Usage:
rknand scan - scan Nand devices
rknand info - show all available Nand devices
rknand device [dev] - show or set current Nand device
rknand part [dev] - print partition table of one or all Nand devices
rknand read addr blk# cnt - read `cnt' blocks starting at block
`blk#' to memory address `addr'
rknand write addr blk# cnt - write `cnt' blocks starting at block
`blk#' from memory address `addr'