mirror of
https://github.com/Telecominfraproject/OpenCellular.git
synced 2026-01-03 13:39:53 +00:00
a5d2fa9fb4
use the IT8380 SMB0 interface connected to the Servo FTDI chip to access the internal flash. The write-protect is not implemented. Signed-off-by: Vincent Palatin <vpalatin@chromium.org> Signed-off-by: Alec Berg <alecaberg@chromium.org> BRANCH=none BUG=chrome-os-partner:23576 TEST=check waveforms on the Logic analyzer. Change-Id: Ic3402e4e8def731fe4f2fe93be254f5fd0982abf Reviewed-on: https://chromium-review.googlesource.com/175677 Reviewed-by: Vincent Palatin <vpalatin@chromium.org> Commit-Queue: Vincent Palatin <vpalatin@chromium.org> Tested-by: Vincent Palatin <vpalatin@chromium.org>
In the most general case, the flash layout looks something like this: +---------------------+ | Reserved for EC use | +---------------------+ +---------------------+ | Vblock B | +---------------------+ | RW firmware B | +---------------------+ +---------------------+ | Vblock A | +---------------------+ | RW firmware A | +---------------------+ +---------------------+ | FMAP | +---------------------+ | Public root key | +---------------------+ | Read-only firmware | +---------------------+ BIOS firmware (and kernel) put the vblock info at the start of each image where it's easy to find. The Blizzard EC expects the firmware vector table to come first, so we have to put the vblock at the end. This means we have to know where to look for it, but that's built into the FMAP and the RO firmware anyway, so that's not an issue. The RO firmware doesn't need a vblock of course, but it does need some reserved space for vboot-related things. Using SHA256/RSA4096, the vblock is 2468 bytes (0x9a4), while the public root key is 1064 bytes (0x428) and the current FMAP is 644 bytes (0x284). If we reserve 4K at the top of each FW image, that should give us plenty of room for vboot-related stuff.