[U-Boot] Adding a mmc protect command

[Eugene.Cho at dell.com]

Hi all,
I need to implement MMC write protection in u-boot, and was wondering what would be the best way.

Should this be a new mmc command or just APIs? Is there value in pushing this upstream?

I ask because I saw the following submission didn't make it.
http://lists.denx.de/pipermail/u-boot/2015-December/237810.html

The kernel.org's mmc-util has a write protect command we could model after if a "mmc protect" command is a better way to do this...
"writeprotect user set", "<type>" "<start block>" "<blocks>" "<device>\n"

Maybe something like this?
"mmc protect [perm|pwron|tmp|none] blk# cnt - set write protection\n"

Thoughts?