pci-vntb-howto.rst

  1.. SPDX-License-Identifier: GPL-2.0
  2
  3===================================================================
  4PCI Non-Transparent Bridge (NTB) Endpoint Function (EPF) User Guide
  5===================================================================
  6
  7:Author: Frank Li <Frank.Li@nxp.com>
  8
  9This document is a guide to help users use pci-epf-vntb 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-vntb-function.rst
 14
 15Endpoint Device
 16===============
 17
 18Endpoint Controller Devices
 19---------------------------
 20
 21To find the list of endpoint controller devices in the system::
 22
 23        # ls /sys/class/pci_epc/
 24          5f010000.pcie_ep
 25
 26If PCI_ENDPOINT_CONFIGFS is enabled::
 27
 28        # ls /sys/kernel/config/pci_ep/controllers
 29          5f010000.pcie_ep
 30
 31Endpoint Function Drivers
 32-------------------------
 33
 34To find the list of endpoint function drivers in the system::
 35
 36	# ls /sys/bus/pci-epf/drivers
 37	pci_epf_ntb  pci_epf_test  pci_epf_vntb
 38
 39If PCI_ENDPOINT_CONFIGFS is enabled::
 40
 41	# ls /sys/kernel/config/pci_ep/functions
 42	pci_epf_ntb  pci_epf_test  pci_epf_vntb
 43
 44
 45Creating pci-epf-vntb Device
 46----------------------------
 47
 48PCI endpoint function device can be created using the configfs. To create
 49pci-epf-vntb device, the following commands can be used::
 50
 51	# mount -t configfs none /sys/kernel/config
 52	# cd /sys/kernel/config/pci_ep/
 53	# mkdir functions/pci_epf_vntb/func1
 54
 55The "mkdir func1" above creates the pci-epf-vntb function device that will
 56be probed by pci_epf_vntb driver.
 57
 58The PCI endpoint framework populates the directory with the following
 59configurable fields::
 60
 61	# ls functions/pci_epf_vntb/func1
 62	baseclass_code    deviceid          msi_interrupts    pci-epf-vntb.0
 63	progif_code       secondary         subsys_id         vendorid
 64	cache_line_size   interrupt_pin     msix_interrupts   primary
 65	revid             subclass_code     subsys_vendor_id
 66
 67The PCI endpoint function driver populates these entries with default values
 68when the device is bound to the driver. The pci-epf-vntb driver populates
 69vendorid with 0xffff and interrupt_pin with 0x0001::
 70
 71	# cat functions/pci_epf_vntb/func1/vendorid
 72	0xffff
 73	# cat functions/pci_epf_vntb/func1/interrupt_pin
 74	0x0001
 75
 76
 77Configuring pci-epf-vntb Device
 78-------------------------------
 79
 80The user can configure the pci-epf-vntb device using its configfs entry. In order
 81to change the vendorid and the deviceid, the following
 82commands can be used::
 83
 84	# echo 0x1957 > functions/pci_epf_vntb/func1/vendorid
 85	# echo 0x0809 > functions/pci_epf_vntb/func1/deviceid
 86
 87The PCI endpoint framework also automatically creates a sub-directory in the
 88function attribute directory. This sub-directory has the same name as the name
 89of the function device and is populated with the following NTB specific
 90attributes that can be configured by the user::
 91
 92	# ls functions/pci_epf_vntb/func1/pci_epf_vntb.0/
 93	ctrl_bar  db_count  mw1_bar  mw2_bar  mw3_bar  mw4_bar	spad_count
 94	db_bar	  mw1	    mw2      mw3      mw4      num_mws	vbus_number
 95	vntb_vid  vntb_pid
 96
 97A sample configuration for NTB function is given below::
 98
 99	# echo 4 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/db_count
100	# echo 128 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/spad_count
101	# echo 1 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/num_mws
102	# echo 0x100000 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/mw1
103
104By default, each construct is assigned a BAR, as needed and in order.
105Should a specific BAR setup be required by the platform, BAR may be assigned
106to each construct using the related ``XYZ_bar`` entry.
107
108A sample configuration for virtual NTB driver for virtual PCI bus::
109
110	# echo 0x1957 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vntb_vid
111	# echo 0x080A > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vntb_pid
112	# echo 0x10 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vbus_number
113
114Binding pci-epf-vntb Device to EP Controller
115--------------------------------------------
116
117NTB function device should be attached to PCI endpoint controllers
118connected to the host.
119
120	# ln -s controllers/5f010000.pcie_ep functions/pci_epf_vntb/func1/primary
121
122Once the above step is completed, the PCI endpoint controllers are ready to
123establish a link with the host.
124
125
126Start the Link
127--------------
128
129In order for the endpoint device to establish a link with the host, the _start_
130field should be populated with '1'. For NTB, both the PCI endpoint controllers
131should establish link with the host (imx8 don't need this steps)::
132
133	# echo 1 > controllers/5f010000.pcie_ep/start
134
135RootComplex Device
136==================
137
138lspci Output at Host side
139-------------------------
140
141Note that the devices listed here correspond to the values populated in
142"Creating pci-epf-vntb Device" section above::
143
144	# lspci
145        00:00.0 PCI bridge: Freescale Semiconductor Inc Device 0000 (rev 01)
146        01:00.0 RAM memory: Freescale Semiconductor Inc Device 0809
147
148Endpoint Device / Virtual PCI bus
149=================================
150
151lspci Output at EP Side / Virtual PCI bus
152-----------------------------------------
153
154Note that the devices listed here correspond to the values populated in
155"Creating pci-epf-vntb Device" section above::
156
157        # lspci
158        10:00.0 Unassigned class [ffff]: Dawicontrol Computersysteme GmbH Device 1234 (rev ff)
159
160Using ntb_hw_epf Device
161-----------------------
162
163The host side software follows the standard NTB software architecture in Linux.
164All the existing client side NTB utilities like NTB Transport Client and NTB
165Netdev, NTB Ping Pong Test Client and NTB Tool Test Client can be used with NTB
166function device.
167
168For more information on NTB see
169:doc:`Non-Transparent Bridge <../../driver-api/ntb>`