[edk2-devel] How to switch SMBus/I2c bus number in EDK2?

[Pedro Falcato]

Hi,


You're assuming every i2c bus appears as a PCI device - that's not always
the case. In fact, those Synopsys devices usually arent (AFAIK).

Thanks,
Pedro

On Tue, 6 Sept 2022, 12:09 , <gordontcp at gmail.com> wrote:

> 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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