Ignore ABS_MISC as a source of device type information for AES pens

AES sensors "appear" to use protocol 5 since they send ABS_MISC events
which contain information about the tool type in use. The tool type
information sent by AES sensors does not contain stylus/eraser/puck
information, however, so we need to ignore it or else we may randomly
end up treating the pens as erasers if a certian bit is set.

Fixes: linuxwacom#74
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>

src/wcmUSB.c

@@ -1173,18 +1173,25 @@ static int usbFilterEvent(WacomCommonPtr common, struct input_event *event)
 static int usbIdToType(int id)
 {
 	int type = STYLUS_ID;
+	Bool is_aes = id & 1;
 
 	if (!id)
 		return 0;
 
-	/* The existing tool ids have the following patten: all pucks, except
-	 * one, have the third byte set to zero; all erasers have the fourth
-	 * bit set. The rest are styli.
-	 */
-	if (id & ERASER_BIT)
-		type = ERASER_ID;
-	else if (!(id & PUCK_BITS) || (id == PUCK_EXCEPTION))
-		type = CURSOR_ID;
+	if (is_aes) {
+		/* Type information is not available from the ID for AES */
+		return 0;
+	}
+	else {
+		/* The existing EMR tool ids have the following patten: all
+		 * pucks, except one, have the third byte set to zero; all
+		 * erasers have the fourth bit set. The rest are styli.
+		 */
+		if (id & ERASER_BIT)
+			type = ERASER_ID;
+		else if (!(id & PUCK_BITS) || (id == PUCK_EXCEPTION))
+			type = CURSOR_ID;
+	}
 
 	return type;
 }