[PATCH v5 01/11] dt-bindings: document generic access controller
Gatien CHEVALLIER
gatien.chevallier at foss.st.com
Tue Oct 3 00:45:36 PDT 2023
Hi Rob,
On 10/2/23 19:30, Rob Herring wrote:
> On Fri, Sep 29, 2023 at 04:28:42PM +0200, Gatien Chevallier wrote:
>> From: Oleksii Moisieiev <Oleksii_Moisieiev at epam.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 at epam.com>
>> Signed-off-by: Gatien Chevallier <gatien.chevallier at foss.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 at epam.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.
>
Ok, I will drop it for V6
>> + 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.
>
Ok, I wasn't sure. I'll will drop it for V6
>> +
>> + 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
>
Ack
>> + $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 at 50000 {
>> + reg = <0x50000 0x10>;
>> + access-control-provider;
>> + #access-controller-cells = <2>;
>> + };
>> +
>> + bus_controller: bus at 60000 {
>> + reg = <0x60000 0x10000>;
>> + #address-cells = <1>;
>> + #size-cells = <1>;
>> + ranges;
>> + access-control-provider;
>> + #access-controller-cells = <3>;
>> +
>> + uart4: serial at 60100 {
>> + 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
Yes, I agree it's poor naming. I'll come up with something more
adequate. Thank you for the input.
Best regards,
Gatien
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