From: Amir Mizinski <[email protected]> Added a retry mechanism on any protocol error when sending a command or receiving a response. This was changed to comply with the TCG PC Client Device Driver Design Principles for TPM 2.0.
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. 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, a retry is initiated by setting TPM_STS.responseRetry and "__tpm_tis_recv()" is called again. In both cases a retry is attempted up to "TPM_RETRY" times. 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 | 62 ++++++++++++++++++++++++++--------------- drivers/char/tpm/tpm_tis_core.h | 1 + 2 files changed, 41 insertions(+), 22 deletions(-) diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c index 6b33620..e136467 100644 --- a/drivers/char/tpm/tpm_tis_core.c +++ b/drivers/char/tpm/tpm_tis_core.c @@ -305,29 +305,24 @@ 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], @@ -335,22 +330,45 @@ 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 (tpm_tis_wait_for_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; + } + + 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; @@ -375,7 +393,7 @@ 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; } } @@ -384,13 +402,13 @@ 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; } @@ -398,14 +416,10 @@ 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) @@ -434,13 +448,17 @@ 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) + 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..6cc6b76 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 { -- 2.7.4
