AM62L: Persisting Ethernet MAC addresses in eFuses on the AM62L running u-boot + Linux

Hello Simon

This question was misassigned, so did not get assigned appropriately. I will send to a few colleagues, may take a day or two to get back to you. 

Hello Simon,

Apologies for the delayed response.

1. What SDK version are you using?

2. Can you clarify if you are implementing this on a custom AM62L board? I assume it is a custom board.

I'm not sure if you've encountered this link before  [FAQ] Where do the MAC addresses for AM62x and AM64x come from? How do I change the MAC addresses? . On older SDK releases (pre 10.0) only the first ethernet port had the MAC address efused with the other ethernet port MAC addresses read from EEPROM. From SDK 10.0 onwards all ethernet ports had randomly generated MAC addresses. I'm not positive at this moment in time if the other ethernet ports (other than the first port) can have the MAC address be efused and will check with a colleague on this.

Does the second MAC address have to be efused? Do you have an EEPROM on your board from which the second MAC address can be placed?

-Daolin

This is a custom AM62L board. What I am missing is the mapping from "otp mmr xx" to MMR registers in the booted system - at the moment, our system shows random MAC addresses, and I want to set the MMR registers that the DeviceTree tells the system to read from.

We're not directly using a TI SDK - we're building our own system from TI Linux kernel 6.12.57 and TI u-boot 2025.01.

Hello,

Have you already looked at the following FAQ to program the MAC IDs into the Extended OTP

e2e.ti.com/.../faq-how-to-update-ids-usb-pcie-pid-vid-mac-id-by-programming-extended-otp-on-am6x

Simon Farnsworth said:

What is the relationship between the OTP MMR register numbers (0 through 31) in Keywriter Lite, and the `WKUP_CTRL_MMR_CFG0_GP_SW` and `WKUP_CTRL_MMR_CFG0_MAC_ID` registers the ROM fills during boot of the AM62L?

Please note ROM only supports programming the MAC ID, read from the Extended OTP, into the WKUP_CTRL_MMR_CFG0_MAC_ID.

I have seen the FAQ for programming the MAC IDs into the Extended OTP, but it does not answer my question: the documentation tells me that there are 32 "otp mmr xx" registers in the ext_otp area, but that FAQ only tells me that OTP MMR 30 corresponds to CTRLMMR_USB_DEVICE_ID0.

I want to program `WKUP_CTRL_MMR_CFG0_MAC_ID0` and `WKUP_CTRL_MMR_CFG0_MAC_ID1`, along with `WKUP_CTRL_MMR_CFG0_GP_SW0` and `WKUP_CTRL_MMR_CFG0_GP_SW1`, which are all documented as copies of parts of the `ext_otp` area, but I do not know which parts.

Then, once I have these registers programmed from Extended OTP, I can use their contents to set port MAC addresses to fixed values.

Simon Farnsworth said:

the documentation tells me that there are 32 "otp mmr xx" registers in the ext_otp area, but that FAQ only tells me that OTP MMR 30 corresponds to CTRLMMR_USB_DEVICE_ID0.

The FAQ doesn't state that OTP MMR 30 corresponds to USB_DEVICE_ID0. It only shows as an example the programming of the custom USB VID/PID into the Extended OTP.

The screenshots attached in the FAQ indeed show that the OTP MMRs 29 and 30 can be programmed with custom USB VID/PID, PCIe VID/PID, or MAC ID. The interpretation of the values in these MMRs depend on the ID (ID0-3) flags programmed in the MMR 31. If you program these ID0-3 flags with the MAD ID flag values then the ROM interprets the MMR 29 and 30 values as MAC ID. Since, we have only 64 bits so you can program only a single MAC. The ROM populates the WKUP_CTRL_MMR_CFG0_MAC_ID with this single programmed MAC in the Extended OTP.

First, is the AM62L an AM62x for this purpose? Keywriter Lite is different to Keywriter for the AM624, and I don't want to get caught out by differences here.

Second, where did "Fig 1" from the linked FAQ post on ext_otp come from? I can't find it in www.ti.com/.../sprujb4a.pdf

Simon Farnsworth said:

First, is the AM62L an AM62x for this purpose? Keywriter Lite is different to Keywriter for the AM624, and I don't want to get caught out by differences here.

The Extended OTP structure is same on both the devices. It doesn't matter if it is programmed with Keywriter Lite on AM62L or Keywriter on AM62x. Keywriter Lite or Keywriter are only a method of programming the OTP.

Simon Farnsworth said:

Second, where did "Fig 1" from the linked FAQ post on ext_otp come from? I can't find it in www.ti.com/.../sprujb4a.pdf

Those figures are there in the OTP Keywriter user guide.

Where do I find a version of the OTP Keywriter user guide with this figure in it? I have previously been pointed at https://software-dl.ti.com/tisci/esd/latest/6_topic_user_guides/key_writer_lite.html but this does not contain Fig.1 from the FAQ you've linked.

Prashant Shivhare said:

Those figures are there in the OTP Keywriter user guide.

I mean the AM62x OTP Keywriter User Guide which comes with the OTP Keywriter package. As I mentioned, the Extended OTP structure is same so you can follow the FAQ for AM62L as well. You only need to program the values into the relevant MMRs using the Keywriter Lite on AM62L.

Where do I find the OTP Keywriter package for AM62x?