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/sh/cpu/sh4/cpu.c

@@ -0,0 +1,83 @@
+/*
+ * (C) Copyright 2007
+ * Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <netdev.h>
+#include <asm/processor.h>
+#include <asm/cache.h>
+
+int checkcpu(void)
+{
+	puts("CPU: SH4\n");
+	return 0;
+}
+
+int cpu_init (void)
+{
+	return 0;
+}
+
+int cleanup_before_linux (void)
+{
+	disable_interrupts();
+	return 0;
+}
+
+int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	disable_interrupts();
+	reset_cpu (0);
+	return 0;
+}
+
+void flush_cache (unsigned long addr, unsigned long size)
+{
+	invalidate_dcache_range(addr , addr + size);
+}
+
+void icache_enable (void)
+{
+	cache_control(0);
+}
+
+void icache_disable (void)
+{
+	cache_control(1);
+}
+
+int icache_status (void)
+{
+	return 0;
+}
+
+void dcache_enable (void)
+{
+}
+
+void dcache_disable (void)
+{
+}
+
+int dcache_status (void)
+{
+	return 0;
+}
+
+int cpu_eth_init(bd_t *bis)
+{
+#ifdef CONFIG_SH_ETHER
+	sh_eth_initialize(bis);
+#endif
+	return 0;
+}
+
+void relocate_code(ulong start_addr_sp, gd_t *new_gd, ulong relocaaddr)
+{
+	/* TODO(sh maintainer): Implement this */
+	while (1);
+}