Marble's U35 is a Maxlinear XRP7724 Quad PWM Power Controller. It's highly configurable!
MaxLinear supplies a tool (closed-source, unfortunately) for dealing with its hundreds of configuration registers: PowerArchitect Design Tool Version 5 (PA5)
The Marble.pwrxr file in this directory defines the function of the XRP7724 for this board; it's effectively a configuration file for PA5. Its key parameters are:
- Channel 1: 2.5V, 3.16A
- Channel 2: 3.3V, 6.0A
- Channel 3: 1.0V, 10.4A
- Channel 4: 1.8V, 4.0A
There are two corresponding Intel hex files that result:
The first one is for testing, the second to burn the configuration into flash.
That chip's programming gets done over an I2C bus, and at least that process is documented in MaxLinear's ANP-38 and ANP-39. Also see Exar's UnivPMIC project, and the Marble support code in marble_mmc (WIP).