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HID: input: Create a utility class for counting scroll events

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To avoid code duplication, this class counts high-resolution scroll
movements and emits the legacy low-resolution events when appropriate.
Drivers should be able to create one instance for each scroll wheel that
they need to handle.

Signed-off-by: Harry Cutts <hcutts@chromium.org>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This commit is contained in:
Harry Cutts
2018-08-30 14:56:19 -07:00
committed by Jiri Kosina
parent aaf9978c3c
commit 1ff2e1a44e
2 changed files with 73 additions and 0 deletions
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28
include/linux/hid.h
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@@ -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);