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-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;
}