Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.
1 Kernel driver power_meter 2 ========================= 3 4 This driver talks to ACPI 4.0 power meters. 5 6 Supported systems: 7 * Any recent system with ACPI 4.0. 8 Prefix: 'power_meter' 9 Datasheet: http://acpi.info/, section 10.4. 10 11 Author: Darrick J. Wong 12 13 Description 14 ----------- 15 16 This driver implements sensor reading support for the power meters exposed in 17 the ACPI 4.0 spec (Chapter 10.4). These devices have a simple set of 18 features--a power meter that returns average power use over a configurable 19 interval, an optional capping mechanism, and a couple of trip points. The 20 sysfs interface conforms with the specification outlined in the "Power" section 21 of Documentation/hwmon/sysfs-interface. 22 23 Special Features 24 ---------------- 25 26 The power[1-*]_is_battery knob indicates if the power supply is a battery. 27 Both power[1-*]_average_{min,max} must be set before the trip points will work. 28 When both of them are set, an ACPI event will be broadcast on the ACPI netlink 29 socket and a poll notification will be sent to the appropriate 30 power[1-*]_average sysfs file. 31 32 The power[1-*]_{model_number, serial_number, oem_info} fields display arbitrary 33 strings that ACPI provides with the meter. The measures/ directory contains 34 symlinks to the devices that this meter measures. 35 36 Some computers have the ability to enforce a power cap in hardware. If this is 37 the case, the power[1-*]_cap and related sysfs files will appear. When the 38 average power consumption exceeds the cap, an ACPI event will be broadcast on 39 the netlink event socket and a poll notification will be sent to the 40 appropriate power[1-*]_alarm file to indicate that capping has begun, and the 41 hardware has taken action to reduce power consumption. Most likely this will 42 result in reduced performance. 43 44 There are a few other ACPI notifications that can be sent by the firmware. In 45 all cases the ACPI event will be broadcast on the ACPI netlink event socket as 46 well as sent as a poll notification to a sysfs file. The events are as 47 follows: 48 49 power[1-*]_cap will be notified if the firmware changes the power cap. 50 power[1-*]_interval will be notified if the firmware changes the averaging 51 interval.