diff mbox series

[v10,3/8] tpm: tpm_tis: Add retry in case of protocol failure or data integrity (on I2C only) failure.

Message ID 20200604134713.157951-4-amirmizi6@gmail.com (mailing list archive)
State New, archived
Headers show
Series Add tpm i2c ptp driver | expand

Commit Message

Amir Mizinski June 4, 2020, 1:47 p.m. UTC 
From: Amir Mizinski <amirmizi6@gmail.com>

The FIFO protocol described in the TCG PC Client Device Driver Design
Principles for TPM 2.0 advises retrying sending a command or receiving
a response using the FIFO protocol in case of any error in the protocol.

Add a retry mechanism on any protocol error. In addition, in case of a data
integrity issue in the I2C bus protocol, check after sending a command
completion or receiving a response from the TPM.

Co-developed-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Amir Mizinski <amirmizi6@gmail.com>
---
 drivers/char/tpm/tpm_tis_core.c | 106 ++++++++++++++++++++++++----------------
 drivers/char/tpm/tpm_tis_core.h |   3 ++
 2 files changed, 67 insertions(+), 42 deletions(-)

Comments

Jarkko Sakkinen June 17, 2020, 1:17 a.m. UTC | #1 
On Thu, Jun 04, 2020 at 04:47:08PM +0300, amirmizi6@gmail.com wrote:
> From: Amir Mizinski <amirmizi6@gmail.com>
> 
> The FIFO protocol described in the TCG PC Client Device Driver Design
> Principles for TPM 2.0 advises retrying sending a command or receiving
> a response using the FIFO protocol in case of any error in the protocol.
> 
> Add a retry mechanism on any protocol error. In addition, in case of a data
> integrity issue in the I2C bus protocol, check after sending a command
> completion or receiving a response from the TPM.

The first sentence of this paragraph means absolutely nothing but
nonsense. Please describe the implementation broadly instead.

Also the code is organized badly and makes the current code base a mess.
You should derive __tpm_tis_recv() from the "old" tpm_tis_recv(), and
introduce a "new" tpm_tis_recv() that calls __tpm_tis_recv() a number of
times.

/Jarkko
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 6ea70ea..202714d 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -308,7 +308,7 @@  static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 	int size = 0;
-	int status;
+	int status, i;
 	u32 expected;
 
 	if (count < TPM_HEADER_SIZE) {
@@ -316,39 +316,53 @@  static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 		goto out;
 	}
 
-	size = recv_data(chip, buf, TPM_HEADER_SIZE);
-	/* read first 10 bytes, including tag, paramsize, and result */
-	if (size < TPM_HEADER_SIZE) {
-		dev_err(&chip->dev, "Unable to read header\n");
-		goto out;
-	}
+	for (i = 0; i < TPM_RETRY; i++) {
+		size = recv_data(chip, buf, TPM_HEADER_SIZE);
+		/* read first 10 bytes, including tag, paramsize, and result */
+		if (size < TPM_HEADER_SIZE) {
+			dev_err(&chip->dev, "Unable to read header\n");
+			goto retry;
+		}
 
-	expected = be32_to_cpu(*(__be32 *) (buf + 2));
-	if (expected > count || expected < TPM_HEADER_SIZE) {
-		size = -EIO;
-		goto out;
-	}
+		expected = be32_to_cpu(*(__be32 *) (buf + 2));
+		if (expected > count || expected < TPM_HEADER_SIZE) {
+			size = -EIO;
+			goto retry;
+		}
 
-	size += recv_data(chip, &buf[TPM_HEADER_SIZE],
-			  expected - TPM_HEADER_SIZE);
-	if (size < expected) {
-		dev_err(&chip->dev, "Unable to read remainder of result\n");
-		size = -ETIME;
-		goto out;
-	}
+		size += recv_data(chip, &buf[TPM_HEADER_SIZE],
+				  expected - TPM_HEADER_SIZE);
+		if (size < expected) {
+			dev_err(&chip->dev, "Unable to read remainder of result\n");
+			size = -ETIME;
+			goto retry;
+		}
 
-	if (wait_for_tpm_stat(chip, TPM_STS_VALID, TPM_STS_VALID,
-			      chip->timeout_c, &priv->int_queue, false) < 0) {
-		size = -ETIME;
-		goto out;
-	}
-	status = tpm_tis_status(chip);
-	if (status & TPM_STS_DATA_AVAIL) {	/* retry? */
-		dev_err(&chip->dev, "Error left over data\n");
-		size = -EIO;
-		goto out;
-	}
+		if (wait_for_tpm_stat(chip, TPM_STS_VALID, TPM_STS_VALID,
+				      chip->timeout_c, &priv->int_queue,
+				      false) < 0) {
+			size = -ETIME;
+			goto retry;
+		}
+
+		status = tpm_tis_status(chip);
+		if (status & TPM_STS_DATA_AVAIL) {	/* retry? */
+			dev_err(&chip->dev, "Error left over data\n");
+			size = -EIO;
+			goto retry;
+		}
 
+		if (priv->phy_ops->verify_data_integrity)
+			if (!priv->phy_ops->verify_data_integrity(priv, buf,
+								  size))
+				size = -EIO;
+retry:
+		if (size <= 0)
+			tpm_tis_write8(priv, TPM_STS(priv->locality),
+				       TPM_STS_RESPONSE_RETRY);
+		else
+			goto out;
+	}
 out:
 	tpm_tis_ready(chip);
 	return size;
@@ -372,7 +386,7 @@  static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
 				      TPM_STS_COMMAND_READY, chip->timeout_b,
 				      &priv->int_queue, false) < 0) {
 			rc = -ETIME;
-			goto out_err;
+			return rc;
 		}
 	}
 
@@ -381,13 +395,13 @@  static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
 		if (burstcnt < 0) {
 			dev_err(&chip->dev, "Unable to read burstcount\n");
 			rc = burstcnt;
-			goto out_err;
+			return rc;
 		}
 		burstcnt = min_t(int, burstcnt, len - count);
 		rc = tpm_tis_write_bytes(priv, TPM_DATA_FIFO(priv->locality),
 					 burstcnt, buf + count);
 		if (rc < 0)
-			goto out_err;
+			return rc;
 
 		count += burstcnt;
 	}
@@ -395,14 +409,10 @@  static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
 			      TPM_STS_VALID, chip->timeout_a, &priv->int_queue,
 			      false) < 0) {
 		rc = -ETIME;
-		goto out_err;
+		return rc;
 	}
 
 	return 0;
-
-out_err:
-	tpm_tis_ready(chip);
-	return rc;
 }
 
 static void disable_interrupts(struct tpm_chip *chip)
@@ -431,13 +441,25 @@  static void disable_interrupts(struct tpm_chip *chip)
 static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
 {
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
-	int rc;
+	int rc, i;
 	u32 ordinal;
 	unsigned long dur;
 
-	rc = tpm_tis_send_data(chip, buf, len);
-	if (rc < 0)
-		return rc;
+	for (i = 0; i < TPM_RETRY; i++) {
+		rc = tpm_tis_send_data(chip, buf, len);
+		if (rc < 0)
+			continue;
+		if (priv->phy_ops->verify_data_integrity) {
+			if (!priv->phy_ops->verify_data_integrity(priv, buf,
+								  len)){
+				rc = -EIO;
+				continue;
+			}
+		}
+		break;
+	}
+	if (i == TPM_RETRY)
+		goto out_err;
 
 	/* go and do it */
 	rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index d06c65b..cd97c01 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -34,6 +34,7 @@  enum tis_status {
 	TPM_STS_GO = 0x20,
 	TPM_STS_DATA_AVAIL = 0x10,
 	TPM_STS_DATA_EXPECT = 0x08,
+	TPM_STS_RESPONSE_RETRY = 0x02,
 };
 
 enum tis_int_flags {
@@ -106,6 +107,8 @@  struct tpm_tis_phy_ops {
 	int (*read16)(struct tpm_tis_data *data, u32 addr, u16 *result);
 	int (*read32)(struct tpm_tis_data *data, u32 addr, u32 *result);
 	int (*write32)(struct tpm_tis_data *data, u32 addr, u32 src);
+	bool (*verify_data_integrity)(struct tpm_tis_data *data, const u8 *buf,
+				      size_t len);
 };
 
 static inline int tpm_tis_read_bytes(struct tpm_tis_data *data, u32 addr,