[PATCH 0/2] platform/arm64: Lenovo Yoga Slim 7x Gen 11 embedded controller

[Oleg Keri <okerixx@gmail.com>]

The Lenovo Yoga Slim 7x Gen 11 is a Qualcomm Snapdragon X2 Elite (glymur)
laptop. It carries a Compal EF06 embedded controller on I2C at address
0x70, which is the only source on this machine for the board thermistors,
the battery cell voltages, the fan tachometer, the keyboard backlight, and
the mic-mute and airplane-mode keys.

Patch 1 documents the binding, patch 2 adds the driver.

Why this is not qcom-hamoa-ec
-----------------------------

The Snapdragon reference designs - glymur CRD, hamoa IoT EVK, Asus Zenbook
A16 - place their embedded controller at 0x76, and
drivers/platform/arm64/qcom-hamoa-ec.c drives those. This machine is
different: only 0x70 ACKs, and 0x76 is not populated at all. That is also
why the firmware reports every host fan capability as unsupported, since
profiles, trip points, LUTs and tachometer queries are all addressed to
0x76.

Binding qcom-hamoa-ec here does not work. It speaks a different command set
(0x05/0x0e/0x42), appears to probe only because it never validates the
firmware version it reads back, then reports zero fans and leaves the
interrupt asserted at roughly 25 events/s indefinitely.

The ACPI tables describe both controllers: one at 0x76 (OperationRegion
DVUM, fields FC20-FC2A) inherited from the reference design, and the one
this driver targets at 0x70 (OperationRegion ERAM, battery and charger
fields). Only the latter responds on this board.

Notes
-----

Fan speed is reported but not controlled, deliberately - the EC enforces no
thermal floor over a manual setpoint. Patch 2 has the measurement.

The DT node for the controller is not part of this series; it lands with
the board DTS, which is being upstreamed separately.

Tested on a Lenovo Yoga Slim 7x Gen 11 (DMI 83QR, "Yoga Slim 7 14Q8Y11").

Oleg Keri (2):
  dt-bindings: embedded-controller: add Lenovo Yoga Slim 7x Gen 11 EC
  platform/arm64: add Lenovo Yoga Slim 7x Gen 11 EC driver

 .../sysfs-driver-lenovo-yoga-slim7x-gen11-ec  |  21 +
 .../lenovo,yoga-slim7x-gen11-ec.yaml          |  56 ++
 MAINTAINERS                                   |   8 +
 drivers/platform/arm64/Kconfig                |  22 +
 drivers/platform/arm64/Makefile               |   1 +
 .../arm64/lenovo-yoga-slim7x-gen11-ec.c       | 639 ++++++++++++++++++
 6 files changed, 747 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-driver-lenovo-yoga-slim7x-gen11-ec
 create mode 100644 Documentation/devicetree/bindings/embedded-controller/lenovo,yoga-slim7x-gen11-ec.yaml
 create mode 100644 drivers/platform/arm64/lenovo-yoga-slim7x-gen11-ec.c

-- 
2.55.0

base-commit: 5e036ce12de91c6fd674dad33b169c6150be2a7a