linux.git/Documentation/rtc.txt, branch v4.19

Documentation: rtc: move iotcl interface documentation to ABI

2018-01-11T23:20:41+00:00

The ioctl interface should be in Documentation/ABI along with the rest
of the interfaces.

Signed-off-by: Aishwarya Pant 
Signed-off-by: Alexandre Belloni

Documentation: rtc: move sysfs documentation to ABI

2018-01-11T23:20:40+00:00

The sysfs documentation should be located under Documentation/ABI.

Signed-off-by: Alexandre Belloni

rtc: add generic nvmem support

2017-07-07T11:14:14+00:00

Many RTCs have an on board non volatile storage. It can be battery backed
RAM or an EEPROM. Use the nvmem subsystem to export it to both userspace
and in-kernel consumers.

This stays compatible with the previous (non documented) ABI that was using
/sys/class/rtc/rtcx/device/nvram to export that memory. But will warn about
the deprecation.

Signed-off-by: Alexandre Belloni

rtc.txt: standardize document format

2017-05-31T11:15:28+00:00

Each text file under Documentation follows a different
format. Some doesn't even have titles!

Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:

- adjust identation of the titles;
- mark a table as such;
- don't capitalize chapter names.

Signed-off-by: Mauro Carvalho Chehab 
Signed-off-by: Alexandre Belloni

rtc: implement a sysfs interface for clock offset

2016-03-14T16:08:16+00:00

clock offset may be set and read in decimal parts per billion
attribute is /sys/class/rtc/rtcN/offset
The attribute is only visible for rtcs that have set_offset implemented.

Signed-off-by: Joshua Clayton 
Signed-off-by: Alexandre Belloni

Documentation, split up rtc.txt into documentation and test file

2015-03-25T04:01:58+00:00

This patch splits rtc.txt into two separate files, one for the
documentation itself, and the other for the rtctest.c file.  The rtctest
file is moved into the kernel tools/testing/selftests/timers directory.
This will make automated testing easier.  Note that the only difference in
the rtc.txt file is that the location of the rtctest.c file has changed.

Signed-off-by: Prarit Bhargava 
Acked-by: Jonathan Corbet 
Acked-by: John Stultz 
Cc: corbet@lwn.net
Cc: rtc-linux@googlegroups.com
Cc: linux-doc@vger.kernel.org
Cc: a.zummo@towertech.it
Cc: prarit@redhat.com
Cc: john.stultz@linaro.org
Cc: shuahkh@osg.samsung.com
Signed-off-by: Shuah Khan

rtc: add ability to push out an existing wakealarm using sysfs

2013-07-03T23:07:54+00:00

This adds the ability for the rtc sysfs code to handle += characters at
the beginning of a wakealarm setting string.  This will allow the user
to attempt to push out an existing wakealarm by a provided amount.

In the case that the += characters are provided but the alarm is not
active -EINVAL is returned.

his is useful, at least for my purposes in suspend/resume testing.  The
basic test goes something like:

1. Set a wake alarm from userspace 5 seconds in the future

2. Start the suspend process (echo mem > /sys/power/state)

3. After ~2.5 seconds if userspace is still running (using another
   thread to check this), move the wake alarm 5 more seconds

If the "move" involves an unset of the wakealarm then there's a period
   of time where the system is midway through suspending but has no wake
   alarm.  It will get stuck.

We'd rather not remove the "move" since the idea is to avoid a cancelled
suspend when the alarm fires _during_ suspend.  It is difficult for the
test to tell the difference between a suspend that was cancelled because
the alarm fired too early and a suspend that was

Signed-off-by: Bernie Thompson 
Cc: Alessandro Zummo 
Cc: Doug Anderson 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rtc-proc: permit the /proc/driver/rtc device to use other devices

2012-10-05T18:05:01+00:00

To get time information via /proc/driver/rtc, only the first device (rtc0)
is used.  If the rtcN (eg.  rtc1 or rtc2) is used for the system clock,
there is no way to get information of rtcN via /proc/driver/rtc.  With
this patch, the time data can be retrieved from the system clock RTC.

If the RTC_HCTOSYS_DEVICE is not defined, then rtc0 is used by default.

Signed-off-by: Milo(Woogyom) Kim 
Cc: Alessandro Zummo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

RTC: Fix up rtc.txt documentation to reflect changes to generic rtc layer

2011-03-09T19:25:10+00:00

Now that the genric RTC layer handles much of the RTC functionality,
the rtc.txt documentation needs to be updated to remove outdated information.

CC: Thomas Gleixner 
CC: Alessandro Zummo 
CC: Marcelo Roberto Jimenez 
CC: rtc-linux@googlegroups.com
Signed-off-by: John Stultz

rtc: add boot_timesource sysfs attribute

2009-09-23T14:39:46+00:00

CONFIG_RTC_HCTOSYS allows the kernel to read the system time from the RTC
at boot and resume, avoiding the need for userspace to do so.
Unfortunately userspace currently has no way to know whether this
configuration option is enabled and thus cannot sensibly choose whether to
run hwclock itself or not.  Add a hctosys sysfs attribute which indicates
whether a given RTC set the system clock.

Signed-off-by: Matthew Garrett 
Acked-by: Alessandro Zummo 
Cc: Mark Brown 
Cc: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds