power

Field	Value
Subsystem	legacy `power` class directory; only known in-tree references are ds2760 battery monitor entries inside the power-supply ABI file; implementation file not in cached tree
Config gate	not verifiable from the cached sources (cached tree has no Kconfig or driver files)
ABI documentation	two What entries inside `Documentation/ABI/testing/sysfs-class-power` (`/sys/class/power/ds2760-battery.*/charge_now`, `charge_full`); no sysfs-class-power ABI file of its own
Since	May 2010, KernelVersion 2.6.35 (both entries)
Live (5.10.134 host)	class absent: not in live-sys/class-list.txt, no /sys/class/power
Ledger ID	SYSC-power

What it represents

A distinct sysfs class name power - not to be confused with any of its three namesakes. The only in-tree documentation is device-specific: the ds2760 battery monitor driver’s charge counter files, whose What entries spell the path /sys/class/power/ds2760-battery.*/ and which live, oddly, inside the power-supply ABI file rather than a class file of their own. The cached tree contains no driver or core sources, so nothing more about the class layout or registration can be verified here.

Relationship to the device model

Cannot be documented from the cached sources beyond the two attribute paths. Disambiguation of the three different things called “power”:

/sys/class/power/ - this class (ds2760 battery entries, 2.6.35-era).
/sys/class/power_supply/ - the power supply class: batteries, AC, USB; see power_supply.
/sys/power/ - a top-level sysfs directory (not a class) for system sleep control, documented in Documentation/ABI/testing/sysfs-power (state, mem_sleep, disk).
/sys/devices/.../power/ - per-device runtime-PM and wakeup attributes, documented in Documentation/ABI/testing/sysfs-devices-power.

Attributes

Attribute	R/W	Unit/format	Conditional?	Source
`ds2760-battery.*/charge_now`	RW	current coulomb counter value of the battery monitor chip	ds2760 hardware	ABI `sysfs-class-power`, May 2010, 2.6.35
`ds2760-battery.*/charge_full`	RW	assumed battery full level, adjustable as batteries age	ds2760 hardware	ABI `sysfs-class-power`, May 2010, 2.6.35

Both files are explicitly described as writeable in the ABI text; they tune the gauge’s fuel bookkeeping rather than report measurements.

Safety and writes

Writing charge_full or charge_now corrupts the battery gauge’s idea of its capacity if done wrongly (the ABI describes adjusting full level as batteries age), so these are calibration writes with permanent effects on remaining-capacity reporting. The class does not exist on the live 5.10.134 host; ds2760 is embedded (iPAQ-era) hardware and the entries document legacy interfaces. Beyond the two files above, nothing about this class is verifiable from the cached sources - the page is deliberately source-limited.

References

Documentation/ABI/testing/sysfs-class-power (cached copy; ds2760 entries at lines 683-704)
Documentation/ABI/testing/sysfs-power, Documentation/ABI/testing/sysfs-devices-power (for the disambiguation)
power_supply sibling page; coverage: ledger
Live check: /sys/class/power absent (kernel 5.10.134, read-only enumeration)