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hiddev.c

/*
 *  Copyright (c) 2001 Paul Stewart
 *  Copyright (c) 2001 Vojtech Pavlik
 *
 *  HID char devices, giving access to raw HID device events.
 *
 */

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * 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/module.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/input.h>
#include <linux/usb.h>
#include <linux/hid.h>
#include <linux/hiddev.h>
#include <linux/compat.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    64

struct hiddev {
      int exist;
      int open;
      wait_queue_head_t wait;
      struct hid_device *hid;
      struct list_head list;
      spinlock_t list_lock;
};

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;
};

static struct hiddev *hiddev_table[HIDDEV_MINORS];

/*
 * 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)
{
      int retval;
      struct hiddev_list *list = file->private_data;

      retval = fasync_helper(fd, file, on, &list->fasync);

      return retval < 0 ? retval : 0;
}


/*
 * release file op
 */
static int hiddev_release(struct inode * inode, struct file * file)
{
      struct hiddev_list *list = file->private_data;
      unsigned long flags;

      hiddev_fasync(-1, file, 0);

      spin_lock_irqsave(&list->hiddev->list_lock, flags);
      list_del(&list->node);
      spin_unlock_irqrestore(&list->hiddev->list_lock, flags);

      if (!--list->hiddev->open) {
            if (list->hiddev->exist)
                  usbhid_close(list->hiddev->hid);
            else
                  kfree(list->hiddev);
      }

      kfree(list);

      return 0;
}

/*
 * open file op
 */
static int hiddev_open(struct inode *inode, struct file *file)
{
      struct hiddev_list *list;
      unsigned long flags;

      int i = iminor(inode) - HIDDEV_MINOR_BASE;

      if (i >= HIDDEV_MINORS || !hiddev_table[i])
            return -ENODEV;

      if (!(list = kzalloc(sizeof(struct hiddev_list), GFP_KERNEL)))
            return -ENOMEM;

      list->hiddev = hiddev_table[i];

      spin_lock_irqsave(&list->hiddev->list_lock, flags);
      list_add_tail(&list->node, &hiddev_table[i]->list);
      spin_unlock_irqrestore(&list->hiddev->list_lock, flags);

      file->private_data = list;

      if (!list->hiddev->open++)
            if (list->hiddev->exist)
                  usbhid_open(hiddev_table[i]->hid);

      return 0;
}

/*
 * "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)
{
      DECLARE_WAITQUEUE(wait, current);
      struct hiddev_list *list = file->private_data;
      int event_size;
      int retval = 0;

      event_size = ((list->flags & HIDDEV_FLAG_UREF) != 0) ?
            sizeof(struct hiddev_usage_ref) : sizeof(struct hiddev_event);

      if (count < event_size)
            return 0;

      while (retval == 0) {
            if (list->head == list->tail) {
                  add_wait_queue(&list->hiddev->wait, &wait);
                  set_current_state(TASK_INTERRUPTIBLE);

                  while (list->head == list->tail) {
                        if (file->f_flags & O_NONBLOCK) {
                              retval = -EAGAIN;
                              break;
                        }
                        if (signal_pending(current)) {
                              retval = -ERESTARTSYS;
                              break;
                        }
                        if (!list->hiddev->exist) {
                              retval = -EIO;
                              break;
                        }

                        schedule();
                        set_current_state(TASK_INTERRUPTIBLE);
                  }

                  set_current_state(TASK_RUNNING);
                  remove_wait_queue(&list->hiddev->wait, &wait);
            }

            if (retval)
                  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)))
                                    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)))
                                    return -EFAULT;
                              retval += sizeof(struct hiddev_usage_ref);
                        }
                  }
                  list->tail = (list->tail + 1) & (HIDDEV_BUFFER_SIZE - 1);
            }

      }

      return retval;
}

/*
 * "poll" file op
 * No kernel lock - fine
 */
static unsigned int 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 POLLIN | POLLRDNORM;
      if (!list->hiddev->exist)
            return POLLERR | POLLHUP;
      return 0;
}

/*
 * "ioctl" file op
 */
static int hiddev_ioctl(struct inode *inode, 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 = hiddev->hid;
      struct usb_device *dev = hid_to_usb_dev(hid);
      struct hiddev_collection_info cinfo;
      struct hiddev_report_info rinfo;
      struct hiddev_field_info finfo;
      struct hiddev_usage_ref_multi *uref_multi = NULL;
      struct hiddev_usage_ref *uref;
      struct hiddev_devinfo dinfo;
      struct hid_report *report;
      struct hid_field *field;
      struct usbhid_device *usbhid = hid->driver_data;
      void __user *user_arg = (void __user *)arg;
      int i;

      if (!hiddev->exist)
            return -EIO;

      switch (cmd) {

      case HIDIOCGVERSION:
            return put_user(HID_VERSION, (int __user *)arg);

      case HIDIOCAPPLICATION:
            if (arg < 0 || arg >= hid->maxapplication)
                  return -EINVAL;

            for (i = 0; i < hid->maxcollection; i++)
                  if (hid->collection[i].type ==
                      HID_COLLECTION_APPLICATION && arg-- == 0)
                        break;

            if (i == hid->maxcollection)
                  return -EINVAL;

            return hid->collection[i].usage;

      case HIDIOCGDEVINFO:
            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;
            if (copy_to_user(user_arg, &dinfo, sizeof(dinfo)))
                  return -EFAULT;

            return 0;

      case HIDIOCGFLAG:
            if (put_user(list->flags, (int __user *)arg))
                  return -EFAULT;

            return 0;

      case HIDIOCSFLAG:
            {
                  int newflags;
                  if (get_user(newflags, (int __user *)arg))
                        return -EFAULT;

                  if ((newflags & ~HIDDEV_FLAGS) != 0 ||
                      ((newflags & HIDDEV_FLAG_REPORT) != 0 &&
                       (newflags & HIDDEV_FLAG_UREF) == 0))
                        return -EINVAL;

                  list->flags = newflags;

                  return 0;
            }

      case HIDIOCGSTRING:
            {
                  int idx, len;
                  char *buf;

                  if (get_user(idx, (int __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;
            }

      case HIDIOCINITREPORT:
            usbhid_init_reports(hid);

            return 0;

      case HIDIOCGREPORT:
            if (copy_from_user(&rinfo, user_arg, sizeof(rinfo)))
                  return -EFAULT;

            if (rinfo.report_type == HID_REPORT_TYPE_OUTPUT)
                  return -EINVAL;

            if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
                  return -EINVAL;

            usbhid_submit_report(hid, report, USB_DIR_IN);
            usbhid_wait_io(hid);

            return 0;

      case HIDIOCSREPORT:
            if (copy_from_user(&rinfo, user_arg, sizeof(rinfo)))
                  return -EFAULT;

            if (rinfo.report_type == HID_REPORT_TYPE_INPUT)
                  return -EINVAL;

            if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
                  return -EINVAL;

            usbhid_submit_report(hid, report, USB_DIR_OUT);
            usbhid_wait_io(hid);

            return 0;

      case HIDIOCGREPORTINFO:
            if (copy_from_user(&rinfo, user_arg, sizeof(rinfo)))
                  return -EFAULT;

            if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
                  return -EINVAL;

            rinfo.num_fields = report->maxfield;

            if (copy_to_user(user_arg, &rinfo, sizeof(rinfo)))
                  return -EFAULT;

            return 0;

      case HIDIOCGFIELDINFO:
            if (copy_from_user(&finfo, user_arg, sizeof(finfo)))
                  return -EFAULT;
            rinfo.report_type = finfo.report_type;
            rinfo.report_id = finfo.report_id;
            if ((report = hiddev_lookup_report(hid, &rinfo)) == NULL)
                  return -EINVAL;

            if (finfo.field_index >= report->maxfield)
                  return -EINVAL;

            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;

            if (copy_to_user(user_arg, &finfo, sizeof(finfo)))
                  return -EFAULT;

            return 0;

      case HIDIOCGUCODE:
            uref_multi = kmalloc(sizeof(struct hiddev_usage_ref_multi), GFP_KERNEL);
            if (!uref_multi)
                  return -ENOMEM;
            uref = &uref_multi->uref;
            if (copy_from_user(uref, user_arg, sizeof(*uref)))
                  goto fault;

            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;

            field = report->field[uref->field_index];
            if (uref->usage_index >= field->maxusage)
                  goto inval;

            uref->usage_code = field->usage[uref->usage_index].hid;

            if (copy_to_user(user_arg, uref, sizeof(*uref)))
                  goto fault;

            kfree(uref_multi);
            return 0;

      case HIDIOCGUSAGE:
      case HIDIOCSUSAGE:
      case HIDIOCGUSAGES:
      case HIDIOCSUSAGES:
      case HIDIOCGCOLLECTIONINDEX:
            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;
            }

            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;

                  field = report->field[uref->field_index];

                  if (cmd == HIDIOCGCOLLECTIONINDEX) {
                        if (uref->usage_index >= field->maxusage)
                              goto inval;
                  } else if (uref->usage_index >= field->report_count)
                        goto inval;

                  else if ((cmd == HIDIOCGUSAGES || cmd == HIDIOCSUSAGES) &&
                         (uref_multi->num_values > HID_MAX_MULTI_USAGES ||
                          uref->usage_index + uref_multi->num_values > field->report_count))
                        goto inval;
                  }

            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:
                        kfree(uref_multi);
                        return field->usage[uref->usage_index].collection_index;
                  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;

      case HIDIOCGCOLLECTIONINFO:
            if (copy_from_user(&cinfo, user_arg, sizeof(cinfo)))
                  return -EFAULT;

            if (cinfo.index >= hid->maxcollection)
                  return -EINVAL;

            cinfo.type = hid->collection[cinfo.index].type;
            cinfo.usage = hid->collection[cinfo.index].usage;
            cinfo.level = hid->collection[cinfo.index].level;

            if (copy_to_user(user_arg, &cinfo, sizeof(cinfo)))
                  return -EFAULT;
            return 0;

      default:

            if (_IOC_TYPE(cmd) != 'H' || _IOC_DIR(cmd) != _IOC_READ)
                  return -EINVAL;

            if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGNAME(0))) {
                  int len;
                  if (!hid->name)
                        return 0;
                  len = strlen(hid->name) + 1;
                  if (len > _IOC_SIZE(cmd))
                         len = _IOC_SIZE(cmd);
                  return copy_to_user(user_arg, hid->name, len) ?
                        -EFAULT : len;
            }

            if (_IOC_NR(cmd) == _IOC_NR(HIDIOCGPHYS(0))) {
                  int len;
                  if (!hid->phys)
                        return 0;
                  len = strlen(hid->phys) + 1;
                  if (len > _IOC_SIZE(cmd))
                        len = _IOC_SIZE(cmd);
                  return copy_to_user(user_arg, hid->phys, len) ?
                        -EFAULT : len;
            }
      }
      return -EINVAL;
}

#ifdef CONFIG_COMPAT
static long hiddev_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
      struct inode *inode = file->f_path.dentry->d_inode;
      return hiddev_ioctl(inode, 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,
      .ioctl =    hiddev_ioctl,
      .fasync =   hiddev_fasync,
#ifdef CONFIG_COMPAT
      .compat_ioctl     = hiddev_compat_ioctl,
#endif
};

static struct usb_class_driver hiddev_class = {
      .name =           "hiddev%d",
      .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)
{
      struct hiddev *hiddev;
      struct usbhid_device *usbhid = hid->driver_data;
      int i;
      int retval;

      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 && (hid->quirks & HID_QUIRK_HIDDEV) == 0)
            return -1;

      if (!(hiddev = kzalloc(sizeof(struct hiddev), GFP_KERNEL)))
            return -1;

      retval = usb_register_dev(usbhid->intf, &hiddev_class);
      if (retval) {
            err_hid("Not able to get a minor for this device.");
            kfree(hiddev);
            return -1;
      }

      init_waitqueue_head(&hiddev->wait);
      INIT_LIST_HEAD(&hiddev->list);
      spin_lock_init(&hiddev->list_lock);
      hiddev->hid = hid;
      hiddev->exist = 1;

      hid->minor = usbhid->intf->minor;
      hid->hiddev = hiddev;

      hiddev_table[usbhid->intf->minor - HIDDEV_MINOR_BASE] = hiddev;

      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;

      hiddev->exist = 0;

      hiddev_table[hiddev->hid->minor - HIDDEV_MINOR_BASE] = NULL;
      usb_deregister_dev(usbhid->intf, &hiddev_class);

      if (hiddev->open) {
            usbhid_close(hiddev->hid);
            wake_up_interruptible(&hiddev->wait);
      } else {
            kfree(hiddev);
      }
}

/* Currently this driver is a USB driver.  It's not a conventional one in
 * the sense that it doesn't probe at the USB level.  Instead it waits to
 * be connected by HID through the hiddev_connect / hiddev_disconnect
 * routines.  The reason to register as a USB device is to gain part of the
 * minor number space from the USB major.
 *
 * In theory, should the HID code be generalized to more than one physical
 * medium (say, IEEE 1384), this driver will probably need to register its
 * own major number, and in doing so, no longer need to register with USB.
 * At that point the probe routine and hiddev_driver struct below will no
 * longer be useful.
 */


/* We never attach in this manner, and rely on HID to connect us.  This
 * is why there is no disconnect routine defined in the usb_driver either.
 */
static int hiddev_usbd_probe(struct usb_interface *intf,
                       const struct usb_device_id *hiddev_info)
{
      return -ENODEV;
}


static /* const */ struct usb_driver hiddev_driver = {
      .name =           "hiddev",
      .probe =    hiddev_usbd_probe,
};

int __init hiddev_init(void)
{
      return usb_register(&hiddev_driver);
}

void hiddev_exit(void)
{
      usb_deregister(&hiddev_driver);
}

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