Actually I intended to rewrite the whole HID descriptor and add a sane
mapping for all the buttons (maybe following the Gamepad API and
even using the new ABS_ACCEL_* and ABS_GYRO_* events from David
Hermann).

I think that the root of the problem here is simply the large number of
axis, and that the keycodes start at 'axis-x' then overflow into/past the
MultiTouch keycode.

This problem is going to be a more common one as HID drivers present more
buttons/axis.

We did some patching here:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/hid/hid-sony.c?id=refs/tags/v3.12#n301
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/hid/hid-sony.c?id=61ab44bebdefab296487e7cd723a634849278827

Do we need to fix this is the HID descriptor, or in 'hid-sony' input stuff?

Do you have example of another driver to copy?
Simon