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The ID detection and charging circuits on Spring are very different from that on Kirby. PWM current limit is no longer used. The ID detection sequence is also different. Also, there is no boost circuit on Kirby. Given those hardware issues that we had to work around on Spring, it's unlikely that we will have another board that shares the same/similar ID detection design with Spring. Let's rename extpower_usb to extpower_spring to better reflect this. BUG=None TEST=Build and boot Spring. BRANCH=None Change-Id: I7c212a121eed55665593cb7e1b2b672891819940 Signed-off-by: Vic Yang <victoryang@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/67031
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.