boards: gd323103_eval: add dac support.

add dac support.

Signed-off-by: YuLong Yao <[email protected]>

Author: feilongfl

boards/arm/gd32e103v_eval/gd32e103v_eval-pinctrl.dtsi

@@ -18,6 +18,12 @@
 		};
 	};
 
+	dac_default: dac_default {
+		group1 {
+			pinmux = <DAC_OUT0_PA4>;
+		};
+	};
+
 	i2c0_default: i2c0_default {
 		group1 {
 			pinmux = <I2C0_SCL_PB6_NORMP>, <I2C0_SDA_PB7_NORMP>;

boards/arm/gd32e103v_eval/gd32e103v_eval.dts

@@ -126,3 +126,9 @@
 		timeout = <5>;
 	};
 };
+
+&dac {
+	status = "okay";
+	pinctrl-0 = <&dac_default>;
+	pinctrl-names = "default";
+};

samples/drivers/dac/boards/gd32e103v_eval.overlay

@@ -0,0 +1,13 @@
+/*
+ * Copyright 2021 BrainCo Inc.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	zephyr,user {
+		dac = <&dac>;
+		dac-channel-id = <0>;
+		dac-resolution = <12>;
+	};
+};