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r: 164812
b: refs/heads/master
c: ea3d160
h: refs/heads/master
v: v3
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Matthew Garrett authored and Linus Torvalds committed Sep 23, 2009
1 parent 279f699 commit f86af27
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2 changes: 1 addition & 1 deletion [refs]
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refs/heads/master: dac94d9ec98517e8fe3f980e38f29ea3ac712168
refs/heads/master: ea3d1606fd32059461309099e8856c6652888a79
22 changes: 22 additions & 0 deletions trunk/Documentation/rtc.txt
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Expand Up @@ -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
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