[U-Boot] RW filesystem support for new eMMC, eSD and eLBA flash devices

[twebb]

A relatively new class of flash memory device is available that
generally consists of bulk NAND flash (SLC or MLC) and an on-board
controller (that handles ECC and flash translation layer).  (See
http://www.micron.com/products/nand/managed-nand/index for example.)
Can anyone tell me if u-boot supports read and write access to such a
device?  Of course I know u-boot can read/write nor, nand, and onenand
flash, but can it write SD or MMC flash?  From previous thread here I
believe the answer is no for writing in the a filesystem's format
(i.e. fat32 or ext3 for example).  Is there a method to do "raw"
writes?

Thanks,
twebb