From aaf9978c3c0291ef3beaa97610bc9c3084656a85 Mon Sep 17 00:00:00 2001 From: Harry Cutts Date: Thu, 30 Aug 2018 14:56:18 -0700 Subject: Input: Add the `REL_WHEEL_HI_RES` event code This event code represents scroll reports from high-resolution wheels, and will be used by future patches in this series. See the linux-input "Reporting high-resolution scroll events" thread [0] for more details. [0]: https://www.spinics.net/lists/linux-input/msg57380.html Signed-off-by: Harry Cutts Acked-by: Dmitry Torokhov Reviewed-by: Benjamin Tissoires Signed-off-by: Jiri Kosina --- include/uapi/linux/input-event-codes.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include') diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h index 53fbae27b280..dad8d3890a3a 100644 --- a/include/uapi/linux/input-event-codes.h +++ b/include/uapi/linux/input-event-codes.h @@ -708,6 +708,7 @@ #define REL_DIAL 0x07 #define REL_WHEEL 0x08 #define REL_MISC 0x09 +#define REL_WHEEL_HI_RES 0x0a #define REL_MAX 0x0f #define REL_CNT (REL_MAX+1) -- cgit v1.2.3 From 1ff2e1a44e02d4bdbb9be67c7d9acc240a67141f Mon Sep 17 00:00:00 2001 From: Harry Cutts Date: Thu, 30 Aug 2018 14:56:19 -0700 Subject: 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 Reviewed-by: Benjamin Tissoires Signed-off-by: Jiri Kosina --- drivers/hid/hid-input.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ include/linux/hid.h | 28 ++++++++++++++++++++++++++++ 2 files changed, 73 insertions(+) (limited to 'include') diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c index 4e94ea3e280a..6e84e7b9afcb 100644 --- a/drivers/hid/hid-input.c +++ b/drivers/hid/hid-input.c @@ -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); 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); -- cgit v1.2.3 From d9ca1c990a7ffee7e68ab8d64efacd6c73103203 Mon Sep 17 00:00:00 2001 From: Benjamin Tissoires Date: Thu, 4 Oct 2018 14:34:30 +0200 Subject: Input: reserve 2 events code because of HID Prior to commit 190d7f02ce8e ("HID: input: do not increment usages when a duplicate is found") from the v4.18 kernel, HID used to shift the event codes if a duplicate usage was found. This ended up in a situation where a device would export a ton of ABS_MISC+n event codes, or a ton of REL_MISC+n event codes. This is now fixed, however userspace needs to detect those situation. Fortunately, ABS_MT_SLOT-1 (ABS_MISC+6) was never assigned a code, and so libinput can detect fake multitouch devices from genuine ones by checking if ABS_MT_SLOT-1 is set. Now that we have REL_WHEEL_HI_RES, libinput won't be able to differentiate true high res mice from some other device in a pre-v4.18 kernel. Set in stone that the ABS_MISC+6 and REL_MISC+1 are reserved and should not be used so userspace can properly work around those old kernels. Signed-off-by: Benjamin Tissoires Acked-by: Dmitry Torokhov Signed-off-by: Jiri Kosina --- include/uapi/linux/input-event-codes.h | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) (limited to 'include') diff --git a/include/uapi/linux/input-event-codes.h b/include/uapi/linux/input-event-codes.h index dad8d3890a3a..6d180cc60a5d 100644 --- a/include/uapi/linux/input-event-codes.h +++ b/include/uapi/linux/input-event-codes.h @@ -708,7 +708,15 @@ #define REL_DIAL 0x07 #define REL_WHEEL 0x08 #define REL_MISC 0x09 -#define REL_WHEEL_HI_RES 0x0a +/* + * 0x0a is reserved and should not be used in input drivers. + * It was used by HID as REL_MISC+1 and userspace needs to detect if + * the next REL_* event is correct or is just REL_MISC + n. + * We define here REL_RESERVED so userspace can rely on it and detect + * the situation described above. + */ +#define REL_RESERVED 0x0a +#define REL_WHEEL_HI_RES 0x0b #define REL_MAX 0x0f #define REL_CNT (REL_MAX+1) @@ -745,6 +753,15 @@ #define ABS_MISC 0x28 +/* + * 0x2e is reserved and should not be used in input drivers. + * It was used by HID as ABS_MISC+6 and userspace needs to detect if + * the next ABS_* event is correct or is just ABS_MISC + n. + * We define here ABS_RESERVED so userspace can rely on it and detect + * the situation described above. + */ +#define ABS_RESERVED 0x2e + #define ABS_MT_SLOT 0x2f /* MT slot being modified */ #define ABS_MT_TOUCH_MAJOR 0x30 /* Major axis of touching ellipse */ #define ABS_MT_TOUCH_MINOR 0x31 /* Minor axis (omit if circular) */ -- cgit v1.2.3