tpm: Add tpm_tis_verify_crc to the tpm_tis_phy_ops protocol layer

Some TPMs, e.g. those implementing the I2C variant of TIS, can verify
data transfers to/from the FIFO with a CRC. The CRC is calculated over
the entirety of the FIFO register. Since the phy_ops layer is not aware
when the core layer is done reading/writing the FIFO, CRC verification
must be triggered from the core layer. To this end, add an optional
phy_ops API call.

Co-developed-by: Johannes Holland <johannes.holland@infineon.com>
Signed-off-by: Johannes Holland <johannes.holland@infineon.com>
Signed-off-by: Alexander Steffen <Alexander.Steffen@infineon.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index dc56b976d8162cff62ad6e6d3af5ba60a239606a..757623bacfd502889ec4e0f0020469a1213b9f2b 100644 (file)
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -289,6 +289,7 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
        int size = 0;
        int status;
        u32 expected;
+       int rc;
 
        if (count < TPM_HEADER_SIZE) {
                size = -EIO;
@@ -328,6 +329,13 @@ static int tpm_tis_recv(struct tpm_chip *chip, u8 *buf, size_t count)
                goto out;
        }
 
+       rc = tpm_tis_verify_crc(priv, (size_t)size, buf);
+       if (rc < 0) {
+               dev_err(&chip->dev, "CRC mismatch for response.\n");
+               size = rc;
+               goto out;
+       }
+
 out:
        tpm_tis_ready(chip);
        return size;
@@ -443,6 +451,12 @@ static int tpm_tis_send_main(struct tpm_chip *chip, const u8 *buf, size_t len)
        if (rc < 0)
                return rc;
 
+       rc = tpm_tis_verify_crc(priv, len, buf);
+       if (rc < 0) {
+               dev_err(&chip->dev, "CRC mismatch for command.\n");
+               return rc;
+       }
+
        /* go and do it */
        rc = tpm_tis_write8(priv, TPM_STS(priv->locality), TPM_STS_GO);
        if (rc < 0)

diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index 6c203f36b8a1b2700e8942562237aa61ec2c299b..66a5a13cd1df2939fdf910e4bebf28448bacef60 100644 (file)
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -121,6 +121,8 @@ struct tpm_tis_phy_ops {
                          u8 *result, enum tpm_tis_io_mode mode);
        int (*write_bytes)(struct tpm_tis_data *data, u32 addr, u16 len,
                           const u8 *value, enum tpm_tis_io_mode mode);
+       int (*verify_crc)(struct tpm_tis_data *data, size_t len,
+                         const u8 *value);
 };
 
 static inline int tpm_tis_read_bytes(struct tpm_tis_data *data, u32 addr,
@@ -188,6 +190,14 @@ static inline int tpm_tis_write32(struct tpm_tis_data *data, u32 addr,
        return rc;
 }
 
+static inline int tpm_tis_verify_crc(struct tpm_tis_data *data, size_t len,
+                                    const u8 *value)
+{
+       if (!data->phy_ops->verify_crc)
+               return 0;
+       return data->phy_ops->verify_crc(data, len, value);
+}
+
 static inline bool is_bsw(void)
 {
 #ifdef CONFIG_X86