dts: arm: silabs: Add silabs,buram binding for retained memory

Add binding for the 128-byte Backup RAM.

Signed-off-by: Aksel Skauge Mellbye <[email protected]>

Author: asmellby

dts/arm/silabs/xg21/xg21.dtsi

@@ -442,6 +442,12 @@
 			status = "disabled";
 		};
 
+		buram: retained-memory@50080000 {
+			compatible = "silabs,buram";
+			reg = <0x50080000 0x80>;
+			status = "disabled";
+		};
+
 		rtcc0: stimer0: rtcc@58000000 {
 			compatible = "silabs,gecko-stimer";
 			reg = <0x58000000 0x4000>;

dts/arm/silabs/xg22/xg22.dtsi

@@ -475,6 +475,13 @@
 			status = "disabled";
 		};
 
+		buram: retained-memory@50080000 {
+			compatible = "silabs,buram";
+			reg = <0x50080000 0x80>;
+			clocks = <&cmu CLOCK_BURAM CLOCK_BRANCH_INVALID>;
+			status = "disabled";
+		};
+
 		dcdc: dcdc@50094000 {
 			compatible = "silabs,series2-dcdc";
 			reg = <0x50094000 0x4000>;

dts/arm/silabs/xg23/xg23.dtsi

@@ -477,6 +477,13 @@
 			status = "disabled";
 		};
 
+		buram: retained-memory@50080000 {
+			compatible = "silabs,buram";
+			reg = <0x50080000 0x80>;
+			clocks = <&cmu CLOCK_BURAM CLOCK_BRANCH_INVALID>;
+			status = "disabled";
+		};
+
 		dcdc: dcdc@50094000 {
 			compatible = "silabs,series2-dcdc";
 			reg = <0x50094000 0x4000>;

dts/arm/silabs/xg24/xg24.dtsi

@@ -469,6 +469,13 @@
 			status = "disabled";
 		};
 
+		buram: retained-memory@50080000 {
+			compatible = "silabs,buram";
+			reg = <0x50080000 0x80>;
+			clocks = <&cmu CLOCK_BURAM CLOCK_BRANCH_INVALID>;
+			status = "disabled";
+		};
+
 		dcdc: dcdc@50094000 {
 			compatible = "silabs,series2-dcdc";
 			reg = <0x50094000 0x4000>;

dts/arm/silabs/xg27/xg27.dtsi

@@ -475,6 +475,13 @@
 			status = "disabled";
 		};
 
+		buram: retained-memory@50080000 {
+			compatible = "silabs,buram";
+			reg = <0x50080000 0x80>;
+			clocks = <&cmu CLOCK_BURAM CLOCK_BRANCH_PCLK>;
+			status = "disabled";
+		};
+
 		dcdc: dcdc@50094000 {
 			compatible = "silabs,series2-dcdc";
 			reg = <0x50094000 0x4000>;

dts/arm/silabs/xg28/xg28.dtsi

@@ -477,6 +477,13 @@
 			status = "disabled";
 		};
 
+		buram: retained-memory@50080000 {
+			compatible = "silabs,buram";
+			reg = <0x50080000 0x80>;
+			clocks = <&cmu CLOCK_BURAM CLOCK_BRANCH_INVALID>;
+			status = "disabled";
+		};
+
 		dcdc: dcdc@50094000 {
 			compatible = "silabs,series2-dcdc";
 			reg = <0x50094000 0x4000>;

dts/arm/silabs/xg29/xg29.dtsi

@@ -480,6 +480,13 @@
 			status = "disabled";
 		};
 
+		buram: retained-memory@50080000 {
+			compatible = "silabs,buram";
+			reg = <0x50080000 0x80>;
+			clocks = <&cmu CLOCK_BURAM CLOCK_BRANCH_PCLK>;
+			status = "disabled";
+		};
+
 		dcdc: dcdc@50094000 {
 			compatible = "silabs,series2-dcdc";
 			reg = <0x50094000 0x4000>;

dts/bindings/retained_mem/silabs,buram.yaml

@@ -0,0 +1,23 @@
+# Copyright (c) 2025 Silicon Laboratories Inc.
+# SPDX-License-Identifier: Apache-2.0
+
+title: Silicon Labs Series 2 BURAM (Back-Up Random Access Memory)
+
+description: |
+  The Back-Up RAM (BURAM) is a dedicated 128-byte memory that remains powered when the system enters
+  EM4. Upon exit from EM4, the data retained in the BURAM can be accessed by the application
+  software.
+
+compatible: "silabs,buram"
+
+include: base.yaml
+
+properties:
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+  reg:
+    required: true