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authorLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 12:32:11 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-23 12:32:11 -0400
commitc11f6c82581e8be4e1829c677db54e7f55cebece (patch)
tree1a116241b0831ded998aabe800bdc24104cbd826 /Documentation/hwmon
parent40aba218969914d1b225e742617adb921cf94eae (diff)
parent193a6dec1c0246a80b6d0101e4f351ccf877bcac (diff)
Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (119 commits) ACPI: don't pass handle for fixed hardware notifications ACPI: remove null pointer checks in deferred execution path ACPI: simplify deferred execution path acerhdf: additional BIOS versions acerhdf: convert to dev_pm_ops acerhdf: fix fan control for AOA150 model thermal: add missing Kconfig dependency acpi: switch /proc/acpi/{debug_layer,debug_level} to seq_file hp-wmi: fix rfkill memory leak on unload ACPI: remove unnecessary #ifdef CONFIG_DMI ACPI: linux/acpi.h should not include linux/dmi.h hwmon driver for ACPI 4.0 power meters topstar-laptop: add new driver for hotkeys support on Topstar N01 thinkpad_acpi: fix rfkill memory leak on unload thinkpad-acpi: report brightness events when required thinkpad-acpi: don't poll by default any of the reserved hotkeys thinkpad-acpi: Fix procfs hotkey reset command thinkpad-acpi: deprecate hotkey_bios_mask thinkpad-acpi: hotkey poll fixes thinkpad-acpi: be more strict when detecting a ThinkPad ...
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1Kernel driver power_meter
2=========================
3
4This driver talks to ACPI 4.0 power meters.
5
6Supported systems:
7 * Any recent system with ACPI 4.0.
8 Prefix: 'power_meter'
9 Datasheet: http://acpi.info/, section 10.4.
10
11Author: Darrick J. Wong
12
13Description
14-----------
15
16This driver implements sensor reading support for the power meters exposed in
17the ACPI 4.0 spec (Chapter 10.4). These devices have a simple set of
18features--a power meter that returns average power use over a configurable
19interval, an optional capping mechanism, and a couple of trip points. The
20sysfs interface conforms with the specification outlined in the "Power" section
21of Documentation/hwmon/sysfs-interface.
22
23Special Features
24----------------
25
26The power[1-*]_is_battery knob indicates if the power supply is a battery.
27Both power[1-*]_average_{min,max} must be set before the trip points will work.
28When both of them are set, an ACPI event will be broadcast on the ACPI netlink
29socket and a poll notification will be sent to the appropriate
30power[1-*]_average sysfs file.
31
32The power[1-*]_{model_number, serial_number, oem_info} fields display arbitrary
33strings that ACPI provides with the meter. The measures/ directory contains
34symlinks to the devices that this meter measures.
35
36Some computers have the ability to enforce a power cap in hardware. If this is
37the case, the power[1-*]_cap and related sysfs files will appear. When the
38average power consumption exceeds the cap, an ACPI event will be broadcast on
39the netlink event socket and a poll notification will be sent to the
40appropriate power[1-*]_alarm file to indicate that capping has begun, and the
41hardware has taken action to reduce power consumption. Most likely this will
42result in reduced performance.
43
44There are a few other ACPI notifications that can be sent by the firmware. In
45all cases the ACPI event will be broadcast on the ACPI netlink event socket as
46well as sent as a poll notification to a sysfs file. The events are as
47follows:
48
49power[1-*]_cap will be notified if the firmware changes the power cap.
50power[1-*]_interval will be notified if the firmware changes the averaging
51interval.