Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ea3d1606 authored by Matthew Garrett's avatar Matthew Garrett Committed by Linus Torvalds
Browse files

rtc: document the sysfs interface 



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

Signed-off-by: default avatarMatthew Garrett <mjg@redhat.com>
Cc: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: default avatarAlessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dac94d9e

Documentation/rtc.txt

+22 −0
Original line number Diff line number Diff line
@@ -135,6 +135,28 @@ a high functionality RTC is integrated into the SOC. That system might read 
the system clock from the discrete RTC, but use the integrated one for all

other tasks, because of its greater functionality.



SYSFS INTERFACE

---------------



The sysfs interface under /sys/class/rtc/rtcN provides access to various

rtc attributes without requiring the use of ioctls. All dates and times

are in the RTC's timezone, rather than in system time.



date:  	   	 RTC-provided date

max_user_freq:	 The maximum interrupt rate an unprivileged user may request

		 from this RTC.

name:		 The name of the RTC corresponding to this sysfs directory

since_epoch:	 The number of seconds since the epoch according to the RTC

time:		 RTC-provided time

wakealarm:	 The time at which the clock will generate a system wakeup

		 event. This is a one shot wakeup event, so must be reset

		 after wake if a daily wakeup is required. Format is either

		 seconds since the epoch or, if there's a leading +, seconds

		 in the future.



IOCTL INTERFACE

---------------



The ioctl() calls supported by /dev/rtc are also supported by the RTC class

framework.  However, because the chips and systems are not standardized,

some PC/AT functionality might not be provided.  And in the same way, some