hid device to the hiddev driver
   */
  int hiddev_connect(struct hid_device *hid, unsigned int force)
  {
  	struct hiddev *hiddev;
  	struct usbhid_device *usbhid = hid->driver_data;
  	int retval;
  
  	if (!force) {
  		unsigned int i;
  		for (i = 0; i < hid->maxcollection; i++)
  			if (hid->collection[i].type ==
  			    HID_COLLECTION_APPLICATION &&
  			    !IS_INPUT_APPLICATION(hid->collection[i].usage))
  				break;
  
  		if (i == hid->maxcollection)
  			return -1;
  	}
  
  	if (!(hiddev = kzalloc(sizeof(struct hiddev), GFP_KERNEL)))
  		return -1;
  
  	init_waitqueue_head(&hiddev->wait);
  	INIT_LIST_HEAD(&hiddev->list);
  	spin_lock_init(&hiddev->list_lock);
  	mutex_init(&hiddev->existancelock);
  	hid->hiddev = hiddev;
  	hiddev->hid = hid;
  	hiddev->exist = 1;
  	retval = usb_register_dev(usbhid->intf, &hiddev_class);
  	if (retval) {
  		hid_err(hid, "Not able to get a minor for this device\n");
  		hid->hiddev = NULL;
  		kfree(hiddev);
  		return -1;
  	}
  
  	/*
  	 * If HID_QUIRK_NO_INIT_REPORTS is set, make sure we don't initialize
  	 * the reports.
  	 */
  	hiddev->initialized = hid->quirks & HID_QUIRK_NO_INIT_REPORTS;
  
  	hiddev->minor = usbhid->intf->minor;
  
  	return 0;
  }
  
  /*
   * This is where hid.c calls us to disconnect a hiddev device from the
   * corresponding hid device (usually because the usb device has disconnected)
   */
  static struct usb_class_driver hiddev_class;
  void hiddev_disconnect(struct hid_device *hid)
  {
  	struct hiddev *hiddev = hid->hiddev;
  	struct usbhid_device *usbhid = hid->driver_data;
  
  	usb_deregister_dev(usbhid->intf, &hiddev_class);
  
  	mutex_lock(&hiddev->existancelock);
  	hiddev->exist = 0;
  
  	if (hiddev->open) {
  		hid_hw_close(hiddev->hid);
  		wake_up_interruptible(&hiddev->wait);
  		mutex_unlock(&hiddev->existancelock);
  	} else {
  		mutex_unlock(&hiddev->existancelock);
  		kfree(hiddev);
  	}
  }
  