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From:   Gatien Chevallier <gatien.chevallier@foss.st.com>
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Subject: [PATCH v5 01/11] dt-bindings: document generic access controller
Date:   Fri, 29 Sep 2023 16:28:42 +0200
Message-ID: <20230929142852.578394-2-gatien.chevallier@foss.st.com>
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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

[1]: https://lore.kernel.org/lkml/0c0a82bb-18ae-d057-562b

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
+    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.
+
+  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:
+    $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";
+        };
+    };
-- 
2.25.1