[PATCH v3 11/13] HID: hid-multitouch: support for hovering devices

[Benjamin Tissoires <benjamin.tissoires@gmail.com>]

Win8 devices supporting hovering must provides InRange HID field.
The information that the finger is here but is not touching the surface
is sent to the user space through ABS_MT_DISTANCE as required by the
multitouch protocol.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
---
 drivers/hid/hid-multitouch.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
index b393c6c..1f3d1e0 100644
--- a/drivers/hid/hid-multitouch.c
+++ b/drivers/hid/hid-multitouch.c
@@ -59,6 +59,7 @@ struct mt_slot {
 	__s32 x, y, cx, cy, p, w, h;
 	__s32 contactid;	/* the device ContactID assigned to this slot */
 	bool touch_state;	/* is the touch valid? */
+	bool inrange_state;	/* is the finger in proximity of the sensor? */
 };
 
 struct mt_class {
@@ -397,6 +398,12 @@ static int mt_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 	case HID_UP_DIGITIZER:
 		switch (usage->hid) {
 		case HID_DG_INRANGE:
+			if (cls->quirks & MT_QUIRK_WIN_8_CERTIFIED) {
+				hid_map_usage(hi, usage, bit, max,
+					EV_ABS, ABS_MT_DISTANCE);
+				input_set_abs_params(hi->input,
+					ABS_MT_DISTANCE, -1, 1, 0, 0);
+			}
 			mt_store_field(usage, td, hi);
 			td->last_field_index = field->index;
 			return 1;
@@ -516,6 +523,10 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
 		if (slotnum < 0 || slotnum >= td->maxcontacts)
 			return;
 
+		if (!test_bit(ABS_MT_DISTANCE, input->absbit))
+			/* If InRange is not present, rely on TipSwitch */
+			s->inrange_state = s->touch_state;
+
 		if (td->mtclass.quirks & MT_QUIRK_IGNORE_DUPLICATES &&
 		    input_mt_is_active(&input->mt->slots[slotnum]) &&
 		    input_mt_is_used(input->mt, &input->mt->slots[slotnum]))
@@ -523,9 +534,9 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
 
 		input_mt_slot(input, slotnum);
 		input_mt_report_slot_state(input, MT_TOOL_FINGER,
-			s->touch_state);
-		if (s->touch_state) {
-			/* this finger is on the screen */
+			s->inrange_state);
+		if (s->inrange_state) {
+			/* this finger is in proximity of the sensor */
 			int wide = (s->w > s->h);
 			/* divided by two to match visual scale of touch */
 			int major = max(s->w, s->h) >> 1;
@@ -535,11 +546,14 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
 			input_event(input, EV_ABS, ABS_MT_POSITION_Y, s->y);
 			input_event(input, EV_ABS, ABS_MT_TOOL_X, s->cx);
 			input_event(input, EV_ABS, ABS_MT_TOOL_Y, s->cy);
+			input_event(input, EV_ABS, ABS_MT_DISTANCE,
+				!s->touch_state);
 			input_event(input, EV_ABS, ABS_MT_ORIENTATION, wide);
 			input_event(input, EV_ABS, ABS_MT_PRESSURE, s->p);
 			input_event(input, EV_ABS, ABS_MT_TOUCH_MAJOR, major);
 			input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR, minor);
-		}
+		} else
+			input_event(input, EV_ABS, ABS_MT_DISTANCE, -1);
 	}
 
 	td->num_received++;
@@ -567,6 +581,8 @@ static int mt_event(struct hid_device *hid, struct hid_field *field,
 		case HID_DG_INRANGE:
 			if (quirks & MT_QUIRK_VALID_IS_INRANGE)
 				td->curvalid = value;
+			if (quirks & MT_QUIRK_WIN_8_CERTIFIED)
+				td->curdata.inrange_state = value;
 			break;
 		case HID_DG_TIPSWITCH:
 			if (quirks & MT_QUIRK_NOT_SEEN_MEANS_UP)
-- 
1.7.11.7