STM32MP23 U-Boot

Applicable for

Unknown MPU

This article briefly describes the STM32MP23 unknown microprocessor device support in U-Boot.

1. STM32MP23 unknown microprocessor device support[edit | edit source]

For detailed information, read the file in the delivered U-Boot code = doc/board/st/stm32mp2.rst or the documentation generated by make htlmdocs: board/st/stm32mp2.html.

Code:

arch/arm/mach-stm32mp : arch specific code for STM32 Arm^® Cortex^® MPUs
- arch/arm/mach-stm32mp/Kconfig : generic configuration for STM32 Arm^® Cortex^® MPUs
- arch/arm/mach-stm32mp/Kconfig.23x : specific configuration for STM32MP23 unknown microprocessor device
board/st/common : STMicroelectronics common code
board/st/stm32mp2 : STMicroelectronics boards support for STM32MP2 series
drivers/*/*stm32* : drivers

Configuration files:

defconfig file
- configs/stm32mp23_defconfig
config files
- include/configs/stm32mp23_common.h : generic for STM32MP23 unknown microprocessor device
- include/configs/stm32mp23_st_common.h : STMicroelectronics board for STM32MP23 unknown microprocessor device
STM32_MPU_device_tree in arch/arm/dts : stm32mp23*.dts*
- <Device tree>.dts: same as kernel
- <Device tree>-u-boot.dtsi: addition for u-boot automatically included in build process
- stm32mp23-u-boot.dtsi : SoC add-on file included in <Device tree>-u-boot.dtsi

2. Selecting targets: choose defconfig and device tree[edit | edit source]

The U-Boot configuration with defconfig is stm32mp23_defconfig.

The boards are supported with the associated device tree (same name as kernel):

Board part number	Device tree	Description
STM32MP235F-DK	stm32mp235f-dk	Discovery Board

3. Compilation[edit | edit source]

see U-Boot_overview#U-Boot_build, with installed aarch64 cross-compiler.

For STM32MP235F-DK, the device tree is already selected in defconfig stm32mp23_defconfig

 make stm32mp23_defconfig
 make all

For other boards, you need to select the correct device tree

 make stm32mp23_defconfig
 make DEVICE_TREE=<Device tree> all

The supported variables are:

DEVICE_TREE: select in arch/arm/dts or in EXT_DTS the device tree that is used.
KBUILD_OUTPUT: change the destination directory for the build
EXT_DTB: select external device tree.
EXT_DTS: select PATH of external device tree source, by default the sub-directory "arch/arm/dts/external-dt" is used to allow sub-module.

The output files u-boot.dtb and u-boot-nodtb.bin are integrated in TF-A FIP.

Note: All the compiled devices trees are available in $KBUILD_OUTPUT/arch/arm/dts/*.dtb.
You can select them instead of u-boot.dtb without U-Boot recompilation.

4. Examples[edit | edit source]

4.1. STM32MP235F-DK[edit | edit source]

 make stm32mp23_defconfig
 make DEVICE_TREE=stm32mp235f-dk all

and

 fiptool --verbose update --nt-fw u-boot-nodtb.bin  --hw-config u-boot.dtb \
                        fip-stm32mp235f-dk.bin

4.2. STM32MP235F-DK with export[edit | edit source]

 export KBUILD_OUTPUT=../build/stm32mp23
 export DEVICE_TREE=stm32mp235f-dk
 make stm32mp23_defconfig
 make  all

and

 fiptool --verbose update --nt-fw $KBUILD_OUTPUT/u-boot-nodtb.bin  \
                        --hw-config $KBUILD_OUTPUT/u-boot.dtb \
                        fip-stm32mp235f-dk.bin

4.3. Custom board with external device tree[edit | edit source]

 make stm32mp23_defconfig
 make EXT_DTB=stm32mp235f-myboard.dtb all

 fiptool --verbose update --nt-fw u-boot-nodtb.bin \
             --hw-config  u-boot.dtb \
             fip-stm32mp235f-myboard.bin