Manipulating Device Fuse Data from Linux

[moose]

Hello,

Is there a way to manipulate imx8mn fuses from Linux? Today we use uboot `fuse read` and `fuse program` commands, and we prefer to do it from Linux instead. It was not clear online how to do this on imx8mn devices. Thank you.

[Harvey021]

Hi,

Please refer to the section of One-Time Programmable Controller Driver Using NVMEM Subsystem IMX_LINUX_USERS_GUIDE.pdf 

Regards

Harvey

[moose]

Thank you for the reference. I am now able to read some fuses using the command `hexdump /sys/bus/nvmem/devices/imx-ocotp0/nvmem`; however, I am unclear on how to map them to the fuse table.

The reference manual for imx8mn lists fuse address space from 0x400 to 0x900 but the output of the hexdump command is not the same. I was able to identify the SRK hash fuse, for example, since it has a unique value. It was showing on address 0000060 in the hexdump output yet its fuse address is 0x580. The reference you shared discusses an example for the MAC address, but I don't really understand it.

Could you please elaborate on how we translate the hexdump address into fuse address? Also, is it possible to burn the fuse from Linux?

[moose]

@Harvey021 any update on this?