topic Re: How to access the i.MX6 unique ID/serial number in Linux in i.MX Processors

How to access the i.MX6 unique ID/serial number in Linux

compmas2 — Thu, 15 Sep 2016 15:15:12 GMT

I am working with the 4.1.15 bsp release 1.1.1 for the i.MX6. I am trying to obtain the unique ID/serial number that is available in the processor's fuses at address 0x410 and 0x420 in Linux. I realize that I can enable the /sys/fsl_otp interface, but I don't want that exposed in production runtime images because accidental writes could cause the processor to stop functioning correctly. What I would really like is for the /proc/cpuinfo output to populate the Serial line with the unique number from the fuses.

It appears u-boot is capable of passing the serial number off to the Linux kernel through ATAGS, but with the use of device trees now I don't know if this is possible anymore. In u-boot, my board .h file has the "#define CONFIG_SERIAL_TAG" which is supposed to pass off CPU serial information to Linux.

Additionally it would be nice if the revision of the processor (fuse address 0x430[19:16]) could also be supported in the /proc/cpuinfo data too.

Does anyone have any idea why this doesn't work and how to fix this?

Re: How to access the i.MX6 unique ID/serial number in Linux

b36401 — Fri, 16 Sep 2016 06:13:28 GMT

You can read these fuses from sysfs:

# cat /sys/fsl_otp/HW_OCOTP_CFG0
0xd72d7394
# cat /sys/fsl_otp/HW_OCOTP_CFG1
0xf1361d4
#

Have a great day,
Victor

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Re: How to access the i.MX6 unique ID/serial number in Linux

compmas2 — Mon, 19 Sep 2016 13:24:10 GMT

Victor,

This is what I stated in the original post as something I was aware of but that I did not want to expose the fuses in my runtime environment because of the risk of setting fuses which could break functionality or prevent booting. I am mainly looking for if there is a native way to pass the serial number from the bootloader to the Linux kernel so the kernel interfaces for obtaining the CPU serial number work.

- Matt

Re: How to access the i.MX6 unique ID/serial number in Linux

titggtu — Wed, 26 Jun 2019 07:15:46 GMT

Matthew, did you manage to get access to a unique processor ID from under the Linux kernel? Would you share a solution to this problem?

Re: How to access the i.MX6 unique ID/serial number in Linux

compmas2 — Wed, 26 Jun 2019 15:18:20 GMT

Alexey, I did not get the processor serial number passing through the kernel working without the fsl_otp driver enabled. I ended up implementing my own serial numbering system used by my company for uniqueness.

Re: How to access the i.MX6 unique ID/serial number in Linux

titggtu — Thu, 27 Jun 2019 08:12:31 GMT

Thanks for the answer!

As a result of finding a solution to this problem, the following thought arose.
At the stage of loading in U-Boot, you can read the "unique ID" (addr. 0x021bc410, 0x021bc420 ) with the "md" command, and then put the result as a parameter in the *.dts file. After loading Linux, parameters from the *.dts file can be read from the path /sys/bus/soc/devices/soc0 /parameters, where they are stored as files.