hwclock: add --vl-read, --vl-clear documentation and bash-completion

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>

diff --git a/bash-completion/hwclock b/bash-completion/hwclock
index 6b4c01724dd7e58ef05e35806765313ce90d8776..6240d7d4be646be1ff04e0bd9a8ec72ace663c59 100644 (file)
--- a/bash-completion/hwclock
+++ b/bash-completion/hwclock
@@ -54,6 +54,8 @@ _hwclock_module()
                                --epoch
                                --param-get
                                --param-set
+                               --vl-read
+                               --vl-clear
                                --update-drift
                                --noadjfile
                                --adjfile

diff --git a/sys-utils/hwclock.8.adoc b/sys-utils/hwclock.8.adoc
index 3e181edd23df581b21913e66250ed4e976267c5a..0b23a37e8dae666f16d352a3cbbf73ac0cac0cb9 100644 (file)
--- a/sys-utils/hwclock.8.adoc
+++ b/sys-utils/hwclock.8.adoc
@@ -101,6 +101,11 @@ The first two are only available on the first call of *settimeofday*(2) after bo
 *-w*, *--systohc*::
 Set the Hardware Clock from the System Clock, and update the timestamps in _{ADJTIME_PATH}_. With the *--update-drift* option also (re)calculate the drift factor. Try it without the option if *--systohc* fails. See *--update-drift* below.
 
+*--vl-read*, *--vl-clear*::
+Some RTC devices are able to monitor the voltage of the backup battery and thus provide a way for the user to know that the battery should be replaced. The *--vl-read* function retrieves the Voltage Low information and decodes the result into human-readable form. The *--vl-clear* function resets the Voltage Low information, which is necessary for some RTC devices after a battery replacement.
++
+See the Kernel's _include/uapi/linux/rtc.h_ for details on which pieces of information may be returned. Note that not all RTC devices have this monitoring capability, nor do all drivers necessarily support reading the information.
+
 include::man-common/help-version.adoc[]
 
 == OPTIONS