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Commit d8c3eab5 authored by Bryan Freed's avatar Bryan Freed Committed by Jarkko Sakkinen
Browse files

tpm: Apply a sane minimum adapterlimit value for retransmission. 



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: default avatarBryan Freed <bfreed@chromium.org>
[rework the patch to adapt to the feedback received]
Signed-off-by: default avatarEnric Balletbo i Serra <enric.balletbo@collabora.com>
Acked-by: default avatarAndrew Lunn <andrew@lunn.ch>
Reviewed-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Signed-off-by: default avatarJarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
parent 4cb586a1

drivers/char/tpm/tpm_i2c_infineon.c

+56 −20
Original line number Diff line number Diff line
@@ -70,6 +70,7 @@ struct tpm_inf_dev { 
	u8 buf[TPM_BUFSIZE + sizeof(u8)]; /* max. buffer size + addr */

	struct tpm_chip *chip;

	enum i2c_chip_type chip_type;

	unsigned int adapterlimit;

};



static struct tpm_inf_dev tpm_dev;
@@ -111,6 +112,7 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) 


	int rc = 0;

	int count;

	unsigned int msglen = len;



	/* Lock the adapter for the duration of the whole sequence. */

	if (!tpm_dev.client->adapter->algo->master_xfer)
@@ -131,28 +133,62 @@ static int iic_tpm_read(u8 addr, u8 *buffer, size_t len) 
			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);

				rc = __i2c_transfer(tpm_dev.client->adapter,

						    &msg1, 1);

				if (rc > 0)

					break;	/* break here to skip sleep */



			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);

				usleep_range(SLEEP_DURATION_LOW,

					     SLEEP_DURATION_HI);

			}



			if (rc <= 0)

				goto out;



		/* After the TPM has successfully received the register address

		 * it needs some time, thus we're sleeping here again, before

		 * retrieving the data

			/* After the TPM has successfully received the register

			 * address it needs some time, thus we're sleeping here

			 * again, before retrieving the data

			 */

			for (count = 0; count < MAX_COUNT; count++) {

			usleep_range(SLEEP_DURATION_LOW, SLEEP_DURATION_HI);

			rc = __i2c_transfer(tpm_dev.client->adapter, &msg2, 1);

			if (rc > 0)

				if (tpm_dev.adapterlimit) {

					msglen = min_t(unsigned int,

						       tpm_dev.adapterlimit,

						       len);

					msg2.len = msglen;

				}

				usleep_range(SLEEP_DURATION_LOW,

					     SLEEP_DURATION_HI);

				rc = __i2c_transfer(tpm_dev.client->adapter,

						    &msg2, 1);

				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)

					tpm_dev.adapterlimit =

							I2C_SMBUS_BLOCK_MAX;

			}



			if (rc <= 0)

				goto out;

		}

	}



out: