diff options
| -rw-r--r-- | Documentation/input/alps.txt | 135 |
1 files changed, 124 insertions, 11 deletions
diff --git a/Documentation/input/alps.txt b/Documentation/input/alps.txt index ab5478f92a2b..f274c28b5103 100644 --- a/Documentation/input/alps.txt +++ b/Documentation/input/alps.txt @@ -4,12 +4,9 @@ ALPS Touchpad Protocol Introduction ------------ -Currently the ALPS touchpad driver supports two protocol versions in use by -ALPS touchpads, the "old" and "new" protocol versions. Fundamentally these -differ only in the format of their event packets (in reality many features may -be found on new protocol devices that aren't found on the old protocol -devices, but these are handled transparently as feature differences rather -than protocol differences). +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 --------- @@ -22,10 +19,37 @@ 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 us used. +In the following tables, the following notation is used. CAPITALS = stick, miniscules = touchpad @@ -41,8 +65,8 @@ PS/2 packet format Note that the device never signals overflow condition. -ALPS Absolute Mode - Old Format -------------------------------- +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 @@ -51,8 +75,8 @@ ALPS Absolute Mode - Old Format byte 4: 0 y6 y5 y4 y3 y2 y1 y0 byte 5: 0 z6 z5 z4 z3 z2 z1 z0 -ALPS Absolute Mode - New Format -------------------------------- +ALPS Absolute Mode - Protocol Version 2 +--------------------------------------- byte 0: 1 ? ? ? 1 ? ? ? byte 1: 0 x6 x5 x4 x3 x2 x1 x0 @@ -73,3 +97,92 @@ Dualpoint device -- interleaved packet format 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 +ususally only appears when there are two or more contacts (although +ocassionally 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. |