linux-kernel - Re: [PATCH 1/8] dt/bindings: firmware: Add Qualcomm SCM binding

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Message-ID: <CAL_JsqK0LYCozBohs5QCvuPRR-3s2SMHf7DgwSyVe4Vyeyw9ew@mail.gmail.com>
Date:	Sat, 23 Apr 2016 11:56:50 -0500
From:	Rob Herring <robh@...nel.org>
To:	Andy Gross <andy.gross@...aro.org>
Cc:	linux-arm-msm <linux-arm-msm@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Stephen Boyd <sboyd@...eaurora.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bjorn Andersson <bjorn.andersson@...ymobile.com>,
	jilai wang <jilaiw@...eaurora.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/8] dt/bindings: firmware: Add Qualcomm SCM binding

On Fri, Apr 22, 2016 at 5:17 PM, Andy Gross <andy.gross@...aro.org> wrote:
> This patch adds the device tree support for the Qualcomm SCM firmware.
>
> Signed-off-by: Andy Gross <andy.gross@...aro.org>
> ---
>  .../devicetree/bindings/firmware/qcom,scm.txt      | 31 ++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/firmware/qcom,scm.txt
>
> diff --git a/Documentation/devicetree/bindings/firmware/qcom,scm.txt b/Documentation/devicetree/bindings/firmware/qcom,scm.txt
> new file mode 100644
> index 0000000..57b9b3a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/firmware/qcom,scm.txt
> @@ -0,0 +1,31 @@
> +QCOM Secure Channel Manager (SCM)
> +
> +Qualcomm processors include an interface to communicate to the secure firmware.
> +This interface allows for clients to request different types of actions.  These
> +can include CPU power up/down, HDCP requests, loading of firmware, and other
> +assorted actions.
> +
> +Required properties:
> +- compatible: must contain one of the following:
> + * "qcom,scm-apq8064" for APQ8064
> + * "qcom,scm-apq8084" for MSM8084
> + * "qcom,scm-msm8916" for MSM8916
> + * "qcom,scm-msm8974" for MSM8974
> +- clocks: One to three clocks may be required based on compatible.
> + * Only core clock required for "qcom,scm-apq8064"
> + * Core, iface, and bus clocks required for all other compatibles.
> +- clock-names: Must contain "core" for the core clock, "iface" for the interface
> +  clock and "bus" for the bus clock per the requirements of the compatible.
> +
> +Example for MSM8916:
> +
> +       firmware {
> +               compatible = "simple-bus";

Firmware is a bus? Really? Let's not put hacks in the DT just so you
get automatic probing.

> +
> +               scm {
> +                       compatible = "qcom,scm-msm8916";
> +                       clocks = <&gcc GCC_CRYPTO_CLK> , <&gcc GCC_CRYPTO_AXI_CLK>, <&gcc GCC_CRYPTO_AHB_CLK>;
> +                       clock-names = "core", "bus", "iface";

Generally, /firmware defines an interface to firmware. I don't think
clocks belong here. This implies that non-secure world can turn off
clocks to secure world?

Rob