recently I came across the Linux commit by alistair23. The newer w9013 variant seems to support the X/Y tilting and Pen distance detection. In his commit have something that currently mainline doesn't have, It's the other commands. You can set the report rate and put device to sleep and wake them - via command obviously. Unfortunately, my w9013-s have the firmware version 0x0333 which isn't support the X/Y Tilting and Pen Distance report. but I yet to test the variable sample rate and sleep/wake mode, since this feature is really useful for my Wac0m RipOff BLE project.

His version of wacom_i2c.c can be found here