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

[Jarkko Sakkinen <jarkko@kernel.org>]

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

> +	 * 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