diff mbox series

[V2,2/2] char: tpm: cr50: Move i2c locking to request/relinquish locality ops

Message ID 20241009094207.2897048-3-bernacki@google.com (mailing list archive)
State New
Headers show
Series char: tpm: Adjust cr50_i2c locking mechanism | expand

Commit Message

Grzegorz Bernacki Oct. 9, 2024, 9:42 a.m. UTC 
From: Jan Dabros <jsd@semihalf.com>

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@semihalf.com>
---
 drivers/char/tpm/tpm_tis_i2c_cr50.c | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

Comments

Jarkko Sakkinen Oct. 9, 2024, 4:07 p.m. UTC | #1 
On Wed Oct 9, 2024 at 12:42 PM EEST, Grzegorz Bernacki wrote:
> From: Jan Dabros <jsd@semihalf.com>
>
> 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@semihalf.com>
> ---
>  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
diff mbox series

Patch

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;
 }
 
 /**