Re: [PATCH net-next v8 01/15] Documentation: ACPI: DSD: Document MDIO PHY

[Grant Likely <grant.likely@arm.com>]

On 10/06/2021 17:39, Ioana Ciornei wrote:
> From: Calvin Johnson <calvin.johnson@oss.nxp.com>
> 
> Introduce ACPI mechanism to get PHYs registered on a MDIO bus and
> provide them to be connected to MAC.
> 
> Describe properties "phy-handle" and "phy-mode".
> 
> Signed-off-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
> Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>

Looks reasonable to me. I'm not a kernel maintainer any more, so my 
Acked-by: may not be very valuable, but here it is anyway:

Acked-by: Grant Likely <grant.likely@arm.com>

> --- >
> Changes in v8: None
> Changes in v7: None
> Changes in v6:
> - Minor cleanup
> 
> Changes in v5:
> - More cleanup
> 
> Changes in v4:
> - More cleanup
> 
> Changes in v3: None
> Changes in v2:
> - Updated with more description in document
> 
>   Documentation/firmware-guide/acpi/dsd/phy.rst | 133 ++++++++++++++++++
>   1 file changed, 133 insertions(+)
>   create mode 100644 Documentation/firmware-guide/acpi/dsd/phy.rst
> 
> diff --git a/Documentation/firmware-guide/acpi/dsd/phy.rst b/Documentation/firmware-guide/acpi/dsd/phy.rst
> new file mode 100644
> index 000000000000..7d01ae8b3cc6
> --- /dev/null
> +++ b/Documentation/firmware-guide/acpi/dsd/phy.rst
> @@ -0,0 +1,133 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +=========================
> +MDIO bus and PHYs in ACPI
> +=========================
> +
> +The PHYs on an MDIO bus [1] are probed and registered using
> +fwnode_mdiobus_register_phy().
> +
> +Later, for connecting these PHYs to their respective MACs, the PHYs registered
> +on the MDIO bus have to be referenced.
> +
> +This document introduces two _DSD properties that are to be used
> +for connecting PHYs on the MDIO bus [3] to the MAC layer.
> +
> +These properties are defined in accordance with the "Device
> +Properties UUID For _DSD" [2] document and the
> +daffd814-6eba-4d8c-8a91-bc9bbf4aa301 UUID must be used in the Device
> +Data Descriptors containing them.
> +
> +phy-handle
> +----------
> +For each MAC node, a device property "phy-handle" is used to reference
> +the PHY that is registered on an MDIO bus. This is mandatory for
> +network interfaces that have PHYs connected to MAC via MDIO bus.
> +
> +During the MDIO bus driver initialization, PHYs on this bus are probed
> +using the _ADR object as shown below and are registered on the MDIO bus.
> +
> +::
> +      Scope(\_SB.MDI0)
> +      {
> +        Device(PHY1) {
> +          Name (_ADR, 0x1)
> +        } // end of PHY1
> +
> +        Device(PHY2) {
> +          Name (_ADR, 0x2)
> +        } // end of PHY2
> +      }
> +
> +Later, during the MAC driver initialization, the registered PHY devices
> +have to be retrieved from the MDIO bus. For this, the MAC driver needs
> +references to the previously registered PHYs which are provided
> +as device object references (e.g. \_SB.MDI0.PHY1).
> +
> +phy-mode
> +--------
> +The "phy-mode" _DSD property is used to describe the connection to
> +the PHY. The valid values for "phy-mode" are defined in [4].
> +
> +The following ASL example illustrates the usage of these properties.
> +
> +DSDT entry for MDIO node
> +------------------------
> +
> +The MDIO bus has an SoC component (MDIO controller) and a platform
> +component (PHYs on the MDIO bus).
> +
> +a) Silicon Component
> +This node describes the MDIO controller, MDI0
> +---------------------------------------------
> +::
> +	Scope(_SB)
> +	{
> +	  Device(MDI0) {
> +	    Name(_HID, "NXP0006")
> +	    Name(_CCA, 1)
> +	    Name(_UID, 0)
> +	    Name(_CRS, ResourceTemplate() {
> +	      Memory32Fixed(ReadWrite, MDI0_BASE, MDI_LEN)
> +	      Interrupt(ResourceConsumer, Level, ActiveHigh, Shared)
> +	       {
> +		 MDI0_IT
> +	       }
> +	    }) // end of _CRS for MDI0
> +	  } // end of MDI0
> +	}
> +
> +b) Platform Component
> +The PHY1 and PHY2 nodes represent the PHYs connected to MDIO bus MDI0
> +---------------------------------------------------------------------
> +::
> +	Scope(\_SB.MDI0)
> +	{
> +	  Device(PHY1) {
> +	    Name (_ADR, 0x1)
> +	  } // end of PHY1
> +
> +	  Device(PHY2) {
> +	    Name (_ADR, 0x2)
> +	  } // end of PHY2
> +	}
> +
> +DSDT entries representing MAC nodes
> +-----------------------------------
> +
> +Below are the MAC nodes where PHY nodes are referenced.
> +phy-mode and phy-handle are used as explained earlier.
> +------------------------------------------------------
> +::
> +	Scope(\_SB.MCE0.PR17)
> +	{
> +	  Name (_DSD, Package () {
> +	     ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> +		 Package () {
> +		     Package (2) {"phy-mode", "rgmii-id"},
> +		     Package (2) {"phy-handle", \_SB.MDI0.PHY1}
> +	      }
> +	   })
> +	}
> +
> +	Scope(\_SB.MCE0.PR18)
> +	{
> +	  Name (_DSD, Package () {
> +	    ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> +		Package () {
> +		    Package (2) {"phy-mode", "rgmii-id"},
> +		    Package (2) {"phy-handle", \_SB.MDI0.PHY2}}
> +	    }
> +	  })
> +	}
> +
> +References
> +==========
> +
> +[1] Documentation/networking/phy.rst
> +
> +[2] https://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
> +
> +[3] Documentation/firmware-guide/acpi/DSD-properties-rules.rst
> +
> +[4] Documentation/devicetree/bindings/net/ethernet-controller.yaml
>