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| author | Randall Spangler <rspangler@chromium.org> | 2015-04-16 13:39:53 -0700 |
|---|---|---|
| committer | ChromeOS Commit Bot <chromeos-commit-bot@chromium.org> | 2015-04-17 19:38:17 +0000 |
| commit | 932eb3ddcab387c0207cd6596ef58427358b8c5f (patch) | |
| tree | 5736b2539cbe97ff33cd17a38f0f7a0fe3145b49 /include/flash.h | |
| parent | 0df89000a5bcfc8307a3f8bc85b0fdbe6653da6c (diff) | |
| download | chrome-ec-932eb3ddcab387c0207cd6596ef58427358b8c5f.tar.gz | |
flash: Add option to move pstate inside RO image
Currently, ECs with internal flash store the write protect state for
RO in a separate write/erase block of flash. This is wasteful on
chips where there are not many blocks of flash.
Add a new CONFIG_FLASH_PSTATE_IN_BANK option which is defined by
default. This is the old behavior, for compatibility. (And we're
calling it 'bank' because that's what the existing code does, even if
the terminology is somewhat etymologically... bankrupt.)
If that config is #undef'd, then store the write protect flag directly
inside the RO image. This uses only 4 bytes of the RO image, instead
of an entire erase block. The magic numbers for the pstate values are
chosen such that when protecting RO, bits are only transitioned away
from their erased state. Unprotecting RO once it's protected requires
reflashing RO; it's no longer possible to 'flashwp disable'. But
that's ok, because realistically, the only reason to unprotect RO is
if you're about to flash the RO firmware anyway.
BUG=chromium:476659
BRANCH=none
TEST=Without undefining CONFIG_FLASH_PSTATE_IN_BANK, make sure everything
still works on samus and samus_pd. This ensures we didn't break the
existing functionality:
flashinfo -> no flags
flashwp enable
flashinfo -> ro_at_boot
reboot
flashinfo -> ro_at_boot
flashwp disable
flashinfo -> no flags
Then recompile with #undef CONFIG_FLASH_PSTATE_IN_BANK and test:
flashinfo -> no flags
flashwp enable
flashinfo -> ro_at_boot
reboot
flashinfo -> ro_at_boot
flashwp disable -> fails with access denied
flashinfo -> ro_at_boot
Then reflash to verify that clears the ro_at_boot flag:
flashinfo -> no flags
Change-Id: Ie794b8cfed2a10c50b0e36dcf185884070b04666
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/266095
Reviewed-by: Alec Berg <alecaberg@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Trybot-Ready: Vincent Palatin <vpalatin@chromium.org>
Diffstat (limited to 'include/flash.h')
| -rw-r--r-- | include/flash.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/flash.h b/include/flash.h index f2cc480dba..b724142ffa 100644 --- a/include/flash.h +++ b/include/flash.h @@ -23,11 +23,13 @@ #define RW_BANK_COUNT (CONFIG_FW_RW_SIZE / CONFIG_FLASH_BANK_SIZE) /* Persistent protection state flash offset / size / bank */ -#ifdef CONFIG_FLASH_PSTATE +#if defined(CONFIG_FLASH_PSTATE) && defined(CONFIG_FLASH_PSTATE_BANK) #define PSTATE_OFFSET CONFIG_FW_PSTATE_OFF #define PSTATE_SIZE CONFIG_FW_PSTATE_SIZE #define PSTATE_BANK (PSTATE_OFFSET / CONFIG_FLASH_BANK_SIZE) #define PSTATE_BANK_COUNT (PSTATE_SIZE / CONFIG_FLASH_BANK_SIZE) +#else +#define PSTATE_BANK_COUNT 0 #endif /* Range of write protection */ |