[PATCH 4/8 v3] i2c: i801: check and return errors during byte-by-byte transfers

Daniel Kurtz
2012-06-27T13:56:47Z

If an error is detected in the polling loop, abort the transaction and
return an error code.

* DEV_ERR is set if the device does not respond with an acknowledge, and
the SMBus controller times out (minimum 25ms).
* BUS_ERR is set if a bus arbitration collision is detected. In other
words, when the SMBus controller tries to generate a START condition, but
detects that the SMBDATA is being held low, usually by another SMBus/I2C
master.
* FAILED is only set if a the transaction is set by software (using the
SMBHSTCNT KILL bit).

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
---
drivers/i2c/busses/i2c-i801.c | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 6a53338..ba56b74 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -131,9 +131,11 @@
#define SMBHSTSTS_INTR 0x02
#define SMBHSTSTS_HOST_BUSY 0x01

-#define STATUS_FLAGS (SMBHSTSTS_BYTE_DONE | SMBHSTSTS_FAILED | \
- SMBHSTSTS_BUS_ERR | SMBHSTSTS_DEV_ERR | \
- SMBHSTSTS_INTR)
+#define STATUS_ERROR_FLAGS (SMBHSTSTS_FAILED | SMBHSTSTS_BUS_ERR | \
+ SMBHSTSTS_DEV_ERR)
+
+#define STATUS_FLAGS (SMBHSTSTS_BYTE_DONE | SMBHSTSTS_INTR | \
+ STATUS_ERROR_FLAGS)

/* Older devices have their ID defined in <linux/pci_ids.h> */
#define PCI_DEVICE_ID_INTEL_COUGARPOINT_SMBUS 0x1c22
@@ -385,7 +387,7 @@ static int i801_block_transaction_byte_by_byte(struct i801_priv *priv,
do {
usleep_range(250, 500);
status = inb_p(SMBHSTSTS(priv));
- } while ((!(status & SMBHSTSTS_BYTE_DONE))
+ } while (!(status & (SMBHSTSTS_BYTE_DONE | STATUS_ERROR_FLAGS))
&& (timeout++ < MAX_RETRIES));

result = i801_check_post(priv, status, timeout > MAX_RETRIES);
--
1.7.7.3