PHY on C6474

Hi, guys! I am testing the EMAC module on C6474 through the example CCS3.3\boards\evmc6474_v1\tests\emac, and there is a piece of code puzzled me:

Uint16 phy_getReg(int phynum, int regnum)

{

   Uint16 value;

   MDIO_USERACCESS0 = 0                    // Read Phy Id 1

       | ( 1 << 31 )                       // [31] Go

       | ( 0 << 30 )                       // [30] Read

       | ( 0 << 29 )                       // [29] Ack

       | (regnum << 21 )                       // [25-21] PHY register address

       | (phynum << 16 )                       // [20-16] PHY address

       | ( 0 << 0 )                        // [15-0] Data       ;

        while( MDIO_USERACCESS0 & 0x80000000 ); // Wait for Results

        value = MDIO_USERACCESS0;

   return value;

}

I understand the purpose is to set phy register through MDIO register, but I can't find any infromation about phy register and phy address in datasheet, and information about 88e6122 is very few on the internet. Is there anyone could help me?