Message-ID: <0c0a82bb-18ae-d057-562b-21201bfe4fca@epam.com>
Date:   Thu, 10 Nov 2022 14:01:34 +0000
From:   Oleksii Moisieiev <Oleksii_Moisieiev@...m.com>
To:     "robh+dt@...nel.org" <robh+dt@...nel.org>
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Subject: Re: [PATCH v6 0/2] dt-bindings: Intorduce domain-controller

Hello,

There were typo in the cover letter subject. Patch series are related to 
v6, not v4. I've fixed Subject in this letter.
I'm sorry for the inconvenience.

Thanks,
Oleksii.

On 10.11.22 10:57, Oleksii Moisieiev wrote:
> Introducing the feature domain controller provider/consumenr bindngs which
> allow to divided system on chip into multiple feature domains that
> can be used to select by who hardware blocks could be accessed.
> A feature-domain could be a cluster of CPUs, a group of hardware blocks or
> the set of devices, passed-through to the Guest in the virtualized systems.
> 
> Feature domains controllers are typically used to set the permissions of
> the hardware block. The contents of the feature domain configuration
> properties are defined by the binding for the individual
> feature domain controller device.
> 
> The feature device controller conception in the virtualized systems is to
> set the device configuration for SCMI (System Control and Management
> Interface) which controls clocks/power-domains/resets etc from the
> Firmware. This configuratio sets the device_id to set the device
> permissions for the Firmware using BASE_SET_DEVICE_PERMISSIONS
> message (see 4.2.2.10 of [0]).
> There is no BASE_GET_DEVICE_PERMISSIONS call in SCMI and the way to
> determine device_id is not covered by the specification.
> Device permissions management described in DEN 0056, Section 4.2.2.10 [0].
> Given parameter should set the device_id, needed to set device
> permissions in the Firmware.
> This property is used by trusted Agent (which is hypervisor in our case)
> to set permissions for the devices, passed-through to the non-trusted
> Agents. Trusted Agent will use device-perms to set the Device
> permissions for the Firmware (See Section 4.2.2.10 [0] for details).
> Agents concept is described in Section 4.2.1 [0].
> 
> Feature-Domains in Device-tree node example:
> usb@...90000
> {
>      feature-domains = <&scmi 19>; //Set domain id 19 to usb node
>      feature-domain-names = "scmi";
>      clocks = <&scmi_clock 3>, <&scmi_clock 2>;
>      resets = <&scmi_reset 10>, <&scmi_reset 9>;
>      power-domains = <&scmi_power 0>;
> };
> 
> &scmi {
>      feature-domain-controller;
>      #feature-domain-cells = <1>;
> }
> 
> All mentioned bindings are going to be processed by XEN SCMI mediator
> feature, which is responsible to redirect SCMI calls from guests to the
> firmware, and not going be passed to the guests.
> 
> Feature-domain-controller provider/consumenr concept was taken from the bus
> controller framework patch series, provided in the following thread:
> [1].
> 
> I think we can cooperate with the bus controller framework developers
> and produce the common binding, which will fit the requirements of both
> features
> 
> Also, I think that binding can also be used for STM32 ETZPC bus
> controller feature, proposed in the following thread: [2].
> 
> Looking forward for your thoughts and ideas.
> 
> [0] https://developer.arm.com/documentation/den0056/latest
> [1] https://lore.kernel.org/all/20190318100605.29120-1-benjamin.gaignard@st.com/
> [2] https://lore.kernel.org/all/20200701132523.32533-1-benjamin.gaignard@st.com/
> 
> ---
> Changes v1 -> V2:
>     - update parameter name, made it xen-specific
>     - add xen vendor bindings
> 
> Changes V2 -> V3:
>     - update parameter name, make it generic
>     - update parameter format, add link to controller
>     - do not include xen vendor bindings as already upstreamed
> 
> Changes V3 -> V4:
>     - introduce domain controller provider/consumer device tree bindings
>     - making scmi node to act as domain controller provider when the
>       device permissions should be configured
> 
> Changes V4 -> V5:
>     - rename domain-controller to feature-domain-controller
>     - feature-domains format fixes
> 
> Changes V5 -> V6:
>     - formatting fixes
> 
> Oleksii Moisieiev (2):
>    dt-bindings: Update scmi node description
>    dt-bindings: Document common device controller bindings
> 
>   .../feature-domain-controller.yaml            | 84 +++++++++++++++++++
>   .../bindings/firmware/arm,scmi.yaml           | 28 +++++++
>   MAINTAINERS                                   |  6 ++
>   3 files changed, 118 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/feature-controllers/feature-domain-controller.yaml
> 

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