setting up the timer fails, because on some types of chips that's the
first attempt to access the device. If the chip is missing/non-responsive
then you'd get a driver that attached and didn't register the rtc, with
no clue about why. On other chip types there are inits that come before
timer setup, and they already print messages about errors.
generic driver with minimal feature support for a large number of chips.
More featureful per-chip drivers might exist (especially out-of-tree) and
those should win the bidding even if they use BUS_PROBE_DEFAULT.
between 12/24 hour mode. Also fix conversion between 12 and 24 hour mode.
It's not as easy as adding/subtracting 12, because the clock doesn't roll
over 11->0, it rolls over 12->1; 0 isn't a valid hour in AM/PM mode.
all the chips in the NXP PCA212x and PCA/PCF85xx series. In addition to
supporting more chips, this driver uses the countdown timer on the chips as
a fractional seconds counter, giving it a resolution of about 15 milliseconds.
