Access SPI EEPROM on boot


I have two boards based on Carambola2 module. Boards have external SPI EEPROM on board with board version written in it. When system is booted up, I can access this EEPROM in /sys/class/spi_master/spi0/spi0.2/eeprom. Both boards have different GPIO wiring, but I want to use single firmware file on them, so I need to make runtime modifications in mach-*.c files. How can I access EEPROM flash in mach-*.c files?

If SPI access in mach file isn't possible, I have a plan B: U-Boot reads SPI EEPROM and passes board version with kernel command line. But than ... how can I access kernel command line arguments in mach-*.c files?