How to read otp register in linux?

[MJerm.1]

I need to store a password for encryption in otp registers. I configured device tree in tfa:

&bsec{

status = "okay";

secure-status = "okay";

enc_pass: enc_pass@0x170 {

 reg = <0x170 0x10>;

 st,non-secure-otp;

 };

};

&nvmem_layout {

    nvmem-cells = <&enc_pass>;

    nvmem-cell-names = "enc_pass";

};

And in uboot and kernel:

&bsec{

status = "okay";

enc_pass: enc_pass@0x170 {

 reg = <0x170 0x10>;

 st,non-secure-otp;

 };

};

NVMEM is configured in kernel defconfig. I can read and write to set otp register in uboot, but i cant read data in linux.

I tried this:

hexdump -C -v /sys/bus/nvmem/devices/stm32-romem0/nvmem

and

dd if=/sys/bus/nvmem/devices/stm32-romem0/nvmem of=/tmp/file

And i have that error:

stm32-romem 5c005000.efuse: Can't read data32 (-5)

hexdump: /sys/bus/nvmem/devices/stm32-romem0/nvmem: Input/output error

[OlivierK · Accepted solution]

Hi MJerm.1 (Community Member)

If you are using OpenSTLinux DV3.1 then you should point to the previous wiki version:

https://wiki.st.com/stm32mpu-ecosystem-v3/wiki/NVMEM_overview#How_to_read_BSEC_lower_OTPs_using_NVMEM

Using the DV3.1 version, and the wiki 3.1, I can read upper OTP from linux as OTP57 is by default unprotected in the BSEC on DK2 board.

root@stm32mp1:~# dd if=/sys/bus/nvmem/devices/stm32-romem0/nvmem of=/tmp/file sk

ip=57 bs=4 count=2 status=none                          

root@stm32mp1:~# hexdump -C -v /tmp/file 

00000000 00 80 e1 42 7c d1 00 00              |...B|...| 

Also, no issues found with the starter package DV4.0 /OP-TEE image and the current wiki, with the hexdump command.

root@stm32mp1:~# hexdump -C -v /sys/bus/nvmem/devices/stm32-romem0/nvmem 

00000000 17 00 00 00 80 80 00 00 00 00 20 a0 00 00 00 00 |.......... .....|

00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|

00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|

00000030 ed f0 f5 7c 2a 00 34 00 18 51 38 34 38 32 38 36 |...|*.4..Q848286|

00000040 e1 75 95 12 65 13 31 3b 40 01 85 7a 1a 14 bd 06 |.u..e.1;@..z....|

00000050 3b 00 f2 5d 00 00 00 00 00 00 00 00 6e 30 16 40 |;..]........n0.@|

00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|

00000070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|

00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|

00000090 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|

000000a0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

000000b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

000000c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

000000d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

000000e0 00 00 00 00 00 80 e1 42 7c ed 00 00 02 43 72 12 |.......B|....Cr.|  

000000f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000100 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000130 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000150 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000160 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000170 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000180 

After unprotecting all the upper OTP...

root@stm32mp1:~# hexdump -C -v /sys/bus/nvmem/devices/stm32-romem0/nvmem     

00000000 17 00 00 00 80 80 00 00 00 00 20 a0 00 00 00 00 |.......... .....|  

00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000020 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000030 ed f0 f5 7c 2a 00 34 00 18 51 38 34 38 32 38 36 |...|*.4..Q848286|  

00000040 e1 75 95 12 65 13 31 3b 40 01 85 7a 1a 14 bd 06 |.u..e.1;@..z....|  

00000050 3b 00 f2 5d 00 00 00 00 00 00 00 00 6e 30 16 40 |;..]........n0.@|  

00000060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000090 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

000000a0 4d 4c 9b a0 00 ba 21 1d 92 89 ac fb 5a a4 0f 28 |ML....!.....Z..(|  

000000b0 49 8f 2f b0 8d 8d 2c bd c6 39 c1 af df ac e7 7a |I./...,..9.....z|  

000000c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

000000d0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

000000e0 00 00 00 00 00 80 e1 42 7c ed 00 00 00 00 00 00 |.......B|.......|  

000000f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000100 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000120 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000130 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000140 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000150 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000160 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000170 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|  

00000180                                   

[MJerm.1]

Thank you, it helped, I didn't notice that the version had already changed

[OlivierK]

In order to give better visibility on the answered topics, please click on 'Select as Best' on the reply which solved your issue or answered your question. See also 'Best Answers'