135 lines
4.3 KiB
ReStructuredText
135 lines
4.3 KiB
ReStructuredText
.. _blinfo_api:
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Bootloader Information
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######################
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The bootloader information (abbreviated to blinfo) subsystem is an extension of
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the :ref:`retention_api` which allows for reading shared data from a bootloader
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and allowing applications to query it. It has an optional feature of organising
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the information retrieved from the bootloader and storing it in the
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:ref:`settings_api` with the ``blinfo/`` prefix.
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Devicetree setup
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****************
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To use the bootloader information subsystem, a retention area needs to be
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created which has a retained data section as its parent, generally non-init RAM
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is used for this purpose. See the following example (examples in this guide are
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based on the :ref:`nrf52840dk_nrf52840` board and memory layout):
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.. code-block:: devicetree
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/ {
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sram@2003F000 {
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compatible = "zephyr,memory-region", "mmio-sram";
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reg = <0x2003F000 DT_SIZE_K(1)>;
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zephyr,memory-region = "RetainedMem";
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status = "okay";
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retainedmem {
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compatible = "zephyr,retained-ram";
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status = "okay";
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#address-cells = <1>;
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#size-cells = <1>;
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boot_info0: boot_info@0 {
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compatible = "zephyr,retention";
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status = "okay";
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reg = <0x0 0x100>;
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};
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};
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};
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chosen {
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zephyr,bootloader-info = &boot_info0;
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};
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};
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/* Reduce SRAM0 usage by 1KB to account for non-init area */
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&sram0 {
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reg = <0x20000000 DT_SIZE_K(255)>;
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};
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Note that this configuration needs to be applied on both the bootloader
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(MCUboot) and application to be usable. It can be combined with other retention
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system APIs such as the :ref:`boot_mode_api`
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MCUboot setup
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*************
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Once the above devicetree configuration is applied, MCUboot needs to be
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configured to store the shared data in this area, the following Kconfigs need
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to be set for this:
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* :kconfig:option:`CONFIG_RETAINED_MEM` - Enables retained memory driver
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* :kconfig:option:`CONFIG_RETENTION` - Enables retention system
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* :kconfig:option:`CONFIG_BOOT_SHARE_DATA` - Enables shared data
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* :kconfig:option:`CONFIG_BOOT_SHARE_DATA_BOOTINFO` - Enables boot information
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shared data type
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* :kconfig:option:`CONFIG_BOOT_SHARE_BACKEND_RETENTION` - Stores shared data
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using retention/blinfo subsystem
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Application setup
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*****************
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The application must enable the following base Kconfig options for the
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bootloader information subsystem to function:
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* :kconfig:option:`CONFIG_RETAINED_MEM`
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* :kconfig:option:`CONFIG_RETENTION`
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* :kconfig:option:`CONFIG_RETENTION_BOOTLOADER_INFO`
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* :kconfig:option:`CONFIG_RETENTION_BOOTLOADER_INFO_TYPE_MCUBOOT`
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The following include is needed to use the bootloader information subsystem:
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.. code-block:: C
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#include <zephyr/retention/blinfo.h>
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By default, only the lookup function is provided: :c:func:`blinfo_lookup`, the
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application can call this to query the information from the bootloader. This
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function is enabled by default with
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:kconfig:option:`CONFIG_RETENTION_BOOTLOADER_INFO_OUTPUT_FUNCTION`, however,
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applications can optionally choose to use the settings storage feature instead.
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In this mode, the bootloader information can be queries by using settings keys,
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the following Kconfig options need to be enabled for this mode:
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* :kconfig:option:`CONFIG_SETTINGS`
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* :kconfig:option:`CONFIG_SETTINGS_RUNTIME`
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* :kconfig:option:`CONFIG_RETENTION_BOOTLOADER_INFO_OUTPUT_SETTINGS`
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This allows the information to be queried via the
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:c:func:`settings_runtime_get` function with the following keys:
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* ``blinfo/mode`` The mode that MCUboot is configured for
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(``enum mcuboot_mode`` value)
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* ``blinfo/signature_type`` The signature type MCUboot is configured for
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(``enum mcuboot_signature_type`` value)
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* ``blinfo/recovery`` The recovery type enabled in MCUboot
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(``enum mcuboot_recovery_mode`` value)
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* ``blinfo/running_slot`` The running slot, useful for direct-XIP mode to know
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which slot to use for an update
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* ``blinfo/bootloader_version`` Version of the bootloader
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(``struct image_version`` object)
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* ``blinfo/max_application_size`` Maximum size of an application (in bytes)
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that can be loaded
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In addition to the previous include, the following includes are required for
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this mode:
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.. code-block:: C
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#include <bootutil/boot_status.h>
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#include <bootutil/image.h>
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#include <zephyr/mcuboot_version.h>
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#include <zephyr/settings/settings.h>
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API Reference
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*************
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Bootloader information API
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==========================
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.. doxygengroup:: bootloader_info_interface
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