[RFC PATCH v2 2/7] dt-bindings: bus: add STM32 System Bus

[Gatien Chevallier <gatien.chevallier@foss.st.com>]

Document STM32 System Bus. This bus is intended to control firewall
access for the peripherals connected to it.

Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Signed-off-by: Loic PALLARDY <loic.pallardy@st.com>
---

Changes in V2: 
	- Corrected errors highlighted by Rob's robot
	- Re-ordered Signed-off-by tags

 .../devicetree/bindings/bus/st,sys-bus.yaml   | 88 +++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/st,sys-bus.yaml

diff --git a/Documentation/devicetree/bindings/bus/st,sys-bus.yaml b/Documentation/devicetree/bindings/bus/st,sys-bus.yaml
new file mode 100644
index 000000000000..d246fbdd6dea
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/st,sys-bus.yaml
@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/st,sys-bus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STM32 System Bus
+
+description: |
+  The STM32 System Bus is an internal bus to which some internal peripherals
+  are connected. STM32 System Bus integrates a firewall controlling access to each
+  device. This bus prevents non-accessible devices to be probed.
+
+  To see which peripherals are securable, please check the SoC reference manual.
+
+maintainers:
+  - Gatien Chevallier <gatien.chevallier@foss.st.com>
+
+allOf:
+  - $ref: /schemas/feature-controllers/feature-domain-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - st,stm32mp13-sys-bus
+      - st,stm32mp15-sys-bus
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+  '#feature-domain-cells':
+    minimum: 1
+
+  ranges: true
+
+  feature-domain-controller: true
+
+patternProperties:
+  "^.*@[0-9a-f]+$":
+    description: Devices attached to system bus
+    type: object
+    properties:
+      feature-domains:
+        $ref: /schemas/feature-controllers/feature-domain-controller.yaml#/properties/feature-domains
+
+required:
+  - compatible
+  - reg
+  - "#address-cells"
+  - "#size-cells"
+  - feature-domain-controller
+  - '#feature-domain-cells'
+  - ranges
+
+additionalProperties: false
+
+examples:
+  - |
+    // In this example,
+    // - the foo1 device refers to etzpc as his domain controller.
+    // - same goes for foo2.
+    // Access rights are verified before creating devices.
+
+    etzpc: etzpc@5c007000 {
+        compatible = "st,stm32mp15-sys-bus";
+        reg = <0x5c007000 0x400>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges;
+        feature-domain-controller;
+        #feature-domain-cells = <1>;
+
+        foo1: foo@1000000 {
+          reg = <0x0 0x1000000>;
+          feature-domains = <&etzpc 0>;
+        };
+
+        foo2: foo@2000000 {
+          reg = <0x0 0x2000000>;
+          feature-domains = <&etzpc 0>;
+        };
+    };
-- 
2.25.1