Accessing imx6 CPUID from nvmem (/sys/fsl_opt/ is missing)

[jsmith883]

Hello,

I'm using the 5.4.x kernel and I noticed that I do not have access to /sys/fsl_opt/ to read the CPUID.  I checked the kernel config and I do have everything selected in the NVMEM section, but it's still not showing up.  If I use hexdump and have a look at /sys/bus/nvmem/devices/imx-ocotp0/nvmem, I can see that it's probably in there somewhere, but not sure how to read this.  Is there a better way to get the CPUID, or is there something I need to do to enable /sys/fsl_opt/?  Also I tried: cat /proc/cpuinfo, but it just shows all zeros for the serial number.

# hexdump /sys/bus/nvmem/devices/imx-ocotp0/nvmem
0000000 0003 2022 9502 ee7f 11d4 1e0d 0076 2002
0000010 0302 0062 5870 0000 0010 0000 0000 0000
0000020 00c0 0000 0040 0000 00cc 0000 0000 0000
0000030 0000 0000 0000 0000 e37d 5754 0000 0000
0000040 bada bada bada bada bada bada bada bada
*
0000060 0000 0000 0000 0000 0000 0000 0000 0000
*
0000100 bada bada bada bada bada bada bada bada
*
0000200

[n_e_ha_ka_kk_a_]

You can refer Section 46.5.10 & 46.5.11 for CPUID, That is: OTP Bank0 Word1 - contains the first word of the CPUID OTP Bank0 Word2 - contains the second word of the CPUID. 

Repelisplus tv

[radhikasomaiya]

Hi jsmith883 ,

You can refer Section 46.5.10 & 46.5.11 for CPUID, That is: OTP Bank0 Word1 - contains the first word of the CPUID OTP Bank0 Word2 - contains the second word of the CPUID. 

You can use u-boot command md as per below  or  fuse read command to read Bank 0 Word 1 and Bank 0 Word 2.

               => md.l 21bc410

Regards,

Radhika Somaiya.

[radhikasomaiya]

Hi jsmith883 ,

Which board are you using? i.MX evk or custom board? As we are able to get cpu serial number from cpuinfo. and we are using BSP version L5.4.3_1.0.0 (Yocto Project 3.0 (Zeus)). 

Regards,

Radhika Somaiya.