Re: [PATCH v4 4/8] tpm: redefine read_log() to handle ACPI/OF at runtime

[Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>]

On Wed, Sep 28, 2016 at 04:34:38AM -0400, Nayna Jain wrote:
> Currently, read_log() has two implementations: one for ACPI platforms
> and the other for OF platforms. The proper one is selected at compile
> time using Kconfig and #ifdef in the Makefile, which is not the
> recommended approach.
> 
> This patch removes the #ifdef in the Makefile by defining a single
> read_log() method, which checks for ACPI/OF event log properties at
> runtime.
> 
> Suggested-by: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
> Signed-off-by: Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
> Reviewed-by: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
> ---
>  drivers/char/tpm/Makefile       | 14 ++++----------
>  drivers/char/tpm/tpm_acpi.c     |  9 ++-------
>  drivers/char/tpm/tpm_eventlog.c | 18 ++++++++++++++++++
>  drivers/char/tpm/tpm_eventlog.h | 22 +++++++++++++---------
>  drivers/char/tpm/tpm_of.c       |  8 ++------
>  5 files changed, 39 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index a385fb8..a05b1eb 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -2,16 +2,10 @@
>  # Makefile for the kernel tpm device drivers.
>  #
>  obj-$(CONFIG_TCG_TPM) += tpm.o
> -tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o
> -tpm-$(CONFIG_ACPI) += tpm_ppi.o
> -
> -ifdef CONFIG_ACPI
> -	tpm-y += tpm_eventlog.o tpm_acpi.o
> -else
> -ifdef CONFIG_TCG_IBMVTPM
> -	tpm-y += tpm_eventlog.o tpm_of.o
> -endif
> -endif
> +tpm-y := tpm-interface.o tpm-dev.o tpm-sysfs.o tpm-chip.o tpm2-cmd.o \
> +		tpm_eventlog.o
> +tpm-$(CONFIG_ACPI) += tpm_ppi.o tpm_acpi.o
> +tpm-$(CONFIG_OF) += tpm_of.o
>  obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
>  obj-$(CONFIG_TCG_TIS) += tpm_tis.o
>  obj-$(CONFIG_TCG_TIS_SPI) += tpm_tis_spi.o
> diff --git a/drivers/char/tpm/tpm_acpi.c b/drivers/char/tpm/tpm_acpi.c
> index 4d6c2d7..859bdba 100644
> --- a/drivers/char/tpm/tpm_acpi.c
> +++ b/drivers/char/tpm/tpm_acpi.c
> @@ -6,6 +6,7 @@
>   *	Stefan Berger <stefanb-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
>   *	Reiner Sailer <sailer-aZOuKsOsJu3MbYB6QlFGEg@public.gmane.org>
>   *	Kylene Hall <kjhall-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org>
> + *	Nayna Jain <nayna-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
>   *
>   * Maintained by: <tpmdd-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
>   *
> @@ -45,7 +46,7 @@ struct acpi_tcpa {
>  };
>  
>  /* read binary bios log */
> -int read_log(struct tpm_chip *chip)
> +int read_log_acpi(struct tpm_chip *chip)
>  {
>  	struct acpi_tcpa *buff;
>  	acpi_status status;
> @@ -54,12 +55,6 @@ int read_log(struct tpm_chip *chip)
>  	struct tpm_bios_log *log;
>  
>  	log = &chip->log;
> -	if (log->bios_event_log != NULL) {
> -		printk(KERN_ERR
> -		       "%s: ERROR - Eventlog already initialized\n",
> -		       __func__);
> -		return -EFAULT;
> -	}
>  
>  	/* Find TCPA entry in RSDT (ACPI_LOGICAL_ADDRESSING) */
>  	status = acpi_get_table(ACPI_SIG_TCPA, 1,
> diff --git a/drivers/char/tpm/tpm_eventlog.c b/drivers/char/tpm/tpm_eventlog.c
> index a8cd4a1..c327089 100644
> --- a/drivers/char/tpm/tpm_eventlog.c
> +++ b/drivers/char/tpm/tpm_eventlog.c
> @@ -346,6 +346,24 @@ static int is_bad(void *p)
>  	return 0;
>  }
>  
> +int read_log(struct tpm_chip *chip)
> +{
> +	int rc;
> +
> +	if (chip->log.bios_event_log != NULL) {
> +		dev_dbg(&chip->dev, "%s: ERROR - Eventlog already initialized\n",
> +			__func__);
> +		return -EFAULT;
> +	}
> +
> +	rc = read_log_acpi(chip);
> +	if ((rc == 0) || (rc == -ENOMEM))
> +		return rc;
> +	rc = read_log_of(chip);
> +	return rc;
> +
> +}

I'm wondering if it is a better idea to leverage tpm_class_ops? This
would be kind of cool idea to implement this because then the decision
to support event log could be leveraged to the driver level.

If the event_log pointer is NULL, then event log is not supported.

/Jarkko

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