[PATCH v8 01/13] dt-bindings: document generic access controllers

Gatien Chevallier
2023-12-12T15:24:43Z

From: Oleksii Moisieiev <Oleksii_Moisieiev@epam.com>

Introducing of the generic access controllers 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 V6:
- Renamed access-controller to access-controllers
- Example updated
- Removal of access-control-provider property

Changes in V5:
- Diffs with [1]
- Discarded the [IGNORE] tag as the patch is now part of the
patchset

.../access-controllers.yaml | 84 +++++++++++++++++++
1 file changed, 84 insertions(+)
create mode 100644 Documentation/devicetree/bindings/access-controllers/access-controllers.yaml

diff --git a/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml b/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml
new file mode 100644
index 000000000000..99e2865f0e46
--- /dev/null
+++ b/Documentation/devicetree/bindings/access-controllers/access-controllers.yaml
@@ -0,0 +1,84 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/access-controllers/access-controllers.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic Domain Access Controllers
+
+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 binding can be used to bind devices to their access
+ controller provided by access-controllers 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":
+ description:
+ Number of cells in an access-controllers specifier;
+ Can be any value as specified by device tree binding documentation
+ of a particular provider. The node is an access controller.
+
+ access-controller-names:
+ $ref: /schemas/types.yaml#/definitions/string-array
+ description:
+ A list of access-controllers names, sorted in the same order as
+ access-controllers entries. Consumer drivers will use
+ access-controller-names to match with existing access-controllers entries.
+
+ access-controllers:
+ $ref: /schemas/types.yaml#/definitions/phandle-array
+ description:
+ A list of access controller specifiers, as defined by the
+ bindings of the access-controllers provider.
+
+additionalProperties: true
+
+examples:
+ - |
+ clock_controller: access-controllers@50000 {
+ reg = <0x50000 0x400>;
+ #access-controller-cells = <2>;
+ };
+
+ bus_controller: bus@60000 {
+ reg = <0x60000 0x10000>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+ #access-controller-cells = <3>;
+
+ uart4: serial@60100 {
+ reg = <0x60100 0x400>;
+ clocks = <&clk_serial>;
+ access-controllers = <&clock_controller 1 2>,
+ <&bus_controller 1 3 5>;
+ access-controller-names = "clock", "bus";
+ };
+ };