1. Article purpose[edit source]
The purpose of this article is to explain how to configure the RCC internal peripheral resets using the device tree mechanism, relying on the bindings documentation, that is the description of the required and optional device-tree properties.
The peripheral can be assigned to different contexts/software components, depending on the final product needs. Refer to How to assign an internal peripheral to a runtime context article for guidelines on this configuration .
2. DT bindings documentation[edit source]
The device tree binding documents are stored either in the given applicable components listed below, or in the Linux kernel repository:
As RCC IP is both a reset and a clock controller, the device tree binding is same document.
- TF-A BL2:
- for STM32MP13x lines
docs/devicetree/bindings/clock/st,stm32mp13-rcc.txt - for STM32MP15x lines docs/devicetree/bindings/clock/st,stm32mp1-rcc.txt
- for STM32MP13x lines
- OP-TEE:
- for STM32MP13x lines documentation/devicetree/bindings/clock/st,stm32mp13-rcc.yaml
- for STM32MP13x lines
- U-Boot, Linux® OS:
- for example: STM32MP1x device tree bindings: Documentation/devicetree/bindings/clock/st,stm32mp1-rcc.yaml
3. DT configuration[edit source]
This hardware description is a combination of the STM32 microprocessor device tree files (.dtsi extension) and board device tree files (.dts extension). See the Device tree for an explanation of the device tree file organization.
STM32CubeMX can be used to generate the board device tree. Refer to How to configure the DT using STM32CubeMX for more details.
3.1. DT configuration (STM32/SoC level)[edit source]
The RCC node is located in the device tree file for the software components, supporting the peripheral and listed in the above DT bindings documentation paragraph.
3.2. DT configuration (board level)[edit source]
This chapter explains how to enable and configure the RCC DT nodes for a board.
The peripheral configuration must be done in the specific board device tree files (board dts file).
3.3. DT configuration examples[edit source]
&rcc {
status = "okay";
};
4. How to configure the DT using STM32CubeMX[edit source]
The STM32CubeMX tool can be used to configure the STM32MP1 device and get the corresponding platform configuration device tree files.
The STM32CubeMX may not support all the properties described in the above DT bindings documentation paragraph. If so, the tool inserts user sections in the generated device tree. These sections can then be edited to add some properties, which are preserved from one generation to another. Refer to STM32CubeMX user manual for further information.
5. References[edit source]
Please refer to the following links for additional information: