Re: [RFC PATCH 0/3] acpi: Add acpi mdio support code

Hi Andrew,

On 2018/11/9 7:23, Andrew Lunn wrote:

On Thu, Nov 08, 2018 at 03:21:29PM +0800, Wang Dongsheng wrote:

quoted

Originally I just push "phy-handle" support for ACPI on the QCOM QDF2400
platform. After some discussion and following Andrew's advice, I send
out with a generic version of ACPI.

Current there is no clear documentation about MDIO/PHY for ACPI, so when
I reading some documents about ACPI [1], I think we just need to reuse the
DT binding in the ACPI.[2]. However, this series of patches are not
fully compatible with all contents specified in DT binding.

The most important thing about this iseries is link the phy device and
fwnode of acpi. Besides, we need to carry out bus scan at the mdio
register. Therefore, I am not compatible with more DT binding properties
in this series of patches. More support will be in the follow-up patches
support, or some people do the support.

Example:
Based on ACPI doc:
    Documentation/acpi/dsd/data-node-references.txt
    Documentation/acpi/dsd/graph.txt
With _DSD device properties we can finally do this:
    Device (MDIO) {
        Name (_DSD, Package () {
            ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
            Package () { Package () { "ethernet-phy@0", PHY0 }, }
        })
        Name (PHY0, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () { Package () { "reg", 0x0 }, }
        })

I don't know much about ACPI. I do know DT. MDIO busses can have
multiple PHYs on them. Is the following valid to list two PHYs?

     Device (MDIO) {
         Name (_DSD, Package () {
             ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
             Package () { Package () { "ethernet-phy@0", PHY0 }, }
         })
         Name (PHY0, Package() {
             ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
             Package () { Package () { "reg", 0x0 }, }
         })
         Name (_DSD, Package () {
             ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
             Package () { Package () { "ethernet-phy@10", PHY1 }, }
         })
         Name (PHY1, Package() {
             ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
             Package () { Package () { "reg", 0x10 }, }
         })
     }

Multiple PHYs example:


    Device (MDIO)
    {
        Name (_DSD, Package () {
        ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
            Package () {

                Package () { "ethernet-phy@0", PHY0 },

                Package () { "ethernet-phy@1", PHY1 },
                ...

                ...

            }
        })
       
        Name (PHY0, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "reg", 0x0 },
            }
        })


        Name (PHY1, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "reg", 0x1 },
            }
        })
   }

    Device (MAC0)

    {

        // _DSD: Device-Specific Data
        Name (_DSD, Package (0x02) {
            ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device
Properties for _DSD */,
            Package () {
                Package () { "phy-handle", Package () { \_SB.MDIO,
"ethernet-phy@0" } },
                ...
                ...
            }
        })

    }


    Device (MAC1)

    {

        // _DSD: Device-Specific Data
        Name (_DSD, Package (0x02) {
            ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device
Properties for _DSD */,
            Package () {
                Package () { "phy-handle", Package () { \_SB.MDIO,
"ethernet-phy@1" } },
                ...
                ...
            }
        })

    }

An MDIO bus can also have more than PHYs on them. There can be
Ethernet switches. Broadcom also have some with generic PHY devices on
them, and other odd things. That means whatever is on an MDIO bus is a
device in the Linux device model. How does that work? Do we need some
form Device (PHY) {}?

ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b") describes a ACPI data node.

The data node can contain property or pointer.


Let's look at the table I'm using:

Device (MAC1)
{
    // _DSD: Device-Specific Data
    Name (_DSD, Package (0x02) {
        ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device
Properties for _DSD */,
        Package (0x07) {
            Package () { "phy-handle", Package () { \_SB.MAC1.MDIO,
"ethernet-phy@1" } },
            Package () { "dev-refs", \_SB.MAC0 },
            Package () { "refs0-dev", Package () { \_SB.MAC1.MDIO,
"refs@0" } },
            Package () { "refs1-dev", Package () { \_SB.MAC1.MDIO,
"refs@1" } },
            ...
            ...
        }
    })

    Device (MDIO)
    {
        Name (_DSD, Package () {
        ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
            Package () {
                Package () { "ethernet-phy@1", PHY1 },
                Package () { "refs@0",  REF0},
                Package () { "refs@1",  REF1},
            }
        })
        
        //Contain a property
        Name (PHY1, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "reg", 0x1 },
            }
        })
        
        //Point to a device
        Name (REF0, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "child-refs-dev", \_SB.MAC0 },
            }
        })
        
        //Contain a property and a pointer that point to a device
        Name (REF1, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "property", 0x5 },
                Package () { "child-refs-dev", \_SB.MAC0 },
            }
        })
    }
}

     Device (MDIO) {
         Device (PHY) {
             Name (_DSD, Package () {
                 ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
                 Package () { Package () { "ethernet-phy@0", PHY0 }, }
             })
             Name (PHY0, Package() {
                 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
                 Package () { Package () { "reg", 0x0 }, }
             })
         }
         Device (PHY) {
             Name (_DSD, Package () {
                 ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
                 Package () { Package () { "ethernet-phy@10", PHY1 }, }
             })
             Name (PHY1, Package() {
                 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
                 Package () { Package () { "reg", 0x10 }, }
             })
         Device (SWITCH) {
             Name (_DSD, Package () {
                 ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
                 Package () { Package () { "switch@11", SWITCH0 }, }
             })
             Name (SWITCH0, Package() {
                 ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
                 Package () { Package () { "reg", 0x11 }, }
             })
         }

    Device (MDIO)
    {
        Name (_DSD, Package () {
        ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
            Package () {
                Package () { "ethernet-phy@1", PHY1 },
                Package () { "switch@0",  SW00 },

                Package () { "switch@1",  SW01 },
            }
        })
        
        //Contain a property
        Name (PHY1, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "reg", 0x1 },
            }
        })
 
        Name (SW00, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "reg", 0x0 },
            }
        })

        Name (SW01, Package() {
            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
            Package () {
                Package () { "property", 0x5 },
            }
        })
    }

      }

I'm just trying to ensure whatever is defined is flexible enough that
we really can later support everything which DT does. We have PHYs on
MDIO busses, inside switches, which are on MDIO busses, which are
inside Ethernet interfaces, etc.

I think it can be satisfied. See the table I'm using above.

An MDIO bus is very similar to an i2c bus. How is that described in
ACPI? Anything we can learn from that?

About the data node, I just read the Kernel Documentation/acpi/dsd/

And others learn from ACPI spec.


Cheers,

Dongsheng