mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-26 06:04:14 +08:00
7ebd8b66dd
Now that all files were converted to ReST format, rename them and add an index. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
55 lines
2.1 KiB
ReStructuredText
55 lines
2.1 KiB
ReStructuredText
Kernel driver power_meter
|
|
=========================
|
|
|
|
This driver talks to ACPI 4.0 power meters.
|
|
|
|
Supported systems:
|
|
|
|
* Any recent system with ACPI 4.0.
|
|
|
|
Prefix: 'power_meter'
|
|
|
|
Datasheet: http://acpi.info/, section 10.4.
|
|
|
|
Author: Darrick J. Wong
|
|
|
|
Description
|
|
-----------
|
|
|
|
This driver implements sensor reading support for the power meters exposed in
|
|
the ACPI 4.0 spec (Chapter 10.4). These devices have a simple set of
|
|
features--a power meter that returns average power use over a configurable
|
|
interval, an optional capping mechanism, and a couple of trip points. The
|
|
sysfs interface conforms with the specification outlined in the "Power" section
|
|
of Documentation/hwmon/sysfs-interface.rst.
|
|
|
|
Special Features
|
|
----------------
|
|
|
|
The `power[1-*]_is_battery` knob indicates if the power supply is a battery.
|
|
Both `power[1-*]_average_{min,max}` must be set before the trip points will work.
|
|
When both of them are set, an ACPI event will be broadcast on the ACPI netlink
|
|
socket and a poll notification will be sent to the appropriate
|
|
`power[1-*]_average` sysfs file.
|
|
|
|
The `power[1-*]_{model_number, serial_number, oem_info}` fields display
|
|
arbitrary strings that ACPI provides with the meter. The measures/ directory
|
|
contains symlinks to the devices that this meter measures.
|
|
|
|
Some computers have the ability to enforce a power cap in hardware. If this is
|
|
the case, the `power[1-*]_cap` and related sysfs files will appear. When the
|
|
average power consumption exceeds the cap, an ACPI event will be broadcast on
|
|
the netlink event socket and a poll notification will be sent to the
|
|
appropriate `power[1-*]_alarm` file to indicate that capping has begun, and the
|
|
hardware has taken action to reduce power consumption. Most likely this will
|
|
result in reduced performance.
|
|
|
|
There are a few other ACPI notifications that can be sent by the firmware. In
|
|
all cases the ACPI event will be broadcast on the ACPI netlink event socket as
|
|
well as sent as a poll notification to a sysfs file. The events are as
|
|
follows:
|
|
|
|
`power[1-*]_cap` will be notified if the firmware changes the power cap.
|
|
`power[1-*]_interval` will be notified if the firmware changes the averaging
|
|
interval.
|