9f794056 - platform/surface: Add KIP/POS tablet-mode switch driver

Fri, 24 Jun 2022 18:36:40 +0000

platform/surface: Add KIP/POS tablet-mode switch driverAdd a driver providing a tablet-mode switch input device for MicrosoftSurface devices using the Surface Aggregator KIP subsystem (to managedetachable peripherals) or POS subsystem (to obtain device postureinformation).The KIP (full name unknown, abbreviation found through reverseengineering) subsystem is used on the Surface Pro 8 and Surface Pro X tomanage the keyboard cover. Among other things, it provides informationon the positioning (posture) of the cover (closed, laptop-style,detached, folded-back, ...), which can be used to implement an inputdevice providing the SW_TABLET_MODE event. Similarly, the POS (postureinformation) subsystem provides such information on the Surface LaptopStudio, with the difference being that the keyboard is not detachable.As implementing the tablet-mode switch for both subsystems is largelysimilar, the driver proposed in this commit, in large, acts as a generictablet mode switch driver framework for the Surface Aggregator Module.Specific implementations using this framework are provided for the KIPand POS subsystems, adding tablet-mode switch support to theaforementioned devices.A few more notes on the Surface Laptop Studio:A peculiarity of the Surface Laptop Studio is its "slate/tent" mode(symbolized: user> _/\). In this mode, the screen covers the keyboardbut leaves the touchpad exposed. This is essentially a mode in-betweentablet and laptop, and it is debatable whether tablet-mode should beenabled in this mode. We therefore let the user decide this via a moduleparameter.In particular, tablet-mode may bring up the on-screen touch keyboardmore easily, which would be desirable in this mode. However, someuser-space software currently also decides to disable keyboard and, moreimportantly, touchpad input, while the touchpad is still accessible inthe "slate/tent" mode. Furthermore, this mode shares its identifier with"slate/flipped" mode where the screen is flipped 180° and the keyboardpoints away from the user (symbolized: user> /_). In this mode we wouldlike to enable auto-rotation, something that user-space software mayonly do when tablet-mode is enabled. We therefore default to theslate-mode enabling the tablet-mode switch.Signed-off-by: Maximilian Luz Link: https://lore.kernel.org/r/20220624183642.910893-3-luzmaximilian@gmail.comReviewed-by: Hans de Goede Signed-off-by: Hans de Goede List of files: /linux-6.15/Documentation/ABI/testing/sysfs-bus-surface_aggregator-tabletsw

Changes in sysfs-bus-surface_aggregator-tabletsw

9f794056 - platform/surface: Add KIP/POS tablet-mode switch driver