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rtc/ab8500: add calibration attribute to AB8500 RTC
[~shefty/rdma-dev.git] / Documentation / ABI / testing / sysfs-class-rtc-rtc0-device-rtc_calibration
1 What:           Attribute for calibrating ST-Ericsson AB8500 Real Time Clock
2 Date:           Oct 2011
3 KernelVersion:  3.0
4 Contact:        Mark Godfrey <mark.godfrey@stericsson.com>
5 Description:    The rtc_calibration attribute allows the userspace to
6                 calibrate the AB8500.s 32KHz Real Time Clock.
7                 Every 60 seconds the AB8500 will correct the RTC's value
8                 by adding to it the value of this attribute.
9                 The range of the attribute is -127 to +127 in units of
10                 30.5 micro-seconds (half-parts-per-million of the 32KHz clock)
11 Users:          The /vendor/st-ericsson/base_utilities/core/rtc_calibration
12                 daemon uses this interface.