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/cmd/help.c

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2000-2009
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_help(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+#ifdef CONFIG_CMDLINE
+	cmd_tbl_t *start = ll_entry_start(cmd_tbl_t, cmd);
+	const int len = ll_entry_count(cmd_tbl_t, cmd);
+	return _do_help(start, len, cmdtp, flag, argc, argv);
+#else
+	return 0;
+#endif
+}
+
+U_BOOT_CMD(
+	help,	CONFIG_SYS_MAXARGS,	1,	do_help,
+	"print command description/usage",
+	"\n"
+	"	- print brief description of all commands\n"
+	"help command ...\n"
+	"	- print detailed usage of 'command'"
+);
+
+/* This does not use the U_BOOT_CMD macro as ? can't be used in symbol names */
+ll_entry_declare(cmd_tbl_t, question_mark, cmd) = {
+	"?",	CONFIG_SYS_MAXARGS,	1,	do_help,
+	"alias for 'help'",
+#ifdef  CONFIG_SYS_LONGHELP
+	""
+#endif /* CONFIG_SYS_LONGHELP */
+};