[PATCH v8 0/6] Add support for ZTE zx297520v3

[Stefan Dösinger]

Hi,

This is a follow-up on my RFC patches from January [0] for ZTE's 
zx297520v3 chipset. This chipset is popular in cheap LTE-to-wifi routers
sold in developing countries. My goal is to run OpenWRT on them. I made 
more progress in more work on this SoC and it is time to get serious 
about code review and upstreaming.

Since my version in January I managed to get more hardware running: SPI, 
I2C, PMIC with real time clock and voltage regulators, Watchdog. LTE is 
not working yet, but I am able to start the coprocessor that handles it 
and talk to it via mailbox + shared memory. Wifi is working on a few 
more devices. Since WiFi, USB and Ethernet are working, the devices can 
have actual use with OpenWRT even without LTE.

Another hacker created a free software program to talk to the USB loader 
[1] and boot U-Boot and Linux without modifying the on disk files. At 
the moment it needs a proprietary blob, so my documentation is 
emphasising booting with the on-device U-Boot.

This patchset here is mostly unmodified from the version I sent in 
January. It is the bare minimum to get an interactive shell working on 
the UART. Future patches can be found on my git repository [2] for those 
curious to peek ahead. The first 30 patches are in reasonable shape, but 
the further you go the more cleanup is necessary. I expect all of the 
patches go require a few rounds of feedback though.

My plan for upstreaming is largly this:

1) This bare minimum boot patchset
2) Add clock and pinctrl drivers
3) Add standard hardware to the device tree
4) Add zx29 specific drivers one by one: Watchdog, spi, i2c, DMA, PMIC, 
battery
5) SDIO backend for rtl8xxxu
6) rproc, mailbox and rpmsg

I am willing to maintain support for the SoC within reason. My patches 
add myself as maintainer. This is a hobby project for me though, keep 
that in mind if you want to ship a commercial product with these SoCs 
and upstreaming Linux.

Cheers,
Stefan

0: https://lists.infradead.org/pipermail/linux-arm-kernel/2026-January/1099306.html
1: https://github.com/zx297520v3-mainline/zx297520v3-loader
2: https://gitlab.com/stefandoesinger/zx297520-kernel/

Signed-off-by: Stefan Dösinger <stefandoesinger@xxxxxxxxx>
---
Changes in v8: A number of Sashiko suggestions:
Add new documentation files to the documentation index
Add new documentation directory to MAINTAINERS
Remove a redundant "if ARCH_ZTE"
Set ARM_PSCI_FW because ARM_GIC_V3 needs it
Use the correct UART01x_FR_BUSY flag in lldebug asm
Remove an accidentally duplicated label from the DTSI file, properly use 
"arm,pl011", "arm,primecell" for all UARTs
Remove BINFMT_FLAT from defconfig. I have no idea how that got enabled.

Point to a sane (but not yet upstream) U-Boot that sets up the GIC 
correctly for this board. Improve the provided example GIC setup code to 
detect this for reusing one binary for both boot chains.

Changes in v7:
Fix line order in mach-zte/Kconfig
Use "zx297520v3 SoC" as the option name for CONFIG_SOC_ZX297520V3

Changes in v6:
Squashed DT commits into one
Removed for-now unused board DT bindings
Add "zte" to DT patch subject
Regenerate the defconfig with make savedefconfig
- Link to v5: https://lore.kernel.org/r/20260421-send-v5-0-ace038e63515@xxxxxxxxx

v5:
Spelling fixes
Renamed dlink-dwr-932m.dts to zx297520v3-dlink-dwr932m.dts
DT binding indentation fixes
Use a manufacturer 0x8b for the UART, fix patch prefix
Declare all UARTs, remove uart aliases for now
Consistent license declarations. I made every new file except the DT 
binding GPL-2.0-only but I don't particularly mind GPL-2.0-or-later 
either.
- Link to v4: https://lore.kernel.org/r/20260416-send-v4-0-e19d02b944ec@xxxxxxxxx

v4: rename zx29.yaml to zte.yaml and add board enums
v3: Remove [RFC] tag, add defconfig
v2: checkpatch.pl fixes

---
Stefan Dösinger (6):
      dt-bindings: arm: zte: Add D-Link DWR932M board based on zx297520v3 SoC
      ARM: zte: Add zx297520v3 platform support
      ARM: zte: Add support for zx29 low level debug
      amba/serial: amba-pl011: Bring back zx29 UART support
      ARM: dts: zte: Add D-Link DWR-932M support
      ARM: zte: defconfig: Add a zx29 defconfig file

 Documentation/arch/arm/index.rst                   |   2 +
 Documentation/arch/arm/zte/index.rst               |  10 ++
 Documentation/arch/arm/zte/zx297520v3.rst          | 167 +++++++++++++++++++++
 Documentation/devicetree/bindings/arm/zte.yaml     |  26 ++++
 MAINTAINERS                                        |   8 +
 arch/arm/Kconfig                                   |   2 +
 arch/arm/Kconfig.debug                             |  12 ++
 arch/arm/Makefile                                  |   1 +
 arch/arm/boot/dts/Makefile                         |   1 +
 arch/arm/boot/dts/zte/Makefile                     |   3 +
 arch/arm/boot/dts/zte/zx297520v3-dlink-dwr932m.dts |  22 +++
 arch/arm/boot/dts/zte/zx297520v3.dtsi              | 103 +++++++++++++
 arch/arm/configs/zx29_defconfig                    |  53 +++++++
 arch/arm/include/debug/pl01x.S                     |   9 ++
 arch/arm/mach-zte/Kconfig                          |  29 ++++
 arch/arm/mach-zte/Makefile                         |   2 +
 arch/arm/mach-zte/zx297520v3.c                     |  16 ++
 drivers/tty/serial/amba-pl011.c                    |  42 ++++++
 18 files changed, 508 insertions(+)
---
base-commit: 028ef9c96e96197026887c0f092424679298aae8
change-id: 20260416-send-5c08e095e5c9

Best regards,
-- 
Stefan Dösinger <stefandoesinger@xxxxxxxxx>