Differential D57844

asmc: try PIO before MMIO to avoid false T2 detection
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Authored by seuros on Jun 25 2026, 3:23 PM.

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drivers
apple (x86)

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rG95aa170e6358: asmc: try PIO before MMIO to avoid false T2 detection
rGb6fb80014c46: asmc: try PIO before MMIO to avoid false T2 detection
rGbb1e071be47f: asmc: try PIO before MMIO to avoid false T2 detection

Summary

Add hw.asmc.system-state and hw.asmc.board-id read-only sysctls to
expose the T2 system state register and Mac board identifier via SMC.

Try PIO access before MMIO during probe to prevent false T2 detection
on Macs that happen to have something mapped at the T2 BAR address.

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rG FreeBSD src repository

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Buildable 74250
Build 71133: arc lint + arc unit

Event Timeline

seuros created this revision.Jun 25 2026, 3:23 PM

Herald added a subscriber: imp. · View Herald TranscriptJun 25 2026, 3:23 PM

seuros requested review of this revision.Jun 25 2026, 3:23 PM

Harbormaster completed remote builds in B74250: Diff 180623.Jun 25 2026, 3:23 PM

make sure you add a "tested" block showing a couple of devices you tested this on just to verify

oh and i think you should split this into two parts:

one that changes the probe order due to apple revisions
one that adds all the extra keys/sysctl stuff

splitting

Harbormaster completed remote builds in B74264: Diff 180644.Jun 25 2026, 8:02 PM

I'm splitting them into 3 into a stack.

The fix is this diff, the next ones is how you can test it and some cleanup.

seuros added a child revision: D57853: asmc: add system state and board identity sysctls.Jun 25 2026, 9:48 PM

adrian added inline comments.Jun 26 2026, 10:35 PM

sys/dev/asmc/asmc.c
444	Just change this to if (sc->sc_ioport == NULL) so you don't need the empty section

ngie subscribed.Jun 26 2026, 10:39 PM

ngie added inline comments.

sys/dev/asmc/asmc.c
442–444

ngie added inline comments.Jun 26 2026, 11:07 PM

sys/dev/asmc/asmc.c
445–463	This logic seems like a good candidate for another helper probe function for clarity and to make the logic cleaner for humans to parse.
450	I know this requires additional changes, but this seems best expressed via a bool quantity (true/false).

seuros retitled this revision from asmc: add system state, board identity sysctls, and PIO-first probe order to asmc: try PIO before MMIO to avoid false T2 detection.Jun 27 2026, 6:50 PM

addressing review

Harbormaster completed remote builds in B74335: Diff 180831.Jun 27 2026, 6:52 PM

seuros marked 3 inline comments as done.Jun 27 2026, 6:56 PM

seuros added inline comments.

sys/dev/asmc/asmc.c
442–444	I had it empty because i don't know if T1 Mac will need it.. We still need to test this driver in some 2016s hardware.

ngie added inline comments.Jun 27 2026, 6:57 PM

sys/dev/asmc/asmc.c
442–444	I had it empty because i don't know if T1 Mac will need it.. We still need to test this driver in some 2016s hardware. I can confirm that after this lands (I have a '16 MBP, which has a T1 chip).

@guest-seuros: can this change land independent of D57853?

adrian accepted this revision.Jun 27 2026, 8:30 PM

This revision is now accepted and ready to land.Jun 27 2026, 8:30 PM

The other diff is how i verified that this change worked, it is not a requirement.

You can land this one standalone.

Closed by commit rGbb1e071be47f: asmc: try PIO before MMIO to avoid false T2 detection. · Explain WhyJul 1 2026, 12:20 AM

This revision was automatically updated to reflect the committed changes.

adrian added a commit: rGbb1e071be47f: asmc: try PIO before MMIO to avoid false T2 detection.

ngie added a commit: rGb6fb80014c46: asmc: try PIO before MMIO to avoid false T2 detection.Sep 4 2026, 11:09 PM

ngie added a commit: rG95aa170e6358: asmc: try PIO before MMIO to avoid false T2 detection.Sep 5 2026, 11:33 PM

Revision Contents
Changeset List

Path

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sys/

dev/

asmc/

382 lines

17 lines

Diff 180623

sys/dev/asmc/asmc.c

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sys/dev/asmc/asmcvar.h

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