AM3358: System clock and Functional clock

Part Number:AM3358

Could any one suggest me :-

Is System clock and Functional clock both are same ? I want to set prescaler value to obtain   12 Mhz frequency for I2C2 and In AM335x TRM  section no. 21.3.9 mentioned "I2C module operated with functional clock (SCLK) frequency that can be in range of 12-100Mhz. As i know maximum  functional clock frequency for I2C module is 48 Mhz,so should i divide 48 Mhz (FCLK) to obtain 12 Mhz  for prescaler.