TPS65950 address on I2C

Hi,
How to know the TPS65950 address which happens to be slave for the
omap i2c controller, and a sub question ,how to access the registers
of TPS65950 . My BB version is C3 .
I am following the u-boot code to understand i2c writes and this part
confuses me..

  byte = 0x20;
  i2c_write(0x4B, 0x7A, 1, &byte, 1);

is the part where i2c write happens.
        int i2c_write (uchar chip, uint addr, int alen, uchar *
buffer, int len)
        {
              //do some settings
    if (i2c_write_byte (chip, addr + i, buffer[i]))
        }
What is chip and how does this work ?

Please pardon my ignorance .

I'm not sure, but:

chip - I2C address of a chip
addr - local threshold in a registers map of that chip