Linux kernel stable tree (mirror) https://git.radix-linux.su/kernel/linux.git/atom?h=v6.18.21 2025-07-24T08:47:33+00:00 2025-07-24T08:47:33+00:00 Sven Peter sven@kernel.org 2025-06-10T15:29:46+00:00 urn:sha1:e038d985c9823a12cd64fa077d0c5aca2c644b67 The System Management Controller (SMC) on Apple Silicon machines is a piece of hardware that exposes various functionalities such as temperature sensors, voltage/power meters, shutdown/reboot handling, GPIOs and more. Communication happens via a shared mailbox using the RTKit protocol which is also used for other co-processors. The SMC protocol then allows reading and writing many different keys which implement the various features. The MFD core device handles this protocol and exposes it to the sub-devices. Some of the sub-devices are potentially also useful on pre-M1 Apple machines and support for SMCs on these machines can be added at a later time. Co-developed-by: Hector Martin <marcan@marcan.st> Signed-off-by: Hector Martin <marcan@marcan.st> Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io> Reviewed-by: Neal Gompa <neal@gompa.dev> Signed-off-by: Sven Peter <sven@kernel.org> Link: https://lore.kernel.org/r/20250610-smc-6-15-v7-5-556cafd771d3@kernel.org Signed-off-by: Lee Jones <lee@kernel.org>