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The /zephyr,user node

Zephyr’s devicetree scripts handle the /zephyr,user node as a special case: you can put essentially arbitrary properties inside it and retrieve their values without having to write a binding. It is meant as a convenient container when only a few simple properties are needed.

Note

This node is meant for sample code and user applications. It should not be used in the upstream Zephyr source code for device drivers, subsystems, etc.

Simple values

You can store numeric or array values in /zephyr,user if you want them to be configurable at build time via devicetree.

For example, with this devicetree overlay:

/ {
     zephyr,user {
             boolean;
             bytes = [81 82 83];
             number = <23>;
             numbers = <1>, <2>, <3>;
             string = "text";
             strings = "a", "b", "c";
     };
};

You can get the above property values in C/C++ code like this:

#define ZEPHYR_USER_NODE DT_PATH(zephyr_user)

DT_PROP(ZEPHYR_USER_NODE, boolean) // 1
DT_PROP(ZEPHYR_USER_NODE, bytes)   // {0x81, 0x82, 0x83}
DT_PROP(ZEPHYR_USER_NODE, number)  // 23
DT_PROP(ZEPHYR_USER_NODE, numbers) // {1, 2, 3}
DT_PROP(ZEPHYR_USER_NODE, string)  // "text"
DT_PROP(ZEPHYR_USER_NODE, strings) // {"a", "b", "c"}

Devices

You can store phandles in /zephyr,user if you want to be able to reconfigure which devices your application uses in simple cases using devicetree overlays.

For example, with this devicetree overlay:

/ {
     zephyr,user {
             handle = <&gpio0>;
             handles = <&gpio0>, <&gpio1>;
     };
};

You can convert the phandles in the handle and handles properties to device pointers like this:

/*
 * Same thing as:
 *
 * ... my_dev = DEVICE_DT_GET(DT_NODELABEL(gpio0));
 */
const struct device *my_device =
     DEVICE_DT_GET(DT_PROP(ZEPHYR_USER_NODE, handle));

#define PHANDLE_TO_DEVICE(node_id, prop, idx) \
     DEVICE_DT_GET(DT_PHANDLE_BY_IDX(node_id, prop, idx)),

/*
 * Same thing as:
 *
 * ... *my_devices[] = {
 *         DEVICE_DT_GET(DT_NODELABEL(gpio0)),
 *         DEVICE_DT_GET(DT_NODELABEL(gpio1)),
 * };
 */
const struct device *my_devices[] = {
     DT_FOREACH_PROP_ELEM(ZEPHYR_USER_NODE, handles, PHANDLE_TO_DEVICE)
};

GPIOs

The /zephyr,user node is a convenient place to store application-specific GPIOs that you want to be able to reconfigure with a devicetree overlay.

For example, with this devicetree overlay:

#include <zephyr/dt-bindings/gpio/gpio.h>

/ {
     zephyr,user {
             signal-gpios = <&gpio0 1 GPIO_ACTIVE_HIGH>;
     };
};

You can convert the pin defined in signal-gpios to a struct gpio_dt_spec in your source code, then use it like this:

#include <zephyr/drivers/gpio.h>

#define ZEPHYR_USER_NODE DT_PATH(zephyr_user)

const struct gpio_dt_spec signal =
        GPIO_DT_SPEC_GET(ZEPHYR_USER_NODE, signal_gpios);

/* Configure the pin */
gpio_pin_configure_dt(&signal, GPIO_OUTPUT_INACTIVE);

/* Set the pin to its active level */
gpio_pin_set_dt(&signal, 1);

(See gpio_dt_spec, GPIO_DT_SPEC_GET, and gpio_pin_configure_dt() for details on these APIs.)