The base port numbers and addresses for the OLPC platform as established by Open Firmware are as follows.
Please note - these ports and addresses are written to MSR registers by the firmware - other Geode BIOS implementations may use different values. When in doubt, you can always get the base addresses by scanning the PCI configuration.
 I/O ports
18b0 : SMBUS 1000 : GPIO 1800 : MFGPT 1880 : IRQ mapper 1400 : PM 1841 : ACPI 1480 : AC-97. Audio Codec: Explanations are in Datasheet Page 9
 Memory space
fd000000 : Frame buffer fe000000 : Graphics processor fe004000 : Video processor fe008000 : Display controller. Display/Video/Graphics Controller/processor: Explanation in Geode Gx datasheet Chapter 6 fe01a000 : OHCI (USB1) fe01b000 : EHCI (USB2) efc00000 : UOC (USB option controller). USB Controller: Explanation in AMD Geode Companion Device Databook Chapter 5.5 fe00c000 : CaFe NAND fe010000 : CaFe SD fe014000 : CaFe Camera
These addresses can be "discovered" by doing PCI configuration reads to PCI device base address registers or by browing the Open Firmware device tree.