Re: [PATCH v5 01/11] dt-bindings: document generic access controller

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@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

Signed-off-by: Oleksii Moisieiev oleksii_moisieiev@epam.com Signed-off-by: Gatien Chevallier gatien.chevallier@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@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@50000 {

•    reg = <0x50000 0x10>;
  

•    access-control-provider;
  

•    #access-controller-cells = <2>;
  

• };
• bus_controller: bus@60000 {

•    reg = <0x60000 0x10000>;
  

•    #address-cells = <1>;
  

•    #size-cells = <1>;
  

•    ranges;
  

•    access-control-provider;
  

•    #access-controller-cells = <3>;
  

•    uart4: serial@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