linux-kernel - Re: [PATCH v3] tpm: do not suspend/resume if power stays on

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Message-ID: <20170306144308.xpvnipto2cyj7pox@intel.com>
Date:   Mon, 6 Mar 2017 16:43:08 +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>,
        Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        tpmdd-devel@...ts.sourceforge.net,
        Sonny Rao <sonnyrao@...omium.org>
Subject: Re: [PATCH v3] tpm: do not suspend/resume if power stays on

On Fri, Mar 03, 2017 at 05:09:59PM +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>

Thanks. Looks good to me.

Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

/Jarkko

> ---
> Changes since v2:
>  Jarkko Sakkinen
>   - Add a new TPM_CHIP_FLAG_ALWAYS_POWERED flag instead of using a boolean variable.
>   - Remove a trailing newline.
> 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                                     | 1 +
>  drivers/char/tpm/tpm_of.c                                  | 3 +++
>  4 files changed, 13 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..6869093 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->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
> +		return 0;
> +
>  	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..0ce379c 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -146,6 +146,7 @@ enum tpm_chip_flags {
>  	TPM_CHIP_FLAG_IRQ		= BIT(2),
>  	TPM_CHIP_FLAG_VIRTUAL		= BIT(3),
>  	TPM_CHIP_FLAG_HAVE_TIMEOUTS	= BIT(4),
> +	TPM_CHIP_FLAG_ALWAYS_POWERED	= BIT(5),
>  };
>  
>  struct tpm_chip_seqops {
> diff --git a/drivers/char/tpm/tpm_of.c b/drivers/char/tpm/tpm_of.c
> index 7dee42d7..e89276c 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;
>  
> +	if (of_property_read_bool(np, "powered-while-suspended"))
> +		chip->flags |= TPM_CHIP_FLAG_ALWAYS_POWERED;
> +
>  	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
>