[PATCH v4 6/6] pds_fwctl: add Documentation entries

[Shannon Nelson <shannon.nelson@amd.com>]

Add pds_fwctl to the driver and fwctl documentation pages.

Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
---
 Documentation/userspace-api/fwctl/fwctl.rst   |  1 +
 Documentation/userspace-api/fwctl/index.rst   |  1 +
 .../userspace-api/fwctl/pds_fwctl.rst         | 48 +++++++++++++++++++
 3 files changed, 50 insertions(+)
 create mode 100644 Documentation/userspace-api/fwctl/pds_fwctl.rst

diff --git a/Documentation/userspace-api/fwctl/fwctl.rst b/Documentation/userspace-api/fwctl/fwctl.rst
index 04ad78a7cd48..fdcfe418a83f 100644
--- a/Documentation/userspace-api/fwctl/fwctl.rst
+++ b/Documentation/userspace-api/fwctl/fwctl.rst
@@ -150,6 +150,7 @@ fwctl User API
 
 .. kernel-doc:: include/uapi/fwctl/fwctl.h
 .. kernel-doc:: include/uapi/fwctl/mlx5.h
+.. kernel-doc:: include/uapi/fwctl/pds.h
 
 sysfs Class
 -----------
diff --git a/Documentation/userspace-api/fwctl/index.rst b/Documentation/userspace-api/fwctl/index.rst
index d9d40a468a31..316ac456ad3b 100644
--- a/Documentation/userspace-api/fwctl/index.rst
+++ b/Documentation/userspace-api/fwctl/index.rst
@@ -11,3 +11,4 @@ to securely construct and execute RPCs inside device firmware.
 
    fwctl
    fwctl-cxl
+   pds_fwctl
diff --git a/Documentation/userspace-api/fwctl/pds_fwctl.rst b/Documentation/userspace-api/fwctl/pds_fwctl.rst
new file mode 100644
index 000000000000..a8f5a457ba0f
--- /dev/null
+++ b/Documentation/userspace-api/fwctl/pds_fwctl.rst
@@ -0,0 +1,48 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+fwctl pds driver
+================
+
+:Author: Shannon Nelson
+
+Overview
+========
+
+The PDS Core device makes a fwctl service available through an
+auxiliary_device named pds_core.fwctl.N.  The pds_fwctl driver binds to
+this device and registers itself with the fwctl subsystem.  The resulting
+userspace interface is used by an application that is a part of the
+AMD Pensando software package for the Distributed Service Card (DSC).
+
+The pds_fwctl driver has little knowledge of the firmware's internals.
+It only knows how to send commands through pds_core's message queue to the
+firmware for fwctl requests.  The set of fwctl operations available
+depends on the firmware in the DSC, and the userspace application
+version must match the firmware so that they can talk to each other.
+
+When a connection is created the pds_fwctl driver requests from the
+firmware a list of firmware object endpoints, and for each endpoint the
+driver requests a list of operations for that endpoint.
+
+Each operation description includes a firmware defined command attribute
+that maps to the FWCTL scope levels.  The driver translates those firmware
+values into the FWCTL scope values which can then be used for filtering the
+scoped user requests.
+
+pds_fwctl User API
+==================
+
+.. kernel-doc:: include/uapi/fwctl/pds.h
+
+Each RPC request includes the target endpoint and the operation id, and in
+and out buffer lengths and pointers.  The driver verifies the existence
+of the requested endpoint and operations, then checks the request scope
+against the required scope of the operation.  The request is then put
+together with the request data and sent through pds_core's message queue
+to the firmware, and the results are returned to the caller.
+
+The RPC endpoints, operations, and buffer contents are defined by the
+particular firmware package in the device, which varies across the
+available product configurations.  The details are available in the
+specific product SDK documentation.
-- 
2.17.1