dt-bindings: stm32: convert mlahb to json-schema

Convert the ML-AHB bus bindings to DT schema format using json-schema
Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/stm32/mlahb.txt

-ML-AHB interconnect bindings
-
-These bindings describe the STM32 SoCs ML-AHB interconnect bus which connects
-a Cortex-M subsystem with dedicated memories.
-The MCU SRAM and RETRAM memory parts can be accessed through different addresses
-(see "RAM aliases" in [1]) using different buses (see [2]) : balancing the
-Cortex-M firmware accesses among those ports allows to tune the system
-performance.
-
-[1]: https://www.st.com/resource/en/reference_manual/dm00327659.pdf
-[2]: https://wiki.st.com/stm32mpu/wiki/STM32MP15_RAM_mapping
-
-Required properties:
-- compatible: should be "simple-bus"
-- dma-ranges: describes memory addresses translation between the local CPU and
-	   the remote Cortex-M processor. Each memory region, is declared with
-	   3 parameters:
-		 - param 1: device base address (Cortex-M processor address)
-		 - param 2: physical base address (local CPU address)
-		 - param 3: size of the memory region.
-
-The Cortex-M remote processor accessed via the mlahb interconnect is described
-by a child node.
-
-Example:
-mlahb {
-	compatible = "simple-bus";
-	#address-cells = <1>;
-	#size-cells = <1>;
-	dma-ranges = <0x00000000 0x38000000 0x10000>,
-		     <0x10000000 0x10000000 0x60000>,
-		     <0x30000000 0x30000000 0x60000>;
-
-	m4_rproc: m4@10000000 {
-		...
-	};
-};

Documentation/devicetree/bindings/arm/stm32/st,mlahb.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: "http://devicetree.org/schemas/arm/stm32/st,mlahb.yaml#"
+$schema: "http://devicetree.org/meta-schemas/core.yaml#"
+
+title: STMicroelectronics STM32 ML-AHB interconnect bindings
+
+maintainers:
+  - Fabien Dessenne <fabien.dessenne@st.com>
+  - Arnaud Pouliquen <arnaud.pouliquen@st.com>
+
+description: |
+  These bindings describe the STM32 SoCs ML-AHB interconnect bus which connects
+  a Cortex-M subsystem with dedicated memories. The MCU SRAM and RETRAM memory
+  parts can be accessed through different addresses (see "RAM aliases" in [1])
+  using different buses (see [2]): balancing the Cortex-M firmware accesses
+  among those ports allows to tune the system performance.
+  [1]: https://www.st.com/resource/en/reference_manual/dm00327659.pdf
+  [2]: https://wiki.st.com/stm32mpu/wiki/STM32MP15_RAM_mapping
+
+allOf:
+ - $ref: /schemas/simple-bus.yaml#
+
+properties:
+  compatible:
+    contains:
+      enum:
+        - st,mlahb
+
+  dma-ranges:
+    description: |
+      Describe memory addresses translation between the local CPU and the
+      remote Cortex-M processor. Each memory region, is declared with
+      3 parameters:
+      - param 1: device base address (Cortex-M processor address)
+      - param 2: physical base address (local CPU address)
+      - param 3: size of the memory region.
+    maxItems: 3
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 1
+
+required:
+  - compatible
+  - '#address-cells'
+  - '#size-cells'
+  - dma-ranges
+
+examples:
+  - |
+    mlahb: ahb {
+      compatible = "st,mlahb", "simple-bus";
+      #address-cells = <1>;
+      #size-cells = <1>;
+      reg = <0x10000000 0x40000>;
+      ranges;
+      dma-ranges = <0x00000000 0x38000000 0x10000>,
+                   <0x10000000 0x10000000 0x60000>,
+                   <0x30000000 0x30000000 0x60000>;
+
+      m4_rproc: m4@10000000 {
+       reg = <0x10000000 0x40000>;
+      };
+    };
+
+...