Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

11 files changed, 1590 insertions, 0 deletions

diff --git a/Documentation/PCI/endpoint/function/binding/pci-ntb.rst b/Documentation/PCI/endpoint/function/binding/pci-ntb.rst
new file mode 100644
index 0000000000..40253d3d51
--- /dev/null
+++ b/Documentation/PCI/endpoint/function/binding/pci-ntb.rst
@@ -0,0 +1,38 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========================
+PCI NTB Endpoint Function
+==========================
+
+1) Create a subdirectory to pci_epf_ntb directory in configfs.
+
+Standard EPF Configurable Fields:
+
+================   ===========================================================
+vendorid	   should be 0x104c
+deviceid	   should be 0xb00d for TI's J721E SoC
+revid		   don't care
+progif_code	   don't care
+subclass_code	   should be 0x00
+baseclass_code	   should be 0x5
+cache_line_size	   don't care
+subsys_vendor_id   don't care
+subsys_id	   don't care
+interrupt_pin	   don't care
+msi_interrupts	   don't care
+msix_interrupts	   don't care
+================   ===========================================================
+
+2) Create a subdirectory to directory created in 1
+
+NTB EPF specific configurable fields:
+
+================   ===========================================================
+db_count	   Number of doorbells; default = 4
+mw1     	   size of memory window1
+mw2     	   size of memory window2
+mw3     	   size of memory window3
+mw4     	   size of memory window4
+num_mws     	   Number of memory windows; max = 4
+spad_count     	   Number of scratchpad registers; default = 64
+================   ===========================================================
diff --git a/Documentation/PCI/endpoint/function/binding/pci-test.rst b/Documentation/PCI/endpoint/function/binding/pci-test.rst
new file mode 100644
index 0000000000..57ee866fb1
--- /dev/null
+++ b/Documentation/PCI/endpoint/function/binding/pci-test.rst
@@ -0,0 +1,26 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==========================
+PCI Test Endpoint Function
+==========================
+
+name: Should be "pci_epf_test" to bind to the pci_epf_test driver.
+
+Configurable Fields:
+
+================   ===========================================================
+vendorid	   should be 0x104c
+deviceid	   should be 0xb500 for DRA74x and 0xb501 for DRA72x
+revid		   don't care
+progif_code	   don't care
+subclass_code	   don't care
+baseclass_code	   should be 0xff
+cache_line_size	   don't care
+subsys_vendor_id   don't care
+subsys_id	   don't care
+interrupt_pin	   Should be 1 - INTA, 2 - INTB, 3 - INTC, 4 -INTD
+msi_interrupts	   Should be 1 to 32 depending on the number of MSI interrupts
+		   to test
+msix_interrupts	   Should be 1 to 2048 depending on the number of MSI-X
+		   interrupts to test
+================   ===========================================================
diff --git a/Documentation/PCI/endpoint/index.rst b/Documentation/PCI/endpoint/index.rst
new file mode 100644
index 0000000000..4d2333e7ae
--- /dev/null
+++ b/Documentation/PCI/endpoint/index.rst
@@ -0,0 +1,20 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+======================
+PCI Endpoint Framework
+======================
+
+.. toctree::
+   :maxdepth: 2
+
+   pci-endpoint
+   pci-endpoint-cfs
+   pci-test-function
+   pci-test-howto
+   pci-ntb-function
+   pci-ntb-howto
+   pci-vntb-function
+   pci-vntb-howto
+
+   function/binding/pci-test
+   function/binding/pci-ntb
diff --git a/Documentation/PCI/endpoint/pci-endpoint-cfs.rst b/Documentation/PCI/endpoint/pci-endpoint-cfs.rst
new file mode 100644
index 0000000000..fb73345cfb
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-endpoint-cfs.rst
@@ -0,0 +1,138 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======================================
+Configuring PCI Endpoint Using CONFIGFS
+=======================================
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+The PCI Endpoint Core exposes configfs entry (pci_ep) to configure the
+PCI endpoint function and to bind the endpoint function
+with the endpoint controller. (For introducing other mechanisms to
+configure the PCI Endpoint Function refer to [1]).
+
+Mounting configfs
+=================
+
+The PCI Endpoint Core layer creates pci_ep directory in the mounted configfs
+directory. configfs can be mounted using the following command::
+
+	mount -t configfs none /sys/kernel/config
+
+Directory Structure
+===================
+
+The pci_ep configfs has two directories at its root: controllers and
+functions. Every EPC device present in the system will have an entry in
+the *controllers* directory and every EPF driver present in the system
+will have an entry in the *functions* directory.
+::
+
+	/sys/kernel/config/pci_ep/
+		.. controllers/
+		.. functions/
+
+Creating EPF Device
+===================
+
+Every registered EPF driver will be listed in controllers directory. The
+entries corresponding to EPF driver will be created by the EPF core.
+::
+
+	/sys/kernel/config/pci_ep/functions/
+		.. <EPF Driver1>/
+			... <EPF Device 11>/
+			... <EPF Device 21>/
+			... <EPF Device 31>/
+		.. <EPF Driver2>/
+			... <EPF Device 12>/
+			... <EPF Device 22>/
+
+In order to create a <EPF device> of the type probed by <EPF Driver>, the
+user has to create a directory inside <EPF DriverN>.
+
+Every <EPF device> directory consists of the following entries that can be
+used to configure the standard configuration header of the endpoint function.
+(These entries are created by the framework when any new <EPF Device> is
+created)
+::
+
+		.. <EPF Driver1>/
+			... <EPF Device 11>/
+				... vendorid
+				... deviceid
+				... revid
+				... progif_code
+				... subclass_code
+				... baseclass_code
+				... cache_line_size
+				... subsys_vendor_id
+				... subsys_id
+				... interrupt_pin
+			        ... <Symlink EPF Device 31>/
+                                ... primary/
+			                ... <Symlink EPC Device1>/
+                                ... secondary/
+			                ... <Symlink EPC Device2>/
+
+If an EPF device has to be associated with 2 EPCs (like in the case of
+Non-transparent bridge), symlink of endpoint controller connected to primary
+interface should be added in 'primary' directory and symlink of endpoint
+controller connected to secondary interface should be added in 'secondary'
+directory.
+
+The <EPF Device> directory can have a list of symbolic links
+(<Symlink EPF Device 31>) to other <EPF Device>. These symbolic links should
+be created by the user to represent the virtual functions that are bound to
+the physical function. In the above directory structure <EPF Device 11> is a
+physical function and <EPF Device 31> is a virtual function. An EPF device once
+it's linked to another EPF device, cannot be linked to a EPC device.
+
+EPC Device
+==========
+
+Every registered EPC device will be listed in controllers directory. The
+entries corresponding to EPC device will be created by the EPC core.
+::
+
+	/sys/kernel/config/pci_ep/controllers/
+		.. <EPC Device1>/
+			... <Symlink EPF Device11>/
+			... <Symlink EPF Device12>/
+			... start
+		.. <EPC Device2>/
+			... <Symlink EPF Device21>/
+			... <Symlink EPF Device22>/
+			... start
+
+The <EPC Device> directory will have a list of symbolic links to
+<EPF Device>. These symbolic links should be created by the user to
+represent the functions present in the endpoint device. Only <EPF Device>
+that represents a physical function can be linked to a EPC device.
+
+The <EPC Device> directory will also have a *start* field. Once
+"1" is written to this field, the endpoint device will be ready to
+establish the link with the host. This is usually done after
+all the EPF devices are created and linked with the EPC device.
+::
+
+			 | controllers/
+				| <Directory: EPC name>/
+					| <Symbolic Link: Function>
+					| start
+			 | functions/
+				| <Directory: EPF driver>/
+					| <Directory: EPF device>/
+						| vendorid
+						| deviceid
+						| revid
+						| progif_code
+						| subclass_code
+						| baseclass_code
+						| cache_line_size
+						| subsys_vendor_id
+						| subsys_id
+						| interrupt_pin
+						| function
+
+[1] Documentation/PCI/endpoint/pci-endpoint.rst
diff --git a/Documentation/PCI/endpoint/pci-endpoint.rst b/Documentation/PCI/endpoint/pci-endpoint.rst
new file mode 100644
index 0000000000..4f5622a655
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-endpoint.rst
@@ -0,0 +1,231 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+This document is a guide to use the PCI Endpoint Framework in order to create
+endpoint controller driver, endpoint function driver, and using configfs
+interface to bind the function driver to the controller driver.
+
+Introduction
+============
+
+Linux has a comprehensive PCI subsystem to support PCI controllers that
+operates in Root Complex mode. The subsystem has capability to scan PCI bus,
+assign memory resources and IRQ resources, load PCI driver (based on
+vendor ID, device ID), support other services like hot-plug, power management,
+advanced error reporting and virtual channels.
+
+However the PCI controller IP integrated in some SoCs is capable of operating
+either in Root Complex mode or Endpoint mode. PCI Endpoint Framework will
+add endpoint mode support in Linux. This will help to run Linux in an
+EP system which can have a wide variety of use cases from testing or
+validation, co-processor accelerator, etc.
+
+PCI Endpoint Core
+=================
+
+The PCI Endpoint Core layer comprises 3 components: the Endpoint Controller
+library, the Endpoint Function library, and the configfs layer to bind the
+endpoint function with the endpoint controller.
+
+PCI Endpoint Controller(EPC) Library
+------------------------------------
+
+The EPC library provides APIs to be used by the controller that can operate
+in endpoint mode. It also provides APIs to be used by function driver/library
+in order to implement a particular endpoint function.
+
+APIs for the PCI controller Driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the PCI Endpoint core provides to be used
+by the PCI controller driver.
+
+* devm_pci_epc_create()/pci_epc_create()
+
+   The PCI controller driver should implement the following ops:
+
+	 * write_header: ops to populate configuration space header
+	 * set_bar: ops to configure the BAR
+	 * clear_bar: ops to reset the BAR
+	 * alloc_addr_space: ops to allocate in PCI controller address space
+	 * free_addr_space: ops to free the allocated address space
+	 * raise_irq: ops to raise a legacy, MSI or MSI-X interrupt
+	 * start: ops to start the PCI link
+	 * stop: ops to stop the PCI link
+
+   The PCI controller driver can then create a new EPC device by invoking
+   devm_pci_epc_create()/pci_epc_create().
+
+* devm_pci_epc_destroy()/pci_epc_destroy()
+
+   The PCI controller driver can destroy the EPC device created by either
+   devm_pci_epc_create() or pci_epc_create() using devm_pci_epc_destroy() or
+   pci_epc_destroy().
+
+* pci_epc_linkup()
+
+   In order to notify all the function devices that the EPC device to which
+   they are linked has established a link with the host, the PCI controller
+   driver should invoke pci_epc_linkup().
+
+* pci_epc_mem_init()
+
+   Initialize the pci_epc_mem structure used for allocating EPC addr space.
+
+* pci_epc_mem_exit()
+
+   Cleanup the pci_epc_mem structure allocated during pci_epc_mem_init().
+
+
+EPC APIs for the PCI Endpoint Function Driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the PCI Endpoint core provides to be used
+by the PCI endpoint function driver.
+
+* pci_epc_write_header()
+
+   The PCI endpoint function driver should use pci_epc_write_header() to
+   write the standard configuration header to the endpoint controller.
+
+* pci_epc_set_bar()
+
+   The PCI endpoint function driver should use pci_epc_set_bar() to configure
+   the Base Address Register in order for the host to assign PCI addr space.
+   Register space of the function driver is usually configured
+   using this API.
+
+* pci_epc_clear_bar()
+
+   The PCI endpoint function driver should use pci_epc_clear_bar() to reset
+   the BAR.
+
+* pci_epc_raise_irq()
+
+   The PCI endpoint function driver should use pci_epc_raise_irq() to raise
+   Legacy Interrupt, MSI or MSI-X Interrupt.
+
+* pci_epc_mem_alloc_addr()
+
+   The PCI endpoint function driver should use pci_epc_mem_alloc_addr(), to
+   allocate memory address from EPC addr space which is required to access
+   RC's buffer
+
+* pci_epc_mem_free_addr()
+
+   The PCI endpoint function driver should use pci_epc_mem_free_addr() to
+   free the memory space allocated using pci_epc_mem_alloc_addr().
+
+Other EPC APIs
+~~~~~~~~~~~~~~
+
+There are other APIs provided by the EPC library. These are used for binding
+the EPF device with EPC device. pci-ep-cfs.c can be used as reference for
+using these APIs.
+
+* pci_epc_get()
+
+   Get a reference to the PCI endpoint controller based on the device name of
+   the controller.
+
+* pci_epc_put()
+
+   Release the reference to the PCI endpoint controller obtained using
+   pci_epc_get()
+
+* pci_epc_add_epf()
+
+   Add a PCI endpoint function to a PCI endpoint controller. A PCIe device
+   can have up to 8 functions according to the specification.
+
+* pci_epc_remove_epf()
+
+   Remove the PCI endpoint function from PCI endpoint controller.
+
+* pci_epc_start()
+
+   The PCI endpoint function driver should invoke pci_epc_start() once it
+   has configured the endpoint function and wants to start the PCI link.
+
+* pci_epc_stop()
+
+   The PCI endpoint function driver should invoke pci_epc_stop() to stop
+   the PCI LINK.
+
+
+PCI Endpoint Function(EPF) Library
+----------------------------------
+
+The EPF library provides APIs to be used by the function driver and the EPC
+library to provide endpoint mode functionality.
+
+EPF APIs for the PCI Endpoint Function Driver
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the PCI Endpoint core provides to be used
+by the PCI endpoint function driver.
+
+* pci_epf_register_driver()
+
+   The PCI Endpoint Function driver should implement the following ops:
+	 * bind: ops to perform when a EPC device has been bound to EPF device
+	 * unbind: ops to perform when a binding has been lost between a EPC
+	   device and EPF device
+	 * linkup: ops to perform when the EPC device has established a
+	   connection with a host system
+
+  The PCI Function driver can then register the PCI EPF driver by using
+  pci_epf_register_driver().
+
+* pci_epf_unregister_driver()
+
+  The PCI Function driver can unregister the PCI EPF driver by using
+  pci_epf_unregister_driver().
+
+* pci_epf_alloc_space()
+
+  The PCI Function driver can allocate space for a particular BAR using
+  pci_epf_alloc_space().
+
+* pci_epf_free_space()
+
+  The PCI Function driver can free the allocated space
+  (using pci_epf_alloc_space) by invoking pci_epf_free_space().
+
+APIs for the PCI Endpoint Controller Library
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+This section lists the APIs that the PCI Endpoint core provides to be used
+by the PCI endpoint controller library.
+
+* pci_epf_linkup()
+
+   The PCI endpoint controller library invokes pci_epf_linkup() when the
+   EPC device has established the connection to the host.
+
+Other EPF APIs
+~~~~~~~~~~~~~~
+
+There are other APIs provided by the EPF library. These are used to notify
+the function driver when the EPF device is bound to the EPC device.
+pci-ep-cfs.c can be used as reference for using these APIs.
+
+* pci_epf_create()
+
+   Create a new PCI EPF device by passing the name of the PCI EPF device.
+   This name will be used to bind the EPF device to a EPF driver.
+
+* pci_epf_destroy()
+
+   Destroy the created PCI EPF device.
+
+* pci_epf_bind()
+
+   pci_epf_bind() should be invoked when the EPF device has been bound to
+   a EPC device.
+
+* pci_epf_unbind()
+
+   pci_epf_unbind() should be invoked when the binding between EPC device
+   and EPF device is lost.
diff --git a/Documentation/PCI/endpoint/pci-ntb-function.rst b/Documentation/PCI/endpoint/pci-ntb-function.rst
new file mode 100644
index 0000000000..3b9d836a49
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-ntb-function.rst
@@ -0,0 +1,348 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+PCI NTB Function
+=================
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+PCI Non-Transparent Bridges (NTB) allow two host systems to communicate
+with each other by exposing each host as a device to the other host.
+NTBs typically support the ability to generate interrupts on the remote
+machine, expose memory ranges as BARs, and perform DMA.  They also support
+scratchpads, which are areas of memory within the NTB that are accessible
+from both machines.
+
+PCI NTB Function allows two different systems (or hosts) to communicate
+with each other by configuring the endpoint instances in such a way that
+transactions from one system are routed to the other system.
+
+In the below diagram, PCI NTB function configures the SoC with multiple
+PCI Endpoint (EP) instances in such a way that transactions from one EP
+controller are routed to the other EP controller. Once PCI NTB function
+configures the SoC with multiple EP instances, HOST1 and HOST2 can
+communicate with each other using SoC as a bridge.
+
+.. code-block:: text
+
+    +-------------+                                   +-------------+
+    |             |                                   |             |
+    |    HOST1    |                                   |    HOST2    |
+    |             |                                   |             |
+    +------^------+                                   +------^------+
+           |                                                 |
+           |                                                 |
+ +---------|-------------------------------------------------|---------+
+ |  +------v------+                                   +------v------+  |
+ |  |             |                                   |             |  |
+ |  |     EP      |                                   |     EP      |  |
+ |  | CONTROLLER1 |                                   | CONTROLLER2 |  |
+ |  |             <----------------------------------->             |  |
+ |  |             |                                   |             |  |
+ |  |             |                                   |             |  |
+ |  |             |  SoC With Multiple EP Instances   |             |  |
+ |  |             |  (Configured using NTB Function)  |             |  |
+ |  +-------------+                                   +-------------+  |
+ +---------------------------------------------------------------------+
+
+Constructs used for Implementing NTB
+====================================
+
+	1) Config Region
+	2) Self Scratchpad Registers
+	3) Peer Scratchpad Registers
+	4) Doorbell (DB) Registers
+	5) Memory Window (MW)
+
+
+Config Region:
+--------------
+
+Config Region is a construct that is specific to NTB implemented using NTB
+Endpoint Function Driver. The host and endpoint side NTB function driver will
+exchange information with each other using this region. Config Region has
+Control/Status Registers for configuring the Endpoint Controller. Host can
+write into this region for configuring the outbound Address Translation Unit
+(ATU) and to indicate the link status. Endpoint can indicate the status of
+commands issued by host in this region. Endpoint can also indicate the
+scratchpad offset and number of memory windows to the host using this region.
+
+The format of Config Region is given below. All the fields here are 32 bits.
+
+.. code-block:: text
+
+	+------------------------+
+	|         COMMAND        |
+	+------------------------+
+	|         ARGUMENT       |
+	+------------------------+
+	|         STATUS         |
+	+------------------------+
+	|         TOPOLOGY       |
+	+------------------------+
+	|    ADDRESS (LOWER 32)  |
+	+------------------------+
+	|    ADDRESS (UPPER 32)  |
+	+------------------------+
+	|           SIZE         |
+	+------------------------+
+	|   NO OF MEMORY WINDOW  |
+	+------------------------+
+	|  MEMORY WINDOW1 OFFSET |
+	+------------------------+
+	|       SPAD OFFSET      |
+	+------------------------+
+	|        SPAD COUNT      |
+	+------------------------+
+	|      DB ENTRY SIZE     |
+	+------------------------+
+	|         DB DATA        |
+	+------------------------+
+	|            :           |
+	+------------------------+
+	|            :           |
+	+------------------------+
+	|         DB DATA        |
+	+------------------------+
+
+
+  COMMAND:
+
+	NTB function supports three commands:
+
+	  CMD_CONFIGURE_DOORBELL (0x1): Command to configure doorbell. Before
+	invoking this command, the host should allocate and initialize
+	MSI/MSI-X vectors (i.e., initialize the MSI/MSI-X Capability in the
+	Endpoint). The endpoint on receiving this command will configure
+	the outbound ATU such that transactions to Doorbell BAR will be routed
+	to the MSI/MSI-X address programmed by the host. The ARGUMENT
+	register should be populated with number of DBs to configure (in the
+	lower 16 bits) and if MSI or MSI-X should be configured (BIT 16).
+
+	  CMD_CONFIGURE_MW (0x2): Command to configure memory window (MW). The
+	host invokes this command after allocating a buffer that can be
+	accessed by remote host. The allocated address should be programmed
+	in the ADDRESS register (64 bit), the size should be programmed in
+	the SIZE register and the memory window index should be programmed
+	in the ARGUMENT register. The endpoint on receiving this command
+	will configure the outbound ATU such that transactions to MW BAR
+	are routed to the address provided by the host.
+
+	  CMD_LINK_UP (0x3): Command to indicate an NTB application is
+	bound to the EP device on the host side. Once the endpoint
+	receives this command from both the hosts, the endpoint will
+	raise a LINK_UP event to both the hosts to indicate the host
+	NTB applications can start communicating with each other.
+
+  ARGUMENT:
+
+	The value of this register is based on the commands issued in
+	command register. See COMMAND section for more information.
+
+  TOPOLOGY:
+
+	Set to NTB_TOPO_B2B_USD for Primary interface
+	Set to NTB_TOPO_B2B_DSD for Secondary interface
+
+  ADDRESS/SIZE:
+
+	Address and Size to be used while configuring the memory window.
+	See "CMD_CONFIGURE_MW" for more info.
+
+  MEMORY WINDOW1 OFFSET:
+
+	Memory Window 1 and Doorbell registers are packed together in the
+	same BAR. The initial portion of the region will have doorbell
+	registers and the latter portion of the region is for memory window 1.
+	This register will specify the offset of the memory window 1.
+
+  NO OF MEMORY WINDOW:
+
+	Specifies the number of memory windows supported by the NTB device.
+
+  SPAD OFFSET:
+
+	Self scratchpad region and config region are packed together in the
+	same BAR. The initial portion of the region will have config region
+	and the latter portion of the region is for self scratchpad. This
+	register will specify the offset of the self scratchpad registers.
+
+  SPAD COUNT:
+
+	Specifies the number of scratchpad registers supported by the NTB
+	device.
+
+  DB ENTRY SIZE:
+
+	Used to determine the offset within the DB BAR that should be written
+	in order to raise doorbell. EPF NTB can use either MSI or MSI-X to
+	ring doorbell (MSI-X support will be added later). MSI uses same
+	address for all the interrupts and MSI-X can provide different
+	addresses for different interrupts. The MSI/MSI-X address is provided
+	by the host and the address it gives is based on the MSI/MSI-X
+	implementation supported by the host. For instance, ARM platform
+	using GIC ITS will have the same MSI-X address for all the interrupts.
+	In order to support all the combinations and use the same mechanism
+	for both MSI and MSI-X, EPF NTB allocates a separate region in the
+	Outbound Address Space for each of the interrupts. This region will
+	be mapped to the MSI/MSI-X address provided by the host. If a host
+	provides the same address for all the interrupts, all the regions
+	will be translated to the same address. If a host provides different
+	addresses, the regions will be translated to different addresses. This
+	will ensure there is no difference while raising the doorbell.
+
+  DB DATA:
+
+	EPF NTB supports 32 interrupts, so there are 32 DB DATA registers.
+	This holds the MSI/MSI-X data that has to be written to MSI address
+	for raising doorbell interrupt. This will be populated by EPF NTB
+	while invoking CMD_CONFIGURE_DOORBELL.
+
+Scratchpad Registers:
+---------------------
+
+  Each host has its own register space allocated in the memory of NTB endpoint
+  controller. They are both readable and writable from both sides of the bridge.
+  They are used by applications built over NTB and can be used to pass control
+  and status information between both sides of a device.
+
+  Scratchpad registers has 2 parts
+	1) Self Scratchpad: Host's own register space
+	2) Peer Scratchpad: Remote host's register space.
+
+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:
+====================
+
+There are 5 or more distinct regions (config, self scratchpad, peer
+scratchpad, doorbell, one or more memory windows) to be modeled to achieve
+NTB functionality. At least one memory window is required while more than
+one is permitted. All these regions should be mapped to BARs for hosts to
+access these regions.
+
+If one 32-bit BAR is allocated for each of these regions, the scheme would
+look like this:
+
+======  ===============
+BAR NO  CONSTRUCTS USED
+======  ===============
+BAR0    Config Region
+BAR1    Self Scratchpad
+BAR2    Peer Scratchpad
+BAR3    Doorbell
+BAR4    Memory Window 1
+BAR5    Memory Window 2
+======  ===============
+
+However if we allocate a separate BAR for each of the regions, there would not
+be enough BARs for all the regions in a platform that supports only 64-bit
+BARs.
+
+In order to be supported by most of the platforms, the regions should be
+packed and mapped to BARs in a way that provides NTB functionality and
+also makes sure the host doesn't access any region that it is not supposed
+to.
+
+The following scheme is used in EPF NTB Function:
+
+======  ===============================
+BAR NO  CONSTRUCTS USED
+======  ===============================
+BAR0    Config Region + Self Scratchpad
+BAR1    Peer Scratchpad
+BAR2    Doorbell + Memory Window 1
+BAR3    Memory Window 2
+BAR4    Memory Window 3
+BAR5    Memory Window 4
+======  ===============================
+
+With this scheme, for the basic NTB functionality 3 BARs should be sufficient.
+
+Modeling Config/Scratchpad Region:
+----------------------------------
+
+.. code-block:: text
+
+ +-----------------+------->+------------------+        +-----------------+
+ |       BAR0      |        |  CONFIG REGION   |        |       BAR0      |
+ +-----------------+----+   +------------------+<-------+-----------------+
+ |       BAR1      |    |   |SCRATCHPAD REGION |        |       BAR1      |
+ +-----------------+    +-->+------------------+<-------+-----------------+
+ |       BAR2      |            Local Memory            |       BAR2      |
+ +-----------------+                                    +-----------------+
+ |       BAR3      |                                    |       BAR3      |
+ +-----------------+                                    +-----------------+
+ |       BAR4      |                                    |       BAR4      |
+ +-----------------+                                    +-----------------+
+ |       BAR5      |                                    |       BAR5      |
+ +-----------------+                                    +-----------------+
+   EP CONTROLLER 1                                        EP CONTROLLER 2
+
+Above diagram shows Config region + Scratchpad region for HOST1 (connected to
+EP controller 1) allocated in local memory. The HOST1 can access the config
+region and scratchpad region (self scratchpad) using BAR0 of EP controller 1.
+The peer host (HOST2 connected to EP controller 2) can also access this
+scratchpad region (peer scratchpad) using BAR1 of EP controller 2. This
+diagram shows the case where Config region and Scratchpad regions are allocated
+for HOST1, however the same is applicable for HOST2.
+
+Modeling Doorbell/Memory Window 1:
+----------------------------------
+
+.. code-block:: text
+
+ +-----------------+    +----->+----------------+-----------+-----------------+
+ |       BAR0      |    |      |   Doorbell 1   +-----------> MSI-X ADDRESS 1 |
+ +-----------------+    |      +----------------+           +-----------------+
+ |       BAR1      |    |      |   Doorbell 2   +---------+ |                 |
+ +-----------------+----+      +----------------+         | |                 |
+ |       BAR2      |           |   Doorbell 3   +-------+ | +-----------------+
+ +-----------------+----+      +----------------+       | +-> MSI-X ADDRESS 2 |
+ |       BAR3      |    |      |   Doorbell 4   +-----+ |   +-----------------+
+ +-----------------+    |      |----------------+     | |   |                 |
+ |       BAR4      |    |      |                |     | |   +-----------------+
+ +-----------------+    |      |      MW1       +---+ | +-->+ MSI-X ADDRESS 3||
+ |       BAR5      |    |      |                |   | |     +-----------------+
+ +-----------------+    +----->-----------------+   | |     |                 |
+   EP CONTROLLER 1             |                |   | |     +-----------------+
+                               |                |   | +---->+ MSI-X ADDRESS 4 |
+                               +----------------+   |       +-----------------+
+                                EP CONTROLLER 2     |       |                 |
+                                  (OB SPACE)        |       |                 |
+                                                    +------->      MW1        |
+                                                            |                 |
+                                                            |                 |
+                                                            +-----------------+
+                                                            |                 |
+                                                            |                 |
+                                                            |                 |
+                                                            |                 |
+                                                            |                 |
+                                                            +-----------------+
+                                                             PCI Address Space
+                                                             (Managed by HOST2)
+
+Above diagram shows how the doorbell and memory window 1 is mapped so that
+HOST1 can raise doorbell interrupt on HOST2 and also how HOST1 can access
+buffers exposed by HOST2 using memory window1 (MW1). Here doorbell and
+memory window 1 regions are allocated in EP controller 2 outbound (OB) address
+space. Allocating and configuring BARs for doorbell and memory window1
+is done during the initialization phase of NTB endpoint function driver.
+Mapping from EP controller 2 OB space to PCI address space is done when HOST2
+sends CMD_CONFIGURE_MW/CMD_CONFIGURE_DOORBELL.
+
+Modeling Optional Memory Windows:
+---------------------------------
+
+This is modeled the same was as MW1 but each of the additional memory windows
+is mapped to separate BARs.
diff --git a/Documentation/PCI/endpoint/pci-ntb-howto.rst b/Documentation/PCI/endpoint/pci-ntb-howto.rst
new file mode 100644
index 0000000000..4261e7157e
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-ntb-howto.rst
@@ -0,0 +1,158 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================================================================
+PCI Non-Transparent Bridge (NTB) Endpoint Function (EPF) User Guide
+===================================================================
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+This document is a guide to help users use pci-epf-ntb function driver
+and ntb_hw_epf host driver for NTB functionality. The list of steps to
+be followed in the host side and EP side is given below. For the hardware
+configuration and internals of NTB using configurable endpoints see
+Documentation/PCI/endpoint/pci-ntb-function.rst
+
+Endpoint Device
+===============
+
+Endpoint Controller Devices
+---------------------------
+
+For implementing NTB functionality at least two endpoint controller devices
+are required.
+
+To find the list of endpoint controller devices in the system::
+
+	# ls /sys/class/pci_epc/
+	2900000.pcie-ep  2910000.pcie-ep
+
+If PCI_ENDPOINT_CONFIGFS is enabled::
+
+	# ls /sys/kernel/config/pci_ep/controllers
+	2900000.pcie-ep  2910000.pcie-ep
+
+
+Endpoint Function Drivers
+-------------------------
+
+To find the list of endpoint function drivers in the system::
+
+	# ls /sys/bus/pci-epf/drivers
+	pci_epf_ntb   pci_epf_ntb
+
+If PCI_ENDPOINT_CONFIGFS is enabled::
+
+	# ls /sys/kernel/config/pci_ep/functions
+	pci_epf_ntb   pci_epf_ntb
+
+
+Creating pci-epf-ntb Device
+----------------------------
+
+PCI endpoint function device can be created using the configfs. To create
+pci-epf-ntb device, the following commands can be used::
+
+	# mount -t configfs none /sys/kernel/config
+	# cd /sys/kernel/config/pci_ep/
+	# mkdir functions/pci_epf_ntb/func1
+
+The "mkdir func1" above creates the pci-epf-ntb function device that will
+be probed by pci_epf_ntb driver.
+
+The PCI endpoint framework populates the directory with the following
+configurable fields::
+
+	# ls functions/pci_epf_ntb/func1
+	baseclass_code    deviceid          msi_interrupts    pci-epf-ntb.0
+	progif_code       secondary         subsys_id         vendorid
+	cache_line_size   interrupt_pin     msix_interrupts   primary
+	revid             subclass_code     subsys_vendor_id
+
+The PCI endpoint function driver populates these entries with default values
+when the device is bound to the driver. The pci-epf-ntb driver populates
+vendorid with 0xffff and interrupt_pin with 0x0001::
+
+	# cat functions/pci_epf_ntb/func1/vendorid
+	0xffff
+	# cat functions/pci_epf_ntb/func1/interrupt_pin
+	0x0001
+
+
+Configuring pci-epf-ntb Device
+-------------------------------
+
+The user can configure the pci-epf-ntb device using its configfs entry. In order
+to change the vendorid and the deviceid, the following
+commands can be used::
+
+	# echo 0x104c > functions/pci_epf_ntb/func1/vendorid
+	# echo 0xb00d > functions/pci_epf_ntb/func1/deviceid
+
+The PCI endpoint framework also automatically creates a sub-directory in the
+function attribute directory. This sub-directory has the same name as the name
+of the function device and is populated with the following NTB specific
+attributes that can be configured by the user::
+
+	# ls functions/pci_epf_ntb/func1/pci_epf_ntb.0/
+	db_count    mw1         mw2         mw3         mw4         num_mws
+	spad_count
+
+A sample configuration for NTB function is given below::
+
+	# echo 4 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/db_count
+	# echo 128 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/spad_count
+	# echo 2 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/num_mws
+	# echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw1
+	# echo 0x100000 > functions/pci_epf_ntb/func1/pci_epf_ntb.0/mw2
+
+Binding pci-epf-ntb Device to EP Controller
+--------------------------------------------
+
+NTB function device should be attached to two PCI endpoint controllers
+connected to the two hosts. Use the 'primary' and 'secondary' entries
+inside NTB function device to attach one PCI endpoint controller to
+primary interface and the other PCI endpoint controller to the secondary
+interface::
+
+	# ln -s controllers/2900000.pcie-ep/ functions/pci-epf-ntb/func1/primary
+	# ln -s controllers/2910000.pcie-ep/ functions/pci-epf-ntb/func1/secondary
+
+Once the above step is completed, both the PCI endpoint controllers are ready to
+establish a link with the host.
+
+
+Start the Link
+--------------
+
+In order for the endpoint device to establish a link with the host, the _start_
+field should be populated with '1'. For NTB, both the PCI endpoint controllers
+should establish link with the host::
+
+	# echo 1 > controllers/2900000.pcie-ep/start
+	# echo 1 > controllers/2910000.pcie-ep/start
+
+
+RootComplex Device
+==================
+
+lspci Output
+------------
+
+Note that the devices listed here correspond to the values populated in
+"Creating pci-epf-ntb Device" section above::
+
+	# lspci
+	0000:00:00.0 PCI bridge: Texas Instruments Device b00d
+	0000:01:00.0 RAM memory: Texas Instruments Device b00d
+
+
+Using ntb_hw_epf Device
+-----------------------
+
+The host side software follows the standard NTB software architecture in Linux.
+All the existing client side NTB utilities like NTB Transport Client and NTB
+Netdev, NTB Ping Pong Test Client and NTB Tool Test Client can be used with NTB
+function device.
+
+For more information on NTB see
+:doc:`Non-Transparent Bridge <../../driver-api/ntb>`
diff --git a/Documentation/PCI/endpoint/pci-test-function.rst b/Documentation/PCI/endpoint/pci-test-function.rst
new file mode 100644
index 0000000000..3c8521d7aa
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-test-function.rst
@@ -0,0 +1,103 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+PCI Test Function
+=================
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+Traditionally PCI RC has always been validated by using standard
+PCI cards like ethernet PCI cards or USB PCI cards or SATA PCI cards.
+However with the addition of EP-core in linux kernel, it is possible
+to configure a PCI controller that can operate in EP mode to work as
+a test device.
+
+The PCI endpoint test device is a virtual device (defined in software)
+used to test the endpoint functionality and serve as a sample driver
+for other PCI endpoint devices (to use the EP framework).
+
+The PCI endpoint test device has the following registers:
+
+	1) PCI_ENDPOINT_TEST_MAGIC
+	2) PCI_ENDPOINT_TEST_COMMAND
+	3) PCI_ENDPOINT_TEST_STATUS
+	4) PCI_ENDPOINT_TEST_SRC_ADDR
+	5) PCI_ENDPOINT_TEST_DST_ADDR
+	6) PCI_ENDPOINT_TEST_SIZE
+	7) PCI_ENDPOINT_TEST_CHECKSUM
+	8) PCI_ENDPOINT_TEST_IRQ_TYPE
+	9) PCI_ENDPOINT_TEST_IRQ_NUMBER
+
+* PCI_ENDPOINT_TEST_MAGIC
+
+This register will be used to test BAR0. A known pattern will be written
+and read back from MAGIC register to verify BAR0.
+
+* PCI_ENDPOINT_TEST_COMMAND
+
+This register will be used by the host driver to indicate the function
+that the endpoint device must perform.
+
+========	================================================================
+Bitfield	Description
+========	================================================================
+Bit 0		raise legacy IRQ
+Bit 1		raise MSI IRQ
+Bit 2		raise MSI-X IRQ
+Bit 3		read command (read data from RC buffer)
+Bit 4		write command (write data to RC buffer)
+Bit 5		copy command (copy data from one RC buffer to another RC buffer)
+========	================================================================
+
+* PCI_ENDPOINT_TEST_STATUS
+
+This register reflects the status of the PCI endpoint device.
+
+========	==============================
+Bitfield	Description
+========	==============================
+Bit 0		read success
+Bit 1		read fail
+Bit 2		write success
+Bit 3		write fail
+Bit 4		copy success
+Bit 5		copy fail
+Bit 6		IRQ raised
+Bit 7		source address is invalid
+Bit 8		destination address is invalid
+========	==============================
+
+* PCI_ENDPOINT_TEST_SRC_ADDR
+
+This register contains the source address (RC buffer address) for the
+COPY/READ command.
+
+* PCI_ENDPOINT_TEST_DST_ADDR
+
+This register contains the destination address (RC buffer address) for
+the COPY/WRITE command.
+
+* PCI_ENDPOINT_TEST_IRQ_TYPE
+
+This register contains the interrupt type (Legacy/MSI) triggered
+for the READ/WRITE/COPY and raise IRQ (Legacy/MSI) commands.
+
+Possible types:
+
+======	==
+Legacy	0
+MSI	1
+MSI-X	2
+======	==
+
+* PCI_ENDPOINT_TEST_IRQ_NUMBER
+
+This register contains the triggered ID interrupt.
+
+Admissible values:
+
+======	===========
+Legacy	0
+MSI	[1 .. 32]
+MSI-X	[1 .. 2048]
+======	===========
diff --git a/Documentation/PCI/endpoint/pci-test-howto.rst b/Documentation/PCI/endpoint/pci-test-howto.rst
new file mode 100644
index 0000000000..909f770a07
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-test-howto.rst
@@ -0,0 +1,235 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================
+PCI Test User Guide
+===================
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+This document is a guide to help users use pci-epf-test function driver
+and pci_endpoint_test host driver for testing PCI. The list of steps to
+be followed in the host side and EP side is given below.
+
+Endpoint Device
+===============
+
+Endpoint Controller Devices
+---------------------------
+
+To find the list of endpoint controller devices in the system::
+
+	# ls /sys/class/pci_epc/
+	  51000000.pcie_ep
+
+If PCI_ENDPOINT_CONFIGFS is enabled::
+
+	# ls /sys/kernel/config/pci_ep/controllers
+	  51000000.pcie_ep
+
+
+Endpoint Function Drivers
+-------------------------
+
+To find the list of endpoint function drivers in the system::
+
+	# ls /sys/bus/pci-epf/drivers
+	  pci_epf_test
+
+If PCI_ENDPOINT_CONFIGFS is enabled::
+
+	# ls /sys/kernel/config/pci_ep/functions
+	  pci_epf_test
+
+
+Creating pci-epf-test Device
+----------------------------
+
+PCI endpoint function device can be created using the configfs. To create
+pci-epf-test device, the following commands can be used::
+
+	# mount -t configfs none /sys/kernel/config
+	# cd /sys/kernel/config/pci_ep/
+	# mkdir functions/pci_epf_test/func1
+
+The "mkdir func1" above creates the pci-epf-test function device that will
+be probed by pci_epf_test driver.
+
+The PCI endpoint framework populates the directory with the following
+configurable fields::
+
+	# ls functions/pci_epf_test/func1
+	  baseclass_code	interrupt_pin	progif_code	subsys_id
+	  cache_line_size	msi_interrupts	revid		subsys_vendorid
+	  deviceid          	msix_interrupts	subclass_code	vendorid
+
+The PCI endpoint function driver populates these entries with default values
+when the device is bound to the driver. The pci-epf-test driver populates
+vendorid with 0xffff and interrupt_pin with 0x0001::
+
+	# cat functions/pci_epf_test/func1/vendorid
+	  0xffff
+	# cat functions/pci_epf_test/func1/interrupt_pin
+	  0x0001
+
+
+Configuring pci-epf-test Device
+-------------------------------
+
+The user can configure the pci-epf-test device using configfs entry. In order
+to change the vendorid and the number of MSI interrupts used by the function
+device, the following commands can be used::
+
+	# echo 0x104c > functions/pci_epf_test/func1/vendorid
+	# echo 0xb500 > functions/pci_epf_test/func1/deviceid
+	# echo 16 > functions/pci_epf_test/func1/msi_interrupts
+	# echo 8 > functions/pci_epf_test/func1/msix_interrupts
+
+
+Binding pci-epf-test Device to EP Controller
+--------------------------------------------
+
+In order for the endpoint function device to be useful, it has to be bound to
+a PCI endpoint controller driver. Use the configfs to bind the function
+device to one of the controller driver present in the system::
+
+	# ln -s functions/pci_epf_test/func1 controllers/51000000.pcie_ep/
+
+Once the above step is completed, the PCI endpoint is ready to establish a link
+with the host.
+
+
+Start the Link
+--------------
+
+In order for the endpoint device to establish a link with the host, the _start_
+field should be populated with '1'::
+
+	# echo 1 > controllers/51000000.pcie_ep/start
+
+
+RootComplex Device
+==================
+
+lspci Output
+------------
+
+Note that the devices listed here correspond to the value populated in 1.4
+above::
+
+	00:00.0 PCI bridge: Texas Instruments Device 8888 (rev 01)
+	01:00.0 Unassigned class [ff00]: Texas Instruments Device b500
+
+
+Using Endpoint Test function Device
+-----------------------------------
+
+pcitest.sh added in tools/pci/ can be used to run all the default PCI endpoint
+tests. To compile this tool the following commands should be used::
+
+	# cd <kernel-dir>
+	# make -C tools/pci
+
+or if you desire to compile and install in your system::
+
+	# cd <kernel-dir>
+	# make -C tools/pci install
+
+The tool and script will be located in <rootfs>/usr/bin/
+
+
+pcitest.sh Output
+~~~~~~~~~~~~~~~~~
+::
+
+	# pcitest.sh
+	BAR tests
+
+	BAR0:           OKAY
+	BAR1:           OKAY
+	BAR2:           OKAY
+	BAR3:           OKAY
+	BAR4:           NOT OKAY
+	BAR5:           NOT OKAY
+
+	Interrupt tests
+
+	SET IRQ TYPE TO LEGACY:         OKAY
+	LEGACY IRQ:     NOT OKAY
+	SET IRQ TYPE TO MSI:            OKAY
+	MSI1:           OKAY
+	MSI2:           OKAY
+	MSI3:           OKAY
+	MSI4:           OKAY
+	MSI5:           OKAY
+	MSI6:           OKAY
+	MSI7:           OKAY
+	MSI8:           OKAY
+	MSI9:           OKAY
+	MSI10:          OKAY
+	MSI11:          OKAY
+	MSI12:          OKAY
+	MSI13:          OKAY
+	MSI14:          OKAY
+	MSI15:          OKAY
+	MSI16:          OKAY
+	MSI17:          NOT OKAY
+	MSI18:          NOT OKAY
+	MSI19:          NOT OKAY
+	MSI20:          NOT OKAY
+	MSI21:          NOT OKAY
+	MSI22:          NOT OKAY
+	MSI23:          NOT OKAY
+	MSI24:          NOT OKAY
+	MSI25:          NOT OKAY
+	MSI26:          NOT OKAY
+	MSI27:          NOT OKAY
+	MSI28:          NOT OKAY
+	MSI29:          NOT OKAY
+	MSI30:          NOT OKAY
+	MSI31:          NOT OKAY
+	MSI32:          NOT OKAY
+	SET IRQ TYPE TO MSI-X:          OKAY
+	MSI-X1:         OKAY
+	MSI-X2:         OKAY
+	MSI-X3:         OKAY
+	MSI-X4:         OKAY
+	MSI-X5:         OKAY
+	MSI-X6:         OKAY
+	MSI-X7:         OKAY
+	MSI-X8:         OKAY
+	MSI-X9:         NOT OKAY
+	MSI-X10:        NOT OKAY
+	MSI-X11:        NOT OKAY
+	MSI-X12:        NOT OKAY
+	MSI-X13:        NOT OKAY
+	MSI-X14:        NOT OKAY
+	MSI-X15:        NOT OKAY
+	MSI-X16:        NOT OKAY
+	[...]
+	MSI-X2047:      NOT OKAY
+	MSI-X2048:      NOT OKAY
+
+	Read Tests
+
+	SET IRQ TYPE TO MSI:            OKAY
+	READ (      1 bytes):           OKAY
+	READ (   1024 bytes):           OKAY
+	READ (   1025 bytes):           OKAY
+	READ (1024000 bytes):           OKAY
+	READ (1024001 bytes):           OKAY
+
+	Write Tests
+
+	WRITE (      1 bytes):          OKAY
+	WRITE (   1024 bytes):          OKAY
+	WRITE (   1025 bytes):          OKAY
+	WRITE (1024000 bytes):          OKAY
+	WRITE (1024001 bytes):          OKAY
+
+	Copy Tests
+
+	COPY (      1 bytes):           OKAY
+	COPY (   1024 bytes):           OKAY
+	COPY (   1025 bytes):           OKAY
+	COPY (1024000 bytes):           OKAY
+	COPY (1024001 bytes):           OKAY
diff --git a/Documentation/PCI/endpoint/pci-vntb-function.rst b/Documentation/PCI/endpoint/pci-vntb-function.rst
new file mode 100644
index 0000000000..0c51f53ab9
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-vntb-function.rst
@@ -0,0 +1,129 @@
+.. 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
+======  ===============================
+
+
diff --git a/Documentation/PCI/endpoint/pci-vntb-howto.rst b/Documentation/PCI/endpoint/pci-vntb-howto.rst
new file mode 100644
index 0000000000..70d3bc9089
--- /dev/null
+++ b/Documentation/PCI/endpoint/pci-vntb-howto.rst
@@ -0,0 +1,164 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+===================================================================
+PCI Non-Transparent Bridge (NTB) Endpoint Function (EPF) User Guide
+===================================================================
+
+:Author: Frank Li <Frank.Li@nxp.com>
+
+This document is a guide to help users use pci-epf-vntb function driver
+and ntb_hw_epf host driver for NTB functionality. The list of steps to
+be followed in the host side and EP side is given below. For the hardware
+configuration and internals of NTB using configurable endpoints see
+Documentation/PCI/endpoint/pci-vntb-function.rst
+
+Endpoint Device
+===============
+
+Endpoint Controller Devices
+---------------------------
+
+To find the list of endpoint controller devices in the system::
+
+        # ls /sys/class/pci_epc/
+          5f010000.pcie_ep
+
+If PCI_ENDPOINT_CONFIGFS is enabled::
+
+        # ls /sys/kernel/config/pci_ep/controllers
+          5f010000.pcie_ep
+
+Endpoint Function Drivers
+-------------------------
+
+To find the list of endpoint function drivers in the system::
+
+	# ls /sys/bus/pci-epf/drivers
+	pci_epf_ntb  pci_epf_test  pci_epf_vntb
+
+If PCI_ENDPOINT_CONFIGFS is enabled::
+
+	# ls /sys/kernel/config/pci_ep/functions
+	pci_epf_ntb  pci_epf_test  pci_epf_vntb
+
+
+Creating pci-epf-vntb Device
+----------------------------
+
+PCI endpoint function device can be created using the configfs. To create
+pci-epf-vntb device, the following commands can be used::
+
+	# mount -t configfs none /sys/kernel/config
+	# cd /sys/kernel/config/pci_ep/
+	# mkdir functions/pci_epf_vntb/func1
+
+The "mkdir func1" above creates the pci-epf-ntb function device that will
+be probed by pci_epf_vntb driver.
+
+The PCI endpoint framework populates the directory with the following
+configurable fields::
+
+	# ls functions/pci_epf_ntb/func1
+	baseclass_code    deviceid          msi_interrupts    pci-epf-ntb.0
+	progif_code       secondary         subsys_id         vendorid
+	cache_line_size   interrupt_pin     msix_interrupts   primary
+	revid             subclass_code     subsys_vendor_id
+
+The PCI endpoint function driver populates these entries with default values
+when the device is bound to the driver. The pci-epf-vntb driver populates
+vendorid with 0xffff and interrupt_pin with 0x0001::
+
+	# cat functions/pci_epf_vntb/func1/vendorid
+	0xffff
+	# cat functions/pci_epf_vntb/func1/interrupt_pin
+	0x0001
+
+
+Configuring pci-epf-vntb Device
+-------------------------------
+
+The user can configure the pci-epf-vntb device using its configfs entry. In order
+to change the vendorid and the deviceid, the following
+commands can be used::
+
+	# echo 0x1957 > functions/pci_epf_vntb/func1/vendorid
+	# echo 0x0809 > functions/pci_epf_vntb/func1/deviceid
+
+The PCI endpoint framework also automatically creates a sub-directory in the
+function attribute directory. This sub-directory has the same name as the name
+of the function device and is populated with the following NTB specific
+attributes that can be configured by the user::
+
+	# ls functions/pci_epf_vntb/func1/pci_epf_vntb.0/
+	db_count    mw1         mw2         mw3         mw4         num_mws
+	spad_count
+
+A sample configuration for NTB function is given below::
+
+	# echo 4 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/db_count
+	# echo 128 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/spad_count
+	# echo 1 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/num_mws
+	# echo 0x100000 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/mw1
+
+A sample configuration for virtual NTB driver for virtual PCI bus::
+
+	# echo 0x1957 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vntb_vid
+	# echo 0x080A > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vntb_pid
+	# echo 0x10 > functions/pci_epf_vntb/func1/pci_epf_vntb.0/vbus_number
+
+Binding pci-epf-ntb Device to EP Controller
+--------------------------------------------
+
+NTB function device should be attached to PCI endpoint controllers
+connected to the host.
+
+	# ln -s controllers/5f010000.pcie_ep functions/pci-epf-ntb/func1/primary
+
+Once the above step is completed, the PCI endpoint controllers are ready to
+establish a link with the host.
+
+
+Start the Link
+--------------
+
+In order for the endpoint device to establish a link with the host, the _start_
+field should be populated with '1'. For NTB, both the PCI endpoint controllers
+should establish link with the host (imx8 don't need this steps)::
+
+	# echo 1 > controllers/5f010000.pcie_ep/start
+
+RootComplex Device
+==================
+
+lspci Output at Host side
+-------------------------
+
+Note that the devices listed here correspond to the values populated in
+"Creating pci-epf-ntb Device" section above::
+
+	# lspci
+        00:00.0 PCI bridge: Freescale Semiconductor Inc Device 0000 (rev 01)
+        01:00.0 RAM memory: Freescale Semiconductor Inc Device 0809
+
+Endpoint Device / Virtual PCI bus
+=================================
+
+lspci Output at EP Side / Virtual PCI bus
+-----------------------------------------
+
+Note that the devices listed here correspond to the values populated in
+"Creating pci-epf-ntb Device" section above::
+
+        # lspci
+        10:00.0 Unassigned class [ffff]: Dawicontrol Computersysteme GmbH Device 1234 (rev ff)
+
+Using ntb_hw_epf Device
+-----------------------
+
+The host side software follows the standard NTB software architecture in Linux.
+All the existing client side NTB utilities like NTB Transport Client and NTB
+Netdev, NTB Ping Pong Test Client and NTB Tool Test Client can be used with NTB
+function device.
+
+For more information on NTB see
+:doc:`Non-Transparent Bridge <../../driver-api/ntb>`