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struct input_dev{ //代表输入设备,会加到全局input_dev队列
  const char *name;
}
struct input_handler{//代表输入设备的处理方法,会加到全局input_handler队列

}
struct input_handle{//用来关联某个input_dev和某个input_handler

}
//一个input_dev可有多个input_handler:鼠标可有按键事件evdev和移动事件mousedev
//一个input_handler可以用于多个输入设备：比如按键evdev可用于鼠标和键盘

input_table[8]
input_handler_list

input_register_handler(&evdev_handler->handler)
  INIT_LIST_HEAD(&handler->h_list)
  input_table[handler->minor>>5] = handler
  list_add_tail(&handler->node,&input_handler_list)
  list_for_each_entry(dev,&input_dev_list, node)
    input_attach_handler(dev,handler)//遍历执行
      input_match_device(handler,dev)
        if handler->id_table[i].flag & xx
          handler->id_table[i].bustype == dev->id.bustype
          handler..evbit[] == dev..evbit[]
          ...
          return id->struct input_device_id *id
      handler->connect(handler,dev,id) //evdev_connect

evdev_connect(struct input_handler *handler,struct input_dev *dev, const struct input_device_id *id)
  //找evdev_table[]中首个未使用的下标minor
  evdev = kzmalloc()
  INIT_LIST_HEAD(&evdev->client_list)
  dev_set_name(&evdev->dev,"event%d",minor)
  evdev->exist=true
  evdev->minor=minor
  evdev->handle.dev=input_get_device(dev)
  evdev->handle.name=dev_name(&evdev->dev)
  evdev->handle.handler=handler
  evdev->handle.private=evdev
  evdev->dev.devt=MKDEV(INPUT_MAJOR,EVDEV_MINOR_BASE+minor)
  evdev->dev.class=&input_class
  evdev->dev.parent=&dev->dev
  evdev->dev.release=evdev_free
  device_initialize(&evdev->dev)
  input_register_handle(&evdev->handle)
    struct input_handler *handler=handle->handler
    struct input_dev *dev=handle->dev
    list_add_tail_rcu(&handle->d_node,&dev->h_list)
    list_add_tail_rcu(&handle->h_node,&handler->h_list)
    if(handler->start) handler->start(handle)
  evdev_install_chrdev(evdev)
    evdev_table[evdev->minor]=evdev
  device_add(&evdev->dev)//创建设备节点

应用层对设备节点读，就会调用到
evdev_read(struct file *file,char __user *buffer, size_t count, loff_t *ppos)
  struct evdev_client *client = file->private_data;
  struct evdev *evdev = client->evdev;
  struct input_event event;
  if(BLOCK) wait_event_interruptible(evdev->wait,client->packet_head!=client->tail||!evdev->exist)
  while ... evdev_fetch_next_event(client,&event)
    input_event_to_user(buffer+retval,&event)
    retval+=input_event_size()


evdev_open(struct inode *inode,struct file *file)