From: Bryan Freed <bfr...@chromium.org>
When the I2C Infineon part is attached to an I2C adapter that imposes
a size limitation, large requests will fail -EINVAL.
Retry them with size backoff without re-issuing the 0x05 command
as this appears to occasionally put the TPM in a bad state.
Signed-off-by: Bryan Freed <bfr...@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balle...@collabora.com>
---
drivers/char/tpm/tpm_i2c_infineon.c | 44 ++++++++++++++++++++++---------------
1 file changed, 26 insertions(+), 18 deletions(-)
diff --git a/drivers/char/tpm/tpm_i2c_infineon.c
b/drivers/char/tpm/tpm_i2c_infineon.c
index 62ee44e..f04c6b7 100644
--- a/drivers/char/tpm/tpm_i2c_infineon.c
+++ b/drivers/char/tpm/tpm_i2c_infineon.c
@@ -111,35 +111,24 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
int rc = 0;
int count;
+ int adapterlimit = len;
/* Lock the adapter for the duration of the whole sequence. */
if (!tpm_dev.client->adapter->algo->master_xfer)
return -EOPNOTSUPP;
i2c_lock_adapter(tpm_dev.client->adapter);
- if (tpm_dev.chip_type == SLB9645) {
- /* use a combined read for newer chips
- * unfortunately the smbus functions are not suitable due to
- * the 32 byte limit of the smbus.
- * retries should usually not be needed, but are kept just to
- * be on the safe side.
- */
- for (count = 0; count < MAX_COUNT; count++) {
- rc = __i2c_transfer(tpm_dev.client->adapter, msgs, 2);
- if (rc > 0)
- break; /* break here to skip sleep */
- usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
- }
- } else {
+ /* Expect to send one command message and one data message, but
+ * support looping over each or both if necessary.
+ */
+ while (len > 0) {
/* slb9635 protocol should work in all cases */
for (count = 0; count < MAX_COUNT; count++) {
rc = __i2c_transfer(tpm_dev.client->adapter, &msg1, 1);
if (rc > 0)
- break; /* break here to skip sleep */
-
+ break;
usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
}
-
if (rc <= 0)
goto out;
@@ -149,10 +138,29 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
*/
for (count = 0; count < MAX_COUNT; count++) {
usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
+ msg2.len = min(adapterlimit, len);
rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);
- if (rc > 0)
+ if (rc > 0) {
+ /* Since len is unsigned, make doubly sure we
+ * do not underflow it.
+ */
+ if (msg2.len > len)
+ len = 0;
+ else
+ len -= msg2.len;
+ msg2.buf += msg2.len;
break;
+ }
+ /* If the I2C adapter rejected the request,
+ * try a smaller chunk.
+ */
+ if (rc == -EINVAL) {
+ adapterlimit = (adapterlimit + 1) / 2;
+ adapterlimit = max(adapterlimit, 32);
+ }
}
+ if (rc <= 0)
+ goto out;
}
out:
--
2.9.3
