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/echo.c

@@ -0,0 +1,56 @@
+/*
+ * 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_echo(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	int i;
+	int putnl = 1;
+
+	for (i = 1; i < argc; i++) {
+		char *p = argv[i];
+		char *nls; /* new-line suppression */
+
+		if (i > 1)
+			putc(' ');
+
+		nls = strstr(p, "\\c");
+		if (nls) {
+			char *prenls = p;
+
+			putnl = 0;
+			/*
+			 * be paranoid and guess that someone might
+			 * say \c more than once
+			 */
+			while (nls) {
+				*nls = '\0';
+				puts(prenls);
+				*nls = '\\';
+				prenls = nls + 2;
+				nls = strstr(prenls, "\\c");
+			}
+			puts(prenls);
+		} else {
+			puts(p);
+		}
+	}
+
+	if (putnl)
+		putc('\n');
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	echo,	CONFIG_SYS_MAXARGS,	1,	do_echo,
+	"echo args to console",
+	"[args..]\n"
+	"    - echo args to console; \\c suppresses newline"
+);