devlink: Add devlink port documentation
Added documentation for devlink port and port function related commands. Signed-off-by: Parav Pandit <parav@nvidia.com> Reviewed-by: Jiri Pirko <jiri@nvidia.com> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
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Parav Pandit
Saeed Mahameed
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.. SPDX-License-Identifier: GPL-2.0
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.. _devlink_port:
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============
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Devlink Port
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============
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``devlink-port`` is a port that exists on the device. It has a logically
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separate ingress/egress point of the device. A devlink port can be any one
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of many flavours. A devlink port flavour along with port attributes
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describe what a port represents.
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A device driver that intends to publish a devlink port sets the
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devlink port attributes and registers the devlink port.
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Devlink port flavours are described below.
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.. list-table:: List of devlink port flavours
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:widths: 33 90
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* - Flavour
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- Description
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* - ``DEVLINK_PORT_FLAVOUR_PHYSICAL``
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- Any kind of physical port. This can be an eswitch physical port or any
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other physical port on the device.
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* - ``DEVLINK_PORT_FLAVOUR_DSA``
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- This indicates a DSA interconnect port.
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* - ``DEVLINK_PORT_FLAVOUR_CPU``
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- This indicates a CPU port applicable only to DSA.
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* - ``DEVLINK_PORT_FLAVOUR_PCI_PF``
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- This indicates an eswitch port representing a port of PCI
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physical function (PF).
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* - ``DEVLINK_PORT_FLAVOUR_PCI_VF``
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- This indicates an eswitch port representing a port of PCI
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virtual function (VF).
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* - ``DEVLINK_PORT_FLAVOUR_VIRTUAL``
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- This indicates a virtual port for the PCI virtual function.
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Devlink port can have a different type based on the link layer described below.
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.. list-table:: List of devlink port types
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:widths: 23 90
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* - Type
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- Description
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* - ``DEVLINK_PORT_TYPE_ETH``
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- Driver should set this port type when a link layer of the port is
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Ethernet.
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* - ``DEVLINK_PORT_TYPE_IB``
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- Driver should set this port type when a link layer of the port is
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InfiniBand.
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* - ``DEVLINK_PORT_TYPE_AUTO``
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- This type is indicated by the user when driver should detect the port
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type automatically.
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PCI controllers
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---------------
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In most cases a PCI device has only one controller. A controller consists of
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potentially multiple physical and virtual functions. A function consists
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of one or more ports. This port is represented by the devlink eswitch port.
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A PCI device connected to multiple CPUs or multiple PCI root complexes or a
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SmartNIC, however, may have multiple controllers. For a device with multiple
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controllers, each controller is distinguished by a unique controller number.
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An eswitch is on the PCI device which supports ports of multiple controllers.
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An example view of a system with two controllers::
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---------------------------------------------------------
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| |
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| --------- --------- ------- ------- |
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----------- | | vf(s) | | sf(s) | |vf(s)| |sf(s)| |
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| server | | ------- ----/---- ---/----- ------- ---/--- ---/--- |
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| pci rc |=== | pf0 |______/________/ | pf1 |___/_______/ |
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| connect | | ------- ------- |
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----------- | | controller_num=1 (no eswitch) |
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------|--------------------------------------------------
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(internal wire)
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---------------------------------------------------------
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| devlink eswitch ports and reps |
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| ----------------------------------------------------- |
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| |ctrl-0 | ctrl-0 | ctrl-0 | ctrl-0 | ctrl-0 |ctrl-0 | |
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| |pf0 | pf0vfN | pf0sfN | pf1 | pf1vfN |pf1sfN | |
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| ----------------------------------------------------- |
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| |ctrl-1 | ctrl-1 | ctrl-1 | ctrl-1 | ctrl-1 |ctrl-1 | |
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| |pf0 | pf0vfN | pf0sfN | pf1 | pf1vfN |pf1sfN | |
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| ----------------------------------------------------- |
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----------- | --------- --------- ------- ------- |
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| smartNIC| | | vf(s) | | sf(s) | |vf(s)| |sf(s)| |
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| pci rc |==| ------- ----/---- ---/----- ------- ---/--- ---/--- |
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| connect | | | pf0 |______/________/ | pf1 |___/_______/ |
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----------- | ------- ------- |
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| local controller_num=0 (eswitch) |
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---------------------------------------------------------
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In the above example, the external controller (identified by controller number = 1)
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doesn't have the eswitch. Local controller (identified by controller number = 0)
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has the eswitch. The Devlink instance on the local controller has eswitch
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devlink ports for both the controllers.
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Function configuration
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======================
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A user can configure the function attribute before enumerating the PCI
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function. Usually it means, user should configure function attribute
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before a bus specific device for the function is created. However, when
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SRIOV is enabled, virtual function devices are created on the PCI bus.
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Hence, function attribute should be configured before binding virtual
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function device to the driver.
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A user may set the hardware address of the function using
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'devlink port function set hw_addr' command. For Ethernet port function
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this means a MAC address.
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@ -18,6 +18,7 @@ general.
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devlink-info
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devlink-flash
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devlink-params
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devlink-port
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devlink-region
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devlink-resource
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devlink-reload
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