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STMicroelectronics STM32MP
==========================
.. note::
Support for the STM32MP architecure in barebox is still in progress.
Bootstrapping an OS from mainline barebox is not yet supported.
The STM32MP is a line of 32-bit ARM SoCs. They reuse peripherals of the
STM32 line of microcontrollers and can have a STM32 MCU embedded as co-processor
as well.
The boot process of the STM32MP SoC is a two step process.
The first stage boot loader (FSBL) is loaded by the ROM code into the built-in
SYSRAM and executed. The FSBL sets up the SDRAM, install a secure monitor and
then the second stage boot loader (SSBL) is loaded into DRAM.
When building barebox, the resulting ``barebox-${board}.img`` file has the STM32
header preprended, so it can be loaded directly as SSBL by the ARM TF-A
(https://github.com/ARM-software/arm-trusted-firmware). Each entry point has a
header-less image ending in ``*.pblb`` as well.
Use of barebox as FSBL is not supported.
Building barebox
----------------
With multi-image and device trees, it's expected to have ``stm32mp_defconfig``
as sole defconfig for all STM32MP boards::
make ARCH=arm stm32mp_defconfig
The resulting images will be placed under ``images/``:
::
barebox-stm32mp157c-dk2.img
Flashing barebox
----------------
An appropriate image for the boot media can be generated with following
``genimage(1)`` config::
image @STM32MP_BOARD@.img {
hdimage {
align = 1M
gpt = "true"
}
partition fsbl1 {
image = "tf-a-@STM32MP_BOARD@.stm32"
size = 256K
}
partition fsbl2 {
image = "tf-a-@STM32MP_BOARD@.stm32"
size = 256K
}
partition ssbl {
image = "barebox-@STM32MP_BOARD@.img"
size = 1M
}
}
Image can then be flashed on e.g. a SD-Card.
TODO
----
* Extend barebox MMCI support to support the SDMMC2
* Extend barebox DesignWare MAC support to support the stmmac
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