Patch set updated for coreboot: bd92fe7 chromeec: ec_mec: Fix misaligned data access

[Patrick Georgi]

Patrick Georgi ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/9987

-gerrit

commit bd92fe79eebd04cdcd0d65a93c8e03b513543b3a
Author: Shawn Nematbakhsh 
Date:   Tue Apr 21 09:30:10 2015 -0700

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 
    Original-Commit-Id: a7237c8df027ae70a38478846ff3d5ce97543ff1
    Original-Signed-off-by: Shawn Nematbakhsh 
    Original-Change-Id: Id709ca92cc386f9ea5b2a1139733961e1bc59354
    Original-Reviewed-on: https://chromium-review.googlesource.com/266653
    Original-Reviewed-by: Duncan Laurie 
---
 src/ec/google/chromeec/ec_mec.c | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/ec/google/chromeec/ec_mec.c b/src/ec/google/chromeec/ec_mec.c
index 9836eda..264a256 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;
    }