linux.git/Documentation/rtc.txt, branch v3.12

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the rtc.txt documentation needs to be updated to remove outdated information.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

rtc: document the sysfs interface

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

The sysfs interface to the RTC class drivers is currently undocumented.
Add some basic documentation defining the semantics of the fields.

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

rtc: update documentation wrt RTC_PIE/irq_set_state

2009-09-23T14:39:45+00:00

Signed-off-by: Mike Frysinger 
Cc: David Brownell 
Signed-off-by: Alessandro Zummo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rtc: cleanup example code

2008-02-06T18:41:14+00:00

No functional changes here, just tighten up style/whitespace.

Signed-off-by: Mike Frysinger 
Cc: Alessandro Zummo 
Cc: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rtc: update documentation wrt irq_set_freq

2008-02-06T18:41:14+00:00

Document the proper use of the irq_set_freq function.

Signed-off-by: Mike Frysinger 
Cc: Alessandro Zummo 
Cc: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rtc: tweak driver documentation for rtc periodic

2007-11-15T02:45:37+00:00

The max_user_freq member is not really meant for RTC drivers to modify, so
update the rtc documentation so drivers writers know what is expected of
them when handling periodic events.

Signed-off-by: Mike Frysinger 
Acked-by: Alessandro Zummo 
Cc: David Brownell 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rtc: make example code jump to done instead of return when ioctl not supported

2007-07-17T17:23:08+00:00

Signed-off-by: Hans-Christian Egtvedt 
Cc: Haavard Skinnemoen 
Cc: David Brownell 
Cc: Alessandro Zummo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds