[PATCH v11 3/8] tpm: tpm_tis: Add retry in case of protocol failure or data integrity (on I2C only) failure.
From: amirmizi6
Date: Thu Jun 18 2020 - 09:45:35 EST
From: Amir Mizinski <amirmizi6@xxxxxxxxx>
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 <christophe-h.ricard@xxxxxx>
Signed-off-by: Christophe Ricard <christophe-h.ricard@xxxxxx>
Signed-off-by: Amir Mizinski <amirmizi6@xxxxxxxxx>
---
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