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 with -EOPNOTSUPP. Retry
them with a sane minimum size 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>
[rework the patch to adapt to the feedback received]
Signed-off-by: Enric Balletbo i Serra <enric.balle...@collabora.com>
---
This is a reworked version of the original patch based on the
suggestion made by Wolfram Sang to simply fall back to a sane minimum
when the maximum fails.
Changes since v1:
- Check the correct return value (-EOPNOTSUPP instead of -EINVAL)
- Fall back len to I2C_SMBUS_BLOCK_MAX if fails.
drivers/char/tpm/tpm_i2c_infineon.c | 45 +++++++++++++++++++++----------------
1 file changed, 26 insertions(+), 19 deletions(-)
diff --git a/drivers/char/tpm/tpm_i2c_infineon.c
b/drivers/char/tpm/tpm_i2c_infineon.c
index 62ee44e..88bf947 100644
--- a/drivers/char/tpm/tpm_i2c_infineon.c
+++ b/drivers/char/tpm/tpm_i2c_infineon.c
@@ -107,39 +107,27 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
.len = len,
.buf = buffer
};
- struct i2c_msg msgs[] = {msg1, msg2};
int rc = 0;
int count;
+ unsigned 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;
@@ -148,11 +136,30 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len)
* retrieving the data
*/
for (count = 0; count < MAX_COUNT; count++) {
+ unsigned int msglen = msg2.len =
+ min_t(unsigned int, adapterlimit, len);
usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);
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 (msglen > len)
+ len = 0;
+ else
+ len -= msglen;
+ msg2.buf += msglen;
break;
+ }
+ /* If the I2C adapter rejected the request (e.g when
+ * the quirk read_max_len < len) fall back to a sane
+ * minimum value and try again.
+ */
+ if (rc == -EOPNOTSUPP)
+ adapterlimit = I2C_SMBUS_BLOCK_MAX;
}
+ if (rc <= 0)
+ goto out;
}
out:
--
2.9.3
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