External device tree

Applicable for

STM32MP13x lines, STM32MP15x lines, STM32MP21x lines, STM32MP23x 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 .

Find below some types of configurations stored in this repository:

in stm32mp1/ : STM32MP1 ecosystem in addition of the STMicroelectronic board device tree present in each software component.
for example, -ostl device tree for new management of STM32MP1 power or example of device tree with STPMIC1L
in stm32mp2/a35-td/ : STM32MP2 CA35TDCID ecosystem for A35-TD flavor
- ca35tdcid-ostl reference device tree for the STMicroelectronic boards with a complete and secure ecosystem firewall configuration
  in addition of the minimal configuration present in each software component and used for upstream.
- ca35tdcid-ostl-m33-examples device tree, to be used with STM32CubeMP2 M33 examples
in stm32mp2/m33-td/ : STM32MP2 CM33TDCID ecosystem for M33-TD flavor
- cm33tdcid-ostl device tree for the STMicroelectronic board

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 OpenSTLinux 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
TF-M: 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, in A35-TD flavor , and for STM32MP25xF lines (stm32mp257f).

Note: STM32MP23 device trees are only available in software component with a minimal configuration.