linux-kernel - Re: [PATCH v6 0/2] Add Apple Silicon SMC power driver

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Message-ID: <CANpmGNsCC09A4Dgy0NMye83g1c22x1RbOG0KRpvDryPW7H1oNA@mail.gmail.com>
Date: Sat, 31 Jan 2026 10:30:19 +1100
From: Michael Reeves <michael.reeves077@...il.com>
To: Sebastian Reichel <sebastian.reichel@...labora.com>
Cc: Sven Peter <sven@...nel.org>, Janne Grunau <j@...nau.net>, Neal Gompa <neal@...pa.dev>, 
	Lee Jones <lee@...nel.org>, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, 
	asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
	Hector Martin <marcan@...can.st>, Joey Gouly <joey.gouly@....com>
Subject: Re: [PATCH v6 0/2] Add Apple Silicon SMC power driver

Hi,
On Sat, Jan 31, 2026 at 6:54 AM Sebastian Reichel
<sebastian.reichel@...labora.com> wrote:
>
> Hi,
>
> On Mon, Jan 26, 2026 at 10:16:55AM +1100, Michael Reeves via B4 Relay wrote:
> > This series adds a power supply driver for the Apple SMC found on
> > Apple Silicon devices. This allows the kernel to report AC status,
> > battery charging status, and power metrics, and modify the charging
> > behaviour.
> >
> > The first patch adds the driver itself, and the second patch wires it
> > up to the MFD core.
> >
> > The driver is based on an original out-of-tree implementation by
> > Hector Martin. It has been refactored by myself for upstream inclusion,
> > including support for newer SMC firmwares, devices without batteries,
> > dynamic property detection and improved state management, among other
> > things.
> >
> > This series is based ontop of the current linux-next at time of writing,
> > the exact commit hash is listed below.
> >
> > Tested on: Apple M3 (MacBook Air, J613)
> >
> > Signed-off-by: Michael Reeves <michael.reeves077@...il.com>
> > ---
> > Changes in v6:
> > - Add FS header include for emergency_sync()
> > - Link to v5: https://lore.kernel.org/r/20260126-b4-macsmc-power-v5-0-302462673b18@gmail.com
>
> This fails to build as module, since emergency_sync() is not exported:
>
> ERROR: modpost: "emergency_sync" [drivers/power/supply/macsmc-power.ko] undefined!
> make[2]: *** [scripts/Makefile.modpost:147: Module.symvers] Error 1
Thank you for finding this! Sorry, I didn't test building as a module,
only as built-in, I will do this
going forward in future. After some research I've found
hw_protection_trigger which is exported
and will emergency sync and power off (just like this) after a
customisable timeout, which
seems suitable for this usecase. I'll test it now and submit v7 shortly.
>
> Greetings,
>
> -- Sebastian
>
> > Changes in v5:
> > - Readd cover subject that mistakenly got dropped, apologies.
> > - Link to v4: https://lore.kernel.org/r/20260126-b4-macsmc-power-v4-0-aa2a682ca650@gmail.com
> >
> > Changes in v4:
> > - Restore Hector Martin as primary author for the series.
> > - Restore downstream Co-developed-by and Signed-off-by tags.
> > - Add Reviewed-by: Sven Peter <sven@...nel.org>.
> > - Simplify MFD patch authorship and remove redundant tags.
> > - Fix probe return value being overwritten by devm_work_autocancel.
> > - Return -ENODEV in probe if neither battery nor AC adapter are found.
> > - Add bounds check for nprops against MACSMC_MAX_BATT_PROPS.
> > - Refactor macsmc_battery_set_charge_behaviour to remove unnecessary resets.
> > - Improve critical_work shutdown flags and remove return.
> > - Add comments explaining SMC key firmware history and flag meanings.
> > - Clarify event ID descriptions and restore BSFC flag comments.
> > - Remove redundant dev_dbg logs for missing battery or AC.
> > - Link to v3: https://lore.kernel.org/r/20260115-b4-macsmc-power-v3-0-c236e09874be@gmail.com
> >
> > Changes in v3:
> > - Rebase on top of latest linux-next
> > - Drop charge control threshold properties.
> > - Switch to devm_work_autocancel() for critical work.
> > - Add platform ID table and remove MODULE_ALIAS.
> > - Simplify property array management in struct macsmc_power.
> > - Improve probe error handling and device pointer usage.
> > - Minor style and indentation fixes.
> > - Link to v2: https://lore.kernel.org/r/20260109-b4-macsmc-power-v2-0-93818f1e7d62@gmail.com
> >
> > Changes in v2:
> > - Added Reviewed-by: Neal Gompa <neal@...pa.dev> to all patches.
> > - Fixed Makefile alignment by using tabs for the macsmc-power entry.
> > - Upgraded physical battery exhaustion log level to EMERG.
> > - Downgraded software-triggered orderly poweroff log level to CRIT.
> > - Added check for CHIS key to skip AC registration on desktop models.
> > - Link to v1: https://lore.kernel.org/r/20260105-b4-macsmc-power-v1-0-62954c42a555@gmail.com
> >
> > ---
> > Hector Martin (2):
> >       power: supply: Add macsmc-power driver for Apple Silicon
> >       mfd: macsmc: Wire up Apple SMC power driver
> >
> >  MAINTAINERS                         |   1 +
> >  drivers/mfd/macsmc.c                |   1 +
> >  drivers/power/supply/Kconfig        |  11 +
> >  drivers/power/supply/Makefile       |   1 +
> >  drivers/power/supply/macsmc-power.c | 852 ++++++++++++++++++++++++++++++++++++
> >  5 files changed, 866 insertions(+)
> > ---
> > base-commit: ca3a02fda4da8e2c1cb6baee5d72352e9e2cfaea
> > change-id: 20260125-b4-macsmc-power-bb30389e05f1
> >
> > Best regards,
> > --
> > Michael Reeves <michael.reeves077@...il.com>
> >
> >
Thanks again,
Michael