OpenCorePkg/Docs/AcpiSamples/Source/SSDT-SBUS-MCHC.dsl

/*
 * SMBus compatibility table.
 */
DefinitionBlock ("", "SSDT", 2, "ACDT", "MCHCSBUS", 0x00000000)
{
    External (_SB_.PCI0, DeviceObj)
    External (_SB_.PCI0.SBUS, DeviceObj)

    Scope (_SB.PCI0)
    {
        Device (MCHC)
        {
            Name (_ADR, Zero)  // _ADR: Address
            Method (_STA, 0, NotSerialized)  // _STA: Status
            {
                If (_OSI ("Darwin"))
                {
                    Return (0x0F)
                }
                Else
                {
                    Return (Zero)
                }
            }
        }
    }

    Device (_SB.PCI0.SBUS.BUS0)
    {
        Name (_CID, "smbus")  // _CID: Compatible ID
        Name (_ADR, Zero)  // _ADR: Address

        /*
         * Uncomment replacing 0x57 with your own value which might be found
         * in SMBus section of Intel datasheet for your motherboard.
         *
         * The "diagsvault" is the diagnostic vault where messages are stored.
         * It's located at address 87 (0x57) on the SMBus controller.
         * While "diagsvault" may refer to diags, a hardware diagnosis program via EFI for Macs
         * that communicates with the SMBus controller, the effect is really unknown for hacks.
         * Uncomment this with caution.
         */

        /**
        Device (DVL0)
        {
            Name (_ADR, 0x57)  // _ADR: Address
            Name (_CID, "diagsvault")  // _CID: Compatible ID
            Method (_DSM, 4, NotSerialized)  // _DSM: Device-Specific Method
            {
                If (!Arg2)
                {
                    Return (Buffer (One)
                    {
                         0x57                                             // W
                    })
                }

                Return (Package (0x02)
                {
                    "address", 
                    0x57
                })
            }
        }
        **/

        Method (_STA, 0, NotSerialized)  // _STA: Status
        {
            If (_OSI ("Darwin"))
            {
                Return (0x0F)
            }
            Else
            {
                Return (Zero)
            }
        }
    }
}