Add battery subsystem (TC=0x02) devices (battery and AC) to the SSAM
device registry. These devices need to be registered for 7th-generation
Surface models. On 5th- and 6th-generation models, these devices are
handled via the standard ACPI battery/AC interface, which in turn
accesses the same SSAM interface via the Surface ACPI Notify (SAN)
driver.
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210212115439.1525216-4-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
The Surface Book 3 has a detachable base part. While the top part
(so-called clipboard) contains the CPU, touchscreen, and primary
battery, the base contains, among other things, a keyboard, touchpad,
and secondary battery.
Those devices do not react well to being accessed when the base part is
detached and should thus be removed and added in sync with the base. To
facilitate this, we introduce a virtual base device hub, which
automatically removes or adds the devices registered under it.
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210212115439.1525216-3-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
The Surface System Aggregator Module (SSAM) subsystem provides various
functionalities, which are separated by spreading them across multiple
devices and corresponding drivers. Parts of that functionality / some of
those devices, however, can (as far as we currently know) not be
auto-detected by conventional means. While older (specifically 5th- and
6th-)generation models do advertise most of their functionality via
standard platform devices in ACPI, newer generations do not.
As we are currently also not aware of any feasible way to query said
functionalities dynamically, this poses a problem. There is, however, a
device in ACPI that seems to be used by Windows for identifying
different Surface models: The Windows Surface Integration Device (WSID).
This device seems to have a HID corresponding to the overall set of
functionalities SSAM provides for the associated model.
This commit introduces a registry providing non-detectable device
information via software nodes. In addition, a SSAM platform hub driver
is introduced, which takes care of creating and managing the SSAM
devices specified in this registry. This approach allows for a
hierarchical setup akin to ACPI and is easily extendable, e.g. via
firmware node properties.
Note that this commit only provides the basis for the platform hub and
registry, and does not add any content to it. The registry will be
expanded in subsequent commits.
Signed-off-by: Maximilian Luz <luzmaximilian@gmail.com>
Link: https://lore.kernel.org/r/20210212115439.1525216-2-luzmaximilian@gmail.com
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
