U-boot and Flash (NOR, NAND & SPI)

U-boot now has support for 3 different flash technologies:
NOR flash (traditional parallel 8-bit or 16-bit wide data bus, with a dedicated address bus).
NAND flash (newer technology 8-bit or 16-bit data bus, which is multiplexed with the address bus).
SPI serial flash (newer technology, simple 4-wire serial bus).

http://www.stlinux.com/u-boot/flash