1 .. SPDX-License-Identifier: GPL-2.0-or-later
2
3 .. include:: <isonum.txt>
4
5 ===========================
6 Linux HP WMI Sensors Driver
7 ===========================
8
9 :Copyright: |copy| 2023 James Seo <james@equiv.
10
11 Description
12 ===========
13
14 Hewlett-Packard (and some HP Compaq) business-
15 monitoring information via Windows Management
16 This driver exposes that information to the Li
17 userspace utilities like ``sensors`` to gather
18
19 sysfs interface
20 ===============
21
22 When the driver is loaded, it discovers the se
23 system and creates the following sysfs attribu
24 ``/sys/class/hwmon/hwmon[X]``:
25
26 (``[X]`` is some number that depends on other
27
28 ======================= ======= ==============
29 Name Perm Description
30 ======================= ======= ==============
31 ``curr[X]_input`` RO Current in mil
32 ``curr[X]_label`` RO Current sensor
33 ``fan[X]_input`` RO Fan speed in R
34 ``fan[X]_label`` RO Fan sensor lab
35 ``fan[X]_fault`` RO Fan sensor fau
36 ``fan[X]_alarm`` RO Fan sensor ala
37 ``in[X]_input`` RO Voltage in mil
38 ``in[X]_label`` RO Voltage sensor
39 ``temp[X]_input`` RO Temperature in
40 (m\ |deg|\ C).
41 ``temp[X]_label`` RO Temperature se
42 ``temp[X]_fault`` RO Temperature se
43 ``temp[X]_alarm`` RO Temperature se
44 ``intrusion[X]_alarm`` RW Chassis intrus
45 ======================= ======= ==============
46
47 ``fault`` attributes
48 Reading ``1`` instead of ``0`` as the ``faul
49 indicates that it has encountered some issue
50 measurements from it should not be trusted.
51 condition recovers later, reading this attri
52
53 ``alarm`` attributes
54 Reading ``1`` instead of ``0`` as the ``alar
55 indicates that one of the following has occu
56
57 - ``fan``: The fan has stalled or has been d
58 - ``temp``: The sensor reading has reached a
59 The exact threshold is system-dependent.
60 - ``intrusion``: The system's chassis has be
61
62 After ``1`` is read from an ``alarm`` attrib
63 and returns ``0`` on subsequent reads. As an
64 ``intrusion[X]_alarm`` can only be manually
65
66 debugfs interface
67 =================
68
69 .. warning:: The debugfs interface is subject
70 and is only available when the ke
71 ``CONFIG_DEBUG_FS`` defined.
72
73 The standard hwmon interface in sysfs exposes
74 that are connected as of driver initialization
75 other sensors in WMI that do not meet these cr
76 system-dependent "platform events objects" use
77 be present. A debugfs interface is therefore p
78 all available HP WMI sensors and platform even
79
80 ``/sys/kernel/debug/hp-wmi-sensors-[X]/sensor`
81 contains one numbered entry per sensor with th
82
83 =============================== ==============
84 Name Example
85 =============================== ==============
86 ``name`` ``CPU0 Fan``
87 ``description`` ``Reports CPU0
88 ``sensor_type`` ``12``
89 ``other_sensor_type`` (an empty stri
90 ``operational_status`` ``2``
91 ``possible_states`` ``Normal,Cauti
92 ``current_state`` ``Normal``
93 ``base_units`` ``19``
94 ``unit_modifier`` ``0``
95 ``current_reading`` ``1008``
96 ``rate_units`` ``0`` (only ex
97 =============================== ==============
98
99 If platform events objects are available,
100 ``/sys/kernel/debug/hp-wmi-sensors-[X]/platfor
101 contains one numbered entry per object with th
102
103 =============================== ==============
104 Name Example
105 =============================== ==============
106 ``name`` ``CPU0 Fan Sta
107 ``description`` ``CPU0 Fan Spe
108 ``source_namespace`` ``root\wmi``
109 ``source_class`` ``HPBIOS_BIOSE
110 ``category`` ``3``
111 ``possible_severity`` ``25``
112 ``possible_status`` ``5``
113 =============================== ==============
114
115 These represent the properties of the underlyi
116 and ``HPBIOS_PlatformEvents`` WMI objects, whi
117 See [#]_ for more details and Managed Object F
118
119 Known issues and limitations
120 ============================
121
122 - If the existing hp-wmi driver for non-busine
123 loaded, ``alarm`` attributes will be unavail
124 support them. This is because the same WMI e
125 for ``alarm`` attributes is used on those sy
126 - Dubious sensor hardware and inconsistent BIO
127 observed to cause inaccurate readings and pe
128 failing to occur or occurring only once per
129 - Only temperature, fan speed, and intrusion s
130 the wild so far. Support for voltage and cur
131 provisional.
132 - Although HP WMI sensors may claim to be of a
133 types unknown to hwmon will not be supported
134
135 References
136 ==========
137
138 .. [#] Hewlett-Packard Development Company, L.
139 "HP Client Management Interface Technic
140 Available: https://h20331.www2.hp.com/h
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