[PATCH] board: samsung: add support for Samsung Exynos mobile device board
Henrik Grimler
henrik at grimler.se
Fri Oct 24 09:14:38 CEST 2025
Hi Kaustabh,
On Tue, Oct 21, 2025 at 01:49:46PM +0000, Kaustabh Chakraborty wrote:
> On 2025-10-18 19:25, Henrik Grimler wrote:
> > 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.
>
> I get that, but the board file even uses a lot of armv8 specific stuff
> (#include <asm/armv8/mmu.h>) and I don't have any armv7 devices to
> implement or test. So I am kind of unsure as of what to do here.
Yeah, it would be up to the people dealing with armv7 devices, like
myself, to implement and test it I think. Probably cleanest way would
to have two boards, maybe with some functions/parts moved to common dir.
> I may as well add a paragraph for cross-compilers, but then implicitly
> claiming that armv7 is supported while it remains unsupported doesn't
> sit right with me.
>
> And doing this probably requires two defconfigs - one for armv7, another
> for armv8. There's quite a bit of work required for separation, and I
> am not sure anymore if I should continue to brand it as "all exynos"
> (though I'd love to have it that way), or upstream in this condition
> and figure out later.
To start with I think scope should be clarified in docs. If only armv8
exynos socs (with or without QCDT dt.img) will be supported, then
please mention it in intro section, and maybe change title from
`Samsung Exynos Generic Boards` to `Samsung Exynos Generic Arm64
Boards` or something. exynos-mobile as board name should be fine.
If armv7 support is added in future somehow then we can always revise
docs.
Best regards,
Henrik Grimler
> >
> > 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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