Linux Kernel input设备之handler

/**

 * struct input_handler - implements one of interfaces for input devices
 * @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.
 */
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;
};

/**

 * struct input_handle - links input device with an input handler
 * @private: handler-specific data
 * @open: counter showing whether the handle is 'open', i.e. should deliver
 *	events from its device
 * @name: name given to the handle by handler that created it
 * @dev: input device the handle is attached to
 * @handler: handler that works with the device through this handle
 * @d_node: used to put the handle on device's list of attached handles
 * @h_node: used to put the handle on handler's list of handles from which
 *	it gets events
 */
struct input_handle {
	void *private;
	int open;
	const char *name;
	struct input_dev *dev;
	struct input_handler *handler;
	struct list_head	d_node;
	struct list_head	h_node;
};