Message-ID: <20251113191152.96076-1-i@rong.moe>
Date: Fri, 14 Nov 2025 03:11:43 +0800
From: Rong Zhang <i@...g.moe>
To: Mark Pearson <mpearson-lenovo@...ebb.ca>,
	"Derek J. Clark" <derekjohn.clark@...il.com>,
	Armin Wolf <W_Armin@....de>,
	Hans de Goede <hansg@...nel.org>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: Rong Zhang <i@...g.moe>,
	Guenter Roeck <linux@...ck-us.net>,
	platform-driver-x86@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-hwmon@...r.kernel.org
Subject: [PATCH v4 0/7] platform/x86: lenovo-wmi-{capdata,other}: Add HWMON for fan speed

Lenovo WMI Other Mode interface also supports querying or setting fan
speed RPM. This capability is decribed by LENOVO_CAPABILITY_DATA_00.
Besides, LENOVO_FAN_TEST_DATA provides reference data for self-test of
cooling fans, including minimum and maximum fan speed RPM.

This patchset turns lenovo-wmi-capdata01 into a unified driver (now
named lenovo-wmi-capdata) for LENOVO_CAPABILITY_DATA_{00,01} and
LENOVO_FAN_TEST_DATA; then adds HWMON support for lenovo-wmi-other:

 - fanX_enable: enable/disable the fan (tunable)
 - fanX_input: current RPM
 - fanX_max: maximum RPM
 - fanX_min: minimum RPM
 - fanX_target: target RPM (tunable)

LENOVO_CAPABILITY_DATA_{00,01} presents on all devices, so
both binds to lenovo-wmi-other. However, some device does not have
LENOVO_FAN_TEST_DATA and its presence is described by
LENOVO_CAPABILITY_DATA_00; hence, the former binds to the latter and a
callback is used to pass the data to lenovo-wmi-other.

The implementation does not rely on a specific binding sequence. This
has been fuzz-tested using:

	#!/bin/bash

	DRV_DIR=/sys/bus/wmi/drivers/lenovo_wmi_cd
	CAPDATA_GUIDS=(
		$(find "$DRV_DIR"/ -name '*-*-*-*-*-*' -printf "%f ")
	)

	b() { sudo tee "$DRV_DIR"/bind <<<"$1"; }
	u() { sudo tee "$DRV_DIR"/unbind <<<"$1"; }

	for guid in "${CAPDATA_GUIDS[@]}"; do
		u "$guid"
	done

	while read -rsa perm; do
		for guid in "${perm[@]}"; do
			b "$guid"
		done
		sensors | grep -A3 lenovo_wmi_other || true
		for guid in "${perm[@]}"; do
			u "$guid"
		done
	done < <(python3 -c "
	from itertools import permutations
	ps = permutations('${CAPDATA_GUIDS[*]}'.split())
	for p in ps: print(' '.join(p))")

	for guid in "${CAPDATA_GUIDS[@]}"; do
		b "$guid"
	done

Tested on ThinkBook 14 G7+ ASP.

Changes in v4:
- Get rid of wmi_has_guid() (thanks Armin Wolf's inspiration)
  - Add [PATCH v4 6/7], please review & test
  - Rework HWMON registration
    - Collect fan into from capdata00 and capdata_fan separately
    - Use a callback to collect fan info from capdata_fan
    - Trigger HWMON registration only if all fan info is collected
    - Do not check 0x04050000.supported, implied by the presense of
      capdata_fan
- Drop Reviewed-by & Tested-by from [PATCH v4 7/7] due to the changes,
  please review & test
- Link to v3: https://lore.kernel.org/r/20251031155349.24693-1-i@rong.moe/

Changes in v3:
- Fix grammar (thanks Derek J. Clark)
- Link to v2: https://lore.kernel.org/r/20251030193955.107148-1-i@rong.moe/

Changes in v2:
- Add a workaround for ACPI methods that return a 4B buffer for u32
  (thanks Armin Wolf)
- Fix function documentation (thanks kernel test bot)
- Reword documentation (thanks Derek J. Clark)
- Squash min/max reporting patch into the initial HWMON one (ditto)
- Query 0x04050000 for interface availability (ditto)
  - New parameter "expose_all_fans" to skip this check
- Enforce min/max RPM constraint on set (ditto)
  - New parameter "relax_fan_constraint" to disable this behavior
  - Drop parameter "ignore_fan_cap", superseded by the next one
  - New parameter "expose_all_fans" to expose fans w/o such data
- Assume auto mode on probe (ditto)
- Do not register HWMON device if no fan can be exposed
- fanX_target: Return -EBUSY instead of raw target value when fan stops
- Link to v1: https://lore.kernel.org/r/20251019210450.88830-1-i@rong.moe/

Rong Zhang (7):
  platform/x86: lenovo-wmi-helpers: Convert returned buffer into u32
  platform/x86: Rename lenovo-wmi-capdata01 to lenovo-wmi-capdata
  platform/x86: lenovo-wmi-{capdata,other}: Support multiple Capability
    Data
  platform/x86: lenovo-wmi-capdata: Add support for Capability Data 00
  platform/x86: lenovo-wmi-capdata: Add support for Fan Test Data
  platform/x86: lenovo-wmi-capdata: Wire up Fan Test Data
  platform/x86: lenovo-wmi-other: Add HWMON for fan reporting/tuning

 .../wmi/devices/lenovo-wmi-other.rst          |  43 +-
 drivers/platform/x86/lenovo/Kconfig           |   5 +-
 drivers/platform/x86/lenovo/Makefile          |   2 +-
 drivers/platform/x86/lenovo/wmi-capdata.c     | 804 ++++++++++++++++++
 drivers/platform/x86/lenovo/wmi-capdata.h     |  64 ++
 drivers/platform/x86/lenovo/wmi-capdata01.c   | 302 -------
 drivers/platform/x86/lenovo/wmi-capdata01.h   |  25 -
 drivers/platform/x86/lenovo/wmi-helpers.c     |  22 +-
 drivers/platform/x86/lenovo/wmi-other.c       | 511 ++++++++++-
 9 files changed, 1421 insertions(+), 357 deletions(-)
 create mode 100644 drivers/platform/x86/lenovo/wmi-capdata.c
 create mode 100644 drivers/platform/x86/lenovo/wmi-capdata.h
 delete mode 100644 drivers/platform/x86/lenovo/wmi-capdata01.c
 delete mode 100644 drivers/platform/x86/lenovo/wmi-capdata01.h


base-commit: 2ccec5944606ee1389abc7ee41986825c6ceb574
-- 
2.51.0

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