FreeBSD NAND flash driver

[Andrew Turner]

I've been working on a FreeBSD NAND flash driver and NAND simulator [1].
I have tested reading and writing to the simulated NAND device but not
erasing.

It is not usable yet as the write will not perform any deletes from the
device, either the file system or another geom will have to issue
a BIO_DELETE followed by BIO_WRITE's to write to the disk. This is done
to support NAND flash aware file systems.

TODO:
 * ECC support.
 * Add GEOM attributes to get information about the NAND device out,
   eg. Block size, OOB data, etc.
 * Test the erase code.
 * Add support for real hardware.
 * Read the parameter page on parts that support it to get the required
   information.

Andrew

[1] http://fubar.geek.nz/files/freebsd/nand/freebsd-nand-20090405.tar.gz