linux-kernel - Re: [PATCH AUTOSEL 5.4 277/350] tpm: Add a flag to indicate TPM power is managed by firmware

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Date:   Tue, 10 Dec 2019 13:32:15 -0800
From:   Guenter Roeck <groeck@...gle.com>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        "# v4 . 10+" <stable@...r.kernel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Andrey Pronin <apronin@...omium.org>,
        Duncan Laurie <dlaurie@...omium.org>,
        Jason Gunthorpe <jgg@...pe.ca>, Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Guenter Roeck <groeck@...omium.org>,
        Alexander Steffen <Alexander.Steffen@...ineon.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        linux-integrity@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 5.4 277/350] tpm: Add a flag to indicate TPM power
 is managed by firmware

On Tue, Dec 10, 2019 at 1:12 PM Sasha Levin <sashal@...nel.org> wrote:
>
> From: Stephen Boyd <swboyd@...omium.org>
>
> [ Upstream commit 2e2ee5a2db06c4b81315514b01d06fe5644342e9 ]
>
> On some platforms, the TPM power is managed by firmware and therefore we
> don't need to stop the TPM on suspend when going to a light version of
> suspend such as S0ix ("freeze" suspend state). Add a chip flag,
> TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED, to indicate this so that certain
> platforms can probe for the usage of this light suspend and avoid
> touching the TPM state across suspend/resume.
>

Are the patches needed to support CR50 (which need this patch) going
to be applied to v5.4.y as well ? If not, what is the purpose of
applying this patch to v5.4.y ?

Thanks,
Guenter

> Cc: Andrey Pronin <apronin@...omium.org>
> Cc: Duncan Laurie <dlaurie@...omium.org>
> Cc: Jason Gunthorpe <jgg@...pe.ca>
> Cc: Arnd Bergmann <arnd@...db.de>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Guenter Roeck <groeck@...omium.org>
> Cc: Alexander Steffen <Alexander.Steffen@...ineon.com>
> Cc: Heiko Stuebner <heiko@...ech.de>
> Tested-by: Heiko Stuebner <heiko@...ech.de>
> Reviewed-by: Heiko Stuebner <heiko@...ech.de>
> Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> Signed-off-by: Sasha Levin <sashal@...nel.org>
> ---
>  drivers/char/tpm/tpm-interface.c | 8 +++++++-
>  drivers/char/tpm/tpm.h           | 1 +
>  2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index d7a3888ad80f0..7f105490604c8 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -23,6 +23,7 @@
>  #include <linux/slab.h>
>  #include <linux/mutex.h>
>  #include <linux/spinlock.h>
> +#include <linux/suspend.h>
>  #include <linux/freezer.h>
>  #include <linux/tpm_eventlog.h>
>
> @@ -394,7 +395,11 @@ int tpm_pm_suspend(struct device *dev)
>                 return -ENODEV;
>
>         if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
> -               return 0;
> +               goto suspended;
> +
> +       if ((chip->flags & TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED) &&
> +           !pm_suspend_via_firmware())
> +               goto suspended;
>
>         if (!tpm_chip_start(chip)) {
>                 if (chip->flags & TPM_CHIP_FLAG_TPM2)
> @@ -405,6 +410,7 @@ int tpm_pm_suspend(struct device *dev)
>                 tpm_chip_stop(chip);
>         }
>
> +suspended:
>         return rc;
>  }
>  EXPORT_SYMBOL_GPL(tpm_pm_suspend);
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index a7fea3e0ca86a..f3bf2f7f755c8 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -162,6 +162,7 @@ enum tpm_chip_flags {
>         TPM_CHIP_FLAG_VIRTUAL           = BIT(3),
>         TPM_CHIP_FLAG_HAVE_TIMEOUTS     = BIT(4),
>         TPM_CHIP_FLAG_ALWAYS_POWERED    = BIT(5),
> +       TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED    = BIT(6),
>  };
>
>  #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
> --
> 2.20.1
>