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/include/iomux.h

@@ -0,0 +1,32 @@
+/*
+ * (C) Copyright 2008
+ * Gary Jennejohn, DENX Software Engineering GmbH, garyj@denx.de.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _IO_MUX_H
+#define _IO_MUX_H
+
+#include <stdio_dev.h>
+
+/*
+ * Stuff required to support console multiplexing.
+ */
+
+/*
+ * Pointers to devices used for each file type.  Defined in console.c
+ * but storage is allocated in iomux.c.
+ */
+extern struct stdio_dev **console_devices[MAX_FILES];
+/*
+ * The count of devices assigned to each FILE.  Defined in console.c
+ * and populated in iomux.c.
+ */
+extern int cd_count[MAX_FILES];
+
+int iomux_doenv(const int, const char *);
+void iomux_printdevs(const int);
+struct stdio_dev *search_device(int, const char *);
+
+#endif /* _IO_MUX_H */