STM32MP15 U-Boot

This article briefly describes the STM32MP15x lines  support in U-Boot.

1. STM32MP15x lines  support

For detailed information, please read the file in the delivered U-Boot code = doc/board/st/stm32mp1.rst or the stm32mp1 documentation generated by make htlmdocs.

Also available in official U-Boot Git.

Code :

• arch/arm/mach-stm32mp : arch specific code for STM32 Arm^® Cortex^® MPUs 
• board/st/common : STMicroelectronics common code
• board/st/stm32mp1 : generic STMicroelectronics board for STM32MP1 Series
• drivers/*/*stm32* : drivers

Configuration Files:

• defconfig file
  • configs/stm32mp15_trusted_defconfig
  • configs/stm32mp15_basic_defconfig
• config files
  • include/configs/stm32mp1.h
• STM32MP15_device_tree in arch/arm/dts  : stm32mp15*.dts*
  • <Device tree>.dts : same as kernel
  • <Device tree>-u-boot.dtsi : addition for u-boot automatically included in build process

2. Selecting targets : choose defconfig and Device Tree

The STM32 MPU boot chain is supported by one U-Boot configuration with defconfig = stm32mp15_trusted_defconfig

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

Board part number	Device tree	Description
STM32MP157A-EV1 Evaluation board	stm32mp157a-ev1	MB1262+MB1263
STM32MP157C-EV1 Evaluation board	stm32mp157c-ev1
STM32MP157D-EV1 Evaluation board	stm32mp157d-ev1
STM32MP157F-EV1 Evaluation board	stm32mp157f-ev1
STM32MP157A-DK1 Discovery kit	stm32mp157a-dk1	MB1272
STM32MP157D-DK1 Discovery kit	stm32mp157d-dk1
STM32MP157C-DK2 Discovery kit	stm32mp157c-dk2	MB1272+MB1407
STM32MP157F-DK2 Discovery kit	stm32mp157f-dk2

For information the 'Evaluation' daughter-board only (MB1263 without MB1262) is also supported by stm32mp15*-ed1.dts device tree files.

3. Compilation

see U-Boot_overview#U-Boot_build

With the defconfig file: stm32mp15_trusted_defconfig

  make stm32mp15_trusted_defconfig
  make DEVICE_TREE=<Device tree> all

The supported variables are:

• DEVICE_TREE: select in arch/arm/dts the device tree that is used
• KBUILD_OUTPUT: change the destination directory for the build
• EXT_DTB: select external device tree

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

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

The ouput file is u-boot.stm32 for ecosystem release ≤ v2.1.0 or if you activate CONFIG_STM32MP15x_STM32IMAGE in your defconfig for ecosystem release v3.0.0 (this temporary option is only introduced to facilitate the FIP migration but it will be removed in the next EcosystemRelease).

With FIP support for ecosystem release v3.0.0 , the offset on U-Boot environment in NOR are defined in the defconfig with:

 CONFIG_ENV_OFFSET=0x480000
 CONFIG_ENV_OFFSET_REDUND=0x4C0000

Without FIP support these MTD partition offsets in NOR for default flashlayout change and to reuse the ecosystem release ≤ v2.1.0 flashlayout the defconfig options become:

 CONFIG_STM32MP15x_STM32IMAGE=y
 CONFIG_ENV_OFFSET=0x280000
 CONFIG_ENV_OFFSET_REDUND=0x2C0000

4. U-Boot integration in FIP

U-Boot binary and its associated device tree are part of the FIP binary, created with TF-A Makefile option :

• BL33_CFG = u-boot.dtb
• BL33 = u-boot-nodtb.bin

or updated with fiptools:

• --hw-config u-boot.dtb
• --nt-fw u-boot-nodtb.bin

Example for fip upddate of STM32MP157C-EV1 Evaluation board :

  fiptool --verbose update --nt-fw u-boot-nodtb.bin \
             --hw-config  u-boot.dtb \
             tf-a-fip-stm32mp157c-ev1.bin
 
 DEBUG: Replacing nt-fw with.../u-boot-nodtb.bin
 DEBUG: Replacing hw-config with .../u-boot.dtb
 DEBUG: Metadata size: ... bytes
 DEBUG: Payload size: ... bytes

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5. SPL compilation

The alternate boot chain with SPL is also supported by "stm32mp15_basic_defconfig" but only for U-Boot_SPL:_DDR_interactive_mode

With the defconfig file: stm32mp15_basic_defconfig

  make stm32mp15_basic_defconfig
  make DEVICE_TREE=<Device tree> all

The resulting U-Boot files are located in your build directory:

• u-boot-spl.stm32 : FSBL = SPL binary with STM32 image header, loaded by ROM code
• u-boot.img : SSBL = U-Boot binary with U-Boot image header (uImage), loaded by SPL

Warning

This alternate boot chain with SPL is not supported/promoted by STMicroelectronics to make product.

6. Examples

6.1. STM32MP157F-EV1 Evaluation board

  make stm32mp15_trusted_defconfig
  make DEVICE_TREE=stm32mp157f-ev1 all

6.2. STM32MP157C-EV1 Evaluation board

  make stm32mp15_trusted_defconfig
  make DEVICE_TREE=stm32mp157c-ev1 all

6.3. STM32MP157D-DK1 Discovery kit

  make stm32mp15_trusted_defconfig
  make DEVICE_TREE=stm32mp157d-dk1 all

6.4. STM32MP157C-DK2 Discovery kit

Using export to select the device tree

  export KBUILD_OUTPUT=../build/stm32mp15_trusted
  export DEVICE_TREE=stm32mp157c-dk2
  make stm32mp15_trusted_defconfig
  make all

6.5. Custom board with external device tree

  make stm32mp15_trusted_defconfig
  make EXT_DTB=stm32mp151a-myboard.dtb all

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6.6. SPL for STM32MP157F-EV1 Evaluation board

  make stm32mp15_basic_defconfig
  make DEVICE_TREE=stm32mp157f-ev1 all

Das U-Boot -- the Universal Boot Loader (see U-Boot_overview)

Arm^® is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.

Cortex^®

Device Tree Binary (or Blob)

Firmware Image Package is a packaging format used by TF-A

Trusted Firmware for Arm^® Cortex^®-A

Boot Loader stage 3-3

Secondary Program Loader, Also known as U-Boot SPL

First Stage Boot Loader

Read Only Memory

Second Stage Boot Loader

Das U-Boot -- the Universal Boot Loader (see U-Boot_overview)

Arm^® is a registered trademark of Arm Limited (or its subsidiaries) in the US and/or elsewhere.

Cortex^®

Device Tree Binary (or Blob)

Firmware Image Package is a packaging format used by TF-A

Trusted Firmware for Arm^® Cortex^®-A

Boot Loader stage 3-3

Secondary Program Loader, Also known as U-Boot SPL

First Stage Boot Loader

Read Only Memory

Second Stage Boot Loader