linux-kernel - Re: [PATCH] tpm/tpm_crb: revamp starting method setting.

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Date:   Wed, 5 Oct 2016 18:19:46 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Tomas Winkler <tomas.winkler@...el.com>
Cc:     tpmdd-devel@...ts.sourceforge.net,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tpm/tpm_crb: revamp starting method setting.

On Wed, Oct 05, 2016 at 04:12:08PM +0300, Tomas Winkler wrote:
> Encapsulate the start method parsing in a single function
> and add needed debug printouts.
> It eliminates small issue with useless double checking for
> ACPI_TPM2_MEMORY_MAPPED.

Start method is trival to check from TPM2 dump. I'm not sure which
problem is this commit trying to solve.

/Jarkko

> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> ---
>  drivers/char/tpm/tpm_crb.c | 65 +++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 50 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_crb.c b/drivers/char/tpm/tpm_crb.c
> index aa0ef742ac03..aeec313384d7 100644
> --- a/drivers/char/tpm/tpm_crb.c
> +++ b/drivers/char/tpm/tpm_crb.c
> @@ -381,6 +381,52 @@ out:
>  	return ret;
>  }
>  
> +/**
> + * crb_start_method - parse starting method
> + *
> + * @device: acpi device
> + * @sm: starting method
> + *
> + * Return 0 if supported starting method was not found
> + *    CRB_FL_CRB_START or CRB_FL_ACPI_START otherwise
> + */
> +static unsigned int crb_start_method(struct acpi_device *device, u32 sm)
> +{
> +	struct device *dev = &device->dev;
> +	u32 flags;
> +
> +	switch (sm) {
> +	/* Should the FIFO driver handle this? */
> +	case ACPI_TPM2_MEMORY_MAPPED:
> +		dev_dbg(dev, "starting method[%d]: MM\n", sm);
> +		return 0;
> +	case ACPI_TPM2_COMMAND_BUFFER:
> +		flags = CRB_FL_CRB_START;
> +		dev_dbg(dev, "starting method[%d]: CB\n", sm);
> +		break;
> +	case ACPI_TPM2_START_METHOD:
> +		flags = CRB_FL_ACPI_START;
> +		dev_dbg(dev, "starting method[%d]: SM\n", sm);
> +		break;
> +	case ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD:
> +		flags = CRB_FL_ACPI_START;
> +		dev_dbg(dev, "starting method[%d]: CB w/ SM\n",
> +			sm);
> +		break;
> +	default:
> +		return 0;
> +	}
> +
> +	/* 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
> +	 * ACPI start and CRB start.
> +	 */
> +	if (!strcmp(acpi_device_hid(device), "MSFT0101"))
> +		flags |= CRB_FL_CRB_START;
> +
> +	return flags;
> +}
> +
>  static int crb_acpi_add(struct acpi_device *device)
>  {
>  	struct acpi_table_tpm2 *buf;
> @@ -388,7 +434,7 @@ static int crb_acpi_add(struct acpi_device *device)
>  	struct tpm_chip *chip;
>  	struct device *dev = &device->dev;
>  	acpi_status status;
> -	u32 sm;
> +	unsigned int sm;
>  	int rc;
>  
>  	status = acpi_get_table(ACPI_SIG_TPM2, 1,
> @@ -398,26 +444,15 @@ static int crb_acpi_add(struct acpi_device *device)
>  		return -EINVAL;
>  	}
>  
> -	/* Should the FIFO driver handle this? */
> -	sm = buf->start_method;
> -	if (sm == ACPI_TPM2_MEMORY_MAPPED)
> +	sm = crb_start_method(device, buf->start_method);
> +	if (!sm)
>  		return -ENODEV;
>  
>  	priv = devm_kzalloc(dev, sizeof(struct crb_priv), GFP_KERNEL);
>  	if (!priv)
>  		return -ENOMEM;
>  
> -	/* 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
> -	 * ACPI start and CRB start.
> -	 */
> -	if (sm == ACPI_TPM2_COMMAND_BUFFER || sm == ACPI_TPM2_MEMORY_MAPPED ||
> -	    !strcmp(acpi_device_hid(device), "MSFT0101"))
> -		priv->flags |= CRB_FL_CRB_START;
> -
> -	if (sm == ACPI_TPM2_START_METHOD ||
> -	    sm == ACPI_TPM2_COMMAND_BUFFER_WITH_START_METHOD)
> -		priv->flags |= CRB_FL_ACPI_START;
> +	priv->flags = sm;
>  
>  	rc = crb_map_io(device, priv, buf);
>  	if (rc)
> -- 
> 2.7.4
>