Programming SJC_DISABLE, JTAG_SMODE fuses on iMX8MM

TBYE · ‎07-20-2021

Hi, How can i fuse SJC_DISABLE or enable Secure JTAG on imx8mm

Where can i find the fuse bit, word and bank

Silvarye · ‎07-21-2021

Hi,

yes, so with uboot you can program SJC_DISABLE like this :

=> fuse prog 1 3 0x200000

And for enable Secure JTAG check the fuse Map in the reference manual at the address 0x470[23:22]

So, for find the fuse bit, word and bank,

1st, you need to find in the fuse map what you search, after you have the address (for example 0x470[23;22])

2nd, with the address you can find in the OCOTP memory map which word and bank correspond for your address (for example 470 correspond to Value of OTP Bank1 Word3)

3rd, use Uboot : => fuse prog <bank> <word> <bit address>

For example, for SJC_DISABLE it's 0x470[21]

so 470 --> bank 1 word 3

bit 21 -> 1 : 0x200000 (1000000000000000000000)

so you have your command : => fuse prog 1 3 0x200000

Hope I was clear

Best regards,

Alexandre.

TBYE · ‎07-21-2021

@Silvarye is this address 0x470[23:22] for imx8m mini?

IF yes please share the reference.

Silvarye · ‎07-21-2021

I work on the imx8m Nano, but you can do a request for your board : Security Reference Manual for i.MX 8M Mini Applications Processor (nxp.com)

For answer to your question I think it's the same fuse so, yes 0x470[23:22] (JTAG_SMODE) it's for imx8m mini too.

But before burning fuse, when you will have this document check in the Fuse Map for your board, it's more safe.

Best regards,

Alexandre.

antho · ‎03-21-2023

Hi,

What's register 0x470[23:22] (JTAG_SMODE) value to configure JTAG in mode #1 please ?

I asked NXP for security documentation but have no response yet...

Thanks !