HID: wacom: generic: Add support for height, tilt, and twist usages

The HID standard defines usages that allow digitizers to report the pen's
height, tilt, and rotation and which are used by Wacom's new "MobileStudio
Pro" devices.

Note that 'hidinput_calc_abs_res' expects ABS_Z (historically used by our
driver to report twist) to have linear units. To ensure it calculates a
resolution with the actually-angular units provided in the HID descriptor
we nedd to lie and tell it we're calculating it for the (rotational) ABS_RZ
axis instead.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/wacom_wac.c

@@ -1440,6 +1440,11 @@ static void wacom_map_usage(struct input_dev *input, struct hid_usage *usage,
 {
 	int fmin = field->logical_minimum;
 	int fmax = field->logical_maximum;
+	int resolution_code = code;
+
+	if (usage->hid == HID_DG_TWIST) {
+		resolution_code = ABS_RZ;
+	}
 
 	usage->type = type;
 	usage->code = code;
@@ -1450,7 +1455,7 @@ static void wacom_map_usage(struct input_dev *input, struct hid_usage *usage,
 	case EV_ABS:
 		input_set_abs_params(input, code, fmin, fmax, fuzz, 0);
 		input_abs_set_res(input, code,
-				  hidinput_calc_abs_res(field, code));
+				  hidinput_calc_abs_res(field, resolution_code));
 		break;
 	case EV_KEY:
 		input_set_capability(input, EV_KEY, code);
@@ -1475,6 +1480,9 @@ static void wacom_wac_pen_usage_mapping(struct hid_device *hdev,
 	case HID_GD_Y:
 		wacom_map_usage(input, usage, field, EV_ABS, ABS_Y, 4);
 		break;
+	case HID_GD_Z:
+		wacom_map_usage(input, usage, field, EV_ABS, ABS_DISTANCE, 0);
+		break;
 	case HID_DG_TIPPRESSURE:
 		wacom_map_usage(input, usage, field, EV_ABS, ABS_PRESSURE, 0);
 		break;
@@ -1485,6 +1493,15 @@ static void wacom_wac_pen_usage_mapping(struct hid_device *hdev,
 		wacom_map_usage(input, usage, field, EV_KEY,
 				BTN_TOOL_RUBBER, 0);
 		break;
+	case HID_DG_TILT_X:
+		wacom_map_usage(input, usage, field, EV_ABS, ABS_TILT_X, 0);
+		break;
+	case HID_DG_TILT_Y:
+		wacom_map_usage(input, usage, field, EV_ABS, ABS_TILT_Y, 0);
+		break;
+	case HID_DG_TWIST:
+		wacom_map_usage(input, usage, field, EV_ABS, ABS_Z, 0);
+		break;
 	case HID_DG_ERASER:
 	case HID_DG_TIPSWITCH:
 		wacom_map_usage(input, usage, field, EV_KEY, BTN_TOUCH, 0);
@@ -1508,8 +1525,15 @@ static int wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field,
 	struct wacom_wac *wacom_wac = &wacom->wacom_wac;
 	struct input_dev *input = wacom_wac->pen_input;
 
-	/* checking which Tool / tip switch to send */
 	switch (usage->hid) {
+	case HID_GD_Z:
+		/*
+		 * HID_GD_Z "should increase as the control's position is
+		 * moved from high to low", while ABS_DISTANCE instead
+		 * increases in value as the tool moves from low to high.
+		 */
+		value = field->logical_maximum - value;
+		break;
 	case HID_DG_INRANGE:
 		wacom_wac->hid_data.inrange_state = value;
 		return 0;

include/linux/hid.h

@@ -232,6 +232,9 @@ struct hid_item {
 #define HID_DG_TABLETFUNCTIONKEY	0x000d0039
 #define HID_DG_PROGRAMCHANGEKEY	0x000d003a
 #define HID_DG_INVERT		0x000d003c
+#define HID_DG_TILT_X		0x000d003d
+#define HID_DG_TILT_Y		0x000d003e
+#define HID_DG_TWIST		0x000d0041
 #define HID_DG_TIPSWITCH	0x000d0042
 #define HID_DG_TIPSWITCH2	0x000d0043
 #define HID_DG_BARRELSWITCH	0x000d0044