Re: [PATCH REVIEW 1/2] tpm: provide a way to override the chip returned durations

[Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>]

On Fri, Dec 14, 2018 at 01:21:14PM +0000, Alexey Klimov wrote:
> Patch adds method ->update_durations to override returned
> durations in case TPM chip misbehaves for TPM 1.2 drivers.
> 
> Cc: Jerry Snitselaar <jsnitsel@redhat.com>
> Signed-off-by: Alexey Klimov <aklimov@redhat.com>
> ---
>  drivers/char/tpm/tpm-interface.c | 18 ++++++++++++++++++
>  include/linux/tpm.h              |  2 ++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 129f640424b7..5cb90918938d 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -768,6 +768,7 @@ int tpm_get_timeouts(struct tpm_chip *chip)
>  {
>  	cap_t cap;
>  	unsigned long timeout_old[4], timeout_chip[4], timeout_eff[4];
> +	unsigned long durations[3];
>  	ssize_t rc;
>  
>  	if (chip->flags & TPM_CHIP_FLAG_HAVE_TIMEOUTS)
> @@ -877,6 +878,23 @@ int tpm_get_timeouts(struct tpm_chip *chip)
>  		usecs_to_jiffies(be32_to_cpu(cap.duration.tpm_long));
>  	chip->duration[TPM_LONG_LONG] = 0; /* not used under 1.2 */
>  
> +	/*
> +	 * Provide ability for vendor overrides of duration values in case
> +	 * of misreporting.
> +	 */
> +	if (chip->ops->update_durations != NULL)
> +		chip->duration_adjusted =
> +			chip->ops->update_durations(chip, durations);
> +
> +	/* Report and set adjusted timeouts */
> +	if (chip->duration_adjusted) {
> +

Can you remove the extra newline?

> +		dev_info(&chip->dev, HW_ERR "Adjusting reported durations\n");
> +		chip->duration[TPM_SHORT] = durations[0];
> +		chip->duration[TPM_MEDIUM] = durations[1];
> +		chip->duration[TPM_LONG] = durations[2];
> +	}
> +
>  	/* The Broadcom BCM0102 chipset in a Dell Latitude D820 gets the above
>  	 * value wrong and apparently reports msecs rather than usecs. So we
>  	 * fix up the resulting too-small TPM_SHORT value to make things work.
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index 4609b94142d4..d6018431b478 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -43,6 +43,8 @@ struct tpm_class_ops {
>  	u8 (*status) (struct tpm_chip *chip);
>  	bool (*update_timeouts)(struct tpm_chip *chip,
>  				unsigned long *timeout_cap);
> +	bool (*update_durations)(struct tpm_chip *chip,
> +				unsigned long *durations_cap);
>  	int (*go_idle)(struct tpm_chip *chip);
>  	int (*cmd_ready)(struct tpm_chip *chip);
>  	int (*request_locality)(struct tpm_chip *chip, int loc);
> -- 
> 2.14.4
> 

/Jarkko