Add driver for Radxa Rock Pi 4B Plus (#1918)

* Add driver for Radxa Rock Pi 4B Plus

* make the class as public

* fix formatting

* add `Board specific drivers` to readme

* driver name and link to source

* Fix markdown error
Co-authored-by: NPatrick Grawehr <Patrick.Grawehr@leica-geosystems.com>

src/devices/Gpio/Drivers/RockPi4BPlusDriver.cs

+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+
+namespace Iot.Device.Gpio.Drivers
+{
+    /// <summary>
+    /// A GPIO driver for the Rock Pi 4B Plus.
+    /// </summary>
+    /// <remarks>
+    /// SoC: Rockchip RK3399
+    /// </remarks>
+    public class RockPi4bPlusDriver : Rk3399Driver
+    {
+        private static readonly int[] _pinNumberConverter = new int[]
+        {
+            -1, -1, MapPinNumber(2, 'A', 7), -1, MapPinNumber(2, 'B', 0), -1, MapPinNumber(2, 'B', 3),
+            MapPinNumber(4, 'C', 4), -1, MapPinNumber(4, 'C', 3), MapPinNumber(4, 'C', 2), MapPinNumber(4, 'A', 3),
+            MapPinNumber(4, 'C', 6), -1, MapPinNumber(4, 'C', 5), MapPinNumber(4, 'D', 2), -1, MapPinNumber(4, 'D', 4),
+            MapPinNumber(1, 'B', 0), -1, MapPinNumber(1, 'A', 7), MapPinNumber(4, 'D', 5), MapPinNumber(1, 'B', 1),
+            MapPinNumber(1, 'B', 2), -1, -1, MapPinNumber(2, 'A', 0), MapPinNumber(2, 'A', 1), MapPinNumber(2, 'B', 2),
+            -1, MapPinNumber(2, 'B', 1), MapPinNumber(3, 'C', 0), MapPinNumber(2, 'B', 4), -1, MapPinNumber(4, 'A', 5),
+            MapPinNumber(4, 'A', 4), MapPinNumber(4, 'D', 6), MapPinNumber(4, 'A', 6), -1, MapPinNumber(4, 'A', 7)
+        };
+
+        /// <inheritdoc/>
+        protected override int PinCount => 40;
+
+        /// <inheritdoc/>
+        protected override int ConvertPinNumberToLogicalNumberingScheme(int pinNumber)
+        {
+            int num = _pinNumberConverter[pinNumber];
+
+            return num != -1 ? num : throw new ArgumentException($"Board (header) pin {pinNumber} is not a GPIO pin on the {GetType().Name} device.", nameof(pinNumber));
+        }
+    }
+}

src/devices/Gpio/README.md

@@ -7,6 +7,17 @@ This project contains some **full function(PULL-UP, PULL-DOWN)** generic GPIO dr
 * For Allwinner SoCs: [SunxiDriver](Drivers/Sunxi/README.md)
 * For Rockchip SoCs: [RockchipDriver](Drivers/Rockchip/README.md)
 
+## Board specific drivers
+
+| Board | Driver |
+| :-: | :-: |
+| Orange Pi 4 | [OrangePi4Driver](./Drivers/OrangePi4Driver.cs) |
+| Orange Pi Lite | [OrangePiLiteDriver](./Drivers/OrangePiLiteDriver.cs)  |
+| Orange Pi Lite 2 | [OrangePiLite2Driver](./Drivers/OrangePiLite2Driver.cs) |
+| Orange Pi Zero | [OrangePiZeroDriver](./Drivers/OrangePiZeroDriver.cs) |
+| Orange Pi Zero 2 | [OrangePiZero2Driver](./Drivers/OrangePiZero2Driver.cs) |
+| Rock Pi 4B Plus | [RockPi4bPlusDriver](./Drivers/RockPi4bPlusDriver.cs) |
+
 ## Benchmarks
 
 The test uses different GPIO drivers to quickly switch the state of GPIO, and uses an oscilloscope to measure the average frequency of GPIO externally.