pci-ntb-howto.rst (5223B)
1.. SPDX-License-Identifier: GPL-2.0 2 3=================================================================== 4PCI Non-Transparent Bridge (NTB) Endpoint Function (EPF) User Guide 5=================================================================== 6 7:Author: Kishon Vijay Abraham I <kishon@ti.com> 8 9This document is a guide to help users use pci-epf-ntb function driver 10and ntb_hw_epf host driver for NTB functionality. The list of steps to 11be followed in the host side and EP side is given below. For the hardware 12configuration and internals of NTB using configurable endpoints see 13Documentation/PCI/endpoint/pci-ntb-function.rst 14 15Endpoint Device 16=============== 17 18Endpoint Controller Devices 19--------------------------- 20 21For implementing NTB functionality at least two endpoint controller devices 22are required. 23 24To find the list of endpoint controller devices in the system:: 25 26 # ls /sys/class/pci_epc/ 27 2900000.pcie-ep 2910000.pcie-ep 28 29If PCI_ENDPOINT_CONFIGFS is enabled:: 30 31 # ls /sys/kernel/config/pci_ep/controllers 32 2900000.pcie-ep 2910000.pcie-ep 33 34 35Endpoint Function Drivers 36------------------------- 37 38To find the list of endpoint function drivers in the system:: 39 40 # ls /sys/bus/pci-epf/drivers 41 pci_epf_ntb pci_epf_ntb 42 43If PCI_ENDPOINT_CONFIGFS is enabled:: 44 45 # ls /sys/kernel/config/pci_ep/functions 46 pci_epf_ntb pci_epf_ntb 47 48 49Creating pci-epf-ntb Device 50---------------------------- 51 52PCI endpoint function device can be created using the configfs. To create 53pci-epf-ntb device, the following commands can be used:: 54 55 # mount -t configfs none /sys/kernel/config 56 # cd /sys/kernel/config/pci_ep/ 57 # mkdir functions/pci_epf_ntb/func1 58 59The "mkdir func1" above creates the pci-epf-ntb function device that will 60be probed by pci_epf_ntb driver. 61 62The PCI endpoint framework populates the directory with the following 63configurable fields:: 64 65 # ls functions/pci_epf_ntb/func1 66 baseclass_code deviceid msi_interrupts pci-epf-ntb.0 67 progif_code secondary subsys_id vendorid 68 cache_line_size interrupt_pin msix_interrupts primary 69 revid subclass_code subsys_vendor_id 70 71The PCI endpoint function driver populates these entries with default values 72when the device is bound to the driver. The pci-epf-ntb driver populates 73vendorid with 0xffff and interrupt_pin with 0x0001:: 74 75 # cat functions/pci_epf_ntb/func1/vendorid 76 0xffff 77 # cat functions/pci_epf_ntb/func1/interrupt_pin 78 0x0001 79 80 81Configuring pci-epf-ntb Device 82------------------------------- 83 84The user can configure the pci-epf-ntb device using its configfs entry. In order 85to change the vendorid and the deviceid, the following 86commands can be used:: 87 88 # echo 0x104c > functions/pci_epf_ntb/func1/vendorid 89 # echo 0xb00d > functions/pci_epf_ntb/func1/deviceid 90 91In order to configure NTB specific attributes, a new sub-directory to func1 92should be created:: 93 94 # mkdir functions/pci_epf_ntb/func1/pci_epf_ntb.0/ 95 96The NTB function driver will populate this directory with various attributes 97that can be configured by the user:: 98 99 # ls functions/pci_epf_ntb/func1/pci_epf_ntb.0/ 100 db_count mw1 mw2 mw3 mw4 num_mws 101 spad_count 102 103A sample configuration for NTB function is given below:: 104 105 # echo 4 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/db_count 106 # echo 128 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/spad_count 107 # echo 2 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/num_mws 108 # echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw1 109 # echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw2 110 111Binding pci-epf-ntb Device to EP Controller 112-------------------------------------------- 113 114NTB function device should be attached to two PCI endpoint controllers 115connected to the two hosts. Use the 'primary' and 'secondary' entries 116inside NTB function device to attach one PCI endpoint controller to 117primary interface and the other PCI endpoint controller to the secondary 118interface:: 119 120 # ln -s controllers/2900000.pcie-ep/ functions/pci-epf-ntb/func1/primary 121 # ln -s controllers/2910000.pcie-ep/ functions/pci-epf-ntb/func1/secondary 122 123Once the above step is completed, both the PCI endpoint controllers are ready to 124establish a link with the host. 125 126 127Start the Link 128-------------- 129 130In order for the endpoint device to establish a link with the host, the _start_ 131field should be populated with '1'. For NTB, both the PCI endpoint controllers 132should establish link with the host:: 133 134 # echo 1 > controllers/2900000.pcie-ep/start 135 # echo 1 > controllers/2910000.pcie-ep/start 136 137 138RootComplex Device 139================== 140 141lspci Output 142------------ 143 144Note that the devices listed here correspond to the values populated in 145"Creating pci-epf-ntb Device" section above:: 146 147 # lspci 148 0000:00:00.0 PCI bridge: Texas Instruments Device b00d 149 0000:01:00.0 RAM memory: Texas Instruments Device b00d 150 151 152Using ntb_hw_epf Device 153----------------------- 154 155The host side software follows the standard NTB software architecture in Linux. 156All the existing client side NTB utilities like NTB Transport Client and NTB 157Netdev, NTB Ping Pong Test Client and NTB Tool Test Client can be used with NTB 158function device. 159 160For more information on NTB see 161:doc:`Non-Transparent Bridge <../../driver-api/ntb>`