Re: [net-next PATCH v3 01/15] Documentation: ACPI: DSD: Document MDIO PHY

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 <redacted>
---

Changes in v3: None
Changes in v2:
- Updated with more description in document

 Documentation/firmware-guide/acpi/dsd/phy.rst | 129 ++++++++++++++++++
 1 file changed, 129 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..a2e4fdcdbf53
--- /dev/null
+++ b/Documentation/firmware-guide/acpi/dsd/phy.rst

@@ -0,0 +1,129 @@
+.. 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 MAC, the PHYs registered on the
+mdiobus have to be referenced.
+
+UUID given below should be used as mentioned in the "Device Properties

+UUID For _DSD" [2] document.
+   - UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301
+
+This document introduces two _DSD properties that are to be used
+for PHYs on the MDIO bus.[3]
+
+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, MAC driver needs

+reference to the previously registered PHYs which are provided
+using reference to the device as {\_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].
+
+
+An ASL example of this is shown below.
+
+DSDT entry for MDIO node
+------------------------
+The MDIO bus has an SoC component(mdio controller) and a platform

+
+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
+This node defines the PHYs that are connected to the MDIO bus, MDI0
+-------------------------------------------------------------------