External device tree

Applicable for

STM32MP13x lines, STM32MP15x lines, STM32MP25x lines

1. Introduction to external device tree component[edit | edit source]

The external device tree component is used to host STM32 MPU embedded software device tree configurations in addition of the ones present in each software component (TF-A, OP-TEE, U-BOOT, LINUX, TF-M).
The external device tree repository can be found here .

Please, find below some types of configurations stored in this repository:

Linux RT for STM32MP1 series and STM32MP2 series.
STM32MP2xx CA35TDCID ecosystem (for example, ostl device tree) in addition of the minimal configuration present in each software component.
STM32CubeMP2 M33 examples (for example, ostl-m33-examples device tree)
... other configurations to come soon... (STM32MP2xx CM33TDCID ecosystem, ...)

As configurations become increasingly complex, it is important to synchronize all software components device trees in one place. This centralization permits to have a coherent configuration across all of them.
This consistent product configuration is given as an example by ST in this external device tree repository and is used by the YOCTO build system.

2. Component usage[edit | edit source]

It can be used directly by the OSTL YOCTO build system or directly by each software component. Here is how to use it:

TF-A: External device tree in TF-A
OP-TEE: External device tree in OP-TEE
U-Boot: External device tree in U-Boot
Linux: External device tree in kernel Linux
TFM: External device tree in TF-M

3. STM32MP2 ecosystem device tree details[edit | edit source]

The firewall configuration (RIF) has been introduced in STM32MP2 series and it involves creating coherence and synchronization between these system configuration files (rcc, rif, and resmem).
The device tree files, related to the "SoC" definition, are located as described below:

RIF (firewall) configuration in OP-TEE: stm32mp257f-ev1-ca35tdcid-ostl-rif.dtsi
RCC (Clock tree) configuration in TF-A and OP-TEE: stm32mp257f-ev1-ca35tdcid-ostl-rcc.dtsi
Memory mapping configuration in all components: stm32mp257f-ev1-ca35tdcid-ostl-resmem.dtsi
Board configuration in all components: stm32mp257f-ev1-ca35tdcid-ostl.dts

DT name example given for an EV1 ("ev1") board with Cortex-A35 ("ca35") set as main processor for STM32MP25xF lines (stm32mp257f).