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Message-ID: <20231002173019.GA2037244-robh@kernel.org>
Date: Mon, 2 Oct 2023 12:30:19 -0500
From: Rob Herring <robh@...nel.org>
To: Gatien Chevallier <gatien.chevallier@...s.st.com>
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Subject: Re: [PATCH v5 01/11] dt-bindings: document generic access controller
On Fri, Sep 29, 2023 at 04:28:42PM +0200, Gatien Chevallier wrote:
> From: Oleksii Moisieiev <Oleksii_Moisieiev@...m.com>
>
> Introducing of the generic access controller bindings for the
> access controller provider and consumer devices. Those bindings are
> intended to allow a better handling of accesses to resources in a
> hardware architecture supporting several compartments.
>
> This patch is based on [1]. It is integrated in this patchset as it
> provides a use-case for it.
>
> Diffs with [1]:
> - Rename feature-domain* properties to access-control* to narrow
> down the scope of the binding
> - YAML errors and typos corrected.
> - Example updated
> - Some rephrasing in the binding description
>
> [1]: https://lore.kernel.org/lkml/0c0a82bb-18ae-d057-562b
>
> Signed-off-by: Oleksii Moisieiev <oleksii_moisieiev@...m.com>
> Signed-off-by: Gatien Chevallier <gatien.chevallier@...s.st.com>
>
> ---
> Changes in V5:
> - Diffs with [1]
> - Discarded the [IGNORE] tag as the patch is now part of the
> patchset
>
> .../access-controllers/access-controller.yaml | 90 +++++++++++++++++++
> 1 file changed, 90 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/access-controllers/access-controller.yaml
>
> diff --git a/Documentation/devicetree/bindings/access-controllers/access-controller.yaml b/Documentation/devicetree/bindings/access-controllers/access-controller.yaml
> new file mode 100644
> index 000000000000..9d305fccc333
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/access-controllers/access-controller.yaml
> @@ -0,0 +1,90 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/access-controllers/access-controller.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Generic Domain Access Controller
> +
> +maintainers:
> + - Oleksii Moisieiev <oleksii_moisieiev@...m.com>
> +
> +description: |+
> + Common access controllers properties
> +
> + Access controllers are in charge of stating which of the hardware blocks under
> + their responsibility (their domain) can be accesssed by which compartment. A
> + compartment can be a cluster of CPUs (or coprocessors), a range of addresses
> + or a group of hardware blocks. An access controller's domain is the set of
> + resources covered by the access controller.
> +
> + This device tree bindings can be used to bind devices to their access
> + controller provided by access-controller property. In this case, the device is
> + a consumer and the access controller is the provider.
> +
> + An access controller can be represented by any node in the device tree and
> + can provide one or more configuration parameters, needed to control parameters
> + of the consumer device. A consumer node can refer to the provider by phandle
> + and a set of phandle arguments, specified by '#access-controller-cells'
> + property in the access controller node.
> +
> + Access controllers are typically used to set/read the permissions of a
> + hardware block and grant access to it. Any of which depends on the access
> + controller. The capabilities of each access controller are defined by the
> + binding of the access controller device.
> +
> + Each node can be a consumer for the several access controllers.
> +
> +# always select the core schema
> +select: true
> +
> +properties:
> + "#access-controller-cells":
> + $ref: /schemas/types.yaml#/definitions/uint32
Drop. "#.*-cells" already defines the type.
> + description:
> + Number of cells in a access-controller specifier;
> + Can be any value as specified by device tree binding documentation
> + of a particular provider.
> +
> + access-control-provider:
> + description:
> + Indicates that the node is an access controller.
Drop. The presence of "#access-controller-cells" is enough to do that.
> +
> + access-controller-names:
> + $ref: /schemas/types.yaml#/definitions/string-array
> + description:
> + A list of access-controller names, sorted in the same order as
> + access-controller entries. Consumer drivers will use
> + access-controller-names to match with existing access-controller entries.
> +
> + access-controller:
For consistency with other provider bindings: access-controllers
> + $ref: /schemas/types.yaml#/definitions/phandle-array
> + description:
> + A list of access controller specifiers, as defined by the
> + bindings of the access-controller provider.
> +
> +additionalProperties: true
> +
> +examples:
> + - |
> + uart_controller: access-controller@...00 {
> + reg = <0x50000 0x10>;
> + access-control-provider;
> + #access-controller-cells = <2>;
> + };
> +
> + bus_controller: bus@...00 {
> + reg = <0x60000 0x10000>;
> + #address-cells = <1>;
> + #size-cells = <1>;
> + ranges;
> + access-control-provider;
> + #access-controller-cells = <3>;
> +
> + uart4: serial@...00 {
> + reg = <0x60100 0x400>;
> + access-controller = <&uart_controller 1 2>,
> + <&bus_controller 1 3 5>;
> + access-controller-names = "controller", "bus-controller";
Not great names. It should indicate what access is being controlled
locally. Perhaps "reg" for register access, "dma" or "bus" for bus
master access. (Not sure what your uart_controller is controlling access
to.)
Rob
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