rtc: Document RTC_VL_READ and RTC_VL_CLR ioctls

RTC_VL_READ and RTC_VL_CLR have been introduced in 2012 with commit
0f20b767e2 ("drivers/rtc/rtc-pcf8563.c: add RTC_VL_READ/RTC_VL_CLR ioctl
feature")

Document them now that they have been unified.

Link: https://lore.kernel.org/r/20191214220259.621996-3-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Alexandre Belloni 2019-12-14 23:02:44 +01:00
parent 3431ca4837
commit 790a19f18a
1 changed files with 8 additions and 0 deletions

View File

@ -33,6 +33,14 @@ Description:
Requires a separate RTC_PIE_ON call to enable the periodic
interrupts.
* RTC_VL_READ: Read the voltage inputs status of the RTC when
supported. The value is a bit field of RTC_VL_*, giving the
status of the main and backup voltages.
* RTC_VL_CLEAR: Clear the voltage status of the RTC. Some RTCs
need user interaction when the backup power provider is
replaced or charged to be able to clear the status.
The ioctl() calls supported by the older /dev/rtc interface are
also supported by the newer RTC class framework. However,
because the chips and systems are not standardized, some PC/AT