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diff --git a/Documentation/networking/devlink/devlink-port.rst b/Documentation/networking/devlink/devlink-port.rst new file mode 100644 index 000000000000..e99b41599465 --- /dev/null +++ b/Documentation/networking/devlink/devlink-port.rst @@ -0,0 +1,199 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. _devlink_port: + +============ +Devlink Port +============ + +``devlink-port`` is a port that exists on the device. It has a logically +separate ingress/egress point of the device. A devlink port can be any one +of many flavours. A devlink port flavour along with port attributes +describe what a port represents. + +A device driver that intends to publish a devlink port sets the +devlink port attributes and registers the devlink port. + +Devlink port flavours are described below. + +.. list-table:: List of devlink port flavours + :widths: 33 90 + + * - Flavour + - Description + * - ``DEVLINK_PORT_FLAVOUR_PHYSICAL`` + - Any kind of physical port. This can be an eswitch physical port or any + other physical port on the device. + * - ``DEVLINK_PORT_FLAVOUR_DSA`` + - This indicates a DSA interconnect port. + * - ``DEVLINK_PORT_FLAVOUR_CPU`` + - This indicates a CPU port applicable only to DSA. + * - ``DEVLINK_PORT_FLAVOUR_PCI_PF`` + - This indicates an eswitch port representing a port of PCI + physical function (PF). + * - ``DEVLINK_PORT_FLAVOUR_PCI_VF`` + - This indicates an eswitch port representing a port of PCI + virtual function (VF). + * - ``DEVLINK_PORT_FLAVOUR_PCI_SF`` + - This indicates an eswitch port representing a port of PCI + subfunction (SF). + * - ``DEVLINK_PORT_FLAVOUR_VIRTUAL`` + - This indicates a virtual port for the PCI virtual function. + +Devlink port can have a different type based on the link layer described below. + +.. list-table:: List of devlink port types + :widths: 23 90 + + * - Type + - Description + * - ``DEVLINK_PORT_TYPE_ETH`` + - Driver should set this port type when a link layer of the port is + Ethernet. + * - ``DEVLINK_PORT_TYPE_IB`` + - Driver should set this port type when a link layer of the port is + InfiniBand. + * - ``DEVLINK_PORT_TYPE_AUTO`` + - This type is indicated by the user when driver should detect the port + type automatically. + +PCI controllers +--------------- +In most cases a PCI device has only one controller. A controller consists of +potentially multiple physical, virtual functions and subfunctions. A function +consists of one or more ports. This port is represented by the devlink eswitch +port. + +A PCI device connected to multiple CPUs or multiple PCI root complexes or a +SmartNIC, however, may have multiple controllers. For a device with multiple +controllers, each controller is distinguished by a unique controller number. +An eswitch is on the PCI device which supports ports of multiple controllers. + +An example view of a system with two controllers:: + + --------------------------------------------------------- + | | + | --------- --------- ------- ------- | + ----------- | | vf(s) | | sf(s) | |vf(s)| |sf(s)| | + | server | | ------- ----/---- ---/----- ------- ---/--- ---/--- | + | pci rc |=== | pf0 |______/________/ | pf1 |___/_______/ | + | connect | | ------- ------- | + ----------- | | controller_num=1 (no eswitch) | + ------|-------------------------------------------------- + (internal wire) + | + --------------------------------------------------------- + | devlink eswitch ports and reps | + | ----------------------------------------------------- | + | |ctrl-0 | ctrl-0 | ctrl-0 | ctrl-0 | ctrl-0 |ctrl-0 | | + | |pf0 | pf0vfN | pf0sfN | pf1 | pf1vfN |pf1sfN | | + | ----------------------------------------------------- | + | |ctrl-1 | ctrl-1 | ctrl-1 | ctrl-1 | ctrl-1 |ctrl-1 | | + | |pf0 | pf0vfN | pf0sfN | pf1 | pf1vfN |pf1sfN | | + | ----------------------------------------------------- | + | | + | | + ----------- | --------- --------- ------- ------- | + | smartNIC| | | vf(s) | | sf(s) | |vf(s)| |sf(s)| | + | pci rc |==| ------- ----/---- ---/----- ------- ---/--- ---/--- | + | connect | | | pf0 |______/________/ | pf1 |___/_______/ | + ----------- | ------- ------- | + | | + | local controller_num=0 (eswitch) | + --------------------------------------------------------- + +In the above example, the external controller (identified by controller number = 1) +doesn't have the eswitch. Local controller (identified by controller number = 0) +has the eswitch. The Devlink instance on the local controller has eswitch +devlink ports for both the controllers. + +Function configuration +====================== + +A user can configure the function attribute before enumerating the PCI +function. Usually it means, user should configure function attribute +before a bus specific device for the function is created. However, when +SRIOV is enabled, virtual function devices are created on the PCI bus. +Hence, function attribute should be configured before binding virtual +function device to the driver. For subfunctions, this means user should +configure port function attribute before activating the port function. + +A user may set the hardware address of the function using +'devlink port function set hw_addr' command. For Ethernet port function +this means a MAC address. + +Subfunction +============ + +Subfunction is a lightweight function that has a parent PCI function on which +it is deployed. Subfunction is created and deployed in unit of 1. Unlike +SRIOV VFs, a subfunction doesn't require its own PCI virtual function. +A subfunction communicates with the hardware through the parent PCI function. + +To use a subfunction, 3 steps setup sequence is followed. +(1) create - create a subfunction; +(2) configure - configure subfunction attributes; +(3) deploy - deploy the subfunction; + +Subfunction management is done using devlink port user interface. +User performs setup on the subfunction management device. + +(1) Create +---------- +A subfunction is created using a devlink port interface. A user adds the +subfunction by adding a devlink port of subfunction flavour. The devlink +kernel code calls down to subfunction management driver (devlink ops) and asks +it to create a subfunction devlink port. Driver then instantiates the +subfunction port and any associated objects such as health reporters and +representor netdevice. + +(2) Configure +------------- +A subfunction devlink port is created but it is not active yet. That means the +entities are created on devlink side, the e-switch port representor is created, +but the subfunction device itself it not created. A user might use e-switch port +representor to do settings, putting it into bridge, adding TC rules, etc. A user +might as well configure the hardware address (such as MAC address) of the +subfunction while subfunction is inactive. + +(3) Deploy +---------- +Once a subfunction is configured, user must activate it to use it. Upon +activation, subfunction management driver asks the subfunction management +device to instantiate the subfunction device on particular PCI function. +A subfunction device is created on the :ref:`Documentation/driver-api/auxiliary_bus.rst <auxiliary_bus>`. +At this point a matching subfunction driver binds to the subfunction's auxiliary device. + +Terms and Definitions +===================== + +.. list-table:: Terms and Definitions + :widths: 22 90 + + * - Term + - Definitions + * - ``PCI device`` + - A physical PCI device having one or more PCI bus consists of one or + more PCI controllers. + * - ``PCI controller`` + - A controller consists of potentially multiple physical functions, + virtual functions and subfunctions. + * - ``Port function`` + - An object to manage the function of a port. + * - ``Subfunction`` + - A lightweight function that has parent PCI function on which it is + deployed. + * - ``Subfunction device`` + - A bus device of the subfunction, usually on a auxiliary bus. + * - ``Subfunction driver`` + - A device driver for the subfunction auxiliary device. + * - ``Subfunction management device`` + - A PCI physical function that supports subfunction management. + * - ``Subfunction management driver`` + - A device driver for PCI physical function that supports + subfunction management using devlink port interface. + * - ``Subfunction host driver`` + - A device driver for PCI physical function that hosts subfunction + devices. In most cases it is same as subfunction management driver. When + subfunction is used on external controller, subfunction management and + host drivers are different. |