How to switch SMBus/I2c bus number in EDK2?

[gordontcp@gmail.com]

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Hi all,
My platform information is as follows:
Minnowboard Max.
I use i2cdetect under Linux to detect multiple I2c buses, such as:

I2c-0 Synopsys DesignWare I2C adapter
I2c-10 SMBus I801 adapter at 2000

I can scan the I2c-10 SMbus slave address 0x50 from the SpdRead code in the UEFI shell to have a slave device. Methods as below:

UINT32 FindSmBusDev()
{
...
Addr = 0x80000000;
for(Bus = 0x00; Bus < 0xFF; Bus++) {
for(Dev = 0x00; Dev <= 0x1F; Dev++) {
 for(Fun = 0x00; Fun <= 0x07; Fun++) {
  Addr &= 0xFF000000;//clean the address
  Addr |= ((Bus << 16) | (Dev << 11) | (Fun << 8));//set the pci bus dev and fun IoWrite32(PCI_INDEX_IO_PORT, Addr);
 if(IoRead32(PCI_DATA_IO_PORT) != 0xFFFFFFFF) {
    Addr = Addr + 0x08;//read class code
   IoWrite32(PCI_INDEX_IO_PORT, Addr);
   if (IoRead32(PCI_DATA_IO_PORT) >> 16 == 0x0C05)//it's Smbus class code
   {
      return Addr - 0x08;
   }
  }
 }
}
}
return Addr;
}

My question is:
How to switch to I2c-0 bus under UEFI to perform I2C IO operation on the slave device of Synopsys I2C controller?
Any suggestion is greatly appreciated!

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