Input: elantech - fix for newer hardware versions (v7)

* Fix version recognition in elantech_set_properties

  The new hardware reports itself as v7 but the packets'
  structure is unaltered.

* Fix packet type recognition in elantech_packet_check_v4

  The bitmask used for v6 is too wide, only the last three bits of
  the third byte in a packet (packet[3] & 0x03) are actually used to
  distinguish between packet types.
  Starting from v7, additional information (to be interpreted) is
  stored in the remaining bits (packets[3] & 0x1c).
  In addition, the value stored in (packet[0] & 0x0c) is no longer
  a constant but contains additional information yet to be deciphered.
  This change should be backwards compatible with v6 hardware.

Additional-author: Giovanni Frigione <gio.frigione@gmail.com>
Signed-off-by: Matteo Delfino <kendatsuba@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/mouse/elantech.c

@@ -694,18 +694,18 @@ static int elantech_packet_check_v3(struct psmouse *psmouse)
 static int elantech_packet_check_v4(struct psmouse *psmouse)
 {
 	unsigned char *packet = psmouse->packet;
+	unsigned char packet_type = packet[3] & 0x03;
 
-	if ((packet[0] & 0x0c) == 0x04 &&
-	    (packet[3] & 0x1f) == 0x11)
+	switch (packet_type) {
+	case 0:
+		return PACKET_V4_STATUS;
+
+	case 1:
 		return PACKET_V4_HEAD;
 
-	if ((packet[0] & 0x0c) == 0x04 &&
-	    (packet[3] & 0x1f) == 0x12)
+	case 2:
 		return PACKET_V4_MOTION;
-
-	if ((packet[0] & 0x0c) == 0x04 &&
-	    (packet[3] & 0x1f) == 0x10)
-		return PACKET_V4_STATUS;
+	}
 
 	return PACKET_UNKNOWN;
 }
@@ -1282,6 +1282,7 @@ static int elantech_set_properties(struct elantech_data *etd)
 			etd->hw_version = 3;
 			break;
 		case 6:
+		case 7:
 			etd->hw_version = 4;
 			break;
 		default: