Re: [RFC PATCH edk2-platforms 1/2] SbsaQemu: Add acpi0016 & acpi0017 objects into DSDT

[Jonathan Cameron]

On Fri, 30 Aug 2024 11:15:44 +0800
Yuquan Wang <wangyuquan1236@phytium.com.cn> wrote:

> This adds relevant definitions and descriptions of acpi0016 and
> acpi0017 to support CXL.
> 
> With the implementation of pxb-cxl on the original pcie host bridge,
> the previous space layout of mmio32 & mmio64 have to be divided to
> provide the mmio space for cxl host bridge.
> 
> I'm not sure if the new space layout would bring a series of bad
> influence, but it seems that the base address and size of cxl host
> bridge is ok.
> 
> Signed-off-by: Yuquan Wang <wangyuquan1236@phytium.com.cn>

I'll go as far as saying this looks about right to me, but needs
some more eyes to be more certain. 
Trivial comments inline.

Jonathan

> diff --git a/Silicon/Qemu/SbsaQemu/AcpiTables/Dsdt.asl 
> b/Silicon/Qemu/SbsaQemu/AcpiTables/Dsdt.asl
> index c134fb66e860..94d0b2cbb118 100644
> --- a/Silicon/Qemu/SbsaQemu/AcpiTables/Dsdt.asl
> +++ b/Silicon/Qemu/SbsaQemu/AcpiTables/Dsdt.asl

> @@ -483,5 +849,45 @@ DefinitionBlock ("DsdtTable.aml", "DSDT",
>          }
>        } // End _OSC
>      }
> +
> +    Scope (\_SB)
> +    {
> +        // CXL Root for OS Driver
> +        Device (CXLM)
> +        {
> +            Name (_HID, "ACPI0017")  // _HID: Hardware ID
> +            Method (_STA, 0, NotSerialized)  // _STA: Status
> +            {
> +                Return (0x0B)
> +            }
> +
> +            Method (_DSM, 4, Serialized)  // _DSM: Device-Specific Method
> +            {
> +                If ((Arg0 == ToUUID ("f365f9a6-a7de-4071-a66a-b40c0b4f8e52") 
> /* Unknown UUID */))
Name that UUID in the comment.  I was thinking you didn't have QTG querying 
supported
because oddly I can't remember the uuid :)

> +                {
> +                    If ((Arg2 == Zero))
> +                    {
> +                        Return (Buffer (One)
> +                        {
> +                         0x01                                             // 
> .
> +                        })
> +                    }
> +
> +                    If ((Arg2 == One))
> +                    {
> +                        Return (Package (0x02)
> +                        {
> +                            One,
> +                            Package (0x02)
> +                            {
> +                                Zero,
> +                                One
Hmm. I probably have this wrong in the qemu code, but it should be safe.
This is saying QTG 0 default with fallback to 1.  We don't have anything
in group 1.
Ah well never mind.  
> +                            }
> +                        })
> +                    }
> +                }
> +            }
> +        }
> +    }
>    } // Scope (_SB)
>  }