[PATCH v11 09/14] tpm, tpm: Implement usage counter for locality

Lino Sanfilippo
2022-11-24T13:56:48Z

From: Lino Sanfilippo <l.sanfilippo@kunbus.com>

Implement a usage counter for the (default) locality used by the TPM TIS
driver:
Request the locality from the TPM if it has not been claimed yet, otherwise
only increment the counter. Also release the locality if the counter is 0
otherwise only decrement the counter. Since in case of SPI the register
accesses are locked by means of the SPI bus mutex use a sleepable lock
(i.e. also a mutex) to ensure thread-safety of the counter which may be
accessed by both a userspace thread and the interrupt handler.

By doing this refactor the names of the amended functions to use a more
appropriate prefix.

Signed-off-by: Lino Sanfilippo <l.sanfilippo@kunbus.com>
Tested-by: Michael Niewöhner <linux@mniewoehner.de>
---
drivers/char/tpm/tpm_tis_core.c | 63 +++++++++++++++++++++++----------
drivers/char/tpm/tpm_tis_core.h | 2 ++
2 files changed, 47 insertions(+), 18 deletions(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index d705dfb64cf9..f00f1057fd27 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -165,16 +165,27 @@ static bool check_locality(struct tpm_chip *chip, int l)
return false;
}

-static int release_locality(struct tpm_chip *chip, int l)
+static int __tpm_tis_relinquish_locality(struct tpm_tis_data *priv, int l)
+{
+ tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
+
+ return 0;
+}
+
+static int tpm_tis_relinquish_locality(struct tpm_chip *chip, int l)
{
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);

- tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
+ mutex_lock(&priv->locality_count_mutex);
+ priv->locality_count--;
+ if (priv->locality_count == 0)
+ __tpm_tis_relinquish_locality(priv, l);
+ mutex_unlock(&priv->locality_count_mutex);

return 0;
}

-static int request_locality(struct tpm_chip *chip, int l)
+static int __tpm_tis_request_locality(struct tpm_chip *chip, int l)
{
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
unsigned long stop, timeout;
@@ -215,6 +226,20 @@ static int request_locality(struct tpm_chip *chip, int l)
return -1;
}

+static int tpm_tis_request_locality(struct tpm_chip *chip, int l)
+{
+ struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
+ int ret = 0;
+
+ mutex_lock(&priv->locality_count_mutex);
+ if (priv->locality_count == 0)
+ ret = __tpm_tis_request_locality(chip, l);
+ if (!ret)
+ priv->locality_count++;
+ mutex_unlock(&priv->locality_count_mutex);
+ return ret;
+}
+
static u8 tpm_tis_status(struct tpm_chip *chip)
{
struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
@@ -682,7 +707,7 @@ static int probe_itpm(struct tpm_chip *chip)
if (vendor != TPM_VID_INTEL)
return 0;

- if (request_locality(chip, 0) != 0)
+ if (tpm_tis_request_locality(chip, 0) != 0)
return -EBUSY;

rc = tpm_tis_send_data(chip, cmd_getticks, len);
@@ -703,7 +728,7 @@ static int probe_itpm(struct tpm_chip *chip)

out:
tpm_tis_ready(chip);
- release_locality(chip, priv->locality);
+ tpm_tis_relinquish_locality(chip, priv->locality);

return rc;
}
@@ -788,14 +813,14 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
}
priv->irq = irq;

- rc = request_locality(chip, 0);
+ rc = tpm_tis_request_locality(chip, 0);
if (rc < 0)
return rc;

rc = tpm_tis_read8(priv, TPM_INT_VECTOR(priv->locality),
&original_int_vec);
if (rc < 0) {
- release_locality(chip, priv->locality);
+ tpm_tis_relinquish_locality(chip, priv->locality);
return rc;
}

@@ -834,7 +859,7 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip, u32 intmask,
rc = -1;
}

- release_locality(chip, priv->locality);
+ tpm_tis_relinquish_locality(chip, priv->locality);

return rc;
}
@@ -950,8 +975,8 @@ static const struct tpm_class_ops tpm_tis = {
.req_complete_mask = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
.req_complete_val = TPM_STS_DATA_AVAIL | TPM_STS_VALID,
.req_canceled = tpm_tis_req_canceled,
- .request_locality = request_locality,
- .relinquish_locality = release_locality,
+ .request_locality = tpm_tis_request_locality,
+ .relinquish_locality = tpm_tis_relinquish_locality,
.clk_enable = tpm_tis_clkrun_enable,
};

@@ -985,6 +1010,8 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
priv->timeout_min = TPM_TIMEOUT_USECS_MIN;
priv->timeout_max = TPM_TIMEOUT_USECS_MAX;
priv->phy_ops = phy_ops;
+ priv->locality_count = 0;
+ mutex_init(&priv->locality_count_mutex);

dev_set_drvdata(&chip->dev, priv);

@@ -1063,14 +1090,14 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,

intmask &= ~TPM_GLOBAL_INT_ENABLE;

- rc = request_locality(chip, 0);
+ rc = tpm_tis_request_locality(chip, 0);
if (rc < 0) {
rc = -ENODEV;
goto out_err;
}

tpm_tis_write32(priv, TPM_INT_ENABLE(priv->locality), intmask);
- release_locality(chip, 0);
+ tpm_tis_relinquish_locality(chip, 0);

rc = tpm_chip_start(chip);
if (rc)
@@ -1104,13 +1131,13 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
* proper timeouts for the driver.
*/

- rc = request_locality(chip, 0);
+ rc = tpm_tis_request_locality(chip, 0);
if (rc < 0)
goto out_err;

rc = tpm_get_timeouts(chip);

- release_locality(chip, 0);
+ tpm_tis_relinquish_locality(chip, 0);

if (rc) {
dev_err(dev, "Could not get TPM timeouts and durations\n");
@@ -1130,11 +1157,11 @@ int tpm_tis_core_init(struct device *dev, struct tpm_tis_data *priv, int irq,
dev_err(&chip->dev, FW_BUG
"TPM interrupt not working, polling instead\n");

- rc = request_locality(chip, 0);
+ rc = tpm_tis_request_locality(chip, 0);
if (rc < 0)
goto out_err;
disable_interrupts(chip);
- release_locality(chip, 0);
+ tpm_tis_relinquish_locality(chip, 0);
}
}

@@ -1201,13 +1228,13 @@ int tpm_tis_resume(struct device *dev)
* an error code but for unknown reason it isn't handled.
*/
if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
- ret = request_locality(chip, 0);
+ ret = tpm_tis_request_locality(chip, 0);
if (ret < 0)
return ret;

tpm1_do_selftest(chip);

- release_locality(chip, 0);
+ tpm_tis_relinquish_locality(chip, 0);
}

return 0;
diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
index 2deef11c88db..13bdcf38e56f 100644
--- a/drivers/char/tpm/tpm_tis_core.h
+++ b/drivers/char/tpm/tpm_tis_core.h
@@ -91,6 +91,8 @@ enum tpm_tis_flags {

struct tpm_tis_data {
u16 manufacturer_id;
+ struct mutex locality_count_mutex;
+ unsigned int locality_count;
int locality;
int irq;
unsigned int int_mask;
--
2.36.1