| 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). |
| |
| 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 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. |
| |
| Packet Format |
| ------------- |
| |
| In the following tables, the following notation us 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 - Old Format |
| ------------------------------- |
| |
| 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 - New Format |
| ------------------------------- |
| |
| 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 |
