This isn't an mcu, it is a processor with memory management. There typically isn't direct access to the registers from user applications once Linux is running, so you need to rely on drivers.
If you search for 'beaglebone i2c' you'll find examples in many languages on how to access I2C. For example using Python or C. Some notes on using C are here: BBB - I2C notes
Thanks for your help. Actually i want to change the frequency of I2C on run time that is why i want to access I2C registers. Can you suggest some way to achieve the same..?
Thanks and Regards