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