No way to get device serial number from /proc/cpuinfo or elsewhere.

[Alexey Guskov]

Hey guys, looks like there's no support for board serial number in latest images for Station M2.
Serial number on rk356x is coming from otp memory, so:
1) there are no bindings for `otp` and `cpuinfo` devices in .dts, like here
2) there are no kernel driver to extract data from otp memory, like here
I'm ready to contribute, but not sure what's the future plan for those.

Edited June 1, 2022 by Alexey Guskov
adding links

[Myron]

What does this command report on your system:

cat /proc/cpuinfo

As far as I know there is no /dev/cpuinfo.

[balbes150]

There is no support for this driver in the main kernel, it is only in the old BSP.

[Alexey Guskov]

  On 6/1/2022 at 12:07 PM, Myron said:

What does this command report on your system:

cat /proc/cpuinfo

As far as I know there is no /dev/cpuinfo.

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sorry, a typo. Of course i meant

/proc/cpuinfo

 

[Alexey Guskov]

  On 6/1/2022 at 12:11 PM, balbes150 said:

There is no support for this driver in the main kernel, it is only in the old BSP.

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I know there's no support, I checked the sources. But the driver seems to be simple enough and .dts changes are trivial. I can port the code from firefly kernel and create PR, but will probably need some help.

[balbes150]

  On 6/1/2022 at 2:29 PM, Alexey Guskov said:

I can port the code from firefly kernel and create PR, but will probably need some help.

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Ok

[Alexey Guskov]

  On 6/1/2022 at 2:50 PM, balbes150 said:

Ok

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I'll start with questions then: 
1) i got the armbian 5.17 kernel, patched the dts file, built a new .dtd, tried that on my device
2) Now i can see OTP device: 
 

# find /sys/firmware/devicetree/base/otp\@fe38c000/
/sys/firmware/devicetree/base/otp@fe38c000/
/sys/firmware/devicetree/base/otp@fe38c000/#address-cells
/sys/firmware/devicetree/base/otp@fe38c000/cpu-leakage@1a
/sys/firmware/devicetree/base/otp@fe38c000/cpu-leakage@1a/reg
....

and cpuinfo device:
 

# find /sys/firmware/devicetree/base/cpuinfo
/sys/firmware/devicetree/base/cpuinfo
/sys/firmware/devicetree/base/cpuinfo/nvmem-cells
/sys/firmware/devicetree/base/cpuinfo/compatible
/sys/firmware/devicetree/base/cpuinfo/nvmem-cell-names
/sys/firmware/devicetree/base/cpuinfo/name

But if I understand correctly, devices with NVMEM cells should be exposed to userspace as /sys/bus/nvmem/devices/somethingsomething/nvmem, but i got nothing there:
 

# find /sys/bus/nvmem/
/sys/bus/nvmem/
/sys/bus/nvmem/uevent
/sys/bus/nvmem/drivers_autoprobe
/sys/bus/nvmem/devices
/sys/bus/nvmem/drivers_probe
/sys/bus/nvmem/drivers

 

So, am I doing something wrong or this is expected behaviour? Do I need a loaded and active device driver for nvmem cells to be available via /sys/bus/nvmem or correct device tree definition should be enough?

[9bx154]

This should work:

# cat /proc/device-tree/serial-number

[Alexey Guskov]

  On 6/1/2022 at 4:43 PM, 9bx154 said:

This should work:

# cat /proc/device-tree/serial-number

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Nope

 

# find /proc/device-tree/serial-number
find: ‘/proc/device-tree/serial-number’: No such file or directory

 

Don't see a 'serial-number' device in .dts files for rk356x, are you sure it works on Station M2 for you? 

[Alexey Guskov]

Okay, silly me, of course a device wont work if there's no driver for it

[Myron]

  On 6/1/2022 at 2:20 PM, Alexey Guskov said:

sorry, a typo. Of course i meant

/proc/cpuinfo

 

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  On 6/1/2022 at 2:20 PM, Alexey Guskov said:

sorry, a typo. Of course i meant

/proc/cpuinfo

 

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I've corrected the topic subject for you.