GNU Linux-libre 6.1.91-gnu
[releases.git] / 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 .. code-block:: text
64
65
66   +--------------------------------------------------+ Base
67   |                                                  |
68   |                                                  |
69   |                                                  |
70   |          Common Config Register                  |
71   |                                                  |
72   |                                                  |
73   |                                                  |
74   +-----------------------+--------------------------+ Base + span_offset
75   |                       |                          |
76   |    Peer Span Space    |    Span Space            |
77   |                       |                          |
78   |                       |                          |
79   +-----------------------+--------------------------+ Base + span_offset
80   |                       |                          |      + span_count * 4
81   |                       |                          |
82   |     Span Space        |   Peer Span Space        |
83   |                       |                          |
84   +-----------------------+--------------------------+
85         Virtual PCI             Pcie Endpoint
86         NTB Driver               NTB Driver
87
88
89 Doorbell Registers:
90 -------------------
91
92   Doorbell Registers are used by the hosts to interrupt each other.
93
94 Memory Window:
95 --------------
96
97   Actual transfer of data between the two hosts will happen using the
98   memory window.
99
100 Modeling Constructs:
101 ====================
102
103 32-bit BARs.
104
105 ======  ===============
106 BAR NO  CONSTRUCTS USED
107 ======  ===============
108 BAR0    Config Region
109 BAR1    Doorbell
110 BAR2    Memory Window 1
111 BAR3    Memory Window 2
112 BAR4    Memory Window 3
113 BAR5    Memory Window 4
114 ======  ===============
115
116 64-bit BARs.
117
118 ======  ===============================
119 BAR NO  CONSTRUCTS USED
120 ======  ===============================
121 BAR0    Config Region + Scratchpad
122 BAR1
123 BAR2    Doorbell
124 BAR3
125 BAR4    Memory Window 1
126 BAR5
127 ======  ===============================
128
129