linux/Documentation/ABI/testing/sysfs-class-rtc-rtc0-device-rtc_calibration

What:           /sys/class/rtc/rtc0/device/rtc_calibration
Date:           Oct 2011
KernelVersion:  3.0
Contact:        Mark Godfrey <[email protected]>
Description:    Attribute for calibrating ST-Ericsson AB8500 Real Time Clock
		The rtc_calibration attribute allows the userspace to
                calibrate the AB8500.s 32KHz Real Time Clock.
                Every 60 seconds the AB8500 will correct the RTC's value
                by adding to it the value of this attribute.

                The range of the attribute is -127 to +127 in units of
                30.5 micro-seconds (half-parts-per-million of the 32KHz clock)
Users:          The /vendor/st-ericsson/base_utilities/core/rtc_calibration
                daemon uses this interface.