tests: drivers: adc: Add overlay file for EK-RX261 board

Add overlay file for EK-RX261 board

Signed-off-by: Hau Ho <[email protected]>

Author: Hau Ho

tests/drivers/adc/adc_accuracy_test/boards/ek_rx261.conf

@@ -0,0 +1 @@
+CONFIG_REFERENCE_VOLTAGE_TEST=y

tests/drivers/adc/adc_accuracy_test/boards/ek_rx261.overlay

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2025 Renesas Electronics Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	zephyr,user {
+		io-channels = <&adc 0>;
+		reference-mv = <3300>;
+		expected-accuracy = <32>;
+	};
+};
+
+&adc {
+	pinctrl-0 = <&adc_default>;
+	pinctrl-names = "default";
+	#address-cells = <1>;
+	#size-cells = <0>;
+	status = "okay";
+
+	channel@0 {
+		reg = <0>;
+		zephyr,gain = "ADC_GAIN_1";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
+		zephyr,resolution = <12>;
+		zephyr,vref-mv = <3300>;
+		zephyr,oversampling = <1>;
+	};
+
+	channel@1 {
+		reg = <1>;
+		zephyr,gain = "ADC_GAIN_1";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
+		zephyr,resolution = <12>;
+		zephyr,vref-mv = <3300>;
+	};
+};

tests/drivers/adc/adc_api/boards/ek_rx261.overlay

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2025 Renesas Electronics Corporation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	zephyr,user {
+		io-channels = <&adc 0>, <&adc 2>;
+	};
+};
+
+&adc {
+	pinctrl-0 = <&adc_default>;
+	pinctrl-names = "default";
+	status = "okay";
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	channel@0 {
+		reg = <0>;
+		zephyr,gain = "ADC_GAIN_1";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,resolution = <12>;
+		zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
+		zephyr,vref-mv = <3300>;
+	};
+
+	channel@2 {
+		reg = <2>;
+		zephyr,gain = "ADC_GAIN_1";
+		zephyr,reference = "ADC_REF_INTERNAL";
+		zephyr,resolution = <12>;
+		zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
+		zephyr,vref-mv = <3300>;
+	};
+};