linux-kernel - Re: [PATCH v4 2/5] tpm_crb: clean-up and refactor check for idle support

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Message-ID: <5c17c24e8bfb73967c1f20b6a94064b05856875a.camel@iki.fi>
Date: Tue, 18 Feb 2025 17:52:35 +0200
From: Jarkko Sakkinen <jarkko.sakkinen@....fi>
To: Stuart Yoder <stuart.yoder@....com>, linux-integrity@...r.kernel.org, 
	jarkko@...nel.org, peterhuewe@....de, jgg@...pe.ca, sudeep.holla@....com, 
	rafael@...nel.org, lenb@...nel.org
Cc: linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/5] tpm_crb: clean-up and refactor check for idle
 support

On Mon, 2025-02-17 at 16:49 -0600, Stuart Yoder wrote:
> -Clean up unnecessary parenthesis usage
> -Refactor the two checks for whether the TPM supports idle into a
> single
>  inline function.

IMHO, this would be better:

"Refactor TPM idle check to tpm_crb_has_idle(), and reduce paraentheses
usage in start method checks."

> 
> Signed-off-by: Stuart Yoder <stuart.yoder@....com>
> ---
>  drivers/char/tpm/tpm_crb.c | 36 +++++++++++++++++++++---------------
>  1 file changed, 21 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index ea085b14ab7c..31db879f1324 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -115,6 +115,16 @@ struct tpm2_crb_pluton {
>  	u64 reply_addr;
>  };
>  
> +/*
> + * Returns true if the start method supports idle.
> + */
> +static inline bool tpm_crb_has_idle(u32 start_method)
> +{
> +	return start_method == ACPI_TPM2_START_METHOD ||
> +	       start_method ==
> ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD ||
> +	       start_method ==
> ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC;
> +}
> +
>  static bool crb_wait_for_reg_32(u32 __iomem *reg, u32 mask, u32
> value,
>  				unsigned long timeout)
>  {
> @@ -173,9 +183,7 @@ static int __crb_go_idle(struct device *dev,
> struct crb_priv *priv)
>  {
>  	int rc;
>  
> -	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
> -	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> ||
> -	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
> +	if (!tpm_crb_has_idle(priv->sm))
>  		return 0;
>  
>  	iowrite32(CRB_CTRL_REQ_GO_IDLE, &priv->regs_t->ctrl_req);
> @@ -222,9 +230,7 @@ static int __crb_cmd_ready(struct device *dev,
> struct crb_priv *priv)
>  {
>  	int rc;
>  
> -	if ((priv->sm == ACPI_TPM2_START_METHOD) ||
> -	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> ||
> -	    (priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_ARM_SMC))
> +	if (!tpm_crb_has_idle(priv->sm))
>  		return 0;
>  
>  	iowrite32(CRB_CTRL_REQ_CMD_READY, &priv->regs_t->ctrl_req);
> @@ -423,13 +429,13 @@ static int crb_send(struct tpm_chip *chip, u8
> *buf, size_t len)
>  	 * 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")))
> +	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))
> +	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) {
> @@ -449,8 +455,8 @@ static void crb_cancel(struct tpm_chip *chip)
>  
>  	iowrite32(CRB_CANCEL_INVOKE, &priv->regs_t->ctrl_cancel);
>  
> -	if (((priv->sm == ACPI_TPM2_START_METHOD) ||
> -	    (priv->sm ==
> ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)) &&
> +	if ((priv->sm == ACPI_TPM2_START_METHOD ||
> +	     priv->sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> &&
>  	     crb_do_acpi_start(chip))
>  		dev_err(&chip->dev, "ACPI Start failed\n");
>  }
> @@ -609,8 +615,8 @@ static int crb_map_io(struct acpi_device *device,
> struct crb_priv *priv,
>  	 * the control area, as one nice sane region except for some
> older
>  	 * stuff that puts the control area outside the ACPI IO
> region.
>  	 */
> -	if ((priv->sm == ACPI_TPM2_COMMAND_BUFFER) ||
> -	    (priv->sm == ACPI_TPM2_MEMORY_MAPPED)) {
> +	if (priv->sm == ACPI_TPM2_COMMAND_BUFFER ||
> +	    priv->sm == ACPI_TPM2_MEMORY_MAPPED) {
>  		if (iores &&
>  		    buf->control_address == iores->start +
>  		    sizeof(*priv->regs_h))


BR, Jarkko