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