1. Introduction to external device tree component
The external device tree component is used to host STM32 MPU embedded software device tree (aka OSTL device tree) configurations.
As configurations become increasingly complex, especially for the firewall configuration (RIF), clock tree and memory mapping, it is important and mandatory to synchronize all software components device trees in one place. This permits to have a coherent configuration across all of them.
A consistent product configuration is given as example by ST in this repository. Note that a board device tree, with minimal configuration, is still present in each software component like it was on previous releases.
This configuration can also be named "open", disabling the CID filtering and only securing peripheral used by secure world.
2. Component split
The external device tree component collapses product/boards device tree of all software components used in STM32 MPU embedded software delivery. The device tree files, related to the "SoC" definition, are located in each software component:
- RIF (firewall) configuration: stm32mp257f-ev1-ca35tdcid-ostl-rif.dtsi
- RCC (Clock tree) configuration: stm32mp257f-ev1-ca35tdcid-ostl-rcc.dtsi
- Memory mapping configuration: stm32mp257f-ev1-ca35tdcid-ostl-resmem.dtsi
- Board configuration: 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).
Note that this repository is not self-content as it relies on "SoC" dtsi files defined in each software component.
3. Component usage
The external device tree repository can be found here . It can directly be used by OSTL Yocto build system or directly by each software component. Let see how to use it:
- Yocto:
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Coming soon |
- TF-A: External device tree in TF-A
- OPTEE:
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Coming soon |
- U-Boot: External device tree in U-Boot
- Linux: External device tree in kernel Linux
- TFM:
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Coming soon |