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+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+PCI vNTB Function
+=================
+
+:Author: Frank Li <Frank.Li@nxp.com>
+
+The difference between PCI NTB function and PCI vNTB function is
+
+PCI NTB function need at two endpoint instances and connect HOST1
+and HOST2.
+
+PCI vNTB function only use one host and one endpoint(EP), use NTB
+connect EP and PCI host
+
+.. code-block:: text
+
+
+ +------------+ +---------------------------------------+
+ | | | |
+ +------------+ | +--------------+
+ | NTB | | | NTB |
+ | NetDev | | | NetDev |
+ +------------+ | +--------------+
+ | NTB | | | NTB |
+ | Transfer | | | Transfer |
+ +------------+ | +--------------+
+ | | | | |
+ | PCI NTB | | | |
+ | EPF | | | |
+ | Driver | | | PCI Virtual |
+ | | +---------------+ | NTB Driver |
+ | | | PCI EP NTB |<------>| |
+ | | | FN Driver | | |
+ +------------+ +---------------+ +--------------+
+ | | | | | |
+ | PCI BUS | <-----> | PCI EP BUS | | Virtual PCI |
+ | | PCI | | | BUS |
+ +------------+ +---------------+--------+--------------+
+ PCI RC PCI EP
+
+Constructs used for Implementing vNTB
+=====================================
+
+ 1) Config Region
+ 2) Self Scratchpad Registers
+ 3) Peer Scratchpad Registers
+ 4) Doorbell (DB) Registers
+ 5) Memory Window (MW)
+
+
+Config Region:
+--------------
+
+It is same as PCI NTB Function driver
+
+Scratchpad Registers:
+---------------------
+
+It is appended after Config region.
+
+.. code-block:: text
+
+
+ +--------------------------------------------------+ Base
+ | |
+ | |
+ | |
+ | Common Config Register |
+ | |
+ | |
+ | |
+ +-----------------------+--------------------------+ Base + span_offset
+ | | |
+ | Peer Span Space | Span Space |
+ | | |
+ | | |
+ +-----------------------+--------------------------+ Base + span_offset
+ | | | + span_count * 4
+ | | |
+ | Span Space | Peer Span Space |
+ | | |
+ +-----------------------+--------------------------+
+ Virtual PCI Pcie Endpoint
+ NTB Driver NTB Driver
+
+
+Doorbell Registers:
+-------------------
+
+ Doorbell Registers are used by the hosts to interrupt each other.
+
+Memory Window:
+--------------
+
+ Actual transfer of data between the two hosts will happen using the
+ memory window.
+
+Modeling Constructs:
+====================
+
+32-bit BARs.
+
+====== ===============
+BAR NO CONSTRUCTS USED
+====== ===============
+BAR0 Config Region
+BAR1 Doorbell
+BAR2 Memory Window 1
+BAR3 Memory Window 2
+BAR4 Memory Window 3
+BAR5 Memory Window 4
+====== ===============
+
+64-bit BARs.
+
+====== ===============================
+BAR NO CONSTRUCTS USED
+====== ===============================
+BAR0 Config Region + Scratchpad
+BAR1
+BAR2 Doorbell
+BAR3
+BAR4 Memory Window 1
+BAR5
+====== ===============================
+
+