avionic design with actual uboot and tooling

submodule of avionic design uboot bootloader and with included tools to
get you started , read readme.md and readme-tk1-loader.md

u-boot/arch/arm/cpu/armv8/cpu.c

@@ -0,0 +1,43 @@
+/*
+ * (C) Copyright 2008 Texas Insturments
+ *
+ * (C) Copyright 2002
+ * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
+ * Marius Groeger <mgroeger@sysgo.de>
+ *
+ * (C) Copyright 2002
+ * Gary Jennejohn, DENX Software Engineering, <garyj@denx.de>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <asm/system.h>
+#include <linux/compiler.h>
+
+int cleanup_before_linux(void)
+{
+	/*
+	 * this function is called just before we call linux
+	 * it prepares the processor for linux
+	 *
+	 * disable interrupt and turn off caches etc ...
+	 */
+	disable_interrupts();
+
+	/*
+	 * Turn off I-cache and invalidate it
+	 */
+	icache_disable();
+	invalidate_icache_all();
+
+	/*
+	 * turn off D-cache
+	 * dcache_disable() in turn flushes the d-cache and disables MMU
+	 */
+	dcache_disable();
+	invalidate_dcache_all();
+
+	return 0;
+}