cr50: add vendor command to restore corrupted header
The upcoming move of the Cr50 firmware update to the background
requires postponing the activation of the newly uploaded Cr50 image to
a later point in time, when the AP is ready to switch to start using
the new Cr50 image.
The suggested way of achieving it is as follows: when downloading the
new image, the current Cr50 code modifies the header's 'image_size'
field, setting its top bit to 1. This both makes the size invalid and
guarantees that the new image would not verify on the following Cr50
restarts.
When the AP is ready to switch to running the new Cr50 image, it will
send a vendor command, which would trigger the currently running Cr50
image to restore the other image's size field. This vendor command
would also communicate the timeout for the Cr50 to wait before
rebooting, if there has been at least one header (ro or rw) restored.
Rebooting the Cr50 would trigger rebooting the AP, resulting in the
entire system running the updated firmware.
Response sent to the AP will indicate if there has been a header
restored and the reboot is indeed upcoming, this would allow the AP to
quiesce the state of the device to handle the reboot gracefully.
BRANCH=cr50
BUG=b:35580805
TEST=with the rest of the patches applied observed the system properly
after the new header version was restored.
Change-Id: Ia1edee67b6aa8f458810d5dc2931477cfaab1566
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/457676
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
4 files changed
