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char: tpm: cr50: Move i2c locking to request/relinquish locality ops

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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>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
This commit is contained in:
Jan Dabros 2024-10-10 09:15:59 +00:00 committed by Jarkko Sakkinen
parent 932e3a5e1e
commit 44637b0b40
1 changed files with 13 additions and 9 deletions
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22
drivers/char/tpm/tpm_tis_i2c_cr50.c
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@ -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;
}
/**