Atmosic Settings Subsystem (ATM_SETTINGS)

The Atmosic Settings Subsystem (ATM_SETTINGS) integrates the Zephyr settings subsystem to enhance flexibility and compatibility, and supports Factory data and Settings storage for applications to use according to specifications or requirements.

The ATM_SETTINGS includes several Zephyr settings configuration options and invokes Zephyr’s settings APIs. Therefore, when Zephyr settings subsystem is upgraded, ATM_SETTINGS is also upgraded accordingly to stay in sync.

The main purpose of ATM_SETTINGS is to extend the initialization capabilities of the Zephyr settings subsystem. The standard settings initialization in Zephyr only supports the settings storage partition. With the ATM_SETTINGS, an additional read-only factory data partition is also initialized.

However, access to these partitions is still performed through the standard Zephyr settings APIs.

Note

For detailed information about the Zephyr settings subsystem, please refer to the official Zephyr documentation at Zephyr Settings Subsystem.

ATM_SETTINGS Configuration

The application uses the ATM_SETTINGS configuration to initialize the Zephyr settings subsystem, allowing access to the settings storage and factory data located in the flash partitions defined in the devicetree.

Note

The files related to ATM_SETTINGS are located in the openair\subsys\settings directory.

The CONFIG_ATM_SETTINGS configuration is defined in Kconfig to enable the ATM_SETTINGS feature. When enabled, it automatically selects required configurations such as CONFIG_FLASH, CONFIG_FLASH_MAP, CONFIG_NVS, and CONFIG_SETTINGS.

File: openair\subsys\settings\Kconfig

config ATM_SETTINGS
    bool "Proprietary settings subsystem library"
    select FLASH
    select FLASH_MAP
    select NVS
    select SETTINGS

The CONFIG_ATM_SETTINGS configuration option adds the atm_settings include directory and atm_settings source code to Zephyr’s build system.

Configuring the CONFIG_ATM_SETTINGS option in the project configuration file will activate the Zephyr settings subsystem and the related ATM_SETTINGS functions.

ATM_SETTINGS only supports the SETTINGS_NVS backend. ATM_SETTINGS will only access data when used in conjunction with the SETTINGS_NVS backend, and will treat all other backends as equivalent to SETTINGS_NONE.

File: prj.conf

CONFIG_ATM_SETTINGS=y

ATM_SETTINGS Initialization

The ATM_SETTINGS provides several functions, which are described below. However, users only need to focus on the atm_settings_init() function for initializing ATM_SETTINGS. The ATM_SETTINGS initialization is designed to mount and start up the settings storage and factory data within the Zephyr settings subsystem.

atm_settings_init() initializes the settings subsystem based on the settings storage partition and factory data partition defined in the device tree.
atm_settings_subsys_init() provides proprietary settings subsystem initialization that allows for more flexibility in configuring the settings subsystem instead of settings storage partition only.
atm_settings_factory_partition_info_get() gets the factory partition information defined in the device tree.
atm_get_device_partition_info() gets the specified partition information defined in the device tree based on the partition ID.
atm_settings_backend_init() initializes the settings subsystem backends based on the specified settings configuration information instead of settings storage partition.

ATM_SETTINGS Factory Data Write Protection

To prevent the factory data from being unexpectedly modified, it is set to read-only during ATM_SETTINGS initialization. Additionally, hardware-level write protection is applied during system startup.

ATM_SETTINGS Sample

The ATM_SETTINGS sample demonstrates how to use the ATM_SETTINGS and the Zephyr settings subsystem related functions to access factory data and settings storage. Some of the Zephyr APIs used in the ATM_SETTINGS sample are shown below.