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Most systems don't have a lightbar. Those that do need a way to detect that one exists. That's easily done by just sending a EC_CMD_LIGHTBAR_CMD command to the EC and checking the result. If the response is EC_RES_INVALID_COMMAND, there isn't a lightbar. But what .cmd value should we use in struct ec_params_lightbar? Future lightbar implementations (if any), could remove existing functions or add new ones, so there isn't a safe choice. This change adds a LIGHTBAR_CMD_VERSION operation to determine if any new implementation exists. Future systems should return some useful information in response to this command. Existing systems will return EC_RES_INVALID_PARAM, which is enough to distinguish them. BUG=chromium:239205 BRANCH=none TEST=manual make BOARD=link make BOARD=link runtests There are no user-visible changes in functionality to anything. Change-Id: Ibe37f74a4dcbf68dd6bfd1963530aec907e67534 Signed-off-by: Bill Richardson <wfrichar@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/167549 Reviewed-by: Randall Spangler <rspangler@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.