On Fri, Jun 10, 2022 at 01:08:43PM +0200, LinoSanfilippo@xxxxxx wrote:
> From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
>
> 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. Ensure thread-safety by protecting
> the counter with a mutex.
>
> This allows to request and release the locality from a thread and the
> interrupt handler at the same time without the danger to interfere with
> each other.
>
> Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>
> ---
> drivers/char/tpm/tpm_tis_core.c | 30 ++++++++++++++++++++++++++++--
> drivers/char/tpm/tpm_tis_core.h | 2 ++
> 2 files changed, 30 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 028bec44362d..0ef74979bc2c 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -158,16 +158,26 @@ static bool check_locality(struct tpm_chip *chip, int l)
> return false;
> }
>
> +static int release_locality_locked(struct tpm_tis_data *priv, int l)
> +{
> + tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
nit: empty line here
Also it would not hurt to prefix it with tpm_tis.
This is for simple and practical reasons, like grepping. I don't
mind if you do that also for other functions (if you want to).
> + return 0;
> +}
> +
> static int release_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)
> + release_locality_locked(priv, l);
> + mutex_unlock(&priv->locality_count_mutex);
>
> return 0;
> }
>
> -static int request_locality(struct tpm_chip *chip, int l)
> +static int request_locality_locked(struct tpm_chip *chip, int l)
> {
> struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
> unsigned long stop, timeout;
> @@ -208,6 +218,20 @@ static int request_locality(struct tpm_chip *chip, int l)
> return -1;
> }
>
> +static int 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 = request_locality_locked(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);
> @@ -987,6 +1011,8 @@ 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);
>
> diff --git a/drivers/char/tpm/tpm_tis_core.h b/drivers/char/tpm/tpm_tis_core.h
> index 8e02faa4079d..e1871c482da2 100644
> --- a/drivers/char/tpm/tpm_tis_core.h
> +++ b/drivers/char/tpm/tpm_tis_core.h
> @@ -94,6 +94,8 @@ enum tpm_tis_irqtest_flags {
>
> struct tpm_tis_data {
> u16 manufacturer_id;
> + struct mutex locality_count_mutex;
> + unsigned int locality_count;
> int locality;
> int irq;
> unsigned int irqs_in_use;
> --
> 2.36.1
>
BR, Jarkko
