U-Boot > i2c dev < busnumber >
U-Boot > i2c probe

example

U-Boot > i2c dev 0
U-Boot > i2c probe

i2c md 0x50 0x20.2 read MAC adress
i2c md 0x50 0x30.2 read serial number

root@MBaXXX:~ i2cdetect <busnumber>

example

root@MBaXXX:~ i2cdetect 1