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