[PATCH 3/3] HID: wacom: report ABS_TWIST alongside ABS_Z for pen twist

[Siarhei Vishniakou <svv@google.com>]

Historically, Wacom tablets reported stylus barrel rotation (twist)
via ABS_Z because a dedicated evdev axis did not exist. Now that we
have this axis, report pen twist on ABS_TWIST in addition to ABS_Z.

Keep reporting ABS_Z to maintain backward compatibility for existing
applications that support Wacom devices.

Signed-off-by: Siarhei Vishniakou <svv@google.com>
---
 drivers/hid/wacom_wac.c | 35 +++++++++++++++++++++++++++++------
 1 file changed, 29 insertions(+), 6 deletions(-)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index 614f2adab563..7676bc26a027 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -802,8 +802,10 @@ static void wacom_exit_report(struct wacom_wac *wacom)
 		input_report_key(input, BTN_STYLUS2, 0);
 		input_report_key(input, BTN_TOUCH, 0);
 		input_report_abs(input, ABS_WHEEL, 0);
-		if (features->type >= INTUOS3S)
+		if (features->type >= INTUOS3S) {
 			input_report_abs(input, ABS_Z, 0);
+			input_report_abs(input, ABS_TWIST, 0);
+		}
 	}
 	input_report_key(input, wacom->tool[idx], 0);
 	input_report_abs(input, ABS_MISC, 0); /* reset tool id */
@@ -981,6 +983,7 @@ static int wacom_intuos_general(struct wacom_wac *wacom)
 			t = (data[7] & 0x20) ? ((t > 900) ? ((t-1) / 2 - 1350) :
 				((t-1) / 2 + 450)) : (450 - t / 2) ;
 			input_report_abs(input, ABS_Z, t);
+			input_report_abs(input, ABS_TWIST, t);
 		} else {
 			/* 4D mouse 2nd packet */
 			t = (data[6] << 3) | ((data[7] >> 5) & 7);
@@ -1411,6 +1414,7 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
 				input_report_abs(pen_input, ABS_TILT_Y,
 						 (signed char)frame[8]);
 				input_report_abs(pen_input, ABS_Z, rotation);
+				input_report_abs(pen_input, ABS_TWIST, rotation);
 				input_report_abs(pen_input, ABS_WHEEL,
 						 get_unaligned_le16(&frame[11]));
 			}
@@ -1935,7 +1939,7 @@ static void wacom_map_usage(struct input_dev *input, struct hid_usage *usage,
 	int resolution;
 
 	if (equivalent_usage == HID_DG_TWIST) {
-		resolution_code = ABS_RZ;
+		resolution_code = ABS_TWIST;
 	}
 
 	resolution = hidinput_calc_abs_res(field, resolution_code);
@@ -2332,6 +2336,7 @@ static void wacom_wac_pen_usage_mapping(struct hid_device *hdev,
 		break;
 	case HID_DG_TWIST:
 		wacom_map_usage(input, usage, field, EV_ABS, ABS_Z, 0);
+		wacom_map_usage(input, usage, field, EV_ABS, ABS_TWIST, 0);
 		break;
 	case HID_DG_ERASER:
 		input_set_capability(input, EV_KEY, BTN_TOOL_RUBBER);
@@ -2522,10 +2527,21 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 		return;
 
 	/* send pen events only when the pen is in range */
-	if (wacom_wac->hid_data.inrange_state)
-		input_event(input, usage->type, usage->code, value);
-	else if (wacom_wac->shared->stylus_in_proximity && !wacom_wac->hid_data.sense_state)
-		input_event(input, usage->type, usage->code, 0);
+	if (!wacom_wac->hid_data.inrange_state) {
+		if (!wacom_wac->shared->stylus_in_proximity ||
+		    wacom_wac->hid_data.sense_state)
+			return;
+		value = 0;
+	}
+
+	input_event(input, usage->type, usage->code, value);
+	/*
+	 * ABS_Z was used to report twist data, because ABS_TWIST was not yet
+	 * defined at the time. For compatibility purposes, also report twist
+	 * via ABS_Z.
+	 */
+	if (equivalent_usage == HID_DG_TWIST)
+		input_report_abs(input, ABS_Z, value);
 }
 
 static void wacom_wac_pen_pre_report(struct hid_device *hdev,
@@ -3741,6 +3757,7 @@ void wacom_setup_device_quirks(struct wacom *wacom)
 		__clear_bit(BTN_TOOL_PENCIL, wacom_wac->pen_input->keybit);
 		__clear_bit(BTN_TOOL_AIRBRUSH, wacom_wac->pen_input->keybit);
 		__clear_bit(ABS_Z, wacom_wac->pen_input->absbit);
+		__clear_bit(ABS_TWIST, wacom_wac->pen_input->absbit);
 		__clear_bit(ABS_DISTANCE, wacom_wac->pen_input->absbit);
 		__clear_bit(ABS_TILT_X, wacom_wac->pen_input->absbit);
 		__clear_bit(ABS_TILT_Y, wacom_wac->pen_input->absbit);
@@ -3823,6 +3840,8 @@ int wacom_setup_pen_input_capabilities(struct input_dev *input_dev,
 	case CINTIQ_COMPANION_2:
 		input_set_abs_params(input_dev, ABS_Z, -900, 899, 0, 0);
 		input_abs_set_res(input_dev, ABS_Z, 287);
+		input_set_abs_params(input_dev, ABS_TWIST, -900, 899, 0, 0);
+		input_abs_set_res(input_dev, ABS_TWIST, 287);
 		wacom_setup_cintiq(wacom_wac);
 		break;
 
@@ -3835,6 +3854,8 @@ int wacom_setup_pen_input_capabilities(struct input_dev *input_dev,
 	case INTUOS4S:
 		input_set_abs_params(input_dev, ABS_Z, -900, 899, 0, 0);
 		input_abs_set_res(input_dev, ABS_Z, 287);
+		input_set_abs_params(input_dev, ABS_TWIST, -900, 899, 0, 0);
+		input_abs_set_res(input_dev, ABS_TWIST, 287);
 		fallthrough;
 
 	case INTUOS:
@@ -3855,6 +3876,8 @@ int wacom_setup_pen_input_capabilities(struct input_dev *input_dev,
 
 		input_set_abs_params(input_dev, ABS_Z, -900, 899, 0, 0);
 		input_abs_set_res(input_dev, ABS_Z, 287);
+		input_set_abs_params(input_dev, ABS_TWIST, -900, 899, 0, 0);
+		input_abs_set_res(input_dev, ABS_TWIST, 287);
 
 		wacom_setup_intuos(wacom_wac);
 		break;
-- 
2.56.0.455.g6c5a503b38-goog