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/i2c/sandbox_i2c.c

@@ -0,0 +1,123 @@
+/*
+ * Simulate an I2C port
+ *
+ * Copyright (c) 2014 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <fdtdec.h>
+#include <i2c.h>
+#include <asm/test.h>
+#include <dm/lists.h>
+#include <dm/device-internal.h>
+#include <dm/root.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct sandbox_i2c_priv {
+	bool test_mode;
+};
+
+static int get_emul(struct udevice *dev, struct udevice **devp,
+		    struct dm_i2c_ops **opsp)
+{
+	struct dm_i2c_chip *plat;
+	struct udevice *child;
+	int ret;
+
+	*devp = NULL;
+	*opsp = NULL;
+	plat = dev_get_parent_platdata(dev);
+	if (!plat->emul) {
+		ret = dm_scan_fdt_node(dev, gd->fdt_blob, dev->of_offset,
+				       false);
+		if (ret)
+			return ret;
+
+		for (device_find_first_child(dev, &child); child;
+		     device_find_next_child(&child)) {
+			if (device_get_uclass_id(child) != UCLASS_I2C_EMUL)
+				continue;
+
+			ret = device_probe(child);
+			if (ret)
+				return ret;
+
+			break;
+		}
+
+		if (child)
+			plat->emul = child;
+		else
+			return -ENODEV;
+	}
+	*devp = plat->emul;
+	*opsp = i2c_get_ops(plat->emul);
+
+	return 0;
+}
+
+void sandbox_i2c_set_test_mode(struct udevice *bus, bool test_mode)
+{
+	struct sandbox_i2c_priv *priv = dev_get_priv(bus);
+
+	priv->test_mode = test_mode;
+}
+
+static int sandbox_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
+			    int nmsgs)
+{
+	struct dm_i2c_bus *i2c = dev_get_uclass_priv(bus);
+	struct sandbox_i2c_priv *priv = dev_get_priv(bus);
+	struct dm_i2c_ops *ops;
+	struct udevice *emul, *dev;
+	bool is_read;
+	int ret;
+
+	/* Special test code to return success but with no emulation */
+	if (priv->test_mode && msg->addr == SANDBOX_I2C_TEST_ADDR)
+		return 0;
+
+	ret = i2c_get_chip(bus, msg->addr, 1, &dev);
+	if (ret)
+		return ret;
+
+	ret = get_emul(dev, &emul, &ops);
+	if (ret)
+		return ret;
+
+	if (priv->test_mode) {
+		/*
+		* For testing, don't allow writing above 100KHz for writes and
+		* 400KHz for reads.
+		*/
+		is_read = nmsgs > 1;
+		if (i2c->speed_hz > (is_read ? 400000 : 100000)) {
+			debug("%s: Max speed exceeded\n", __func__);
+			return -EINVAL;
+		}
+	}
+
+	return ops->xfer(emul, msg, nmsgs);
+}
+
+static const struct dm_i2c_ops sandbox_i2c_ops = {
+	.xfer		= sandbox_i2c_xfer,
+};
+
+static const struct udevice_id sandbox_i2c_ids[] = {
+	{ .compatible = "sandbox,i2c" },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_sandbox) = {
+	.name	= "i2c_sandbox",
+	.id	= UCLASS_I2C,
+	.of_match = sandbox_i2c_ids,
+	.ops	= &sandbox_i2c_ops,
+	.priv_auto_alloc_size = sizeof(struct sandbox_i2c_priv),
+};