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Message-ID: <20220506170013.22598-3-johannes.holland@infineon.com>
Date: Fri, 6 May 2022 19:00:15 +0200
From: Johannes Holland <johannes.holland@...ineon.com>
To: <jarkko@...nel.org>, <linux-kernel@...r.kernel.org>,
<linux-integrity@...r.kernel.org>, <robh+dt@...nel.org>,
<devicetree@...r.kernel.org>
CC: <peterhuewe@....de>, <jgg@...pe.ca>,
<krzysztof.kozlowski+dt@...aro.org>,
Johannes Holland <johannes.holland@...ineon.com>
Subject: [PATCH v2 3/4] tpm: Implement command and response retry in tpm_tis_core
Some errors during command transmission and response reception are
recoverable. Implement the specified retry mechanisms.
Recoverable errors during response reception:
* invalid response size during header read
* left over data:
a communication error can lead to a FIFO read of 0xFFs and an
unexpected STS.dataAvail = 1, subsequently
* CRC mismatch
Recoverable errors during transmit:
* CRC mismatch
Signed-off-by: Johannes Holland <johannes.holland@...ineon.com>
---
drivers/char/tpm/tpm_tis_core.c | 98 +++++++++++++++++++--------------
drivers/char/tpm/tpm_tis_core.h | 1 +
2 files changed, 57 insertions(+), 42 deletions(-)
diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index f1c893a5a38f..a2b6fba7f719 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -287,6 +287,7 @@ 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 i = 0;
int status;
u32 expected;
int rc;
@@ -296,45 +297,52 @@ 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;
- }
+ do {
+ if (size < 0)
+ tpm_tis_write8(priv, TPM_STS(priv->locality),
+ TPM_STS_RESPONSE_RETRY);
+
+ 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;
+ }
- 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) {
+ dev_info(&chip->dev, "Bad response size: %d. Retry...\n", expected);
+ size = -EIO;
+ continue;
+ }
- 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 out;
+ }
- if (wait_for_tpm_stat(chip, 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, chip->timeout_c,
+ &priv->int_queue, false) < 0) {
+ size = -ETIME;
+ goto out;
+ }
+ status = tpm_tis_status(chip);
+ if (status & TPM_STS_DATA_AVAIL) {
+ dev_info(&chip->dev, "Error left over data. Retry...\n");
+ size = -EIO;
+ continue;
+ }
- rc = tpm_tis_verify_crc(priv, (size_t)size, buf);
- if (rc < 0) {
- dev_err(&chip->dev, "Error crc mismatch for response.\n");
- size = rc;
- goto out;
- }
+ rc = tpm_tis_verify_crc(priv, (size_t)size, buf);
+ if (rc < 0) {
+ dev_info(&chip->dev, "Error crc mismatch for response. Retry...\n");
+ size = rc;
+ continue;
+ }
+ } while (unlikely(size < 0) && i++ < TPM_RETRY);
out:
tpm_tis_ready(chip);
@@ -444,18 +452,24 @@ 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 i = 0;
u32 ordinal;
unsigned long dur;
- rc = tpm_tis_send_data(chip, buf, len);
- if (rc < 0)
- return rc;
+ do {
+ rc = tpm_tis_send_data(chip, buf, len);
+ if (rc < 0)
+ return rc;
- rc = tpm_tis_verify_crc(priv, len, buf);
- if (rc < 0) {
- dev_err(&chip->dev, "Error crc mismatch for command.\n");
+ rc = tpm_tis_verify_crc(priv, len, buf);
+ if (rc < 0) {
+ dev_info(&chip->dev, "Error crc mismatch for command. Retry...\n");
+ tpm_tis_ready(chip);
+ }
+ } while (unlikely(rc < 0) && i++ < TPM_RETRY);
+
+ if (rc < 0)
return rc;
- }
/* 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 66a5a13cd1df..d3d7c45cb762 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,
TPM_STS_READ_ZERO = 0x23, /* bits that must be zero on read */
};
--
2.34.1
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