[U-Boot] U-boot : compare read and expect value

Hi, I'm newbie and I want to use scripts to test the board peripherals (I2C, SPI, LAN, PCIe, USB, ...) using u-boot. My problem is how to compare the reading with the expected value? the reading is in an environment variable? If so which one? I searched the forums and docs without success.

Thanks & Best Regards,

Khalid