On Wed Oct 9, 2024 at 12:42 PM EEST, Grzegorz Bernacki wrote:
> From: Jan Dabros <jsd@xxxxxxxxxxxx>
>
> Move i2c locking primitives to request_locality and relinquish_locality
> callbacks, what effectively blocks TPM bus for the whole duration of
> logical TPM operation.
>
> With this in place, cr50-equipped TPM may be shared with external CPUs -
> assuming that underneath i2c controller driver is aware of this setup
> (see i2c-designware-amdpsp as an example).
>
> Signed-off-by: Jan Dabros <jsd@xxxxxxxxxxxx>
> ---
> drivers/char/tpm/tpm_tis_i2c_cr50.c | 22 +++++++++++++---------
> 1 file changed, 13 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_i2c_cr50.c b/drivers/char/tpm/tpm_tis_i2c_cr50.c
> index 1b1e403383fc..104ef6c7f11c 100644
> --- a/drivers/char/tpm/tpm_tis_i2c_cr50.c
> +++ b/drivers/char/tpm/tpm_tis_i2c_cr50.c
> @@ -201,8 +201,6 @@ static int tpm_cr50_i2c_read(struct tpm_chip *chip, u8 addr, u8 *buffer, size_t
> };
> int rc;
>
> - i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
> -
> /* Prepare for completion interrupt */
> tpm_cr50_i2c_enable_tpm_irq(chip);
>
> @@ -221,7 +219,6 @@ static int tpm_cr50_i2c_read(struct tpm_chip *chip, u8 addr, u8 *buffer, size_t
>
> out:
> tpm_cr50_i2c_disable_tpm_irq(chip);
> - i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
>
> if (rc < 0)
> return rc;
> @@ -263,8 +260,6 @@ static int tpm_cr50_i2c_write(struct tpm_chip *chip, u8 addr, u8 *buffer,
> priv->buf[0] = addr;
> memcpy(priv->buf + 1, buffer, len);
>
> - i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
> -
> /* Prepare for completion interrupt */
> tpm_cr50_i2c_enable_tpm_irq(chip);
>
> @@ -278,7 +273,6 @@ static int tpm_cr50_i2c_write(struct tpm_chip *chip, u8 addr, u8 *buffer,
>
> out:
> tpm_cr50_i2c_disable_tpm_irq(chip);
> - i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
>
> if (rc < 0)
> return rc;
> @@ -322,6 +316,7 @@ static int tpm_cr50_check_locality(struct tpm_chip *chip, int loc)
> */
> static int tpm_cr50_release_locality(struct tpm_chip *chip, int loc)
> {
> + struct i2c_client *client = to_i2c_client(chip->dev.parent);
> u8 mask = TPM_ACCESS_VALID | TPM_ACCESS_REQUEST_PENDING;
> u8 addr = TPM_I2C_ACCESS(loc);
> u8 buf;
> @@ -329,13 +324,15 @@ static int tpm_cr50_release_locality(struct tpm_chip *chip, int loc)
>
> rc = tpm_cr50_i2c_read(chip, addr, &buf, sizeof(buf));
> if (rc < 0)
> - return rc;
> + goto unlock_out;
>
> if ((buf & mask) == mask) {
> buf = TPM_ACCESS_ACTIVE_LOCALITY;
> rc = tpm_cr50_i2c_write(chip, addr, &buf, sizeof(buf));
> }
>
> +unlock_out:
> + i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
> return rc;
> }
>
> @@ -350,16 +347,19 @@ static int tpm_cr50_release_locality(struct tpm_chip *chip, int loc)
> */
> static int tpm_cr50_request_locality(struct tpm_chip *chip, int loc)
> {
> + struct i2c_client *client = to_i2c_client(chip->dev.parent);
> u8 buf = TPM_ACCESS_REQUEST_USE;
> unsigned long stop;
> int rc;
>
> + i2c_lock_bus(client->adapter, I2C_LOCK_SEGMENT);
> +
> if (tpm_cr50_check_locality(chip, loc) == loc)
> return loc;
>
> rc = tpm_cr50_i2c_write(chip, TPM_I2C_ACCESS(loc), &buf, sizeof(buf));
> if (rc < 0)
> - return rc;
> + goto unlock_out;
>
> stop = jiffies + chip->timeout_a;
> do {
> @@ -369,7 +369,11 @@ static int tpm_cr50_request_locality(struct tpm_chip *chip, int loc)
> msleep(TPM_CR50_TIMEOUT_SHORT_MS);
> } while (time_before(jiffies, stop));
>
> - return -ETIMEDOUT;
> + rc = -ETIMEDOUT;
> +
> +unlock_out:
> + i2c_unlock_bus(client->adapter, I2C_LOCK_SEGMENT);
> + return rc;
> }
>
> /**
Nothing apparently wrong in this. Will re-check after 1/2 is good.
BR, Jarkko
