[nrf fromlist] samples: boards: nordic: system_off: Run on nrf54l20pdk

Add overlays to execute system_off tests on nrf54l20pdk.

Upstream PR #: 82925

Signed-off-by: Sebastian Głąb <[email protected]>

Author: nordic-segl

samples/boards/nordic/system_off/boards/nrf54l20pdk_nrf54l20_cpuapp.overlay

@@ -0,0 +1,25 @@
+/ {
+	cpuapp_sram@2007ec00 {
+		compatible = "zephyr,memory-region", "mmio-sram";
+		reg = <0x2007ec00 DT_SIZE_K(4)>;
+		zephyr,memory-region = "RetainedMem";
+		status = "okay";
+
+		retainedmem0: retainedmem {
+			compatible = "zephyr,retained-ram";
+			status = "okay";
+		};
+	};
+
+	aliases {
+		retainedmemdevice = &retainedmem0;
+	};
+};
+
+&cpuapp_sram {
+	/* Shrink SRAM size to avoid overlap with retained memory region:
+	 * 511 - 4 = 507KB = 0x7ec00
+	 */
+	reg = <0x20000000 DT_SIZE_K(507)>;
+	ranges = <0x0 0x20000000 0x7ec00>;
+};

samples/boards/nordic/system_off/sample.yaml

@@ -14,6 +14,7 @@ tests:
       - nrf54l15dk/nrf54l05/cpuapp
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l15/cpuapp
+      - nrf54l20pdk/nrf54l20/cpuapp
     harness: console
     harness_config:
       type: multi_line
@@ -31,6 +32,7 @@ tests:
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l05/cpuapp
+      - nrf54l20pdk/nrf54l20/cpuapp
     extra_configs:
       - CONFIG_APP_USE_RETAINED_MEM=y
     harness: console
@@ -49,6 +51,7 @@ tests:
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l05/cpuapp
+      - nrf54l20pdk/nrf54l20/cpuapp
     extra_configs:
       - CONFIG_GRTC_WAKEUP_ENABLE=y
     harness: console
@@ -70,6 +73,7 @@ tests:
       - nrf54l15dk/nrf54l15/cpuapp
       - nrf54l15dk/nrf54l10/cpuapp
       - nrf54l15dk/nrf54l05/cpuapp
+      - nrf54l20pdk/nrf54l20/cpuapp
     extra_configs:
       - CONFIG_APP_USE_RETAINED_MEM=y
       - CONFIG_GRTC_WAKEUP_ENABLE=y