struct_input_handler (9)

struct input_handler {
  void * private;
  void (* event) (struct input_handle *handle, unsigned int type, unsigned int code, int value);
  void (* events) (struct input_handle *handle,const struct input_value *vals, unsigned int count);
  bool (* filter) (struct input_handle *handle, unsigned int type, unsigned int code, int value);
  bool (* match) (struct input_handler *handler, struct input_dev *dev);
  int (* connect) (struct input_handler *handler, struct input_dev *dev, const struct input_device_id *id);
  void (* disconnect) (struct input_handle *handle);
  void (* start) (struct input_handle *handle);
  bool legacy_minors;
  int minor;
  const char * name;
  const struct input_device_id * id_table;
  struct list_head h_list;
  struct list_head node;
};

private

driver-specific data

event

event handler. This method is being called by input core with interrupts disabled and dev->event_lock spinlock held and so it may not sleep

events

event sequence handler. This method is being called by input core with interrupts disabled and dev->event_lock spinlock held and so it may not sleep

filter

similar to event; separates normal event handlers from “filters”.

match

called after comparing device's id with handler's id_table to perform fine-grained matching between device and handler

connect

called when attaching a handler to an input device

disconnect

disconnects a handler from input device

start

starts handler for given handle. This function is called by input core right after connect method and also when a process that “grabbed” a device releases it

legacy_minors

set to true by drivers using legacy minor ranges

minor

beginning of range of 32 legacy minors for devices this driver can provide

name

name of the handler, to be shown in /proc/bus/input/handlers

id_table

pointer to a table of input_device_ids this driver can handle

h_list

list of input handles associated with the handler

node

for placing the driver onto input_handler_list

Input handlers attach to input devices and create input handles. There are likely several handlers attached to any given input device at the same time. All of them will get their copy of input event generated by the device.

The very same structure is used to implement input filters. Input core allows filters to run first and will not pass event to regular handlers if any of the filters indicate that the event should be filtered (by returning true from their filter method).

Note that input core serializes calls to connect and disconnect methods.