Kernel: Improve the aarch64 kernel source files disk layout

Kernel/Arch/aarch64/RPi/GPIO.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2021, Nico Weber <thakis@chromium.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Array.h>
+#include <AK/Types.h>
+
+namespace Prekernel {
+
+struct GPIOControlRegisters;
+
+// Can configure the general-purpose I/O registers on a Raspberry Pi.
+class GPIO {
+public:
+    enum class PinFunction {
+        Input = 0,
+        Output = 1,
+        Alternate0 = 0b100,
+        Alternate1 = 0b101,
+        Alternate2 = 0b110,
+        Alternate3 = 0b111,
+        Alternate4 = 0b011,
+        Alternate5 = 0b010,
+    };
+
+    static GPIO& the();
+
+    void set_pin_function(unsigned pin_number, PinFunction);
+
+    enum class PullUpDownState {
+        Disable = 0,
+        PullDown = 1,
+        PullUp = 2,
+    };
+
+    template<size_t N>
+    void set_pin_pull_up_down_state(Array<int, N> pins, PullUpDownState state)
+    {
+        u32 enable[2] = {};
+        for (int pin : pins) {
+            if (pin < 32)
+                enable[0] |= (1 << pin);
+            else
+                enable[1] |= (1 << (pin - 32));
+        }
+        internal_enable_pins(enable, state);
+    }
+
+private:
+    GPIO();
+    void internal_enable_pins(u32 enable[2], PullUpDownState state);
+
+    GPIOControlRegisters volatile* m_registers;
+};
+
+}