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From:   Rob Herring <robh+dt@kernel.org>
Date:   Tue, 9 Apr 2019 16:18:29 -0500
Message-ID: <CAL_JsqLXcY9VFuY8xZvek0ybUXetS27jL-PW0XGLSVQR3Nc5aw@mail.gmail.com>
Subject: Re: [PATCH v2 1/3] ftpm: dt-binding: add dts documentation for fTPM driver
To:     Sasha Levin <sashal@kernel.org>
Cc:     Peter Huewe <peterhuewe@gmx.de>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        jgg@ziepe.ca, Mark Rutland <mark.rutland@arm.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linux Doc Mailing List <linux-doc@vger.kernel.org>,
        linux-integrity@vger.kernel.org, linux-kernel@microsoft.com,
        thiruan@microsoft.com, bryankel@microsoft.com
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On Tue, Apr 9, 2019 at 1:50 PM Sasha Levin <sashal@kernel.org> wrote:
>
> The parameters are similar to the ones used by IBM's vTPM and the
> various I2C tpm drivers.

Bindings describe h/w (or firmware interfaces in this case), not drivers.

>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>  .../bindings/security/tpm/tpm_ftpm_tee.txt          | 13 +++++++++++++
>  .../devicetree/bindings/vendor-prefixes.txt         |  1 +
>  2 files changed, 14 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/security/tpm/tpm_ftpm_tee.txt
>
> diff --git a/Documentation/devicetree/bindings/security/tpm/tpm_ftpm_tee.txt b/Documentation/devicetree/bindings/security/tpm/tpm_ftpm_tee.txt
> new file mode 100644
> index 000000000000..20fca67a56c4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/security/tpm/tpm_ftpm_tee.txt
> @@ -0,0 +1,13 @@
> +Required properties:
> +- compatible: should be "microsoft,ftpm"
> +- linux,sml-base: 64-bit base address of the reserved memory allocated
> +                 for the firmware event log
> +- linux,sml-size: size of the memory allocated for the firmware event log

Firmware is defining linux specific properties? What if I want to run
BSD? We should use 'reg' here instead.

What memory is used here? This should be under /reserved-memory if it
is part of "main" memory.

Really, I'd prefer to not see this in DT at all. Make the firmware
discoverable. Why repeat the mistakes of non-discoverable h/w in s/w
interfaces? OP-Tee at least has defined a mechanism to enumerate TEE
functions IIRC.

Rob