Input: wacom_w8001 - add multitouch slot support

Some serial wacom devices support two-finger touch. Test for this during
init and parse the touch packets accordingly. Touch packets are
processed using Protocol B (MT Slots).

Note: there are several wacom versions that do touch but not two-finger
touch. These are not catered for here, touch events for these are simply
discarded.
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Acked-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

drivers/input/touchscreen/wacom_w8001.c

@@ -48,6 +48,8 @@ MODULE_LICENSE("GPL");
 #define W8001_PKTLEN_TPCCTL	11	/* control packet */
 #define W8001_PKTLEN_TOUCH2FG	13
 
+#define MAX_TRACKING_ID		0xFF	/* arbitrarily chosen */
+
 struct w8001_coord {
 	u8 rdy;
 	u8 tsw;
@@ -85,6 +87,7 @@ struct w8001 {
 	char phys[32];
 	int type;
 	unsigned int pktlen;
+	int trkid[2];
 };
 
 static void parse_data(u8 *data, struct w8001_coord *coord)
@@ -111,6 +114,35 @@ static void parse_data(u8 *data, struct w8001_coord *coord)
 	coord->tilt_y = data[8] & 0x7F;
 }
 
+static void parse_touch(struct w8001 *w8001)
+{
+	static int trkid;
+	struct input_dev *dev = w8001->dev;
+	unsigned char *data = w8001->data;
+	int i;
+
+	for (i = 0; i < 2; i++) {
+		input_mt_slot(dev, i);
+
+		if (data[0] & (1 << i)) {
+			int x = (data[6 * i + 1] << 7) | (data[6 * i + 2]);
+			int y = (data[6 * i + 3] << 7) | (data[6 * i + 4]);
+			/* data[5,6] and [11,12] is finger capacity */
+
+			input_report_abs(dev, ABS_MT_POSITION_X, x);
+			input_report_abs(dev, ABS_MT_POSITION_Y, y);
+			input_report_abs(dev, ABS_MT_TOOL_TYPE, MT_TOOL_FINGER);
+			if (w8001->trkid[i] < 0)
+				w8001->trkid[i] = trkid++ & MAX_TRACKING_ID;
+		} else {
+			w8001->trkid[i] = -1;
+		}
+		input_report_abs(dev, ABS_MT_TRACKING_ID, w8001->trkid[i]);
+	}
+
+	input_sync(dev);
+}
+
 static void parse_touchquery(u8 *data, struct w8001_touch_query *query)
 {
 	memset(query, 0, sizeof(*query));
@@ -220,10 +252,10 @@ static irqreturn_t w8001_interrupt(struct serio *serio,
 		complete(&w8001->cmd_done);
 		break;
 
+	/* 2 finger touch packet */
 	case W8001_PKTLEN_TOUCH2FG - 1:
-		/* ignore two-finger touch packet. */
-		if (w8001->pktlen == w8001->idx)
-			w8001->idx = 0;
+		w8001->idx = 0;
+		parse_touch(w8001);
 		break;
 	}
 
@@ -285,6 +317,16 @@ static int w8001_setup(struct w8001 *w8001)
 			break;
 		case 5:
 			w8001->pktlen = W8001_PKTLEN_TOUCH2FG;
+
+			input_mt_create_slots(dev, 2);
+			input_set_abs_params(dev, ABS_MT_TRACKING_ID,
+						0, MAX_TRACKING_ID, 0, 0);
+			input_set_abs_params(dev, ABS_MT_POSITION_X,
+						0, touch.x, 0, 0);
+			input_set_abs_params(dev, ABS_MT_POSITION_Y,
+						0, touch.y, 0, 0);
+			input_set_abs_params(dev, ABS_MT_TOOL_TYPE,
+						0, 0, 0, 0);
 			break;
 		}
 	}
@@ -330,6 +372,7 @@ static int w8001_connect(struct serio *serio, struct serio_driver *drv)
 	w8001->serio = serio;
 	w8001->id = serio->id.id;
 	w8001->dev = input_dev;
+	w8001->trkid[0] = w8001->trkid[1] = -1;
 	init_completion(&w8001->cmd_done);
 	snprintf(w8001->phys, sizeof(w8001->phys), "%s/input0", serio->phys);