Re: [PATCH v4 2/6] tpm_crb: Split start method into a separate header

[Arun Menon <armenon@redhat.com>]

Hi Jarkko,
Thanks for the review.

On Sun, Oct 25, 2026 at 10:55:20PM +0200, Jarkko Sakkinen wrote:
> On Mon, Oct 26, 2026 at 01:48:54AM +0530, Arun Menon wrote:
> > From: Arun Menon <armenon@redhat.com>
> > 
> > The current implementation handles different platform start methods
> > (ACPI, ARM SMC, and ARM FFA) directly within crb_send().
> > Move this logic into a new helper function, tpm_crb_start(). This is a
> > pure refactor with no functional changes intended.
> > 
> > Signed-off-by: Arun Menon <armenon@redhat.com>
> > Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
> > ---
> >  drivers/char/tpm/tpm_crb.c | 50 ++++++++++++++++++++------------------
> >  1 file changed, 27 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> > index d76f9e30f036..9a2f512b4ae3 100644
> > --- a/drivers/char/tpm/tpm_crb.c
> > +++ b/drivers/char/tpm/tpm_crb.c
> > @@ -446,6 +446,32 @@ static int tpm_crb_smc_start(struct device *dev, unsigned long func_id)
> >  }
> >  #endif
> >  
> > +static int tpm_crb_start(struct tpm_chip *chip)
> > +{
> > +	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> > +	int rc = 0;
> 
> After declarations thre should be empty line. checkpatch.pl should
> complain about this.
> 
> > +	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
> 
> I probably did not spot this last time but:
> 
> 	/*
> 	 * ...
> 
> https://docs.kernel.org/process/coding-style.html

I will amend the commit. Thanks.

> 
> > +	 * report only ACPI start but in practice seems to require both
> > +	 * CRB start, hence invoking CRB start method if hid == MSFT0101.
> > +	 */
> > +	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER ||
> > +	    priv->sm == ACPI_TPM2_MEMORY_MAPPED ||
> > +	    !strcmp(priv->hid, "MSFT0101"))
> > +		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
> > +	if (priv->sm == ACPI_TPM2_START_METHOD ||
> > +	    priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> > +		rc = crb_do_acpi_start(chip);
> > +	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
> > +		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
> > +		rc = tpm_crb_smc_start(&chip->dev, priv->smc_func_id);
> > +	}
> > +	if (priv->sm == ACPI_TPM2_CRB_WITH_ARM_FFA) {
> > +		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
> > +		rc = tpm_crb_ffa_start(CRB_FFA_START_TYPE_COMMAND, chip->locality);
> > +	}
> > +	return rc;
> > +}
> > +
> >  static int crb_send(struct tpm_chip *chip, u8 *buf, size_t bufsiz, size_t len)
> >  {
> >  	struct crb_priv *priv = dev_get_drvdata(&chip->dev);
> > @@ -471,29 +497,7 @@ static int crb_send(struct tpm_chip *chip, u8 *buf, size_t bufsiz, size_t len)
> >  	/* Make sure that cmd is populated before issuing start. */
> >  	wmb();
> >  
> > -	/* The reason for the extra quirk is that the PTT in 4th Gen Core CPUs
> > -	 * report only ACPI start but in practice seems to require both
> > -	 * CRB start, hence invoking CRB start method if hid == MSFT0101.
> > -	 */
> > -	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER ||
> > -	    priv->sm == ACPI_TPM2_MEMORY_MAPPED ||
> > -	    !strcmp(priv->hid, "MSFT0101"))
> > -		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
> > -
> > -	if (priv->sm == ACPI_TPM2_START_METHOD ||
> > -	    priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> > -		rc = crb_do_acpi_start(chip);
> > -
> > -	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC) {
> > -		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
> > -		rc = tpm_crb_smc_start(&chip->dev, priv->smc_func_id);
> > -	}
> > -
> > -	if (priv->sm == ACPI_TPM2_CRB_WITH_ARM_FFA) {
> > -		iowrite32(CRB_START_INVOKE, &priv->regs_t->ctrl_start);
> > -		rc = tpm_crb_ffa_start(CRB_FFA_START_TYPE_COMMAND, chip->locality);
> > -	}
> > -
> > +	rc = tpm_crb_start(chip);
> >  	if (rc)
> >  		return rc;
> >  
> > -- 
> > 2.54.0
> > 
> 
> Br, Jarkko
> 

Regards,
Arun Menon