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322 lines
14 KiB
Plaintext
322 lines
14 KiB
Plaintext
ALPS Touchpad Protocol
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----------------------
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Introduction
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------------
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Currently the ALPS touchpad driver supports seven protocol versions in use by
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ALPS touchpads, called versions 1, 2, 3, 4, 5, 6 and 7.
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Since roughly mid-2010 several new ALPS touchpads have been released and
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integrated into a variety of laptops and netbooks. These new touchpads
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have enough behavior differences that the alps_model_data definition
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table, describing the properties of the different versions, is no longer
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adequate. The design choices were to re-define the alps_model_data
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table, with the risk of regression testing existing devices, or isolate
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the new devices outside of the alps_model_data table. The latter design
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choice was made. The new touchpad signatures are named: "Rushmore",
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"Pinnacle", and "Dolphin", which you will see in the alps.c code.
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For the purposes of this document, this group of ALPS touchpads will
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generically be called "new ALPS touchpads".
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We experimented with probing the ACPI interface _HID (Hardware ID)/_CID
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(Compatibility ID) definition as a way to uniquely identify the
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different ALPS variants but there did not appear to be a 1:1 mapping.
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In fact, it appeared to be an m:n mapping between the _HID and actual
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hardware type.
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Detection
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---------
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All ALPS touchpads should respond to the "E6 report" command sequence:
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E8-E6-E6-E6-E9. An ALPS touchpad should respond with either 00-00-0A or
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00-00-64 if no buttons are pressed. The bits 0-2 of the first byte will be 1s
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if some buttons are pressed.
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If the E6 report is successful, the touchpad model is identified using the "E7
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report" sequence: E8-E7-E7-E7-E9. The response is the model signature and is
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matched against known models in the alps_model_data_array.
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For older touchpads supporting protocol versions 3 and 4, the E7 report
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model signature is always 73-02-64. To differentiate between these
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versions, the response from the "Enter Command Mode" sequence must be
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inspected as described below.
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The new ALPS touchpads have an E7 signature of 73-03-50 or 73-03-0A but
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seem to be better differentiated by the EC Command Mode response.
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Command Mode
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------------
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Protocol versions 3 and 4 have a command mode that is used to read and write
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one-byte device registers in a 16-bit address space. The command sequence
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EC-EC-EC-E9 places the device in command mode, and the device will respond
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with 88-07 followed by a third byte. This third byte can be used to determine
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whether the devices uses the version 3 or 4 protocol.
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To exit command mode, PSMOUSE_CMD_SETSTREAM (EA) is sent to the touchpad.
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While in command mode, register addresses can be set by first sending a
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specific command, either EC for v3 devices or F5 for v4 devices. Then the
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address is sent one nibble at a time, where each nibble is encoded as a
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command with optional data. This encoding differs slightly between the v3 and
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v4 protocols.
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Once an address has been set, the addressed register can be read by sending
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PSMOUSE_CMD_GETINFO (E9). The first two bytes of the response contains the
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address of the register being read, and the third contains the value of the
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register. Registers are written by writing the value one nibble at a time
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using the same encoding used for addresses.
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For the new ALPS touchpads, the EC command is used to enter command
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mode. The response in the new ALPS touchpads is significantly different,
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and more important in determining the behavior. This code has been
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separated from the original alps_model_data table and put in the
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alps_identify function. For example, there seem to be two hardware init
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sequences for the "Dolphin" touchpads as determined by the second byte
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of the EC response.
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Packet Format
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-------------
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In the following tables, the following notation is used.
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CAPITALS = stick, miniscules = touchpad
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?'s can have different meanings on different models, such as wheel rotation,
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extra buttons, stick buttons on a dualpoint, etc.
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PS/2 packet format
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------------------
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byte 0: 0 0 YSGN XSGN 1 M R L
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byte 1: X7 X6 X5 X4 X3 X2 X1 X0
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byte 2: Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
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Note that the device never signals overflow condition.
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For protocol version 2 devices when the trackpoint is used, and no fingers
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are on the touchpad, the M R L bits signal the combined status of both the
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pointingstick and touchpad buttons.
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ALPS Absolute Mode - Protocol Version 1
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--------------------------------------
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byte 0: 1 0 0 0 1 x9 x8 x7
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byte 1: 0 x6 x5 x4 x3 x2 x1 x0
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byte 2: 0 ? ? l r ? fin ges
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byte 3: 0 ? ? ? ? y9 y8 y7
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byte 4: 0 y6 y5 y4 y3 y2 y1 y0
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byte 5: 0 z6 z5 z4 z3 z2 z1 z0
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ALPS Absolute Mode - Protocol Version 2
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---------------------------------------
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byte 0: 1 ? ? ? 1 PSM PSR PSL
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byte 1: 0 x6 x5 x4 x3 x2 x1 x0
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byte 2: 0 x10 x9 x8 x7 ? fin ges
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byte 3: 0 y9 y8 y7 1 M R L
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byte 4: 0 y6 y5 y4 y3 y2 y1 y0
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byte 5: 0 z6 z5 z4 z3 z2 z1 z0
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Protocol Version 2 DualPoint devices send standard PS/2 mouse packets for
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the DualPoint Stick. The M, R and L bits signal the combined status of both
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the pointingstick and touchpad buttons, except for Dell dualpoint devices
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where the pointingstick buttons get reported separately in the PSM, PSR
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and PSL bits.
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Dualpoint device -- interleaved packet format
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---------------------------------------------
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byte 0: 1 1 0 0 1 1 1 1
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byte 1: 0 x6 x5 x4 x3 x2 x1 x0
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byte 2: 0 x10 x9 x8 x7 0 fin ges
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byte 3: 0 0 YSGN XSGN 1 1 1 1
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byte 4: X7 X6 X5 X4 X3 X2 X1 X0
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byte 5: Y7 Y6 Y5 Y4 Y3 Y2 Y1 Y0
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byte 6: 0 y9 y8 y7 1 m r l
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byte 7: 0 y6 y5 y4 y3 y2 y1 y0
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byte 8: 0 z6 z5 z4 z3 z2 z1 z0
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Devices which use the interleaving format normally send standard PS/2 mouse
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packets for the DualPoint Stick + ALPS Absolute Mode packets for the
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touchpad, switching to the interleaved packet format when both the stick and
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the touchpad are used at the same time.
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ALPS Absolute Mode - Protocol Version 3
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---------------------------------------
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ALPS protocol version 3 has three different packet formats. The first two are
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associated with touchpad events, and the third is associated with trackstick
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events.
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The first type is the touchpad position packet.
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byte 0: 1 ? x1 x0 1 1 1 1
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byte 1: 0 x10 x9 x8 x7 x6 x5 x4
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byte 2: 0 y10 y9 y8 y7 y6 y5 y4
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byte 3: 0 M R L 1 m r l
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byte 4: 0 mt x3 x2 y3 y2 y1 y0
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byte 5: 0 z6 z5 z4 z3 z2 z1 z0
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Note that for some devices the trackstick buttons are reported in this packet,
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and on others it is reported in the trackstick packets.
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The second packet type contains bitmaps representing the x and y axes. In the
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bitmaps a given bit is set if there is a finger covering that position on the
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given axis. Thus the bitmap packet can be used for low-resolution multi-touch
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data, although finger tracking is not possible. This packet also encodes the
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number of contacts (f1 and f0 in the table below).
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byte 0: 1 1 x1 x0 1 1 1 1
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byte 1: 0 x8 x7 x6 x5 x4 x3 x2
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byte 2: 0 y7 y6 y5 y4 y3 y2 y1
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byte 3: 0 y10 y9 y8 1 1 1 1
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byte 4: 0 x14 x13 x12 x11 x10 x9 y0
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byte 5: 0 1 ? ? ? ? f1 f0
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This packet only appears after a position packet with the mt bit set, and
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usually only appears when there are two or more contacts (although
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occasionally it's seen with only a single contact).
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The final v3 packet type is the trackstick packet.
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byte 0: 1 1 x7 y7 1 1 1 1
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byte 1: 0 x6 x5 x4 x3 x2 x1 x0
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byte 2: 0 y6 y5 y4 y3 y2 y1 y0
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byte 3: 0 1 0 0 1 0 0 0
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byte 4: 0 z4 z3 z2 z1 z0 ? ?
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byte 5: 0 0 1 1 1 1 1 1
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ALPS Absolute Mode - Protocol Version 4
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---------------------------------------
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Protocol version 4 has an 8-byte packet format.
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byte 0: 1 ? x1 x0 1 1 1 1
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byte 1: 0 x10 x9 x8 x7 x6 x5 x4
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byte 2: 0 y10 y9 y8 y7 y6 y5 y4
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byte 3: 0 1 x3 x2 y3 y2 y1 y0
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byte 4: 0 ? ? ? 1 ? r l
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byte 5: 0 z6 z5 z4 z3 z2 z1 z0
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byte 6: bitmap data (described below)
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byte 7: bitmap data (described below)
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The last two bytes represent a partial bitmap packet, with 3 full packets
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required to construct a complete bitmap packet. Once assembled, the 6-byte
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bitmap packet has the following format:
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byte 0: 0 1 x7 x6 x5 x4 x3 x2
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byte 1: 0 x1 x0 y4 y3 y2 y1 y0
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byte 2: 0 0 ? x14 x13 x12 x11 x10
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byte 3: 0 x9 x8 y9 y8 y7 y6 y5
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byte 4: 0 0 0 0 0 0 0 0
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byte 5: 0 0 0 0 0 0 0 y10
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There are several things worth noting here.
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1) In the bitmap data, bit 6 of byte 0 serves as a sync byte to
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identify the first fragment of a bitmap packet.
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2) The bitmaps represent the same data as in the v3 bitmap packets, although
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the packet layout is different.
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3) There doesn't seem to be a count of the contact points anywhere in the v4
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protocol packets. Deriving a count of contact points must be done by
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analyzing the bitmaps.
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4) There is a 3 to 1 ratio of position packets to bitmap packets. Therefore
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MT position can only be updated for every third ST position update, and
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the count of contact points can only be updated every third packet as
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well.
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So far no v4 devices with tracksticks have been encountered.
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ALPS Absolute Mode - Protocol Version 5
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---------------------------------------
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This is basically Protocol Version 3 but with different logic for packet
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decode. It uses the same alps_process_touchpad_packet_v3 call with a
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specialized decode_fields function pointer to correctly interpret the
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packets. This appears to only be used by the Dolphin devices.
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For single-touch, the 6-byte packet format is:
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byte 0: 1 1 0 0 1 0 0 0
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byte 1: 0 x6 x5 x4 x3 x2 x1 x0
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byte 2: 0 y6 y5 y4 y3 y2 y1 y0
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byte 3: 0 M R L 1 m r l
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byte 4: y10 y9 y8 y7 x10 x9 x8 x7
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byte 5: 0 z6 z5 z4 z3 z2 z1 z0
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For mt, the format is:
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byte 0: 1 1 1 n3 1 n2 n1 x24
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byte 1: 1 y7 y6 y5 y4 y3 y2 y1
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byte 2: ? x2 x1 y12 y11 y10 y9 y8
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byte 3: 0 x23 x22 x21 x20 x19 x18 x17
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byte 4: 0 x9 x8 x7 x6 x5 x4 x3
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byte 5: 0 x16 x15 x14 x13 x12 x11 x10
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ALPS Absolute Mode - Protocol Version 6
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---------------------------------------
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For trackstick packet, the format is:
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byte 0: 1 1 1 1 1 1 1 1
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byte 1: 0 X6 X5 X4 X3 X2 X1 X0
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byte 2: 0 Y6 Y5 Y4 Y3 Y2 Y1 Y0
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byte 3: ? Y7 X7 ? ? M R L
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byte 4: Z7 Z6 Z5 Z4 Z3 Z2 Z1 Z0
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byte 5: 0 1 1 1 1 1 1 1
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For touchpad packet, the format is:
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byte 0: 1 1 1 1 1 1 1 1
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byte 1: 0 0 0 0 x3 x2 x1 x0
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byte 2: 0 0 0 0 y3 y2 y1 y0
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byte 3: ? x7 x6 x5 x4 ? r l
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byte 4: ? y7 y6 y5 y4 ? ? ?
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byte 5: z7 z6 z5 z4 z3 z2 z1 z0
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(v6 touchpad does not have middle button)
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ALPS Absolute Mode - Protocol Version 7
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---------------------------------------
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For trackstick packet, the format is:
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byte 0: 0 1 0 0 1 0 0 0
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byte 1: 1 1 * * 1 M R L
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byte 2: X7 1 X5 X4 X3 X2 X1 X0
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byte 3: Z6 1 Y6 X6 1 Y2 Y1 Y0
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byte 4: Y7 0 Y5 Y4 Y3 1 1 0
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byte 5: T&P 0 Z5 Z4 Z3 Z2 Z1 Z0
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For touchpad packet, the format is:
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packet-fmt b7 b6 b5 b4 b3 b2 b1 b0
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byte 0: TWO & MULTI L 1 R M 1 Y0-2 Y0-1 Y0-0
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byte 0: NEW L 1 X1-5 1 1 Y0-2 Y0-1 Y0-0
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byte 1: Y0-10 Y0-9 Y0-8 Y0-7 Y0-6 Y0-5 Y0-4 Y0-3
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byte 2: X0-11 1 X0-10 X0-9 X0-8 X0-7 X0-6 X0-5
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byte 3: X1-11 1 X0-4 X0-3 1 X0-2 X0-1 X0-0
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byte 4: TWO X1-10 TWO X1-9 X1-8 X1-7 X1-6 X1-5 X1-4
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byte 4: MULTI X1-10 TWO X1-9 X1-8 X1-7 X1-6 Y1-5 1
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byte 4: NEW X1-10 TWO X1-9 X1-8 X1-7 X1-6 0 0
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byte 5: TWO & NEW Y1-10 0 Y1-9 Y1-8 Y1-7 Y1-6 Y1-5 Y1-4
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byte 5: MULTI Y1-10 0 Y1-9 Y1-8 Y1-7 Y1-6 F-1 F-0
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L: Left button
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R / M: Non-clickpads: Right / Middle button
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Clickpads: When > 2 fingers are down, and some fingers
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are in the button area, then the 2 coordinates reported
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are for fingers outside the button area and these report
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extra fingers being present in the right / left button
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area. Note these fingers are not added to the F field!
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so if a TWO packet is received and R = 1 then there are
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3 fingers down, etc.
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TWO: 1: Two touches present, byte 0/4/5 are in TWO fmt
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0: If byte 4 bit 0 is 1, then byte 0/4/5 are in MULTI fmt
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otherwise byte 0 bit 4 must be set and byte 0/4/5 are
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in NEW fmt
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F: Number of fingers - 3, 0 means 3 fingers, 1 means 4 ...
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