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authorHarry Cutts <hcutts@chromium.org>2018-08-30 14:56:19 -0700
committerJiri Kosina <jkosina@suse.cz>2018-09-05 10:12:07 +0200
commit1ff2e1a44e02d4bdbb9be67c7d9acc240a67141f (patch)
tree96129c381432acfcfe1638d06594d60fc3eb1c8d /include/linux/hid.h
parentaaf9978c3c0291ef3beaa97610bc9c3084656a85 (diff)
HID: input: Create a utility class for counting scroll events
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>
Diffstat (limited to 'include/linux/hid.h')
-rw-r--r--include/linux/hid.h28
1 files changed, 28 insertions, 0 deletions
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 834e6461a690..037e37b0b0e6 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -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);