The tp_smapi kernel module exposes some features of the ThinkPad hardware/firmware via a sysfs interface. Currently, the main implemented functionality is control of battery charging and extended battery status. The underlying hardware interfaces are SMAPI and direct access to the embedded controller.
This package also brings the source for an improved version of HDAPS which should work on newer ThinkPads too (the stock kernel version does not).
This package contains the source to be built with module-assistant or kernel-package.