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ac78e589af
Occasionally the EC wants to ask the AP to throttle itself. Currently, the
only thing that the EC can do (at least on x86) is to assert the PROCHOT#
signal, which is a fairly intrusive operation and one that Intel suggests we
save for emergencies.
This CL adds a new pair of host events to ask the BIOS to throttle the AP
politely, or stop doing so. The turbo charger code will send these events to
the AP if they become necessary.
BUG=chrome-os-partner:20739
BRANCH=falco,peppy
TEST=manual
Tests should still pass, everything else is unchanged.
make BOARD=${BOARD} runtests
Currently, there's nothing on the BIOS/OS side that would respond to these
events, so they're just ignored. You can test that, even without this CL, by
running
hostevent set 0x40000
hostevent set 0x80000
Change-Id: I4a7a1b6eb87e42df94ddd09f4c6abee6ebcbd485
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/63379
Reviewed-by: Aaron Durbin <adurbin@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.