1.. SPDX-License-Identifier: GPL-2.0
2
3=================
4PCI vNTB Function
5=================
6
7:Author: Frank Li <Frank.Li@nxp.com>
8
9The difference between PCI NTB function and PCI vNTB function is
10
11PCI NTB function need at two endpoint instances and connect HOST1
12and HOST2.
13
14PCI vNTB function only use one host and one endpoint(EP), use NTB
15connect 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
43Constructs 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
53Config Region:
54--------------
55
56It is same as PCI NTB Function driver
57
58Scratchpad Registers:
59---------------------
60
61It 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
89Doorbell Registers:
90-------------------
91
92  Doorbell Registers are used by the hosts to interrupt each other.
93
94Memory Window:
95--------------
96
97  Actual transfer of data between the two hosts will happen using the
98  memory window.
99
100Modeling Constructs:
101====================
102
10332-bit BARs.
104
105======  ===============
106BAR NO  CONSTRUCTS USED
107======  ===============
108BAR0    Config Region
109BAR1    Doorbell
110BAR2    Memory Window 1
111BAR3    Memory Window 2
112BAR4    Memory Window 3
113BAR5    Memory Window 4
114======  ===============
115
11664-bit BARs.
117
118======  ===============================
119BAR NO  CONSTRUCTS USED
120======  ===============================
121BAR0    Config Region + Scratchpad
122BAR1
123BAR2    Doorbell
124BAR3
125BAR4    Memory Window 1
126BAR5
127======  ===============================
128
129
130