HID: hid-multitouch: support fine-grain orientation reporting

The current hid-multitouch driver only allow the report of two
orientations, vertical and horizontal. We use the Azimuth orientation
usage 0x3F under the Digitizer usage page to report orientation if the
device supports it.

Changelog:
  v1 -> v2:
   - Fix commit message.
   - Remove resolution reporting for ABS_MT_ORIENTATION.
  v2 -> v3:
   - Fix commit message.
  v3 -> v4:
   - Fix ABS_MT_ORIENTATION ABS param range.
   - Don't set ABS_MT_ORIENTATION in ABS_DG_HEIGHT when it is already
     set by ABS_DG_AZIMUTH.
  v4 -> v5:
   - Improve multi-touch-protocol.rst documentation.

Signed-off-by: Wei-Ning Huang <wnhuang@chromium.org>
Signed-off-by: Wei-Ning Huang <wnhuang@google.com>
Reviewed-by: Dmitry Torokhov <dtor@chromium.org>
Reviewed-by: Henrik Rydberg <rydberg@bitmath.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Documentation/input/multi-touch-protocol.rst

@@ -269,10 +269,11 @@ ABS_MT_ORIENTATION
     The orientation of the touching ellipse. The value should describe a signed
     quarter of a revolution clockwise around the touch center. The signed value
     range is arbitrary, but zero should be returned for an ellipse aligned with
-    the Y axis of the surface, a negative value when the ellipse is turned to
-    the left, and a positive value when the ellipse is turned to the
-    right. When completely aligned with the X axis, the range max should be
-    returned.
+    the Y axis (north) of the surface, a negative value when the ellipse is
+    turned to the left, and a positive value when the ellipse is turned to the
+    right. When aligned with the X axis in the positive direction, the range
+    max should be returned; when aligned with the X axis in the negative
+    direction, the range -max should be returned.
 
     Touch ellipsis are symmetrical by default. For devices capable of true 360
     degree orientation, the reported orientation must exceed the range max to

drivers/hid/hid-multitouch.c

@@ -85,11 +85,12 @@ MODULE_LICENSE("GPL");
 #define MT_IO_FLAGS_PENDING_SLOTS	2
 
 struct mt_slot {
-	__s32 x, y, cx, cy, p, w, h;
+	__s32 x, y, cx, cy, p, w, h, a;
 	__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? */
 	bool confidence_state;  /* is the touch made by a finger? */
+	bool has_azimuth;       /* the contact reports azimuth */
 };
 
 struct mt_class {
@@ -586,8 +587,15 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 			if (!(cls->quirks & MT_QUIRK_NO_AREA)) {
 				set_abs(hi->input, ABS_MT_TOUCH_MINOR, field,
 					cls->sn_height);
-				input_set_abs_params(hi->input,
-					ABS_MT_ORIENTATION, 0, 1, 0, 0);
+
+				/*
+				 * Only set ABS_MT_ORIENTATION if it is not
+				 * already set by the HID_DG_AZIMUTH usage.
+				 */
+				if (!test_bit(ABS_MT_ORIENTATION,
+						hi->input->absbit))
+					input_set_abs_params(hi->input,
+						ABS_MT_ORIENTATION, 0, 1, 0, 0);
 			}
 			mt_store_field(usage, td, hi);
 			return 1;
@@ -618,6 +626,21 @@ static int mt_touch_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 			td->cc_index = field->index;
 			td->cc_value_index = usage->usage_index;
 			return 1;
+		case HID_DG_AZIMUTH:
+			hid_map_usage(hi, usage, bit, max,
+				EV_ABS, ABS_MT_ORIENTATION);
+			/*
+			 * Azimuth has the range of [0, MAX) representing a full
+			 * revolution. Set ABS_MT_ORIENTATION to a quarter of
+			 * MAX according the definition of ABS_MT_ORIENTATION
+			 */
+			input_set_abs_params(hi->input, ABS_MT_ORIENTATION,
+				-field->logical_maximum / 4,
+				field->logical_maximum / 4,
+				cls->sn_move ?
+				field->logical_maximum / cls->sn_move : 0, 0);
+			mt_store_field(usage, td, hi);
+			return 1;
 		case HID_DG_CONTACTMAX:
 			/* we don't set td->last_slot_field as contactcount and
 			 * contact max are global to the report */
@@ -710,6 +733,10 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
 			int wide = (s->w > s->h);
 			int major = max(s->w, s->h);
 			int minor = min(s->w, s->h);
+			int orientation = wide;
+
+			if (s->has_azimuth)
+				orientation = s->a;
 
 			/*
 			 * divided by two to match visual scale of touch
@@ -726,7 +753,8 @@ static void mt_complete_slot(struct mt_device *td, struct input_dev *input)
 			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_ORIENTATION,
+				orientation);
 			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);
@@ -850,6 +878,22 @@ static void mt_process_mt_event(struct hid_device *hid, struct hid_field *field,
 			break;
 		case HID_DG_CONTACTCOUNT:
 			break;
+		case HID_DG_AZIMUTH:
+			/*
+			 * Azimuth is counter-clockwise and ranges from [0, MAX)
+			 * (a full revolution). Convert it to clockwise ranging
+			 * [-MAX/2, MAX/2].
+			 *
+			 * Note that ABS_MT_ORIENTATION require us to report
+			 * the limit of [-MAX/4, MAX/4], but the value can go
+			 * out of range to [-MAX/2, MAX/2] to report an upside
+			 * down ellipsis.
+			 */
+			if (value > field->logical_maximum / 2)
+				value -= field->logical_maximum;
+			td->curdata.a = -value;
+			td->curdata.has_azimuth = true;
+			break;
 		case HID_DG_TOUCH:
 			/* do nothing */
 			break;

include/linux/hid.h

@@ -281,6 +281,7 @@ struct hid_item {
 
 #define HID_DG_DEVICECONFIG	0x000d000e
 #define HID_DG_DEVICESETTINGS	0x000d0023
+#define HID_DG_AZIMUTH		0x000d003f
 #define HID_DG_CONFIDENCE	0x000d0047
 #define HID_DG_WIDTH		0x000d0048
 #define HID_DG_HEIGHT		0x000d0049