acpi_cros_tbmc: New driver for Chromebook "Tablet Motion Controls" (tablet mode switch)

[greg_unrelenting.technology]

Summary

This ACPI device exposed by the Chrome EC reports when a laptop-tablet convertible Chromebook (e.g., Google Pixelbook) is switched to tablet mode. Like on Linux, the reporting is via evdev:

-event3   SWITCH_TOGGLE     +3.27s      switch tablet-mode state 1
 event3   SWITCH_TOGGLE     +8.63s      switch tablet-mode state 0

though I can add more ways of notification (devd events I guess).

Google will eventually replace this device with Intel Virtual Buttons (used by other convertibles), but for now this exists. When I get my debug cable, I'll build firmware with that patch and write a driver for vbtn too.

Is there a good way to autoload such things? (I guess not, since I've had to load acpi_ibm manually on Thinkpads)

[darkfiberiru_gmail.com]

@imp Is it possible to get this and acpi_ibm autoloaded with devmatch? Not sure if it would work with current structure or need additional code paths inside devmatch itself.