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authorShawn Nematbakhsh <shawnn@chromium.org>2015-04-21 09:30:10 -0700
committerPatrick Georgi <pgeorgi@google.com>2015-04-27 20:49:33 +0200
commit16fb9b9f81d0535a2125779e955ada77b40340e1 (patch)
tree23f5db706dd258cb5b3e5af0e3848714a6c313d3
parent8603680c4a5ca3a718e2c21331be6d12fe9de147 (diff)
downloadcoreboot-16fb9b9f81d0535a2125779e955ada77b40340e1.tar.xz
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>
-rw-r--r--src/ec/google/chromeec/ec_mec.c27
1 files changed, 26 insertions, 1 deletions
diff --git a/src/ec/google/chromeec/ec_mec.c b/src/ec/google/chromeec/ec_mec.c
index 9836edad67..264a256036 100644
--- a/src/ec/google/chromeec/ec_mec.c
+++ b/src/ec/google/chromeec/ec_mec.c
@@ -76,12 +76,22 @@ void mec_io_bytes(int write, u16 port, unsigned int length, u8 *buf, u8 *csum)
{
int i = 0;
int io_addr;
+ u8 access_mode, new_access_mode;
if (length == 0)
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 */
- mec_emi_write_address(port, ACCESS_TYPE_LONG_AUTO_INCREMENT);
+ mec_emi_write_address(port, access_mode);
/* Skip bytes in case of misaligned port */
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)
*csum += buf[i];
+ port++;
/* Extra bounds check in case of misaligned length */
if (++i == length)
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 */
io_addr = MEC_EMI_EC_DATA_B0;
}