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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 |