[U-Boot] yaffs2 u-boot patching support

[Charles Manning <manningc2@actrix.gen.nz>]

Hello ubooters and yaffsers

I was commissioned to refresh yaffs2 in u-boot and add a mechanism to support 
dynamic yaffs partition set up (way simpler than screwing around with mtd 
part) and manual configuration.

 Rather than do this as a once off, I set this scripting up so that this can 
be done at any time (painlessly I hope) to bring in the fresh code (as per 
Linux patching).

Basically...

Get latest from yaffs git.

cd yaffs2-dir/direct/u-boot

./patch-u-boot.sh uboot-dir

Edit your u-boot config file and add

#define CONFIG_YAFFS2 1


Rebuild u-boot (mrproper probably a Good Idea). Job done.

OK, so how does the new dynamic partition stuff work?

There are 2 new commands: ydevconfig configures a mount point "partition" and 
ydevls lists the mount points and their state

So for example let us say we want a mount point called foo on NAND device 0 
starting at block 55 and ending at block 999.

ydevconfig foo 0 55 999

Now you want to mount it.

ymount foo

Access files and do stuff...

yls foo
yls -l foo       # more info
ymkdir foo/dir
...

You can have multiple mountpoints in use at the same time though they are not 
allowed to overlap.

inband tags is selected automatically if there is insufficient space in 
oobavail to store the tags.

Have fun.

Charles