w1 / onewire on rk3399 requires 'setexpr' in U-Boot or a workaround on rock se4

[NiklausS]

Creating a bug report/issue

• I have searched the existing open and closed issues

Required Information

• DietPi version | cat /boot/dietpi/.version
  G_DIETPI_VERSION_CORE=9
  G_DIETPI_VERSION_SUB=20
  G_DIETPI_VERSION_RC=1
  G_GITBRANCH='master'
  G_GITOWNER='MichaIng'

• Distro version | trixie

• Kernel version | Linux DietPi 6.12.61-current-rockchip64 Fix warning when running scp over openssh-server #1 SMP PREEMPT Sat Dec 6 21:25:03 UTC 2025 aarch64 GNU/Linux

• SBC model | ROCK 4 (aarch64)

• Power supply used | (EG: 5V 1A RAVpower)

• SD card used | (EG: SanDisk ultra)

Additional Information (if applicable)

onewire support and u-boot regression
when defining
param_w1_pin=xxx
overlays=rk3399-w1-gpio
is not working

Steps to reproduce

when setting up w1 - onewire, the current boot results in:

 ## Executing script at 09000000`
Unknown command 'setexpr' - try 'help'
Unknown command 'setexpr' - try 'help'

Expected behaviour

• ...

Actual behaviour

• ...

Fix

1. enable setexpr into u-boot build
   or
2. Change the params dietpiEnv.txt a bit more specific to

...
#param_w1_bank=gpio4, param_w1_pin=0x16 <- ABCD-> C=2  Pin=6 -> 2*8+6 = 22 => GPIO4_C6
overlays=rk3399-w1-gpio  # Radxa-spezifisch
param_w1_bank=gpio4
param_w1_pin=0x1E
...

and change rockchip-fixup.cmd - remove all lines with setexpr and change the section for w1

...
if test -n "${param_w1_pin}"; then
    fdt get value tmp_pinctrl /__symbols__ ${param_w1_bank}
    fdt get value tmp_phandle ${tmp_pinctrl} phandle
    echo "fdt set /onewire@0 gpios <${tmp_phandle} ${param_w1_pin} 0 0"
    fdt set /onewire@0 gpios "<${tmp_phandle} ${param_w1_pin} 0 0>"
fi
...

[MichaIng]

I remember a recent commit at Armbian which enaables setexpr support for U-Boot, in some cases or even globally. So maybe it is just a rebuild. Otherwise we can add it.

[NiklausS]

sorry - was trying to beautify the text above. :-)
adding it would be nice, at the other hand, removing the dependency in the rockchip-fixup.scr would also work.

Thanks for the quick answer.
Cheers
Nik

[MichaIng]

I am actually not sure what the fixup script does exactly, whether it is needed or even applicable for all Rockchip SBCs etc. I applies some parameters, but at least we do not make use of them in our boot scripts. So probably we can just drop them entirely, and readd them the way we might need them on demand. E.g. some overlays might make use of those parameters, not sure.

But no point to not add some U-Boot console commands, IMO, flexibility is always good. Here the commit I was looking for: armbian/build@826309f
I'll just enable these two options globally. We do the same for Btrfs support and the subvolume commmand already.

[NiklausS]

ok, just for the sake of completeness:
the /boot/dtb/rockchip/overlay/rockchip-fixup.scr makes some heavy use of it, tough it could be done simpler.
and this is only used for the onewire w1 part, nowhere else.

setenv decompose_pin 'setexpr tmp_pinctrl sub "GPIO(0|1|2|3|4)_\\S\\d+" "\\1";
setexpr tmp_bank sub "GPIO\\d_(\\S)\\d+" "\\1";
test "${tmp_bank}" = "A" && setenv tmp_bank 0;
test "${tmp_bank}" = "B" && setenv tmp_bank 1;
test "${tmp_bank}" = "C" && setenv tmp_bank 2;
test "${tmp_bank}" = "D" && setenv tmp_bank 3;
setexpr tmp_pin sub "GPIO\\d_\\S(\\d+)" "\\1";
setexpr tmp_bank ${tmp_bank} * 8;
setexpr tmp_pin ${tmp_bank} + ${tmp_pin}'
...
if test -n "${param_w1_pin}"; then
	setenv tmp_pinctrl "${param_w1_pin}"
	setenv tmp_bank "${param_w1_pin}"
	setenv tmp_pin "${param_w1_pin}"
	run decompose_pin
	#echo "${param_w1_pin} ---> pinctrl = ${tmp_pinctrl}"
	#echo "${param_w1_pin} ---> bank = ${tmp_bank}"
	#echo "${param_w1_pin} ---> pin = ${tmp_pin}"
	fdt get value tmp_pinctrl /__symbols__	gpio${tmp_pinctrl}
	#echo "${param_w1_pin} ---> tmp_pinctrl = ${tmp_pinctrl}"
	fdt get value tmp_phandle ${tmp_pinctrl} phandle
	#echo "${param_w1_pin} ---> tmp_phandle = ${tmp_phandle}"
	fdt set /onewire@0 gpios "<${tmp_phandle} 0x000000${tmp_pin} 0 0>"
	env delete tmp_pinctrl tmp_bank tmp_pin tmp_phandle
fi

[MichaIng]

Ah okay, so the kernel ships an overlay and fixup for that overlay which makes use of commands not supported by the (not so well) matching U-Boot build. So yeah enabling setexpr seems just the right step then.