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/drivers/timer/sandbox_timer.c

@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+#include <os.h>
+
+#define SANDBOX_TIMER_RATE	1000000
+
+/* system timer offset in ms */
+static unsigned long sandbox_timer_offset;
+
+void sandbox_timer_add_offset(unsigned long offset)
+{
+	sandbox_timer_offset += offset;
+}
+
+u64 notrace timer_early_get_count(void)
+{
+	return os_get_nsec() / 1000 + sandbox_timer_offset * 1000;
+}
+
+unsigned long notrace timer_early_get_rate(void)
+{
+	return SANDBOX_TIMER_RATE;
+}
+
+static notrace int sandbox_timer_get_count(struct udevice *dev, u64 *count)
+{
+	*count = timer_early_get_count();
+
+	return 0;
+}
+
+static int sandbox_timer_probe(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	if (!uc_priv->clock_rate)
+		uc_priv->clock_rate = SANDBOX_TIMER_RATE;
+
+	return 0;
+}
+
+static const struct timer_ops sandbox_timer_ops = {
+	.get_count = sandbox_timer_get_count,
+};
+
+static const struct udevice_id sandbox_timer_ids[] = {
+	{ .compatible = "sandbox,timer" },
+	{ }
+};
+
+U_BOOT_DRIVER(sandbox_timer) = {
+	.name	= "sandbox_timer",
+	.id	= UCLASS_TIMER,
+	.of_match = sandbox_timer_ids,
+	.probe = sandbox_timer_probe,
+	.ops	= &sandbox_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};
+
+/* This is here in case we don't have a device tree */
+U_BOOT_DEVICE(sandbox_timer_non_fdt) = {
+	.name = "sandbox_timer",
+};