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

Jarkko Sakkinen
2022-11-28T01:29:06Z

On Thu, Nov 24, 2022 at 02:55:33PM +0100, Lino Sanfilippo wrote:
> 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
>

Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>

BR, Jarkko