HID: input: Create a utility class for counting scroll events (1ff2e1a4) · Commits · 戴 / test

drivers/hid/hid-input.c

+45 −0

Original line number	Diff line number	Diff line
		@@ -1826,3 +1826,48 @@ void hidinput_disconnect(struct hid_device *hid)
		}
		EXPORT_SYMBOL_GPL(hidinput_disconnect);

		/**
		* hid_scroll_counter_handle_scroll() - Send high- and low-resolution scroll
		* events given a high-resolution wheel
		* movement.
		* @counter: a hid_scroll_counter struct describing the wheel.
		* @hi_res_value: the movement of the wheel, in the mouse's high-resolution
		* units.
		*
		* Given a high-resolution movement, this function converts the movement into
		* microns and emits high-resolution scroll events for the input device. It also
		* uses the multiplier from &struct hid_scroll_counter to emit low-resolution
		* scroll events when appropriate for backwards-compatibility with userspace
		* input libraries.
		*/
		void hid_scroll_counter_handle_scroll(struct hid_scroll_counter *counter,
		int hi_res_value)
		{
		int low_res_scroll_amount;
		/* Some wheels will rest 7/8ths of a notch from the previous notch
		* after slow movement, so we want the threshold for low-res events to
		* be in the middle of the notches (e.g. after 4/8ths) as opposed to on
		* the notches themselves (8/8ths).
		*/
		int threshold = counter->resolution_multiplier / 2;

		input_report_rel(counter->dev, REL_WHEEL_HI_RES,
		hi_res_value * counter->microns_per_hi_res_unit);

		counter->remainder += hi_res_value;
		if (abs(counter->remainder) >= threshold) {
		/* Add (or subtract) 1 because we want to trigger when the wheel
		* is half-way to the next notch (i.e. scroll 1 notch after a
		* 1/2 notch movement, 2 notches after a 1 1/2 notch movement,
		* etc.).
		*/
		low_res_scroll_amount =
		counter->remainder / counter->resolution_multiplier
		+ (hi_res_value > 0 ? 1 : -1);
		input_report_rel(counter->dev, REL_WHEEL,
		low_res_scroll_amount);
		counter->remainder -=
		low_res_scroll_amount * counter->resolution_multiplier;
		}
		}
		EXPORT_SYMBOL_GPL(hid_scroll_counter_handle_scroll);

include/linux/hid.h

+28 −0

Original line number	Diff line number	Diff line
		@@ -1138,6 +1138,34 @@ static inline u32 hid_report_len(struct hid_report *report)
		int hid_report_raw_event(struct hid_device hid, int type, u8 data, u32 size,
		int interrupt);


		/**
		* struct hid_scroll_counter - Utility class for processing high-resolution
		* scroll events.
		* @dev: the input device for which events should be reported.
		* @microns_per_hi_res_unit: the amount moved by the user's finger for each
		* high-resolution unit reported by the mouse, in
		* microns.
		* @resolution_multiplier: the wheel's resolution in high-resolution mode as a
		* multiple of its lower resolution. For example, if
		* moving the wheel by one "notch" would result in a
		* value of 1 in low-resolution mode but 8 in
		* high-resolution, the multiplier is 8.
		* @remainder: counts the number of high-resolution units moved since the last
		* low-resolution event (REL_WHEEL or REL_HWHEEL) was sent. Should
		* only be used by class methods.
		*/
		struct hid_scroll_counter {
		struct input_dev *dev;
		int microns_per_hi_res_unit;
		int resolution_multiplier;

		int remainder;
		};

		void hid_scroll_counter_handle_scroll(struct hid_scroll_counter *counter,
		int hi_res_value);

		/* HID quirks API */
		unsigned long hid_lookup_quirk(const struct hid_device *hdev);
		int hid_quirks_init(char **quirks_param, __u16 bus, int count);

Admin message