how to use i2c

when i do i2c detect only i2c1 and i2c3 is detected but i2c2 not. as i have seen that mux of 23 and 24 pin is both set to 0 in i2c mode .then also i2c2 is not detected . pullup register is enabled.
i am using bb xm and kernel 3.2.0-23