In most devices, the button ladder is not actually derived from VDDIO but
from a constant voltage source, making it very easy to read it. However on
some devices like ther ZEN X-Fi Style, the ladder is wired to VDDIO we
can be changed so it's crucial that the button driver correctly scales the
values wrt VDDIO.
Change-Id: Ifc11abe2838fa7d16d0d60ecd96964a8dc5ea6d7
The lradc architecture of the stmp3600 is rather different:
only channels 6 and 7 have configurable source and we need to
take care when allocating channels so that we can actually
measure the right channel! Delegate die temperature sensing to
the power block on stmp3600.
Change-Id: I0860eb4ea98240facc3d4a19d61684eca5f630cc
Rework code to be more useful:
- move battery channel init to lradc
- always init lradc from system (previously from adc)
- don't reserve channels for vddio, nmos or pmos
- implement external temperature sensing using current source
- use this for battery sensing on the Fuze+ (calibration needed)
Change-Id: I5f9a24b9243db7d1e6bdb16b84bc891e61d0c318
