189 lines
7.4 KiB
Text
189 lines
7.4 KiB
Text
ALPS Touchpad Protocol
|
|
----------------------
|
|
|
|
Introduction
|
|
------------
|
|
|
|
Currently the ALPS touchpad driver supports four protocol versions in use by
|
|
ALPS touchpads, called versions 1, 2, 3, and 4. Information about the various
|
|
protocol versions is contained in the following sections.
|
|
|
|
Detection
|
|
---------
|
|
|
|
All ALPS touchpads should respond to the "E6 report" command sequence:
|
|
E8-E6-E6-E6-E9. An ALPS touchpad should respond with either 00-00-0A or
|
|
00-00-64 if no buttons are pressed. The bits 0-2 of the first byte will be 1s
|
|
if some buttons are pressed.
|
|
|
|
If the E6 report is successful, the touchpad model is identified using the "E7
|
|
report" sequence: E8-E7-E7-E7-E9. The response is the model signature and is
|
|
matched against known models in the alps_model_data_array.
|
|
|
|
With protocol versions 3 and 4, the E7 report model signature is always
|
|
73-02-64. To differentiate between these versions, the response from the
|
|
"Enter Command Mode" sequence must be inspected as described below.
|
|
|
|
Command Mode
|
|
------------
|
|
|
|
Protocol versions 3 and 4 have a command mode that is used to read and write
|
|
one-byte device registers in a 16-bit address space. The command sequence
|
|
EC-EC-EC-E9 places the device in command mode, and the device will respond
|
|
with 88-07 followed by a third byte. This third byte can be used to determine
|
|
whether the devices uses the version 3 or 4 protocol.
|
|
|
|
To exit command mode, PSMOUSE_CMD_SETSTREAM (EA) is sent to the touchpad.
|
|
|
|
While in command mode, register addresses can be set by first sending a
|
|
specific command, either EC for v3 devices or F5 for v4 devices. Then the
|
|
address is sent one nibble at a time, where each nibble is encoded as a
|
|
command with optional data. This enoding differs slightly between the v3 and
|
|
v4 protocols.
|
|
|
|
Once an address has been set, the addressed register can be read by sending
|
|
PSMOUSE_CMD_GETINFO (E9). The first two bytes of the response contains the
|
|
address of the register being read, and the third contains the value of the
|
|
register. Registers are written by writing the value one nibble at a time
|
|
using the same encoding used for addresses.
|
|
|
|
Packet Format
|
|
-------------
|
|
|
|
In the following tables, the following notation is used.
|
|
|
|
CAPITALS = stick, miniscules = touchpad
|
|
|
|
?'s can have different meanings on different models, such as wheel rotation,
|
|
extra buttons, stick buttons on a dualpoint, etc.
|
|
|
|
PS/2 packet format
|
|
------------------
|
|
|
|
byte 0: 0 0 YSGN XSGN 1 M R L
|
|
byte 1: X7 X6 X5 X4 X3 X2 X1 X0
|
|
byte 2: Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
|
|
|
|
Note that the device never signals overflow condition.
|
|
|
|
ALPS Absolute Mode - Protocol Verion 1
|
|
--------------------------------------
|
|
|
|
byte 0: 1 0 0 0 1 x9 x8 x7
|
|
byte 1: 0 x6 x5 x4 x3 x2 x1 x0
|
|
byte 2: 0 ? ? l r ? fin ges
|
|
byte 3: 0 ? ? ? ? y9 y8 y7
|
|
byte 4: 0 y6 y5 y4 y3 y2 y1 y0
|
|
byte 5: 0 z6 z5 z4 z3 z2 z1 z0
|
|
|
|
ALPS Absolute Mode - Protocol Version 2
|
|
---------------------------------------
|
|
|
|
byte 0: 1 ? ? ? 1 ? ? ?
|
|
byte 1: 0 x6 x5 x4 x3 x2 x1 x0
|
|
byte 2: 0 x10 x9 x8 x7 ? fin ges
|
|
byte 3: 0 y9 y8 y7 1 M R L
|
|
byte 4: 0 y6 y5 y4 y3 y2 y1 y0
|
|
byte 5: 0 z6 z5 z4 z3 z2 z1 z0
|
|
|
|
Dualpoint device -- interleaved packet format
|
|
---------------------------------------------
|
|
|
|
byte 0: 1 1 0 0 1 1 1 1
|
|
byte 1: 0 x6 x5 x4 x3 x2 x1 x0
|
|
byte 2: 0 x10 x9 x8 x7 0 fin ges
|
|
byte 3: 0 0 YSGN XSGN 1 1 1 1
|
|
byte 4: X7 X6 X5 X4 X3 X2 X1 X0
|
|
byte 5: Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
|
|
byte 6: 0 y9 y8 y7 1 m r l
|
|
byte 7: 0 y6 y5 y4 y3 y2 y1 y0
|
|
byte 8: 0 z6 z5 z4 z3 z2 z1 z0
|
|
|
|
ALPS Absolute Mode - Protocol Version 3
|
|
---------------------------------------
|
|
|
|
ALPS protocol version 3 has three different packet formats. The first two are
|
|
associated with touchpad events, and the third is associatd with trackstick
|
|
events.
|
|
|
|
The first type is the touchpad position packet.
|
|
|
|
byte 0: 1 ? x1 x0 1 1 1 1
|
|
byte 1: 0 x10 x9 x8 x7 x6 x5 x4
|
|
byte 2: 0 y10 y9 y8 y7 y6 y5 y4
|
|
byte 3: 0 M R L 1 m r l
|
|
byte 4: 0 mt x3 x2 y3 y2 y1 y0
|
|
byte 5: 0 z6 z5 z4 z3 z2 z1 z0
|
|
|
|
Note that for some devices the trackstick buttons are reported in this packet,
|
|
and on others it is reported in the trackstick packets.
|
|
|
|
The second packet type contains bitmaps representing the x and y axes. In the
|
|
bitmaps a given bit is set if there is a finger covering that position on the
|
|
given axis. Thus the bitmap packet can be used for low-resolution multi-touch
|
|
data, although finger tracking is not possible. This packet also encodes the
|
|
number of contacts (f1 and f0 in the table below).
|
|
|
|
byte 0: 1 1 x1 x0 1 1 1 1
|
|
byte 1: 0 x8 x7 x6 x5 x4 x3 x2
|
|
byte 2: 0 y7 y6 y5 y4 y3 y2 y1
|
|
byte 3: 0 y10 y9 y8 1 1 1 1
|
|
byte 4: 0 x14 x13 x12 x11 x10 x9 y0
|
|
byte 5: 0 1 ? ? ? ? f1 f0
|
|
|
|
This packet only appears after a position packet with the mt bit set, and
|
|
usually only appears when there are two or more contacts (although
|
|
occasionally it's seen with only a single contact).
|
|
|
|
The final v3 packet type is the trackstick packet.
|
|
|
|
byte 0: 1 1 x7 y7 1 1 1 1
|
|
byte 1: 0 x6 x5 x4 x3 x2 x1 x0
|
|
byte 2: 0 y6 y5 y4 y3 y2 y1 y0
|
|
byte 3: 0 1 0 0 1 0 0 0
|
|
byte 4: 0 z4 z3 z2 z1 z0 ? ?
|
|
byte 5: 0 0 1 1 1 1 1 1
|
|
|
|
ALPS Absolute Mode - Protocol Version 4
|
|
---------------------------------------
|
|
|
|
Protocol version 4 has an 8-byte packet format.
|
|
|
|
byte 0: 1 ? x1 x0 1 1 1 1
|
|
byte 1: 0 x10 x9 x8 x7 x6 x5 x4
|
|
byte 2: 0 y10 y9 y8 y7 y6 y5 y4
|
|
byte 3: 0 1 x3 x2 y3 y2 y1 y0
|
|
byte 4: 0 ? ? ? 1 ? r l
|
|
byte 5: 0 z6 z5 z4 z3 z2 z1 z0
|
|
byte 6: bitmap data (described below)
|
|
byte 7: bitmap data (described below)
|
|
|
|
The last two bytes represent a partial bitmap packet, with 3 full packets
|
|
required to construct a complete bitmap packet. Once assembled, the 6-byte
|
|
bitmap packet has the following format:
|
|
|
|
byte 0: 0 1 x7 x6 x5 x4 x3 x2
|
|
byte 1: 0 x1 x0 y4 y3 y2 y1 y0
|
|
byte 2: 0 0 ? x14 x13 x12 x11 x10
|
|
byte 3: 0 x9 x8 y9 y8 y7 y6 y5
|
|
byte 4: 0 0 0 0 0 0 0 0
|
|
byte 5: 0 0 0 0 0 0 0 y10
|
|
|
|
There are several things worth noting here.
|
|
|
|
1) In the bitmap data, bit 6 of byte 0 serves as a sync byte to
|
|
identify the first fragment of a bitmap packet.
|
|
|
|
2) The bitmaps represent the same data as in the v3 bitmap packets, although
|
|
the packet layout is different.
|
|
|
|
3) There doesn't seem to be a count of the contact points anywhere in the v4
|
|
protocol packets. Deriving a count of contact points must be done by
|
|
analyzing the bitmaps.
|
|
|
|
4) There is a 3 to 1 ratio of position packets to bitmap packets. Therefore
|
|
MT position can only be updated for every third ST position update, and
|
|
the count of contact points can only be updated every third packet as
|
|
well.
|
|
|
|
So far no v4 devices with tracksticks have been encountered.
|