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Diffstat (limited to 'Documentation/input/alps.txt')
| -rw-r--r-- | Documentation/input/alps.txt | 67 |
1 files changed, 60 insertions, 7 deletions
diff --git a/Documentation/input/alps.txt b/Documentation/input/alps.txt index 3262b6e4d686..e544c7ff8cfa 100644 --- a/Documentation/input/alps.txt +++ b/Documentation/input/alps.txt @@ -3,10 +3,26 @@ 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. +Currently the ALPS touchpad driver supports five protocol versions in use by +ALPS touchpads, called versions 1, 2, 3, 4 and 5. + +Since roughly mid-2010 several new ALPS touchpads have been released and +integrated into a variety of laptops and netbooks. These new touchpads +have enough behavior differences that the alps_model_data definition +table, describing the properties of the different versions, is no longer +adequate. The design choices were to re-define the alps_model_data +table, with the risk of regression testing existing devices, or isolate +the new devices outside of the alps_model_data table. The latter design +choice was made. The new touchpad signatures are named: "Rushmore", +"Pinnacle", and "Dolphin", which you will see in the alps.c code. +For the purposes of this document, this group of ALPS touchpads will +generically be called "new ALPS touchpads". + +We experimented with probing the ACPI interface _HID (Hardware ID)/_CID +(Compatibility ID) definition as a way to uniquely identify the +different ALPS variants but there did not appear to be a 1:1 mapping. +In fact, it appeared to be an m:n mapping between the _HID and actual +hardware type. Detection --------- @@ -20,9 +36,13 @@ 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. +For older touchpads supporting 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. + +The new ALPS touchpads have an E7 signature of 73-03-50 or 73-03-0A but +seem to be better differentiated by the EC Command Mode response. Command Mode ------------ @@ -47,6 +67,14 @@ 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. +For the new ALPS touchpads, the EC command is used to enter command +mode. The response in the new ALPS touchpads is significantly different, +and more important in determining the behavior. This code has been +separated from the original alps_model_data table and put in the +alps_identify function. For example, there seem to be two hardware init +sequences for the "Dolphin" touchpads as determined by the second byte +of the EC response. + Packet Format ------------- @@ -187,3 +215,28 @@ There are several things worth noting here. well. So far no v4 devices with tracksticks have been encountered. + +ALPS Absolute Mode - Protocol Version 5 +--------------------------------------- +This is basically Protocol Version 3 but with different logic for packet +decode. It uses the same alps_process_touchpad_packet_v3 call with a +specialized decode_fields function pointer to correctly interpret the +packets. This appears to only be used by the Dolphin devices. + +For single-touch, the 6-byte packet format is: + + byte 0: 1 1 0 0 1 0 0 0 + byte 1: 0 x6 x5 x4 x3 x2 x1 x0 + byte 2: 0 y6 y5 y4 y3 y2 y1 y0 + byte 3: 0 M R L 1 m r l + byte 4: y10 y9 y8 y7 x10 x9 x8 x7 + byte 5: 0 z6 z5 z4 z3 z2 z1 z0 + +For mt, the format is: + + byte 0: 1 1 1 n3 1 n2 n1 x24 + byte 1: 1 y7 y6 y5 y4 y3 y2 y1 + byte 2: ? x2 x1 y12 y11 y10 y9 y8 + byte 3: 0 x23 x22 x21 x20 x19 x18 x17 + byte 4: 0 x9 x8 x7 x6 x5 x4 x3 + byte 5: 0 x16 x15 x14 x13 x12 x11 x10 |