Kernel: Add driver for interrupt controller on the Raspberry Pi

This implements the simpler IRQController class and adds a
pending_interrupts() function to the class.

Kernel/Arch/aarch64/RPi/InterruptController.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2022, Timon Kruiper <timonkruiper@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <Kernel/Arch/aarch64/IRQController.h>
+
+namespace Kernel::RPi {
+
+struct InterruptControllerRegisters;
+
+// This class implements the simple Interrupt Controller found in the BCM2837. (RPi3)
+// A description of this device can be found at chapter 7 (Interrupts) of the manual:
+// https://github.com/raspberrypi/documentation/files/1888662/BCM2837-ARM-Peripherals.-.Revised.-.V2-1.pdf (RPi3)
+class InterruptController : public IRQController {
+public:
+    InterruptController();
+
+private:
+    virtual void enable(GenericInterruptHandler const&) override;
+    virtual void disable(GenericInterruptHandler const&) override;
+
+    virtual void eoi(GenericInterruptHandler const&) const override;
+
+    virtual u64 pending_interrupts() const override;
+
+    virtual StringView model() const override
+    {
+        return "Raspberry Pi Interrupt Controller";
+    }
+
+    InterruptControllerRegisters volatile* m_registers;
+};
+
+}