[PATCH] board: samsung: add support for Samsung Exynos mobile device board
Henrik Grimler
henrik at grimler.se
Sat Oct 18 21:25:39 CEST 2025
Hi Kaustabh,
On Sat, Oct 18, 2025 at 06:04:35PM +0000, Kaustabh Chakraborty wrote:
> On 2025-10-17 20:19, Henrik Grimler wrote:
> > 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.
>
> Well no, any Exynos would be supported by this variant, the only
Ok, any Exynos, then `disguised as an Android boot image` should be
rephrased, as not all Exynos'es support boot images. Next paragraph
should be updated as well.
> factor is that U-Boot is used as a *secondary* boot loader. QCDT is
> specific to the packaging of the u-boot binary (that too, is
> located under a 7870-specific section), and if there are any other
> packing methods, they can be documented here as well.
>
> That being said, I've found 'exynos-mobile' to be most appropriate
> (This is for mobile devices like phones and tablets, where we have
> a proprietary primary boot loader). But if you have suggestions for
> better names, let me know. :)
Sure, if any Exynos is supported, then exynos-mobile is fine.
> > > +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.
Not all Exynos'es have bootloaders that support boot images, and among
the ones that do, not all support dtbs. Please move to 7870 specific
section and/or make the paragraph more generic if it should support
any Exynos.
> >
> > > +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?
>
> Plans were for aarch64. But if its possible to add armv7 support, then
> that would be great! Is multiple arch-es for the same board possible?
Probably not, but not all Exynos'es are armv8, so if instructions
should be for any Exynos then I think it is best to leave $arch out of
the commands.
Best regards,
Henrik Grimler
> > > +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?
>
> I agree. Will 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>
> > >
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