[dpdk-dev] [PATCH v3 11/11] doc: add rawdev library page

[Shreyansh Jain]

Signed-off-by: Shreyansh Jain <shreyansh.jain at nxp.com>
---
 doc/guides/prog_guide/index.rst      |  1 +
 doc/guides/prog_guide/rawdev_lib.rst | 83 ++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 doc/guides/prog_guide/rawdev_lib.rst

diff --git a/doc/guides/prog_guide/index.rst b/doc/guides/prog_guide/index.rst
index af5f65a33..beead3105 100644
--- a/doc/guides/prog_guide/index.rst
+++ b/doc/guides/prog_guide/index.rst
@@ -75,6 +75,7 @@ Programmer's Guide
     vhost_lib
     metrics_lib
     port_hotplug_framework
+    rawdev_lib
     source_org
     dev_kit_build_system
     dev_kit_root_make_help
diff --git a/doc/guides/prog_guide/rawdev_lib.rst b/doc/guides/prog_guide/rawdev_lib.rst
new file mode 100644
index 000000000..d21d284ca
--- /dev/null
+++ b/doc/guides/prog_guide/rawdev_lib.rst
@@ -0,0 +1,83 @@
+..  SPDX-License-Identifier: BSD-3-Clause
+    Copyright 2018 NXP
+
+Rawdevice Library
+=================
+
+Introduction
+------------
+
+In terms of device flavor (type) support, DPDK currently has ethernet
+(lib_ether), cryptodev (libcryptodev), eventdev (libeventdev) and vdev
+(virtual device) support.
+
+For a new type of device, for example an accelerator, there are not many
+options except:
+1. create another lib/librte_MySpecialDev, driver/MySpecialDrv and use it
+through Bus/PMD model.
+2. Or, create a vdev and implement necessary custom APIs which are directly
+exposed from driver layer. However this may still require changes in bus code
+in DPDK.
+
+The DPDK Rawdev library is an abstraction that provides the DPDK framework a
+way to manage such devices in a generic manner without expecting changes to
+library or EAL for each device type. This library provides a generic set of
+operations and APIs for framework and Applications to use, respectively, for
+interfacing with such type of devices.
+
+Design
+------
+
+Key factors guiding design of the Rawdevice library:
+
+1. Following are some generic operations which can be treated as applicable
+   to a large subset of device types. None of the operations are mandatory to
+   be implemented by a driver. Application should also be design for proper
+   handling for unsupported APIs.
+
+  * Device Start/Stop - In some cases, 'reset' might also be required which
+    has different semantics than a start-stop-start cycle.
+  * Configuration - Device, Queue or any other sub-system configuration
+  * I/O - Sending a series of buffers which can enclose any arbitrary data
+  * Statistics - Fetch arbitrary device statistics
+  * Firmware Management - Firmware load/unload/status
+
+2. Application API should be able to pass along arbitrary state information
+   to/fro device driver. This can be achieved by maintaining context
+   information through opaque data or pointers.
+
+Figure below outlines the layout of the rawdevice library and device vis-a-vis
+other well known device types like eth and crypto:
+
+.. code-block:: console
+
+     +-----------------------------------------------------------+
+     |                        Application(s)                     |
+     +------------------------------.----------------------------+
+                                    |
+                                    |
+     +------------------------------'----------------------------+
+     |                     DPDK Framework (APIs)                 |
+     +--------------|----|-----------------|---------------------+
+                   /      \                 \
+            (crypto ops)  (eth ops)      (rawdev ops)        +----+
+            /               \                 \              |DrvA|
+     +-----'---+        +----`----+        +---'-----+       +----+
+     | crypto  |        | ethdev  |        | raw     |
+     +--/------+        +---/-----+        +----/----+       +----+
+       /\                __/\                  /   ..........|DrvB|
+      /  \              /    \                / ../    \     +----+
+  +====+ +====+    +====+ +====+            +==/=+      ```Bus Probe
+  |DevA| |DevB|    |DevC| |DevD|            |DevF|
+  +====+ +====+    +====+ +====+            +====+
+    |      |        |      |                 |
+  ``|``````|````````|``````|`````````````````|````````Bus Scan
+   (PCI)   |       (PCI)  (PCI)            (PCI)
+         (BusA)
+
+ * It is assumed above that DrvB is a PCI type driver which registers itself
+   with PCI Bus
+ * Thereafter, when the PCI scan is done, during probe DrvB would match the
+   rawdev DevF ID and take control of device
+ * Applications can then continue using the device through rawdev API
+   interfaces
-- 
2.14.1