Modify the RTC API to provide one a status for the time reported by
the rtc_get() function:
0 - a reliable time is guaranteed,
< 0 - a reliable time isn't guaranteed (power fault, clock issues,
and so on).
The RTC chip drivers are responsible for providing this info if the
corresponding chip supports such functionality. If not - always
report that the time is reliable.
The POST RTC test was modified to detect the RTC faults utilizing
this new rtc_get() feature.
Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
This driver is based on the driver for the M41T11. In the intended
application, the RTC will be powered by a large capacitor, rather than a
battery. The driver therefore checks to see whether the RTC has lost
power. The chip's OUT bit is normally reset from its power-up state. If
the OUT bit is read as set, or if the date and time are not valid, then the
RTC is assumed to have lost power, and its date and time are reset to
1900-01-01 00:00:00.
Support for adjusting the speed of the clock to improve accuracy is
provided through an environment variable.
Signed-off-by: Larry Johnson <lrj@acm.org>
