Today I've finished first implementation of rx1950 battery driver. It's based on adc-battery driver from hh.org
Charging now work correctly (I've tested it, it can charge my battery to 100%, and then disables charging and makes red LED to light solid)
Battery level estimated only by battery voltage. It's quite inaqurate and I'm trying to find ways to improve it.
Results of my efforts as usually available on hh.org: http://handhelds.org/moin/moin.cgi/HpIpaqRx1950
P.S. Unfortunately, battery driver conflicts with touchscreen driver. I'm working on solution...