Kernel: Move x86-specific HID code to the Arch/x86 directory

The i8042 controller with its attached devices, the PS2 keyboard and
mouse, rely on x86-specific IO instructions to work. Therefore, move
them to the Arch/x86 directory to make it easier to omit the handling
code of these devices.

Kernel/Arch/x86/ISABus/HID/PS2KeyboardDevice.h

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/CircularQueue.h>
+#include <AK/DoublyLinkedList.h>
+#include <AK/Types.h>
+#include <Kernel/API/KeyCode.h>
+#include <Kernel/Arch/x86/ISABus/I8042Controller.h>
+#include <Kernel/Devices/HID/KeyboardDevice.h>
+#include <Kernel/Interrupts/IRQHandler.h>
+#include <Kernel/Random.h>
+
+namespace Kernel {
+
+class PS2KeyboardDevice final : public IRQHandler
+    , public KeyboardDevice
+    , public I8042Device {
+    friend class DeviceManagement;
+
+public:
+    static ErrorOr<NonnullLockRefPtr<PS2KeyboardDevice>> try_to_initialize(I8042Controller const&);
+    virtual ~PS2KeyboardDevice() override;
+    ErrorOr<void> initialize();
+
+    virtual StringView purpose() const override { return class_name(); }
+
+    // ^I8042Device
+    virtual void irq_handle_byte_read(u8 byte) override;
+    virtual void enable_interrupts() override
+    {
+        enable_irq();
+    }
+
+private:
+    explicit PS2KeyboardDevice(I8042Controller const&);
+
+    // ^IRQHandler
+    virtual bool handle_irq(RegisterState const&) override;
+
+    // ^CharacterDevice
+    virtual StringView class_name() const override { return "KeyboardDevice"sv; }
+};
+
+}