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/led/led_gpio.c

@@ -0,0 +1,107 @@
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <led.h>
+#include <asm/gpio.h>
+#include <dm/lists.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct led_gpio_priv {
+	struct gpio_desc gpio;
+};
+
+static int gpio_led_set_on(struct udevice *dev, int on)
+{
+	struct led_gpio_priv *priv = dev_get_priv(dev);
+
+	if (!dm_gpio_is_valid(&priv->gpio))
+		return -EREMOTEIO;
+
+	return dm_gpio_set_value(&priv->gpio, on);
+}
+
+static int led_gpio_probe(struct udevice *dev)
+{
+	struct led_uclass_plat *uc_plat = dev_get_uclass_platdata(dev);
+	struct led_gpio_priv *priv = dev_get_priv(dev);
+
+	/* Ignore the top-level LED node */
+	if (!uc_plat->label)
+		return 0;
+	return gpio_request_by_name(dev, "gpios", 0, &priv->gpio, GPIOD_IS_OUT);
+}
+
+static int led_gpio_remove(struct udevice *dev)
+{
+	/*
+	 * The GPIO driver may have already been removed. We will need to
+	 * address this more generally.
+	 */
+#ifndef CONFIG_SANDBOX
+	struct led_gpio_priv *priv = dev_get_priv(dev);
+
+	if (dm_gpio_is_valid(&priv->gpio))
+		dm_gpio_free(dev, &priv->gpio);
+#endif
+
+	return 0;
+}
+
+static int led_gpio_bind(struct udevice *parent)
+{
+	const void *blob = gd->fdt_blob;
+	struct udevice *dev;
+	int node;
+	int ret;
+
+	for (node = fdt_first_subnode(blob, parent->of_offset);
+	     node > 0;
+	     node = fdt_next_subnode(blob, node)) {
+		struct led_uclass_plat *uc_plat;
+		const char *label;
+
+		label = fdt_getprop(blob, node, "label", NULL);
+		if (!label) {
+			debug("%s: node %s has no label\n", __func__,
+			      fdt_get_name(blob, node, NULL));
+			return -EINVAL;
+		}
+		ret = device_bind_driver_to_node(parent, "gpio_led",
+						 fdt_get_name(blob, node, NULL),
+						 node, &dev);
+		if (ret)
+			return ret;
+		uc_plat = dev_get_uclass_platdata(dev);
+		uc_plat->label = label;
+	}
+
+	return 0;
+}
+
+static const struct led_ops gpio_led_ops = {
+	.set_on		= gpio_led_set_on,
+};
+
+static const struct udevice_id led_gpio_ids[] = {
+	{ .compatible = "gpio-leds" },
+	{ }
+};
+
+U_BOOT_DRIVER(led_gpio) = {
+	.name	= "gpio_led",
+	.id	= UCLASS_LED,
+	.of_match = led_gpio_ids,
+	.ops	= &gpio_led_ops,
+	.priv_auto_alloc_size = sizeof(struct led_gpio_priv),
+	.bind	= led_gpio_bind,
+	.probe	= led_gpio_probe,
+	.remove	= led_gpio_remove,
+};