doc: devicetree: edits to driving gpio guide

Edited the Driving the GPIO pins directly guide for style.
Fixed some style issues in the nordic,gpio-pins.yaml.
Added a generic page about adding drivers.
NCSDK-24813.

Signed-off-by: Grzegorz Ferenc <[email protected]>

doc/nrf/app_dev/config_and_build/hardware/add_new_driver.rst

@@ -0,0 +1,90 @@
+.. _add_new_driver:
+
+Adding new drivers
+##################
+
+.. contents::
+   :local:
+   :depth: 2
+
+Adding drivers to your embedded project allows you to add support for additional hardware components and extend functionalities of your application.
+
+To add a new driver to an application in the |NCS|, complete the following steps:
+
+.. rst-class:: numbered-step
+
+Create a devicetree binding
+***************************
+
+In most of the cases you want to make it possible to configure some properties of your driver instance.
+For example, a sensor may need to allow configuring used GPIO pins or communication interface.
+
+A driver instance can be made configurable through a devicetree node that is compatible with a specific binding.
+The devicetree bindings provide structure for the devicetree by declaring requirements for the content of devicetree nodes.
+The :ref:`compatible <zephyr:dt-bindings-compatible>` property defines compatibility of a devicetree node with a devicetree binding.
+
+You can create a devicetree binding YAML file for your driver in the :file:`dts/bindings` directory of your project.
+If applicable, you can also use one of the existing DTS bindings available in the |NCS| or Zephyr.
+For implementation examples, see :file:`nrf/dts/bindings` and :file:`zephyr/dts/bindings` directories.
+See also :ref:`zephyr:devicetree` documentation for more information about devicetree.
+
+For more information about devicetree bindings, read the :ref:`documentation about them in Zephyr <zephyr:dt-binding-compat>`.
+
+.. rst-class:: numbered-step
+
+Create the driver files
+***********************
+
+First, create the files that will implement driver and expose driver APIs.
+As a reference, you can check the |NCS| :ref:`drivers`, whose code is located at :file:`nrf/drivers`.
+
+You will need the following files:
+
+* :file:`CMakeLists.txt` - This file adds your driver sources to the build as a Zephyr library.
+  See :ref:`app_build_system` for more information about the build system.
+* :file:`Kconfig` - This file will include all custom Kconfig options for your driver, including the Kconfig option to enable and disable the driver.
+  See Zephyr's :ref:`zephyr:kconfig` for more information.
+* Driver's source files - These files will include the code for your driver, such as :ref:`zephyr:device_struct`, device definition through the :c:macro:`DEVICE_DT_DEFINE` macro, and other elements.
+  If possible, your driver should expose a generic API to simplify integrating the driver in user application.
+  For example, the driver could expose sensor driver API (:c:struct:`sensor_driver_api`).
+  See :file:`nrf/drivers/sensor/paw3212/paw3212.c` for an example.
+  See also Zephyr's :ref:`zephyr:device_model_api` for more information, in particular the "Subsystems and API structures" section.
+
+.. rst-class:: numbered-step
+
+Include the driver in your application
+**************************************
+
+To enable the driver in your application's configuration, complete the following steps:
+
+1. Enable the necessary Kconfig options in the application's :file:`prj.conf` file.
+   This includes the Kconfig option you defined for enabling and disabling the driver.
+   See :ref:`configuring_kconfig` for information about how to enable Kconfig options.
+#. Create or modify a devicetree overlay file for your board to add the necessary devicetree node for your custom driver.
+   This step is crucial for connecting the driver to the specific hardware on your board.
+   For information about how to create or modify devicetree files, see :ref:`configuring_devicetree`.
+#. Include the appropriate header file for your custom driver in your application code and use the driver APIs in the application.
+   If your driver exposes a generic API (for example, :ref:`sensor driver API <zephyr:sensor>`), you can use generic headers defined for the API.
+
+DevAcademy courses
+******************
+
+`Nordic Developer Academy`_ contains introductory courses to the |NCS| and Zephyr.
+See the following course lessons to get started with driver development:
+
+* `Lesson 6 – Serial communication (I2C)`_ in `nRF Connect SDK Fundamentals course`_ describes how to communicate with a sensor connected over I2C using I2C APIs.
+* `Lesson 5 – Serial Peripheral Interface (SPI)`_ in `nRF Connect SDK Intermediate course`_ describes how to communicate with sensors over SPI in Zephyr.
+* `Lesson 7 - Device driver model`_ in `nRF Connect SDK Intermediate course`_ describes how to start with adding your own sensor driver in the Exercise 1.
+
+Related documentation
+*********************
+
+The :ref:`nrf_desktop` application describes how to :ref:`add a new motion sensor to the project <porting_guide_adding_sensor>`.
+
+Implementation examples
+***********************
+
+Check the driver implementation examples at the following paths:
+
+* |NCS|: :ref:`drivers`, with code located at :file:`nrf/drivers`.
+* Zephyr: :ref:`zephyr:driver-samples`, with code located at :file:`zephyr/samples/drivers`.

doc/nrf/app_dev/config_and_build/hardware/index.rst

@@ -19,9 +19,14 @@ The following guides provide information about configuring specific aspects of h
 Read them together with Zephyr's :ref:`zephyr:hardware_support` and :ref:`zephyr:dt-guide` guides, and the official `Devicetree Specification`_.
 In particular, :ref:`zephyr:set-devicetree-overlays` explains how the base devicetree files are selected.
 
+.. note::
+   If you want to go through dedicated training related to some of the topics covered here, enroll in the courses in the `Nordic Developer Academy`_.
+   For example, `nRF Connect SDK Fundamentals course`_ describes devicetree in `Lesson 2 <Lesson 2 - Reading buttons and controlling LEDs_>`_.
+
 .. toctree::
    :maxdepth: 1
    :caption: Subpages:
 
+   add_new_driver
    pin_control
    use_gpio_pin_directly

doc/nrf/app_dev/config_and_build/hardware/use_gpio_pin_directly.rst

@@ -7,21 +7,36 @@ Driving a GPIO pin directly
    :local:
    :depth: 2
 
-This user guide shows how to drive a GPIO pin directly.
-In the development phase of an embedded project, it can be used to collect execution timings or as a debugging tool.
+This user guide shows how to control a GPIO pin directly using GPIO driver APIs.
+In the development phase of an embedded project, you can use this configuration to set the pin state using software, without any intermediary circuitry or additional hardware components.
+You can use this solution to collect execution timings, or as a debugging tool.
 
-Declaring the GPIO pin
-**********************
+The following configuration can be copied manually into the devicetree overlay files.
+You can also use the `Devicetree Visual Editor <How to work with Devicetree Visual Editor_>`_ (either in GUI or text mode) in the |nRFVSC| to apply it.
 
-To declare a GPIO pin node, use a DTS node with ``nordic,gpio-pins`` compatible set in the :term:`devicetree <Devicetree>`.
-If your application does not use the same GPIO instance as used by the node, enable the GPIO port instance required by the GPIO driver.
+.. rst-class:: numbered-step
 
-This DTS content can be introduced in the DTS of your board, application, or overlay file.
-Pins defined this way can be accessed using devicetree macros.
+Define the compatible DTS node
+******************************
 
-The following snippet shows the declaration of a GPIO pin node for **Pin 2** of **GPIO0**.
-The node is labeled as ``user-dbg-pin``.
-Additionally, the ``gpio0`` instance and ``gpiote0`` are enabled, so the GPIO driver can be built and executed.
+You need to define a new GPIO pin devicetree node for the pin.
+The devicetree node needs to be compatible with the GPIO devicetree binding.
+GPIO APIs use the devicetree node to refer to the specified GPIO pin.
+
+If you work with a Nordic Semiconductor device, you can use the binding definition in :file:`dts/bindings/gpio`.
+
+See Zephyr's documentation about :ref:`zephyr:devicetree` and :ref:`zephyr:gpio_api` for more information.
+
+.. rst-class:: numbered-step
+
+Configure the GPIO pin through DTS
+**********************************
+
+To declare a GPIO pin node, create a DTS node in the DTS of your board or application's DTS overlay.
+Pins defined this way can be accessed using :ref:`GPIO devicetree APIs<zephyr:gpio_api>`.
+
+Make sure that GPIO ports used by the GPIO pins are enabled.
+The following snippet shows the declaration of a GPIO pin node called ``user_dbg_pin``:
 
 .. code-block:: c
 
@@ -41,8 +56,18 @@ Additionally, the ``gpio0`` instance and ``gpiote0`` are enabled, so the GPIO dr
 		status = "okay";
 	};
 
-Using the pin in your application
-*********************************
+In this snippet:
+
+* The node is labelled as ``user-dbg-pin``.
+* ``compatible`` specifies the binding definition to be used (``nordic,gpio-pins`` from :file:`dts/bindings/gpio`).
+* ``gpios`` specifies which pin node is being used (**Pin 2** of **GPIO0**).
+* ``status`` enables the pin node when it is set to ``"okay"``.
+* Additionally, the ``gpio0`` instance and ``gpiote0`` are enabled, so the GPIO driver can be built and executed.
+
+.. rst-class:: numbered-step
+
+Include the pin in your application
+***********************************
 
 To let your application access the declared pins, use the following devicetree macros:
 
@@ -54,15 +79,15 @@ To let your application access the declared pins, use the following devicetree m
        static const struct gpio_dt_spec pin_dbg =
           GPIO_DT_SPEC_GET_OR(DT_NODELABEL(user_dbg_pin), gpios, {0});
 
-#. Make sure your application initializes the pin:
+#. Make sure your application initializes the pin using the :c:func:`gpio_pin_configure_dt` function:
 
    .. code-block:: c
 
        if (pin_dbg.port) {
           gpio_pin_configure_dt(&pin_dbg, GPIO_OUTPUT_INACTIVE);
     }
 
-#. To let your application drive the pin, add the following code where needed:
+#. Add the following code where needed to let your application drive the pin using the :c:func:`gpio_pin_set_dt` function:
 
    .. code-block:: c
 
@@ -83,7 +108,8 @@ This is an easy way to disable this debugging infrastructure.
 Declaring multiple pins
 ***********************
 
-Multiple pins can be declared in one GPIO property as well.
+You can also declare multiple pins in one GPIO property.
+See the following code snippet:
 
 .. code-block:: c
 
@@ -96,8 +122,7 @@ Multiple pins can be declared in one GPIO property as well.
 		};
 	};
 
-To initialize the defined GPIO pin structures, use the ``GPIO_DT_SPEC_INST_GET_BY_IDX_OR()`` macro.
-
+To initialize the defined GPIO pin structures, use the :c:macro:`GPIO_DT_SPEC_INST_GET_BY_IDX_OR` macro:
 
 .. code-block:: c
 

doc/nrf/links.txt

@@ -908,9 +908,13 @@
 
 .. _`nRF Connect SDK Fundamentals course`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/
 .. _`Installing nRF Connect SDK and VS Code`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/lessons/lesson-1-nrf-connect-sdk-introduction/topic/exercise-1-1/
+.. _`Lesson 2 - Reading buttons and controlling LEDs`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/lessons/lesson-2-reading-buttons-and-controlling-leds/
+.. _`Lesson 6 – Serial communication (I2C)`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-fundamentals/lessons/lesson-6-serial-com-i2c/topic/i2c-driver/
 
 .. _`nRF Connect SDK Intermediate course`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/
 .. _`Lesson 2 - Debugging and troubleshooting`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-2-debugging/
+.. _`Lesson 5 – Serial Peripheral Interface (SPI)`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-5-serial-peripheral-interface-spi/
+.. _`Lesson 7 - Device driver model`: https://academy.nordicsemi.com/courses/nrf-connect-sdk-intermediate/lessons/lesson-7-device-driver-model/
 
 .. _`Cellular IoT Fundamentals course`: https://academy.nordicsemi.com/courses/cellular-iot-fundamentals/
 .. _`Power saving techniques`: https://academy.nordicsemi.com/courses/cellular-iot-fundamentals/lessons/lesson-1-cellular-fundamentals/topic/lesson-1-power-saving-techniques/

dts/bindings/gpio/nordic,gpio-pins.yaml

@@ -2,13 +2,13 @@
 # SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
 
 description: |
-  This allows to define the pin of the GPIO to be owned by the domain.
-  It does not provide any specyfic driver.
-  Its function is to allow us to use two functionalities:
+  This binding allows to assign a GPIO to the domain.
+  It does not provide any specific driver.
+  The binding enables the following functionalities:
 
-  1. Generate the right UICR marking the domain to own the selected pin.
-  2. Access to pins by the macros from zephyr/devicetree/gpio.h file
-     increasing the hardware abstraction this way.
+  - Add an entry in UICR that marks the domain to own the selected pin.
+  - Allow access to pins using the macros from the `zephyr/devicetree/gpio.h` file,
+    which increases the hardware abstraction.
 
 compatible: "nordic,gpio-pins"