E300 doesn’t have I2C hardware, but it’s pretty easy to implement it in software using two GPIO pins. You could use polling, or you could get some hardware assist using PWM and interrupts. Google “i2c bit-bang library” and lots of examples come up. Some porting effort will be required as they’ll generally be for other processors.
If you install the Arduino support for HiFive1 you can find examples of using the Arduino I2C library (which it calls “Wire”) in File/Examples/Wire. You can also examine the source code for the Wire library.