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tpm_tis: Use responseRetry to recover from data transfer errors

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TPM responses may become damaged during transmission, for example due to
bit flips on the wire. Instead of aborting when detecting such issues, the
responseRetry functionality can be used to make the TPM retransmit its
response and receive it again without errors.

Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
This commit is contained in:
Alexander Steffen 2023-06-13 20:02:58 +02:00 committed by Jarkko Sakkinen
parent 32a0c860ff
commit b400f9d33f
2 changed files with 30 additions and 8 deletions
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37
drivers/char/tpm/tpm_tis_core.c
View File

@ -340,7 +340,7 @@ 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_try_recv(struct tpm_chip *chip, u8 *buf, size_t count)
{
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
int size = 0;
@ -348,11 +348,6 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
u32 expected;
int rc;
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) {
@ -385,7 +380,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
goto out;
}
status = tpm_tis_status(chip);
if (status & TPM_STS_DATA_AVAIL) { /* retry? */
if (status & TPM_STS_DATA_AVAIL) {
dev_err(&chip->dev, "Error left over data\n");
size = -EIO;
goto out;
@ -399,10 +394,36 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
}
out:
tpm_tis_ready(chip);
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);
unsigned int try;
int rc = 0;
if (count < TPM_HEADER_SIZE)
return -EIO;
for (try = 0; try < TPM_RETRY; try++) {
rc = tpm_tis_try_recv(chip, buf, count);
if (rc == -EIO)
/* Data transfer errors, indicated by EIO, can be
* recovered by rereading the response.
*/
tpm_tis_write8(priv, TPM_STS(priv->locality),
TPM_STS_RESPONSE_RETRY);
else
break;
}
tpm_tis_ready(chip);
return rc;
}
/*
* 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

1
drivers/char/tpm/tpm_tis_core.h
View File

@ -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 */
};