[PATCH] board: samsung: add support for Samsung Exynos mobile device board
Kaustabh Chakraborty
kauschluss at disroot.org
Tue Oct 21 15:49:46 CEST 2025
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.
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.
>
> 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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