Re: [PATCH v2 4/5] tpm_tis: fix IRQ probing

[Jerry Snitselaar <jsnitsel@redhat.com>]

James Bottomley @ 2020-10-01 11:09 MST:

> There are two problems with our current interrupt probing: firstly the
> TPM_CHIP_FLAG_IRQ never gets set initially, so a check for interrupts
> is never done.  Fix this by setting the flag before we generate and
> interrupt for probing.  Secondly our IRQ setup may be ineffective on a
> TPM without legacy access cycles becuase according to the TPM
> Interface Specification the interrupt registers are only writeable in
> the current locality, so issue a request_locality before setting up
> the interrupts.
>
> Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
>
> ---
>
> v2: improved description
> ---
>  drivers/char/tpm/tpm_tis_core.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
> index 0c07da8cd680..12b657ed3a39 100644
> --- a/drivers/char/tpm/tpm_tis_core.c
> +++ b/drivers/char/tpm/tpm_tis_core.c
> @@ -809,6 +809,19 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip,
>  	}
>  	priv->irq = irq;
>  
> +	/*
> +	 * note writes to the interrupt registers are only effective
> +	 * when the TPM is in the active locality, so we have to
> +	 * request the locality here to get the interrupt set up.
> +	 * This request has no corresponding release, because the
> +	 * locality will be relinquished at the end of the tpm command
> +	 * that probes the interrupts
> +	 */
> +	if (request_locality(chip, 0) != 0) {
> +		dev_err(&chip->dev, "failed to gain locality for irq probe\n");
> +		return -EBUSY;
> +	}
> +
>  	rc = tpm_tis_read8(priv, TPM_INT_VECTOR(priv->locality),
>  			   &original_int_vec);
>  	if (rc < 0)
> @@ -836,6 +849,7 @@ static int tpm_tis_probe_irq_single(struct tpm_chip *chip,
>  		return rc;
>  
>  	priv->irq_tested = false;
> +	chip->flags |= TPM_CHIP_FLAG_IRQ;
>  
>  	/* Generate an interrupt by having the core call through to
>  	 * tpm_tis_send

Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>