mb/opencellular/elgon: Enable write protection

* Verify the flash write protection on each boot
* Program non-volatile write protection on first boot

Tested using I715791b8ae5d1db1ef587321ae5c9daa10eb7dbc.

The bootblock is write-protected as long as the #WP pin is asserted low:
* Reprogramming of the status register fails.
* Trying to write to WP_RO region fails.

Programming the WP_RO is only possible if #WP pin is high.

Change-Id: I6a940c69ecb1dfd9704b2101c263570bebc5540e
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/29532
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

0 files changed, 0 insertions, 0 deletions