dt-bindings: bus: document RIFSC

Document RIFSC (RIF security controller). RIFSC is a firewall controller
composed of different kinds of hardware resources.
Signed-off-by: Gatien Chevallier <gatien.chevallier@foss.st.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com>

Documentation/devicetree/bindings/bus/st,stm32mp25-rifsc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/st,stm32mp25-rifsc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: STM32 Resource isolation framework security controller
+
+maintainers:
+  - Gatien Chevallier <gatien.chevallier@foss.st.com>
+
+description: |
+  Resource isolation framework (RIF) is a comprehensive set of hardware blocks
+  designed to enforce and manage isolation of STM32 hardware resources like
+  memory and peripherals.
+
+  The RIFSC (RIF security controller) is composed of three sets of registers,
+  each managing a specific set of hardware resources:
+    - RISC registers associated with RISUP logic (resource isolation device unit
+      for peripherals), assign all non-RIF aware peripherals to zero, one or
+      any security domains (secure, privilege, compartment).
+    - RIMC registers: associated with RIMU logic (resource isolation master
+      unit), assign all non RIF-aware bus master to one security domain by
+      setting secure, privileged and compartment information on the system bus.
+      Alternatively, the RISUP logic controlling the device port access to a
+      peripheral can assign target bus attributes to this peripheral master port
+      (supported attribute: CID).
+    - RISC registers associated with RISAL logic (resource isolation device unit
+      for address space - Lite version), assign address space subregions to one
+      security domains (secure, privilege, compartment).
+
+select:
+  properties:
+    compatible:
+      contains:
+        const: st,stm32mp25-rifsc
+  required:
+    - compatible
+
+properties:
+  compatible:
+    items:
+      - const: st,stm32mp25-rifsc
+      - const: simple-bus
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+  ranges: true
+
+  "#access-controller-cells":
+    const: 1
+    description:
+      Contains the firewall ID associated to the peripheral.
+
+patternProperties:
+  "^.*@[0-9a-f]+$":
+    description: Peripherals
+    type: object
+
+    additionalProperties: true
+
+    required:
+      - access-controllers
+
+required:
+  - compatible
+  - reg
+  - "#address-cells"
+  - "#size-cells"
+  - "#access-controller-cells"
+  - ranges
+
+additionalProperties: false
+
+examples:
+  - |
+    // In this example, the usart2 device refers to rifsc as its domain
+    // controller.
+    // Access rights are verified before creating devices.
+
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    rifsc: bus@42080000 {
+        compatible = "st,stm32mp25-rifsc", "simple-bus";
+        reg = <0x42080000 0x1000>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        #access-controller-cells = <1>;
+        ranges;
+
+        usart2: serial@400e0000 {
+              compatible = "st,stm32h7-uart";
+              reg = <0x400e0000 0x400>;
+              interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_HIGH>;
+              clocks = <&ck_flexgen_08>;
+              access-controllers = <&rifsc 32>;
+        };
+    };