From: Amir Mizinski <[email protected]> Added a retry mechanism on any protocol error. In addition, a retry is added in case of a data integrity issue in the I2C bus protocol. The check is performed after sending a command to the TPM and after receiving a response from the TPM.
Data integrity is checked if a "verify_data_integrity" handle is defined in "tpm_tis_phy_ops". When sending a command, a loop is added in "tpm_tis_send_main()" that calls "tpm_tis_send_data()" and then issues a retry attempt if any error occurs (protocol or data integrity). When receiving a response, the following new function derived from "tpm_tis_recv()" is added: "__tpm_tis_recv()". "tpm_tis_recv()" is modified to call "__tpm_tis_recv()" in a loop. If any error occurs (protocol or data integrity), a retry is initiated by setting TPM_STS.responseRetry and "__tpm_tis_recv()" is called again. In both cases a retry is attempted "TPM_RETRY" times until reached. Co-developed-by: Christophe Ricard <[email protected]> Signed-off-by: Christophe Ricard <[email protected]> Signed-off-by: Amir Mizinski <[email protected]> --- drivers/char/tpm/tpm_tis_core.c | 78 +++++++++++++++++++++++++++++------------ drivers/char/tpm/tpm_tis_core.h | 3 ++ 2 files changed, 59 insertions(+), 22 deletions(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index d276f03..14ffee4 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -304,29 +304,24 @@ static int recv_data(struct tpm_chip *chip, u8 *buf, size_t count) return size; } -static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count) +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; u32 expected; - if (count < TPM_HEADER_SIZE) { - size = -EIO; - 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; + return size; } expected = be32_to_cpu(*(__be32 *) (buf + 2)); if (expected > count || expected < TPM_HEADER_SIZE) { size = -EIO; - goto out; + return size; } size += recv_data(chip, &buf[TPM_HEADER_SIZE], @@ -334,21 +329,51 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count) if (size < expected) { dev_err(&chip->dev, "Unable to read remainder of result\n"); size = -ETIME; - goto out; + return size; } if (wait_for_tpm_stat(chip, TPM_STS_VALID, TPM_STS_VALID, chip->timeout_c, &priv->int_queue, false) < 0) { size = -ETIME; - goto out; + return size; } + status = tpm_tis_status(chip); if (status & TPM_STS_DATA_AVAIL) { /* retry? */ dev_err(&chip->dev, "Error left over data\n"); size = -EIO; + return size; + } + + if (priv->phy_ops->verify_data_integrity) + if (!priv->phy_ops->verify_data_integrity(priv, buf, + size)) { + size = -EIO; + return size; + } + + return size; +} + +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; + int i; + + if (count < TPM_HEADER_SIZE) { + size = -EIO; goto out; } + for (i = 0; i < TPM_RETRY; i++) { + size = __tpm_tis_recv(chip, buf, count); + 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; @@ -358,6 +383,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count) * If interrupts are used (signaled by an irq set in the vendor structure) * tpm.c can skip polling for the data to be available as the interrupt is * waited for here + */ static int tpm_tis_send_data(struct tpm_chip *chip, const u8 *buf, size_t len) { @@ -372,7 +398,7 @@ 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 +407,13 @@ 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 +421,10 @@ 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 +453,25 @@ 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
