Kernel: Add Framebuffer class for Raspberry Pi

It initializes framebuffer and exposes access to its properties.

Kernel/Prekernel/Arch/aarch64/Framebuffer.h

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2021, Marcin Undak <mcinek@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+
+namespace Prekernel {
+
+class Framebuffer {
+public:
+    enum class PixelOrder {
+        RGB,
+        BGR,
+    };
+
+    static Framebuffer& the();
+
+    bool initialized() const { return m_initialized; }
+    u16 width() const { return m_width; }
+    u16 height() const { return m_height; }
+    u8 depth() const { return m_depth; }
+    u8* gpu_buffer() const { return m_gpu_buffer; }
+    u32 buffer_size() const { return m_buffer_size; }
+    u32 pitch() const { return m_pitch; }
+    PixelOrder pixel_order() { return m_pixel_order; }
+
+private:
+    u16 m_width;
+    u16 m_height;
+    u8 m_depth;
+    u8* m_gpu_buffer;
+    u32 m_buffer_size;
+    u32 m_pitch;
+    bool m_initialized;
+    PixelOrder m_pixel_order;
+
+    Framebuffer();
+};
+}