On 11/22/22 20:23, David Antliff wrote:
Hi,
I'm looking to extract the board's MAC address from serial I2C EEPROM at boot time, so I'm trying to work out how I can tell if U-Boot is actually able to communicate with this EEPROM, outside of manual i2c commands.
I have set CONFIG_ZYNQ_MAC_IN_EEPROM and CONFIG_ZYNQ_MAC_IN_EEPROM however I'm not completely sure that this is working with UltraScale+ Zynq MPSoC boards - I'm using a ZCU208. There's no log message on the U-Boot console to say that there was an attempt to read the MAC address, and with ethaddr unset, this variable is set by U-Boot to the value taken from the device tree rather than EEPROM:
ethernet@ff0e0000 { ... local-mac-address = [00 0a 35 00 22 01]; ...
I would expect it to be 00 0a 35 07 60 1c based on the contents of the EEPROM.
I would like to understand how to debug this. I read that the command "eeprom" has been deprecated for some time (I don't have it enabled), with some I2C serial EEPROM devices now supported by the "Driver Model" - aka DM.
Thus I did find:
dm uclass
... uclass 39: i2c_eeprom 0 eeprom@54 @ 7dd21420 ...
And I'm able to communicate with the device via commands like:
ZynqMP> i2c md 54 0.2 40 200000 0000: 5a 43 55 32 30 38 ff ff ff ff ff ff ff ff ff ff ZCU208.......... 0010: ff 41 30 32 38 33 32 32 30 34 31 34 33 33 32 38 .A02832204143328 0020: 31 2e 33 00 0a 35 07 60 1c 00 0a 35 07 60 1d 00 1.3..5.`...5.`.. 0030: 0a 35 07 60 1e 00 0a 35 07 60 1f 41 08 ff ff ff .5.`...5.`.A....
The MAC address is 6 bytes starting at offset 0x23 (00 0a 35 07 60 1c).
My question is - is the 'i2c' command now the accepted and best way to interact with an I2C EEPROM? Or is there another command I can enable (other than "eeprom") that will provide a generic interface for accessing EEPROMs and prove that U-Boot can "see" this device?
I don't think such an API exists.
The EEPROM device in question is an M24128.
CONFIG_SYS_I2C_EEPROM_ADDR=0x54 CONFIG_SYS_I2C_EEPROM_BUS=6 CONFIG_SYS_EEPROM_SIZE=16384 CONFIG_SYS_I2C_EEPROM_ADDR_LEN=2 CONFIG_ZYNQ_GEM_I2C_MAC_OFFSET=0x23 CONFIG_ZYNQ_MAC_IN_EEPROM=y
U-Boot 2021.01 (Xilinx fork: git://github.com/Xilinx/u-boot-xlnx.git)
P.S. if this is better directed to Xilinx or the Xilinx community then I'm happy to do that, but in case it's a more generic U-Boot issue I thought it best to ask here first. Please don't flame me for using Xilinx, I'm trying to do my best with what I'm given.
-- David.
This doesn't directly address your question, but have you tried using nvmem-cells?
You enable CONFIG_NVMEM and CONFIG_I2C_EEPROM, and modify your device tree like
i2c { eeprom@54 { #address-cells = <1>; #size-cells = <1>; compatible = "atmel,24c08"; reg = <0x54>;
mac_address: mac-address@23 { reg = <0x23 6>; }; }; };
ethernet { nvmem-cells = <&mac_address>; nvmem-cell-names = "mac-address"; };
You'll need 2022.07 for this I think. This is the same method which Linux uses. I added this specificly to be able to load MAC addresses from EEPROMs without needing to hard code stuff into Kconfig.
--Sean