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

    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
    --
    2.31.1
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