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Documentation: PCI: Add PCI endpoint NTB function user guide
Add documentation to help users use pci-epf-ntb function driver and existing host side NTB infrastructure for NTB functionality. [bhelgaas: fix a few typos] Link: https://lore.kernel.org/r/20210201195809.7342-18-kishon@ti.com Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
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Kishon Vijay Abraham I
Bjorn Helgaas
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@ -12,6 +12,7 @@ PCI Endpoint Framework
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pci-test-function
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pci-test-howto
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pci-ntb-function
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pci-ntb-howto
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function/binding/pci-test
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function/binding/pci-ntb
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161
Documentation/PCI/endpoint/pci-ntb-howto.rst
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161
Documentation/PCI/endpoint/pci-ntb-howto.rst
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@ -0,0 +1,161 @@
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.. SPDX-License-Identifier: GPL-2.0
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===================================================================
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PCI Non-Transparent Bridge (NTB) Endpoint Function (EPF) User Guide
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===================================================================
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:Author: Kishon Vijay Abraham I <kishon@ti.com>
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This document is a guide to help users use pci-epf-ntb function driver
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and ntb_hw_epf host driver for NTB functionality. The list of steps to
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be followed in the host side and EP side is given below. For the hardware
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configuration and internals of NTB using configurable endpoints see
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Documentation/PCI/endpoint/pci-ntb-function.rst
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Endpoint Device
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===============
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Endpoint Controller Devices
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---------------------------
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For implementing NTB functionality at least two endpoint controller devices
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are required.
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To find the list of endpoint controller devices in the system::
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# ls /sys/class/pci_epc/
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2900000.pcie-ep 2910000.pcie-ep
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If PCI_ENDPOINT_CONFIGFS is enabled::
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# ls /sys/kernel/config/pci_ep/controllers
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2900000.pcie-ep 2910000.pcie-ep
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Endpoint Function Drivers
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-------------------------
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To find the list of endpoint function drivers in the system::
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# ls /sys/bus/pci-epf/drivers
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pci_epf_ntb pci_epf_ntb
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If PCI_ENDPOINT_CONFIGFS is enabled::
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# ls /sys/kernel/config/pci_ep/functions
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pci_epf_ntb pci_epf_ntb
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Creating pci-epf-ntb Device
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----------------------------
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PCI endpoint function device can be created using the configfs. To create
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pci-epf-ntb device, the following commands can be used::
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# mount -t configfs none /sys/kernel/config
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# cd /sys/kernel/config/pci_ep/
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# mkdir functions/pci_epf_ntb/func1
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The "mkdir func1" above creates the pci-epf-ntb function device that will
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be probed by pci_epf_ntb driver.
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The PCI endpoint framework populates the directory with the following
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configurable fields::
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# ls functions/pci_epf_ntb/func1
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baseclass_code deviceid msi_interrupts pci-epf-ntb.0
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progif_code secondary subsys_id vendorid
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cache_line_size interrupt_pin msix_interrupts primary
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revid subclass_code subsys_vendor_id
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The PCI endpoint function driver populates these entries with default values
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when the device is bound to the driver. The pci-epf-ntb driver populates
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vendorid with 0xffff and interrupt_pin with 0x0001::
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# cat functions/pci_epf_ntb/func1/vendorid
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0xffff
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# cat functions/pci_epf_ntb/func1/interrupt_pin
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0x0001
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Configuring pci-epf-ntb Device
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-------------------------------
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The user can configure the pci-epf-ntb device using its configfs entry. In order
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to change the vendorid and the deviceid, the following
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commands can be used::
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# echo 0x104c > functions/pci_epf_ntb/func1/vendorid
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# echo 0xb00d > functions/pci_epf_ntb/func1/deviceid
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In order to configure NTB specific attributes, a new sub-directory to func1
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should be created::
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# mkdir functions/pci_epf_ntb/func1/pci_epf_ntb.0/
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The NTB function driver will populate this directory with various attributes
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that can be configured by the user::
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# ls functions/pci_epf_ntb/func1/pci_epf_ntb.0/
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db_count mw1 mw2 mw3 mw4 num_mws
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spad_count
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A sample configuration for NTB function is given below::
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# echo 4 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/db_count
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# echo 128 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/spad_count
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# echo 2 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/num_mws
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# echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw1
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# echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw2
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Binding pci-epf-ntb Device to EP Controller
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--------------------------------------------
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NTB function device should be attached to two PCI endpoint controllers
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connected to the two hosts. Use the 'primary' and 'secondary' entries
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inside NTB function device to attach one PCI endpoint controller to
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primary interface and the other PCI endpoint controller to the secondary
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interface::
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# ln -s controllers/2900000.pcie-ep/ functions/pci-epf-ntb/func1/primary
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# ln -s controllers/2910000.pcie-ep/ functions/pci-epf-ntb/func1/secondary
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Once the above step is completed, both the PCI endpoint controllers are ready to
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establish a link with the host.
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Start the Link
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--------------
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In order for the endpoint device to establish a link with the host, the _start_
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field should be populated with '1'. For NTB, both the PCI endpoint controllers
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should establish link with the host::
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# echo 1 > controllers/2900000.pcie-ep/start
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# echo 1 > controllers/2910000.pcie-ep/start
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RootComplex Device
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==================
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lspci Output
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------------
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Note that the devices listed here correspond to the values populated in
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"Creating pci-epf-ntb Device" section above::
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# lspci
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0000:00:00.0 PCI bridge: Texas Instruments Device b00d
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0000:01:00.0 RAM memory: Texas Instruments Device b00d
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Using ntb_hw_epf Device
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-----------------------
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The host side software follows the standard NTB software architecture in Linux.
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All the existing client side NTB utilities like NTB Transport Client and NTB
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Netdev, NTB Ping Pong Test Client and NTB Tool Test Client can be used with NTB
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function device.
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For more information on NTB see
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:doc:`Non-Transparent Bridge <../../driver-api/ntb>`
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