topic About otp and efuse in i.MX Processors

About otp and efuse

jameshe1 — Wed, 31 May 2017 07:38:52 GMT

I enable the fsl_otp feature in the kernel. and i can find /sys/fsl_otp/

I can cat the items under dir /sys/fsl_otp/. such as

cat /sys/fsl_otp/HW_OCOTP_LOCK

cat /sys/fsl_otp/HW_OCOTP_CFG0

cat /sys/fsl_otp/HW_OCOTP_CFG1

i want to use "echo 0x12345678 > /sys/fsl_otp/HW_OCOTP_CFG4" (fusemap: 0x450, boot config) to burn the efuse register. is it ok?

is it one register can be programed once? if then, i should program it bit by bit because i don't konw clearly what's the right value for some bits now.

How can i program the ocotp register by bit, not 4-bytes? i means i should mask some bit while program.

thanks.

Re: About otp and efuse

Yuri — Wed, 31 May 2017 08:22:24 GMT

Hello,

Your understanding regarding fsl_otp feature in the kernel is correct.

The fuses are once programmable. It is needed first to read the fuse and
set only the burning bits : this may be considered as manual bitwise operation.

Have a great day,
Yuri

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Re: About otp and efuse

jameshe1 — Wed, 31 May 2017 08:36:44 GMT

"It is needed first to read the fuse and set only the burning bits"

Do you mean if i write the bit 0, i can write many times. only 0b1 is really programed?

the following case:

I read back cat /sys/fsl_otp/HW_OCOTP_CFG4

0x0

My board is almost same as imx6qp-sabreauto board but the boot config. i need use ECSPI1 and the SS2 pin to boot from SPI NOR flash?

i want to

set HW_OCOTP_CFG4[7:0] to 0x30 change only bit[5:4]

set HW_OCOTP_CFG4[15:8] to 0x00 don't change

set HW_OCOTP_CFG4[23:16] to 0x00 don't change

set HW_OCOTP_CFG4[15:8] to 0x00 don't change

Re: About otp and efuse

jameshe1 — Wed, 31 May 2017 08:44:15 GMT

Continued...

set HW_OCOTP_CFG4[31:24] to 0x28 I use ECSPI1_SS2 and use S25FL256(24-bit address).

then i write 0x28000030 to HW_OCOTP_CFG4 , is it write?

in fact i don't understand HW_OCOTP_CFG4[23:16], now i write it as 0, can i re-program as 1 at some time i know the right value? Could you please give me the right values for the efuse registers can be used on imx6qp-sabreauto board? i want to modify it for my board. thanks.

Re: About otp and efuse

Yuri — Fri, 02 Jun 2017 09:37:50 GMT

Hello,

> ... if i write the bit 0, i can write many times. only 0b1 is really programed?

Yes.

Correct, it is needed to write 0x28000030 to HW_OCOTP_CFG4.

Regards,

Yuri.