2012-06-10 21:16:13 +08:00
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/*
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* User-space I/O driver support for HID subsystem
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* Copyright (c) 2012 David Herrmann
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*/
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/*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include <linux/atomic.h>
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#include <linux/device.h>
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#include <linux/fs.h>
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#include <linux/hid.h>
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#include <linux/input.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/poll.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/uhid.h>
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#include <linux/wait.h>
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#define UHID_NAME "uhid"
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2012-06-10 21:16:14 +08:00
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#define UHID_BUFSIZE 32
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struct uhid_device {
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2012-06-10 21:16:16 +08:00
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struct mutex devlock;
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2012-06-10 21:16:14 +08:00
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struct hid_device *hid;
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2012-06-10 21:16:17 +08:00
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struct uhid_event input_buf;
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2012-06-10 21:16:14 +08:00
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wait_queue_head_t waitq;
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spinlock_t qlock;
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__u8 head;
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__u8 tail;
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struct uhid_event *outq[UHID_BUFSIZE];
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};
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2012-06-10 21:16:13 +08:00
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static struct miscdevice uhid_misc;
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2012-06-10 21:16:14 +08:00
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static void uhid_queue(struct uhid_device *uhid, struct uhid_event *ev)
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{
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__u8 newhead;
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newhead = (uhid->head + 1) % UHID_BUFSIZE;
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if (newhead != uhid->tail) {
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uhid->outq[uhid->head] = ev;
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uhid->head = newhead;
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wake_up_interruptible(&uhid->waitq);
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} else {
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hid_warn(uhid->hid, "Output queue is full\n");
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kfree(ev);
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}
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}
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static int uhid_queue_event(struct uhid_device *uhid, __u32 event)
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{
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unsigned long flags;
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struct uhid_event *ev;
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ev = kzalloc(sizeof(*ev), GFP_KERNEL);
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if (!ev)
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return -ENOMEM;
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ev->type = event;
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spin_lock_irqsave(&uhid->qlock, flags);
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uhid_queue(uhid, ev);
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spin_unlock_irqrestore(&uhid->qlock, flags);
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return 0;
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}
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2012-06-10 21:16:13 +08:00
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static int uhid_char_open(struct inode *inode, struct file *file)
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{
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2012-06-10 21:16:14 +08:00
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struct uhid_device *uhid;
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uhid = kzalloc(sizeof(*uhid), GFP_KERNEL);
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if (!uhid)
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return -ENOMEM;
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2012-06-10 21:16:16 +08:00
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mutex_init(&uhid->devlock);
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2012-06-10 21:16:14 +08:00
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spin_lock_init(&uhid->qlock);
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init_waitqueue_head(&uhid->waitq);
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file->private_data = uhid;
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nonseekable_open(inode, file);
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2012-06-10 21:16:13 +08:00
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return 0;
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}
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static int uhid_char_release(struct inode *inode, struct file *file)
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{
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2012-06-10 21:16:14 +08:00
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struct uhid_device *uhid = file->private_data;
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unsigned int i;
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for (i = 0; i < UHID_BUFSIZE; ++i)
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kfree(uhid->outq[i]);
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kfree(uhid);
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2012-06-10 21:16:13 +08:00
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return 0;
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}
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static ssize_t uhid_char_read(struct file *file, char __user *buffer,
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size_t count, loff_t *ppos)
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{
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2012-06-10 21:16:16 +08:00
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struct uhid_device *uhid = file->private_data;
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int ret;
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unsigned long flags;
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size_t len;
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/* they need at least the "type" member of uhid_event */
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if (count < sizeof(__u32))
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return -EINVAL;
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try_again:
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if (file->f_flags & O_NONBLOCK) {
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if (uhid->head == uhid->tail)
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return -EAGAIN;
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} else {
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ret = wait_event_interruptible(uhid->waitq,
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uhid->head != uhid->tail);
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if (ret)
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return ret;
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}
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ret = mutex_lock_interruptible(&uhid->devlock);
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if (ret)
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return ret;
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if (uhid->head == uhid->tail) {
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mutex_unlock(&uhid->devlock);
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goto try_again;
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} else {
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len = min(count, sizeof(**uhid->outq));
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if (copy_to_user(buffer, &uhid->outq[uhid->tail], len)) {
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ret = -EFAULT;
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} else {
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kfree(uhid->outq[uhid->tail]);
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uhid->outq[uhid->tail] = NULL;
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spin_lock_irqsave(&uhid->qlock, flags);
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uhid->tail = (uhid->tail + 1) % UHID_BUFSIZE;
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spin_unlock_irqrestore(&uhid->qlock, flags);
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}
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}
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mutex_unlock(&uhid->devlock);
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return ret ? ret : len;
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2012-06-10 21:16:13 +08:00
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}
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static ssize_t uhid_char_write(struct file *file, const char __user *buffer,
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size_t count, loff_t *ppos)
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{
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2012-06-10 21:16:17 +08:00
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struct uhid_device *uhid = file->private_data;
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int ret;
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size_t len;
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/* we need at least the "type" member of uhid_event */
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if (count < sizeof(__u32))
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return -EINVAL;
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ret = mutex_lock_interruptible(&uhid->devlock);
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if (ret)
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return ret;
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memset(&uhid->input_buf, 0, sizeof(uhid->input_buf));
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len = min(count, sizeof(uhid->input_buf));
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if (copy_from_user(&uhid->input_buf, buffer, len)) {
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ret = -EFAULT;
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goto unlock;
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}
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switch (uhid->input_buf.type) {
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default:
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ret = -EOPNOTSUPP;
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}
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unlock:
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mutex_unlock(&uhid->devlock);
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/* return "count" not "len" to not confuse the caller */
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return ret ? ret : count;
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2012-06-10 21:16:13 +08:00
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}
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static unsigned int uhid_char_poll(struct file *file, poll_table *wait)
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{
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2012-06-10 21:16:15 +08:00
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struct uhid_device *uhid = file->private_data;
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poll_wait(file, &uhid->waitq, wait);
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if (uhid->head != uhid->tail)
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return POLLIN | POLLRDNORM;
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2012-06-10 21:16:13 +08:00
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return 0;
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}
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static const struct file_operations uhid_fops = {
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.owner = THIS_MODULE,
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.open = uhid_char_open,
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.release = uhid_char_release,
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.read = uhid_char_read,
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.write = uhid_char_write,
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.poll = uhid_char_poll,
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.llseek = no_llseek,
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};
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static struct miscdevice uhid_misc = {
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.fops = &uhid_fops,
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.minor = MISC_DYNAMIC_MINOR,
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.name = UHID_NAME,
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};
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static int __init uhid_init(void)
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{
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return misc_register(&uhid_misc);
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}
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static void __exit uhid_exit(void)
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{
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misc_deregister(&uhid_misc);
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}
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module_init(uhid_init);
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module_exit(uhid_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("David Herrmann <dh.herrmann@gmail.com>");
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MODULE_DESCRIPTION("User-space I/O driver support for HID subsystem");
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