linux-kernel - Re: [PATCH v3 06/13] hwmon: Add Apple Silicon SMC hwmon driver

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Message-ID: <c7d01ff6-0e09-4ea1-8c5d-59be5e3fff16@roeck-us.net>
Date: Wed, 8 Oct 2025 18:58:31 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: James Calligeros <jcalligeros99@...il.com>, Sven Peter <sven@...nel.org>,
 Janne Grunau <j@...nau.net>, Alyssa Rosenzweig <alyssa@...enzweig.io>,
 Neal Gompa <neal@...pa.dev>, Lee Jones <lee@...nel.org>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Alexandre Belloni <alexandre.belloni@...tlin.com>,
 Jean Delvare <jdelvare@...e.com>, Dmitry Torokhov
 <dmitry.torokhov@...il.com>, Jonathan Corbet <corbet@....net>
Cc: asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-rtc@...r.kernel.org, linux-hwmon@...r.kernel.org,
 linux-input@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v3 06/13] hwmon: Add Apple Silicon SMC hwmon driver

On 10/7/25 04:16, James Calligeros wrote:
> The System Management Controller on Apple Silicon devices is responsible
> for integrating and exposing the data reported by the vast array of
> hardware monitoring sensors present on these devices. It is also
> responsible for fan control, and allows users to manually set fan
> speeds if they so desire. Add a hwmon driver to expose current,
> power, temperature, and voltage monitoring sensors, as well as
> fan speed monitoring and control via the SMC on Apple Silicon devices.
> 
> The SMC firmware has no consistency between devices, even when they
> share an SoC. The FourCC keys used to access sensors are almost
> random. An M1 Mac mini will have different FourCCs for its CPU core
> temperature sensors to an M1 MacBook Pro, for example. For this
> reason, the valid sensors for a given device are specified in a
> child of the SMC Devicetree node. The driver uses this information
> to determine which sensors to make available at runtime.
> 
> Reviewed-by: Neal Gompa <neal@...pa.dev>
> Co-developed-by: Janne Grunau <j@...nau.net>
> Signed-off-by: Janne Grunau <j@...nau.net>
> Signed-off-by: James Calligeros <jcalligeros99@...il.com>

Acked-by: Guenter Roeck <linux@...ck-us.net>