[U-Boot] "nand biterr" ... got an implementation?

[David Brownell]

I was hoping that I could use that to test some NAND code, but
then I noticed it wasn't implemented.  I would have expected that
U-Boot command wouldn't exist until they're implemented...

I'm hoping someone has an implementation.  With at least these
characteristics:

 - Doesn't toggle the same bit each time
 - Repeating N times on a block introduces N distinct 1-bit errors
 - Normally affects only the data area, not spare/OOB
     * although forcing bit errors in ECC would be valuable too
     * ditto the rest of the OOB ... though likely they'd be ignored

Am I hoping in vain?  ;)

- Dave