tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Documentation: PCI: Add specification for the PCI vNTB function device
Add specification for the PCI vNTB function device. The endpoint function
driver and the host PCI driver should be created based on this
specification.
Signed-off-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>
+295
+2
Documentation/PCI/endpoint/index.rst
+2
Documentation/PCI/endpoint/index.rst
+126
Documentation/PCI/endpoint/pci-vntb-function.rst
+126
Documentation/PCI/endpoint/pci-vntb-function.rst
···
1
+
.. SPDX-License-Identifier: GPL-2.0
2
+
3
+
=================
4
+
PCI vNTB Function
5
+
=================
6
+
7
+
:Author: Frank Li <Frank.Li@nxp.com>
8
+
9
+
The difference between PCI NTB function and PCI vNTB function is
10
+
11
+
PCI NTB function need at two endpoint instances and connect HOST1
12
+
and HOST2.
13
+
14
+
PCI vNTB function only use one host and one endpoint(EP), use NTB
15
+
connect EP and PCI host
16
+
17
+
.. code-block:: text
18
+
19
+
20
+
+------------+ +---------------------------------------+
21
+
| | | |
22
+
+------------+ | +--------------+
23
+
| NTB | | | NTB |
24
+
| NetDev | | | NetDev |
25
+
+------------+ | +--------------+
26
+
| NTB | | | NTB |
27
+
| Transfer | | | Transfer |
28
+
+------------+ | +--------------+
29
+
| | | | |
30
+
| PCI NTB | | | |
31
+
| EPF | | | |
32
+
| Driver | | | PCI Virtual |
33
+
| | +---------------+ | NTB Driver |
34
+
| | | PCI EP NTB |<------>| |
35
+
| | | FN Driver | | |
36
+
+------------+ +---------------+ +--------------+
37
+
| | | | | |
38
+
| PCI BUS | <-----> | PCI EP BUS | | Virtual PCI |
39
+
| | PCI | | | BUS |
40
+
+------------+ +---------------+--------+--------------+
41
+
PCI RC PCI EP
42
+
43
+
Constructs used for Implementing vNTB
44
+
=====================================
45
+
46
+
1) Config Region
47
+
2) Self Scratchpad Registers
48
+
3) Peer Scratchpad Registers
49
+
4) Doorbell (DB) Registers
50
+
5) Memory Window (MW)
51
+
52
+
53
+
Config Region:
54
+
--------------
55
+
56
+
It is same as PCI NTB Function driver
57
+
58
+
Scratchpad Registers:
59
+
---------------------
60
+
61
+
It is appended after Config region.
62
+
63
+
+--------------------------------------------------+ Base
64
+
| |
65
+
| |
66
+
| |
67
+
| Common Config Register |
68
+
| |
69
+
| |
70
+
| |
71
+
+-----------------------+--------------------------+ Base + span_offset
72
+
| | |
73
+
| Peer Span Space | Span Space |
74
+
| | |
75
+
| | |
76
+
+-----------------------+--------------------------+ Base + span_offset
77
+
| | | + span_count * 4
78
+
| | |
79
+
| Span Space | Peer Span Space |
80
+
| | |
81
+
+-----------------------+--------------------------+
82
+
Virtual PCI Pcie Endpoint
83
+
NTB Driver NTB Driver
84
+
85
+
86
+
Doorbell Registers:
87
+
-------------------
88
+
89
+
Doorbell Registers are used by the hosts to interrupt each other.
90
+
91
+
Memory Window:
92
+
--------------
93
+
94
+
Actual transfer of data between the two hosts will happen using the
95
+
memory window.
96
+
97
+
Modeling Constructs:
98
+
====================
99
+
100
+
32-bit BARs.
101
+
102
+
====== ===============
103
+
BAR NO CONSTRUCTS USED
104
+
====== ===============
105
+
BAR0 Config Region
106
+
BAR1 Doorbell
107
+
BAR2 Memory Window 1
108
+
BAR3 Memory Window 2
109
+
BAR4 Memory Window 3
110
+
BAR5 Memory Window 4
111
+
====== ===============
112
+
113
+
64-bit BARs.
114
+
115
+
====== ===============================
116
+
BAR NO CONSTRUCTS USED
117
+
====== ===============================
118
+
BAR0 Config Region + Scratchpad
119
+
BAR1
120
+
BAR2 Doorbell
121
+
BAR3
122
+
BAR4 Memory Window 1
123
+
BAR5
124
+
====== ===============================
125
+
126
+
+167
Documentation/PCI/endpoint/pci-vntb-howto.rst
+167
Documentation/PCI/endpoint/pci-vntb-howto.rst
···
1
+
.. SPDX-License-Identifier: GPL-2.0
2
+
3
+
===================================================================
4
+
PCI Non-Transparent Bridge (NTB) Endpoint Function (EPF) User Guide
5
+
===================================================================
6
+
7
+
:Author: Frank Li <Frank.Li@nxp.com>
8
+
9
+
This document is a guide to help users use pci-epf-vntb function driver
10
+
and ntb_hw_epf host driver for NTB functionality. The list of steps to
11
+
be followed in the host side and EP side is given below. For the hardware
12
+
configuration and internals of NTB using configurable endpoints see
13
+
Documentation/PCI/endpoint/pci-vntb-function.rst
14
+
15
+
Endpoint Device
16
+
===============
17
+
18
+
Endpoint Controller Devices
19
+
---------------------------
20
+
21
+
To find the list of endpoint controller devices in the system::
22
+
23
+
# ls /sys/class/pci_epc/
24
+
5f010000.pcie_ep
25
+
26
+
If PCI_ENDPOINT_CONFIGFS is enabled::
27
+
28
+
# ls /sys/kernel/config/pci_ep/controllers
29
+
5f010000.pcie_ep
30
+
31
+
Endpoint Function Drivers
32
+
-------------------------
33
+
34
+
To 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
+
39
+
If 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
+
45
+
Creating pci-epf-vntb Device
46
+
----------------------------
47
+
48
+
PCI endpoint function device can be created using the configfs. To create
49
+
pci-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
+
55
+
The "mkdir func1" above creates the pci-epf-ntb function device that will
56
+
be probed by pci_epf_vntb driver.
57
+
58
+
The PCI endpoint framework populates the directory with the following
59
+
configurable fields::
60
+
61
+
# ls functions/pci_epf_ntb/func1
62
+
baseclass_code deviceid msi_interrupts pci-epf-ntb.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
+
67
+
The PCI endpoint function driver populates these entries with default values
68
+
when the device is bound to the driver. The pci-epf-vntb driver populates
69
+
vendorid 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
+
77
+
Configuring pci-epf-vntb Device
78
+
-------------------------------
79
+
80
+
The user can configure the pci-epf-vntb device using its configfs entry. In order
81
+
to change the vendorid and the deviceid, the following
82
+
commands can be used::
83
+
84
+
# echo 0x1957 > functions/pci_epf_vntb/func1/vendorid
85
+
# echo 0x0809 > functions/pci_epf_vntb/func1/deviceid
86
+
87
+
In order to configure NTB specific attributes, a new sub-directory to func1
88
+
should be created::
89
+
90
+
# mkdir functions/pci_epf_vntb/func1/pci_epf_vntb.0/
91
+
92
+
The NTB function driver will populate this directory with various attributes
93
+
that can be configured by the user::
94
+
95
+
# ls functions/pci_epf_vntb/func1/pci_epf_vntb.0/
96
+
db_count mw1 mw2 mw3 mw4 num_mws
97
+
spad_count
98
+
99
+
A sample configuration for NTB function is given below::
100
+
101
+
# echo 4 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/db_count
102
+
# echo 128 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/spad_count
103
+
# echo 1 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/num_mws
104
+
# echo 0x100000 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/mw1
105
+
106
+
A sample configuration for virtual NTB driver for virutal PCI bus::
107
+
108
+
# echo 0x1957 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vntb_vid
109
+
# echo 0x080A > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vntb_pid
110
+
# echo 0x10 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vbus_number
111
+
112
+
Binding pci-epf-ntb Device to EP Controller
113
+
--------------------------------------------
114
+
115
+
NTB function device should be attached to PCI endpoint controllers
116
+
connected to the host.
117
+
118
+
# ln -s controllers/5f010000.pcie_ep functions/pci-epf-ntb/func1/primary
119
+
120
+
Once the above step is completed, the PCI endpoint controllers are ready to
121
+
establish a link with the host.
122
+
123
+
124
+
Start the Link
125
+
--------------
126
+
127
+
In order for the endpoint device to establish a link with the host, the _start_
128
+
field should be populated with '1'. For NTB, both the PCI endpoint controllers
129
+
should establish link with the host (imx8 don't need this steps)::
130
+
131
+
# echo 1 > controllers/5f010000.pcie_ep/start
132
+
133
+
RootComplex Device
134
+
==================
135
+
136
+
lspci Output at Host side
137
+
------------------------
138
+
139
+
Note that the devices listed here correspond to the values populated in
140
+
"Creating pci-epf-ntb Device" section above::
141
+
142
+
# lspci
143
+
00:00.0 PCI bridge: Freescale Semiconductor Inc Device 0000 (rev 01)
144
+
01:00.0 RAM memory: Freescale Semiconductor Inc Device 0809
145
+
146
+
Endpoint Device / Virtual PCI bus
147
+
=================================
148
+
149
+
lspci Output at EP Side / Virtual PCI bus
150
+
-----------------------------------------
151
+
152
+
Note that the devices listed here correspond to the values populated in
153
+
"Creating pci-epf-ntb Device" section above::
154
+
155
+
# lspci
156
+
10:00.0 Unassigned class [ffff]: Dawicontrol Computersysteme GmbH Device 1234 (rev ff)
157
+
158
+
Using ntb_hw_epf Device
159
+
-----------------------
160
+
161
+
The host side software follows the standard NTB software architecture in Linux.
162
+
All the existing client side NTB utilities like NTB Transport Client and NTB
163
+
Netdev, NTB Ping Pong Test Client and NTB Tool Test Client can be used with NTB
164
+
function device.
165
+
166
+
For more information on NTB see
167
+
:doc:`Non-Transparent Bridge <../../driver-api/ntb>`