v4.19.13 snapshot.
diff --git a/Documentation/ABI/testing/sysfs-class-rtc b/Documentation/ABI/testing/sysfs-class-rtc
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+What: /sys/class/rtc/
+Date: March 2006
+KernelVersion: 2.6.17
+Contact: linux-rtc@vger.kernel.org
+Description:
+ The rtc/ class subdirectory belongs to the RTC subsystem.
+
+What: /sys/class/rtc/rtcX/
+Date: March 2006
+KernelVersion: 2.6.17
+Contact: linux-rtc@vger.kernel.org
+Description:
+ The /sys/class/rtc/rtc{0,1,2,3,...} directories correspond
+ to each RTC device.
+
+What: /sys/class/rtc/rtcX/date
+Date: March 2006
+KernelVersion: 2.6.17
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RO) RTC-provided date in YYYY-MM-DD format
+
+What: /sys/class/rtc/rtcX/hctosys
+Date: September 2009
+KernelVersion: 2.6.32
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RO) 1 if the RTC provided the system time at boot via the
+ CONFIG_RTC_HCTOSYS kernel option, 0 otherwise
+
+What: /sys/class/rtc/rtcX/max_user_freq
+Date: October 2007
+KernelVersion: 2.6.24
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RW) The maximum interrupt rate an unprivileged user may request
+ from this RTC.
+
+What: /sys/class/rtc/rtcX/name
+Date: March 2006
+KernelVersion: 2.6.17
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RO) The name of the RTC corresponding to this sysfs directory
+
+What: /sys/class/rtc/rtcX/range
+Date: January 2018
+KernelVersion: 4.16
+Contact: linux-rtc@vger.kernel.org
+Description:
+ Valid time range for the RTC, as seconds from epoch, formatted
+ as [min, max]
+
+What: /sys/class/rtc/rtcX/since_epoch
+Date: March 2006
+KernelVersion: 2.6.17
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RO) RTC-provided time as the number of seconds since the epoch
+
+What: /sys/class/rtc/rtcX/time
+Date: March 2006
+KernelVersion: 2.6.17
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RO) RTC-provided time in 24-hour notation (hh:mm:ss)
+
+What: /sys/class/rtc/rtcX/offset
+Date: February 2016
+KernelVersion: 4.6
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RW) The amount which the rtc clock has been adjusted in
+ firmware. Visible only if the driver supports clock offset
+ adjustment. The unit is parts per billion, i.e. The number of
+ clock ticks which are added to or removed from the rtc's base
+ clock per billion ticks. A positive value makes a day pass more
+ slowly, longer, and a negative value makes a day pass more
+ quickly.
+
+What: /sys/class/rtc/rtcX/wakealarm
+Date: February 2007
+KernelVersion: 2.6.20
+Contact: linux-rtc@vger.kernel.org
+Description:
+ (RW) 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 seconds since the
+ epoch by default, or if there's a leading +, seconds in the
+ future, or if there is a leading +=, seconds ahead of the
+ current alarm.