[PATCH v3 02/13] dt-bindings: hwmon: Add Apple System Management Controller hwmon schema

[Rob Herring (Arm)]

On Tue, 07 Oct 2025 21:16:43 +1000, James Calligeros wrote:
> Apple Silicon devices integrate a vast array of sensors, monitoring
> current, power, temperature, and voltage across almost every part of
> the system. The sensors themselves are all connected to the System
> Management Controller (SMC). The SMC firmware exposes the data
> reported by these sensors via its standard FourCC-based key-value
> API. The SMC is also responsible for monitoring and controlling any
> fans connected to the system, exposing them in the same way.
> 
> For reasons known only to Apple, each device exposes its sensors with
> an almost totally unique set of keys. This is true even for devices
> which share an SoC. An M1 Mac mini, for example, will report its core
> temperatures on different keys to an M1 MacBook Pro. Worse still, the
> SMC does not provide a way to enumerate the available keys at runtime,
> nor do the keys follow any sort of reasonable or consistent naming
> rules that could be used to deduce their purpose. We must therefore
> know which keys are present on any given device, and which function
> they serve, ahead of time.
> 
> Add a schema so that we can describe the available sensors for a given
> Apple Silicon device in the Devicetree.
> 
> Reviewed-by: Neal Gompa <neal at gompa.dev>
> Signed-off-by: James Calligeros <jcalligeros99 at gmail.com>
> ---
>  .../bindings/hwmon/apple,smc-hwmon.yaml  | 86 +++++++++++++++++++++++++
>  .../bindings/mfd/apple,smc.yaml          | 36 +++++++++++
>  MAINTAINERS                              |  1 +
>  3 files changed, 123 insertions(+)
> 

Reviewed-by: Rob Herring (Arm) <robh at kernel.org>