arduino_due: add Arduino connector description

This patch adds the standard Arduino UNO R3 connector description to the
Arduino Due board.

Signed-off-by: Luca Burelli <[email protected]>

boards/arduino/due/arduino_due.dts

@@ -4,6 +4,7 @@
 
 #include <atmel/sam3x.dtsi>
 #include "arduino_due-pinctrl.dtsi"
+#include "arduino_r3_connector.dtsi"
 
 / {
 	model = "Arduino Due with an Atmel SAM3X8E SoC";

boards/arduino/due/arduino_r3_connector.dtsi

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2025 Arduino SA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	arduino_header: connector {
+		compatible = "arduino-header-r3";
+		#gpio-cells = <2>;
+		gpio-map-mask = <0xffffffff 0xffffffc0>;
+		gpio-map-pass-thru = <0 0x3f>;
+		gpio-map = < 0 0 &pioa 16 0>,	/* A0 */
+			   < 1 0 &pioa 24 0>,	/* A1 */
+			   < 2 0 &pioa 23 0>,	/* A2 */
+			   < 3 0 &pioa 22 0>,	/* A3 */
+			   < 4 0 &pioa  6 0>,	/* A4 */
+			   < 5 0 &pioa  4 0>,	/* A5 */
+			   < 6 0 &pioa  8 0>,	/* D0 */
+			   < 7 0 &pioa  9 0>,	/* D1 */
+			   < 8 0 &piob 25 0>,	/* D2 */
+			   < 9 0 &pioc 28 0>,	/* D3 */
+			   <10 0 &pioa 29 0>,	/* D4 */
+			   <11 0 &pioc 25 0>,	/* D5 */
+			   <12 0 &pioc 24 0>,	/* D6 */
+			   <13 0 &pioc 23 0>,	/* D7 */
+			   <14 0 &pioc 22 0>,	/* D8 */
+			   <15 0 &pioc 21 0>,	/* D9 */
+			   <16 0 &pioa 28 0>,	/* D10 */
+			   <17 0 &piod  7 0>,	/* D11 */
+			   <18 0 &piod  8 0>,	/* D12 */
+			   <19 0 &piob 27 0>,	/* D13 */
+			   <20 0 &pioa 17 0>,	/* D20 */
+			   <21 0 &pioa 18 0>;	/* D21 */
+	};
+};