[PATCH] board: samsung: add support for Samsung Exynos mobile device boards
Henrik Grimler
henrik at grimler.se
Fri Oct 17 22:19:36 CEST 2025
Hi Kaustabh,
Nice work on all of the linked patches!
On Fri, Oct 17, 2025 at 10:07:35PM +0530, Kaustabh Chakraborty wrote:
> Add support for a generic platform which intends to support multiple
> boards powerid by Samsung Exynos SoCs. This patch also includes initial
> support for three boards:
> * Samsung Galaxy A2 Core
> * Samsung Galaxy J6
> * Samsung Galaxy J7 Prime
I think it would be easier to review this if you split the patch in two
parts: first adding docs and common parts, and then the specific parts
for exynos7870 and these devices.
> Signed-off-by: Kaustabh Chakraborty <kauschluss at disroot.org>
> ---
> This patch has the following dependencies:
> (NOTE: `x` indicates applied)
>
> armv8-broken-cntfrq - https://patch.msgid.link/20251017-armv8-broken-cntfrq-v2-1-1e043cbb657e@disroot.org
> clk-exynos7870 - https://patch.msgid.link/20251017-clk-exynos7870-v1-0-83f90d425699@disroot.org
> gpio-s5p-bank-fix - https://patch.msgid.link/20251017-gpio-s5p-bank-fix-v1-1-41050462cea5@disroot.org
> i2c-hs-exynos7 - https://patch.msgid.link/20251017-i2c-hs-exynos7-v1-1-ca080895d4b6@disroot.org
> mmc-dw-exynos7870 - https://patch.msgid.link/20251017-mmc-dw-exynos7870-v1-0-a2c5139d9afe@disroot.org
> phy-usb-exynos7870 - https://patch.msgid.link/20251017-phy-usb-exynos7870-v1-0-5885b00f0c87@disroot.org
> pinctrl-exynos7870 - https://patch.msgid.link/20251017-pinctrl-exynos7870-v1-0-beaa92f95a0c@disroot.org
> power-pmic-regulator-s2mpu05 - https://patch.msgid.link/20251017-power-pmic-regulator-s2mpu05-v1-0-91cadc0f4156@disroot.org
> serial-s5p-exynos8895 - https://patch.msgid.link/20251017-serial-s5p-exynos8895-v1-1-b412dd112cfd@disroot.org
> soc-pmu-exynos7 - https://patch.msgid.link/20251017-soc-pmu-exynos7-v1-1-553d18eaab0d@disroot.org
> usb-dwc3-exynos7870 - https://patch.msgid.link/20251017-usb-dwc3-exynos7870-v1-0-fe46e2ed1908@disroot.org
> ---
> arch/arm/mach-exynos/Kconfig | 11 +-
> board/samsung/exynos-mobile/Kconfig | 18 +
> board/samsung/exynos-mobile/MAINTAINERS | 6 +
> board/samsung/exynos-mobile/Makefile | 5 +
> .../samsung/exynos-mobile/debug-exynos7870.config | 7 +
> board/samsung/exynos-mobile/exynos-mobile.c | 372 +++++++++++++++++++++
> board/samsung/exynos-mobile/exynos-mobile.env | 18 +
> configs/exynos-mobile_defconfig | 71 ++++
> doc/board/samsung/exynos-mobile.rst | 112 +++++++
> doc/board/samsung/index.rst | 1 +
> include/configs/exynos-mobile.h | 14 +
> 11 files changed, 634 insertions(+), 1 deletion(-)
[ skipping to docs for now ]
> diff --git a/doc/board/samsung/exynos-mobile.rst b/doc/board/samsung/exynos-mobile.rst
> new file mode 100644
> index 0000000000000000000000000000000000000000..6390c66ffc38a41f01cb51c7406397cfc5a3d223
> --- /dev/null
> +++ b/doc/board/samsung/exynos-mobile.rst
> @@ -0,0 +1,112 @@
> +.. SPDX-License-Identifier: GPL-2.0+
> +.. sectionauthor:: Kaustabh Chakraborty <kauschluss at disroot.org>
> +
> +Samsung Exynos Generic Boards (for mobile devices)
> +==================================================
> +
> +Overview
> +--------
> +This document describes how to build and run U-Boot for Samsung Exynos generic
> +boards. Boards are expected to boot with a primary bootloader, such as S-BOOT or
> +S-LK, which hands off control to U-Boot, disguised as an Android boot image.
In my opinion exynos-mobile is a bit too generic. From the docs here
it seems plan is to support devices that support android boot images
with dt in Samsung's qcdt format. The oldest Exynos mobile device do
not even support boot images though, and dt images has only been
around since something like 2015. If I am not mistaken the newest
devices also does not use dt images.
> +U-Boot is packed with multiple FDTs since it targets multiple boards. The
> +appropriate FDT is selected during boot. Additionally, a DTB is also required
> +for embedding in the Android boot image. The previous bootloader can apply
> +useful overlays on it. Both DTBs are consulted for figuring out the memory
> +layout.
> +Installation
> +------------
> +Building
> +^^^^^^^^
> +To buiid U-Boot, run the following commands
Typo, buiid -> build
> +.. prompt:: bash $
> +
> + make CROSS_COMPILE=aarch64-linux-gnu- O=.output exynos-mobile_defconfig
> + make CROSS_COMPILE=aarch64-linux-gnu- O=.output -j$(nproc)
I think CROSS_COMPILE=aarch64-linux-gnu- can be dropped from the example, or are only
aarch64 devices supported?
> +If succcessful, the U-Boot binary will be present in ``.output/u-boot.bin``.
Typo, succcessful -> successful.
> +
> +Preparation
> +^^^^^^^^^^^
> +The U-Boot binary is not flashable as-is, it needs to be encapsulated in an
> +Android boot image. Since it supports multiple boards, and devices have
> +different requirements (thanks to the lack of standards), this step varies
I think `(thanks to the lack of standards)` is a bit opinionated, and
does not really add anything here, could you please remove it?
> +depending on your target.
> +
> +Exynos 7870 Boards
> +""""""""""""""""""
> +Create the following devicetree (named ``stub.dts``)
> +
> +.. code-block:: devicetree
> +
> + /dts-v1/;
> +
> + / {
> + compatible = "samsung,exynos7870";
> + #address-cells = <2>;
> + #size-cells = <1>;
> +
> + model_info-chip = <7870>;
> + model_info-hw_rev = <0>;
> + model_info-hw_rev_end = <255>;
> +
> + chosen {
> + };
> +
> + memory at 80000000 {
> + device_type = "memory";
> + reg = <0x0 0x80000000 0x0>;
> + };
> +
> + memory at 100000000 {
> + device_type = "memory";
> + reg = <0x1 0x00000000 0x0>;
> + };
> + };
> +
> +The chosen node and memory ranges are populated by S-BOOT.
> +
> +Compile it to a devicetree blob, then use ``dtbTool-exynos`` in order to pack it
> +in the QCDT format [1]_, using the following commands:
> +
> +.. prompt:: bash $
> +
> + dtc -I dts -O dtb -o stub.dtb stub.dts
> + dtbTool-exynos -o stub.dt.img stub.dtb
> +
> +Finally, use mkbootimg by osm0sis [2]_ to generate the boot image:
> +
> +.. prompt:: bash $
> +
> + mkbootimg -o u-boot.img \
> + --kernel .output/u-boot.bin \
> + --dt stub.dt.img
> +
> +Offsets are not provided to ``mkbootimg`` as S-BOOT ignores them.
> +
> +Flashing
> +^^^^^^^^
> +If flashing for the first time, it must be done via Samsung's Download (Odin)
> +mode. Heimdall can be used for flashing, like so:
Maybe it would be useful to link to Heimdall in references as well.
Best regards,
Henrik Grimler
> +.. prompt:: bash $
> +
> + heimdall flash --BOOT u-boot.img
> +
> +However, if U-Boot is already installed, you may also use its fastboot interface
> +for flashing. Boot into the boot menu by holding the volume down key. Enable
> +fastboot mode from there, connect the device to your host, then run:
> +
> +.. prompt:: bash $
> +
> + fastboot flash boot u-boot.img
> +
> +To flash an OS image in internal storage, fastboot is a reliable option.
> +
> +References
> +----------
> +.. [1] https://wiki.postmarketos.org/wiki/QCDT
> +.. [2] https://github.com/osm0sis/mkbootimg
> diff --git a/doc/board/samsung/index.rst b/doc/board/samsung/index.rst
> index 1b92c9518a57df102c2b64ff934b460548ce3d53..1fbe88130c049e1a33d22ae9230fb60ddccea131 100644
> --- a/doc/board/samsung/index.rst
> +++ b/doc/board/samsung/index.rst
> @@ -8,4 +8,5 @@ Samsung
>
> axy17lte
> e850-96
> + exynos-mobile
> n1
> diff --git a/include/configs/exynos-mobile.h b/include/configs/exynos-mobile.h
> new file mode 100644
> index 0000000000000000000000000000000000000000..862db5779ef4c9ff7f53bef78d7cee5107b7226e
> --- /dev/null
> +++ b/include/configs/exynos-mobile.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Samsung Exynos Generic Board Configuration (for mobile devices)
> + *
> + * Copyright (C) 2025 Kaustabh Chakraborty <kauschluss at disroot.org>
> + */
> +
> +#ifndef __CONFIG_EXYNOS_MOBILE_H
> +#define __CONFIG_EXYNOS_MOBILE_H
> +
> +#define CPU_RELEASE_ADDR secondary_boot_addr
> +#define CFG_SYS_BAUDRATE_TABLE {9600, 115200}
> +
> +#endif /* __CONFIG_EXYNOS_MOBILE_H */
>
> ---
> base-commit: 582a04763aa80738c1c8ac60c47d1a5159a42833
> change-id: 20251017-board-exynos-mobile-7c7d43832693
>
> Best regards,
> --
> Kaustabh Chakraborty <kauschluss at disroot.org>
>
More information about the U-Boot
mailing list