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chromeec: ec_mec: Fix misaligned data access 

Long auto-increment access cannot be used when our initial address is
misaligned or when our terminal address is misaligned on write
operations.

BUG=chrome-os-partner:38224
TEST=Verify host command functionality on cyan.
BRANCH=None

Change-Id: Ieba0e8e05dabd44a28c63d5d56a2a634c2d349bf
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: a7237c8df027ae70a38478846ff3d5ce97543ff1
Original-Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Original-Change-Id: Id709ca92cc386f9ea5b2a1139733961e1bc59354
Original-Reviewed-on: https://chromium-review.googlesource.com/266653
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/9987
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
This commit is contained in:
Shawn Nematbakhsh 2015-04-21 09:30:10 -07:00 committed by Patrick Georgi
parent 8603680c4a
commit 16fb9b9f81
1 changed files with 26 additions and 1 deletions
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27
src/ec/google/chromeec/ec_mec.c
View File

@ -76,12 +76,22 @@ void mec_io_bytes(int write, u16 port, unsigned int length, u8 *buf, u8 *csum)
{ {
int i = 0; int i = 0;
int io_addr; int io_addr;
u8 access_mode, new_access_mode;
if (length == 0) if (length == 0)
return; return;
/*
* Long access cannot be used on misaligned data since reading B0 loads
* the data register and writing B3 flushes it.
*/
if (port & 0x3)
access_mode = ACCESS_TYPE_BYTE;
else
access_mode = ACCESS_TYPE_LONG_AUTO_INCREMENT;
/* Initialize I/O at desired address */ /* Initialize I/O at desired address */
mec_emi_write_address(port, ACCESS_TYPE_LONG_AUTO_INCREMENT); mec_emi_write_address(port, access_mode);
/* Skip bytes in case of misaligned port */ /* Skip bytes in case of misaligned port */
io_addr = MEC_EMI_EC_DATA_B0 + (port & 0x3); io_addr = MEC_EMI_EC_DATA_B0 + (port & 0x3);
@ -94,11 +104,26 @@ void mec_io_bytes(int write, u16 port, unsigned int length, u8 *buf, u8 *csum)
if (csum) if (csum)
*csum += buf[i]; *csum += buf[i];
port++;
/* Extra bounds check in case of misaligned length */ /* Extra bounds check in case of misaligned length */
if (++i == length) if (++i == length)
return; return;
} }
/*
* Use long auto-increment access except for misaligned write,
* since writing B3 triggers the flush.
*/
if (length - i < 4 && write)
new_access_mode = ACCESS_TYPE_BYTE;
else
new_access_mode = ACCESS_TYPE_LONG_AUTO_INCREMENT;
if (new_access_mode != access_mode ||
access_mode != ACCESS_TYPE_LONG_AUTO_INCREMENT) {
access_mode = new_access_mode;
mec_emi_write_address(port, access_mode);
}
/* Access [B0, B3] on each loop pass */ /* Access [B0, B3] on each loop pass */
io_addr = MEC_EMI_EC_DATA_B0; io_addr = MEC_EMI_EC_DATA_B0;
} }