[RFC PATCH 0/1] hwmon: Add Minisforum UM780 XTX EC monitoring and fan control

["Sebastián Peyrott" <speyrott@gmail.com>]

This RFC adds a board-specific hwmon driver for the embedded controller in
the Minisforum UM780 XTX. It exposes two fan-control temperatures, both fan
tachometers, the two OEM CPU fan profiles, and the configurable system-fan
transition temperatures.

The controller is an ITE IT5571E, but its observable register layout, OEM
commands, and fan-control behavior are defined by machine-specific
firmware. The driver therefore does not attempt to support arbitrary
IT5571E systems and is limited to the exact board revision and BIOS version
on which the interface was reverse engineered and tested.

The firmware reloads its default fan settings several seconds after s2idle
resume. The driver performs one delayed check and restores the last
coherent settings if they changed. It does not poll during normal
operation.

The EC does not expose the currently applied duty cycle, so pwm1 and pwm2
values are not synthesized. Only automatic modes and known curve settings
are exposed.

A research prototype can also report the seven CPU curve boundaries and
modify six while retaining the firmware slopes and fixed 93 C safety
boundary. This is omitted because adjacent bands require paired EC writes
and the visible values do not fully describe firmware interpolation.

I would appreciate feedback on:

  1. Whether direct use of the ACPI EC helpers and placement in hwmon are
     appropriate for this DMI-gated driver.
  2. Whether pwm1_enable values 2 and 3 appropriately represent the two
     firmware-controlled CPU profiles.
  3. Whether the two stepped system-fan transitions are appropriately
     represented as pwm2 automatic curve points.
  4. Whether read-only CPU curve boundaries would be useful in a follow-up,
     and where experimental writes should live.

The driver was tested on the target hardware with concurrent RPM reads,
profile and curve changes, unload/reload stress, and s2idle resume. The
patch passes checkpatch.pl --strict and builds against hwmon-next.

OpenAI Codex assisted with review, editing, test orchestration, and patch
preparation. I reviewed the result and take responsibility for the
submission.

Sebastián Peyrott (1):
  hwmon: Add Minisforum UM780 XTX EC monitoring and fan control

 Documentation/hwmon/index.rst               |   1 +
 Documentation/hwmon/minisforum-um780xtx.rst |  79 +++
 MAINTAINERS                                 |   7 +
 drivers/hwmon/Kconfig                       |  16 +
 drivers/hwmon/Makefile                      |   1 +
 drivers/hwmon/minisforum-um780xtx.c         | 648 ++++++++++++++++++++
 6 files changed, 752 insertions(+)
 create mode 100644 Documentation/hwmon/minisforum-um780xtx.rst
 create mode 100644 drivers/hwmon/minisforum-um780xtx.c


base-commit: f18a46518561205cd6ff775a488a0c9d9d5edbfb
-- 
2.54.0