STM32MP1 getting started: create machine

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Brief notes about how to create a customized machine based on STM32MP1.

Device tree

dts files should be created at the very beginning. There are 3 dts files need to implement:

  • TF-A device tree
  • U-BOOT device tree
  • Kernel device tree

Machine layer

A custom layer can be created outside of meta-st:

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.
├── conf
│   ├── eula
│   │   └── stm32mp1-cp
│   ├── layer.conf
│   └── machine
│       └── stm32mp1-cp.conf
├── COPYING.MIT
├── README
├── recipes-bsp
│   ├── trusted-firmware-a
│   │   ├── tf-a-stm32mp
│   │   │   └── 0001-tf-a-alex.patch
│   │   └── tf-a-stm32mp_2.0.bbappend
│   └── u-boot
│       ├── u-boot-stm32mp
│       │   └── 0001-u-boot-alex.patch
│       ├── u-boot-stm32mp_2018.11.bbappend
│       ├── u-boot-stm32mp-extlinux
│       │   └── boot.scr.cmd
│       └── u-boot-stm32mp-extlinux.bb
└── recipes-kernel
    └── linux
        ├── linux-stm32mp
        │   └── stm32mp157a-cp.dts
        └── linux-stm32mp_%.bbappend

Here I use patchs and bbappend to add dts files.

Machine conf

Machine conf can be created based on stm32mp1-disco.conf. There are some variables are pre-defined in st-machine-common-stm32mp.inc which need to be override in your machine conf.

U-Boot extlinux

There are some u-boot related env variables are set by UBOOT_EXTLINUX_ started configs in machine conf. In ST U-Boot, there path of extlinux.conf are related to UBOOT_EXTLINUX_BOOTPREFIXES.