Input: elantech - add v3 hardware support

v3 hardware's packet format is almost identical to v2 (one/three finger touch),
except when sensing two finger touch, the hardware sends 12 bytes of data.

Signed-off-by: JJ Ding <jj_ding@emc.com.tw>
Acked-by: Daniel Kurtz <djkurtz@chromium.org>
Acked-by: Éric Piel <eric.piel@tremplin-utc.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

Documentation/input/elantech.txt

@@ -16,15 +16,22 @@ Contents
 
  1. Introduction
  2. Extra knobs
- 3. Hardware version 1
-    3.1 Registers
-    3.2 Native relative mode 4 byte packet format
-    3.3 Native absolute mode 4 byte packet format
- 4. Hardware version 2
+ 3. Differentiating hardware versions
+ 4. Hardware version 1
     4.1 Registers
-    4.2 Native absolute mode 6 byte packet format
-        4.2.1 One finger touch
-        4.2.2 Two finger touch
+    4.2 Native relative mode 4 byte packet format
+    4.3 Native absolute mode 4 byte packet format
+ 5. Hardware version 2
+    5.1 Registers
+    5.2 Native absolute mode 6 byte packet format
+        5.2.1 Parity checking and packet re-synchronization
+        5.2.2 One/Three finger touch
+        5.2.3 Two finger touch
+ 6. Hardware version 3
+    6.1 Registers
+    6.2 Native absolute mode 6 byte packet format
+        6.2.1 One/Three finger touch
+        6.2.2 Two finger touch
 
 
 
@@ -375,7 +382,7 @@ For all the other ones, there are just a few constant bits:
 
 In case an error is detected, all the packets are shifted by one (and packet[0] is discarded).
 
-5.2.1 One/Three finger touch
+5.2.2 One/Three finger touch
       ~~~~~~~~~~~~~~~~
 
 byte 0:
@@ -384,7 +391,7 @@ byte 0:
 	 n1  n0  w3  w2   .   .   R   L
 
          L, R = 1 when Left, Right mouse button pressed
-         n1..n0 = numbers of fingers on touchpad
+         n1..n0 = number of fingers on touchpad
 
 byte 1:
 
@@ -432,7 +439,7 @@ byte 5:
          y11..y0 = absolute y value (vertical)
 
 
-4.2.2 Two finger touch
+5.2.3 Two finger touch
       ~~~~~~~~~~~~~~~~
 
 Note that the two pairs of coordinates are not exactly the coordinates of the
@@ -446,7 +453,7 @@ byte 0:
         n1  n0  ay8 ax8  .   .   R   L
 
          L, R = 1 when Left, Right mouse button pressed
-         n1..n0 = numbers of fingers on touchpad
+         n1..n0 = number of fingers on touchpad
 
 byte 1:
 
@@ -480,3 +487,89 @@ byte 5:
         by7 by8 by5 by4 by3 by2 by1 by0
 
          by8..by0 = upper-right finger absolute y value
+
+/////////////////////////////////////////////////////////////////////////////
+
+6. Hardware version 3
+   ==================
+
+6.1 Registers
+    ~~~~~~~~~
+* reg_10
+
+   bit   7   6   5   4   3   2   1   0
+         0   0   0   0   0   0   0   A
+
+         A: 1 = enable absolute tracking
+
+6.2 Native absolute mode 6 byte packet format
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+1 and 3 finger touch shares the same 6-byte packet format, except that
+3 finger touch only reports the position of the center of all three fingers.
+
+Firmware would send 12 bytes of data for 2 finger touch.
+
+Note on debounce:
+In case the box has unstable power supply or other electricity issues, or
+when number of finger changes, F/W would send "debounce packet" to inform
+driver that the hardware is in debounce status.
+The debouce packet has the following signature:
+    byte 0: 0xc4
+    byte 1: 0xff
+    byte 2: 0xff
+    byte 3: 0x02
+    byte 4: 0xff
+    byte 5: 0xff
+When we encounter this kind of packet, we just ignore it.
+
+6.2.1 One/Three finger touch
+      ~~~~~~~~~~~~~~~~~~~~~~
+
+byte 0:
+
+   bit   7   6   5   4   3   2   1   0
+        n1  n0  w3  w2   0   1   R   L
+
+        L, R = 1 when Left, Right mouse button pressed
+        n1..n0 = number of fingers on touchpad
+
+byte 1:
+
+   bit   7   6   5   4   3   2   1   0
+        p7  p6  p5  p4 x11 x10  x9  x8
+
+byte 2:
+
+   bit   7   6   5   4   3   2   1   0
+        x7  x6  x5  x4  x3  x2  x1  x0
+
+        x11..x0 = absolute x value (horizontal)
+
+byte 3:
+
+   bit   7   6   5   4   3   2   1   0
+         0   0  w1  w0   0   0   1   0
+
+         w3..w0 = width of the finger touch
+
+byte 4:
+
+   bit   7   6   5   4   3   2   1   0
+        p3  p1  p2  p0  y11 y10 y9  y8
+
+        p7..p0 = pressure
+
+byte 5:
+
+   bit   7   6   5   4   3   2   1   0
+        y7  y6  y5  y4  y3  y2  y1  y0
+
+        y11..y0 = absolute y value (vertical)
+
+6.2.2 Two finger touch
+      ~~~~~~~~~~~~~~~~
+
+The packet format is exactly the same for two finger touch, except the hardware
+sends two 6 byte packets. The first packet contains data for the first finger,
+the second packet has data for the second finger. So for two finger touch a
+total of 12 bytes are sent.