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In-Reply-To: <1545908831-25910-2-git-send-email-sumit.garg@linaro.org>
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Thu, 27 Dec 2018 14:39:52 +0100
Message-ID: <CAKv+Gu8o_6Mu8_2vNHXEy46mZ6xrSPekcwPH7BvxR8nec37Ktw@mail.gmail.com>
Subject: Re: [PATCH v1 1/2] dt/bindings: add bindings for optional optee
 rng-uuid property
To: Sumit Garg <sumit.garg@linaro.org>
Cc: "open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
        <linux-crypto@vger.kernel.org>,
        Devicetree List <devicetree@vger.kernel.org>, mpm@selenic.com,
        Herbert Xu <herbert@gondor.apana.org.au>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jens Wiklander <jens.wiklander@linaro.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Bhupesh Sharma <bhsharma@redhat.com>, tee-dev@lists.linaro.org
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Sender: linux-crypto-owner@vger.kernel.org

On Thu, 27 Dec 2018 at 12:08, Sumit Garg <sumit.garg@linaro.org> wrote:
>
> Add bindings for OP-TEE based optional hardware random number
> generator identifier property. It could be used on ARM based devices
> where entropy source is not accessible to normal world (linux in this
> case).
>
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> ---
>  Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt
> index d38834c..e3a4c35 100644
> --- a/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt
> +++ b/Documentation/devicetree/bindings/arm/firmware/linaro,optee-tz.txt
> @@ -20,6 +20,9 @@ the reference implementation maintained by Linaro.
>                     "hvc" : HVC #0, with the register assignments specified
>                            in drivers/tee/optee/optee_smc.h
>
> +- rng-uuid       : Optional OP-TEE based RNG service identifier in case
> +                   hardware entropy source is not accesible to normal world
> +                   (Linux).
>
>
>  Example:
> @@ -27,5 +30,6 @@ Example:
>                 optee {
>                         compatible = "linaro,optee-tz";
>                         method = "smc";
> +                       rng-uuid = "ab7a617c-b8e7-4d8f-8301-d09b61036b64";

If OP-TEE is going to expose devices in this way, it should be modeled
more like a bus driver, i.e., sub-nodes that represent the devices,
with compatible strings, and perhaps even 'reg' properties for the
UUIDs.

>                 };
>         };
> --
> 2.7.4
>