The newest open-source Apple Silicon driver being submitted for review in working toward its inclusion in the mainline Linux kernel is the Apple Silicon SMC power driver for being able to expose MacBook battery power metrics as well as AC power adapter status reporting under Linux.
Michael Reeves posted the set of patches today for the nearly 900 lines of code power driver for Apple’s System Management Controller. This new “macsmc-power” driver allows for the Linux kernel to report the AC charging status as well as battery status and power metrics to user-space. This driver is based on code for the out-of-tree driver within the Asahi Linux kernel tree but then refactored for upstream inclusion, The revised code also better handles newer Apple System Management Controller firmware, devices without batteries, and other improvements.
This driver can be enabled via the MACSMC_POWER Kconfig switch it introduces and via the Apple SMC can then report the battery capacity, voltage, current, and charging status. This is reported via Linux’s conventional power supply framework so it jives with existing Linux user-space utilities already taking advantage of said interfaces.
This is a nice and long sought after addition, especially for those wanting to be able to compare the battery power consumption of Apple Silicon MacBooks against Intel Core and AMD Ryzen laptops under Linux, etc. Not to mention those using Apple Silicon MacBooks for actual daily use under Linux and wanting to be able to reliably monitor their battery charge.
At this time the driver is mainly about Apple M1 / M2 / M3 hardware with Apple M4 and M5 especially expected to be a ways out from enjoying good Linux support.
See this patch series for those interested in this Apple SMC power driver now under review for the Linux kernel.
