linux-kernel - Re: [tpmdd-devel] [PATCH v2] tpm: do not suspend/resume if power stays on

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Date:   Fri, 3 Mar 2017 17:12:36 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Enric Balletbo i Serra <enric.balletbo@...labora.com>
Cc:     Rob Herring <robh+dt@...nel.org>, Peter Huewe <peterhuewe@....de>,
        Mark Rutland <mark.rutland@....com>,
        tpmdd-devel@...ts.sourceforge.net,
        Sonny Rao <sonnyrao@...omium.org>, linux-kernel@...r.kernel.org
Subject: Re: [tpmdd-devel] [PATCH v2] tpm: do not suspend/resume if power
 stays on

On Thu, Mar 02, 2017 at 04:42:57PM +0100, Enric Balletbo i Serra wrote:
> From: Sonny Rao <sonnyrao@...omium.org>
> 
> The suspend/resume behavior of the TPM can be controlled by setting
> "powered-while-suspended" in the DTS. This is useful for the cases
> when hardware does not power-off the TPM.
> 
> Signed-off-by: Sonny Rao <sonnyrao@...omium.org>
> Signed-off-by: Enric Balletbo i Serra <enric.balletbo@...labora.com>
> ---
> 
> Changes since v1:
>  Jason Gunthorpe :
>   - Move the code to handle suspend/resume in the common chip code.
> 
>  Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt | 6 ++++++
>  drivers/char/tpm/tpm-interface.c                           | 3 +++
>  drivers/char/tpm/tpm.h                                     | 3 +++
>  drivers/char/tpm/tpm_of.c                                  | 3 +++
>  4 files changed, 15 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt b/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
> index 8cb638b..85c8216 100644
> --- a/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
> +++ b/Documentation/devicetree/bindings/security/tpm/tpm-i2c.txt
> @@ -8,6 +8,12 @@ Required properties:
>                     the firmware event log
>  - linux,sml-size : size of the memory allocated for the firmware event log
>  
> +Optional properties:
> +
> +- powered-while-suspended: present when the TPM is left powered on between
> +                           suspend and resume (makes the suspend/resume
> +                           callbacks do nothing).
> +
>  Example (for OpenPower Systems with Nuvoton TPM 2.0 on I2C)
>  ----------------------------------------------------------
>  
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index a2688ac..7f60780 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -944,6 +944,9 @@ int tpm_pm_suspend(struct device *dev)
>  	if (chip == NULL)
>  		return -ENODEV;
>  
> +	if (chip->powered_while_suspended)
> +		return 0;

Why there can't just be TPM_CHIP_FLAG_ALWAYS_POWERED or something similar?

> +
>  	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
>  		tpm2_shutdown(chip, TPM2_SU_STATE);
>  		return 0;
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index 1ae9768..c8f796c 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -183,10 +183,13 @@ struct tpm_chip {
>  	unsigned long duration[3]; /* jiffies */
>  	bool duration_adjusted;
>  
> +	bool powered_while_suspended;
> +
>  	struct dentry *bios_dir[TPM_NUM_EVENT_LOG_FILES];
>  
>  	const struct attribute_group *groups[3];
>  	unsigned int groups_cnt;
> +

trailing newline

>  #ifdef CONFIG_ACPI
>  	acpi_handle acpi_dev_handle;
>  	char ppi_version[TPM_PPI_VERSION_LEN + 1];
> diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
> index 7dee42d7..33eddd4 100644
> --- a/drivers/char/tpm/tpm_of.c
> +++ b/drivers/char/tpm/tpm_of.c
> @@ -34,6 +34,9 @@ int tpm_read_log_of(struct tpm_chip *chip)
>  	else
>  		return -ENODEV;
>  
> +	chip->powered_while_suspended = of_property_read_bool(np,
> +						"powered-while-suspended");
> +
>  	sizep = of_get_property(np, "linux,sml-size", NULL);
>  	basep = of_get_property(np, "linux,sml-base", NULL);
>  	if (sizep == NULL && basep == NULL)
> -- 
> 2.9.3
> 
> 
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