Documentation/hwmon/hp-wmi-sensors.rst

Source file repositories/reference/linux-study-clean/Documentation/hwmon/hp-wmi-sensors.rst

File Facts

System
Linux kernel
Corpus path
Documentation/hwmon/hp-wmi-sensors.rst
Extension
.rst
Size
6393 bytes
Lines
141
Domain
Support Tooling And Documentation
Bucket
Documentation
Inferred role
Support Tooling And Documentation: documentation
Status
atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

.. SPDX-License-Identifier: GPL-2.0-or-later

.. include:: <isonum.txt>

===========================
Linux HP WMI Sensors Driver
===========================

:Copyright: |copy| 2023 James Seo <james@equiv.tech>

Description
===========

Hewlett-Packard (and some HP Compaq) business-class computers report hardware
monitoring information via Windows Management Instrumentation (WMI).
This driver exposes that information to the Linux hwmon subsystem, allowing
userspace utilities like ``sensors`` to gather numeric sensor readings.

sysfs interface
===============

When the driver is loaded, it discovers the sensors available on the
system and creates the following sysfs attributes as necessary within
``/sys/class/hwmon/hwmon[X]``:

(``[X]`` is some number that depends on other system components.)

======================= ======= ===================================
Name                    Perm    Description
======================= ======= ===================================
``curr[X]_input``       RO      Current in milliamperes (mA).
``curr[X]_label``       RO      Current sensor label.
``fan[X]_input``        RO      Fan speed in RPM.
``fan[X]_label``        RO      Fan sensor label.
``fan[X]_fault``        RO      Fan sensor fault indicator.
``fan[X]_alarm``        RO      Fan sensor alarm indicator.
``in[X]_input``         RO      Voltage in millivolts (mV).
``in[X]_label``         RO      Voltage sensor label.
``temp[X]_input``       RO      Temperature in millidegrees Celsius
                                (m\ |deg|\ C).
``temp[X]_label``       RO      Temperature sensor label.
``temp[X]_fault``       RO      Temperature sensor fault indicator.
``temp[X]_alarm``       RO      Temperature sensor alarm indicator.
``intrusion[X]_alarm``  RW      Chassis intrusion alarm indicator.
======================= ======= ===================================

``fault`` attributes
  Reading ``1`` instead of ``0`` as the ``fault`` attribute for a sensor
  indicates that it has encountered some issue during operation such that
  measurements from it should not be trusted. If a sensor with the fault
  condition recovers later, reading this attribute will return ``0`` again.

``alarm`` attributes
  Reading ``1`` instead of ``0`` as the ``alarm`` attribute for a sensor
  indicates that one of the following has occurred, depending on its type:

  - ``fan``: The fan has stalled or has been disconnected while running.
  - ``temp``: The sensor reading has reached a critical threshold.
    The exact threshold is system-dependent.
  - ``intrusion``: The system's chassis has been opened.

  After ``1`` is read from an ``alarm`` attribute, the attribute resets itself
  and returns ``0`` on subsequent reads. As an exception, an
  ``intrusion[X]_alarm`` can only be manually reset by writing ``0`` to it.

debugfs interface
=================

.. warning:: The debugfs interface is subject to change without notice
             and is only available when the kernel is compiled with

Annotation

Implementation Notes