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Subject[PATCH v9 3/8] tpm: tpm_tis: Add retry in case of protocol failure or data integrity (on I2C only) failure.
Date
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 | 107 ++++++++++++++++++++++++----------------
drivers/char/tpm/tpm_tis_core.h | 3 ++
2 files changed, 67 insertions(+), 43 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index c725b68..97eae72 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -312,7 +312,7 @@ 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) {
@@ -320,40 +320,53 @@ 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_result(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_result(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;
@@ -378,7 +391,7 @@ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len)
chip->timeout_b,
&priv->int_queue, false) < 0) {
rc = -ETIME;
- goto out_err;
+ return rc;
}
}

@@ -387,13 +400,13 @@ 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;
}
@@ -401,14 +414,10 @@ 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)
@@ -437,13 +446,25 @@ 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,
--
2.7.4
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