[PATCH v2 6/6] pds_fwctl: add Documentation entries

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

Add pds_fwctl to the driver and fwctl documentation pages.

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         | 41 +++++++++++++++++++
 3 files changed, 43 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 428f6f5bb9b4..72853b0d3dc8 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 06959fbf1547..12a559fcf1b2 100644
--- a/Documentation/userspace-api/fwctl/index.rst
+++ b/Documentation/userspace-api/fwctl/index.rst
@@ -10,3 +10,4 @@ to securely construct and execute RPCs inside device firmware.
    :maxdepth: 1
 
    fwctl
+   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..f34645dbf5ea
--- /dev/null
+++ b/Documentation/userspace-api/fwctl/pds_fwctl.rst
@@ -0,0 +1,40 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+fwctl pds driver
+================
+
+:Author: Shannon Nelson
+
+Overview
+========
+
+The PDS Core device makes an 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 bus.  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,
+only knows how to send commands through pds_core's message queue to the
+firmware for fwctl requests.  The set of operations available through this
+interface depends on the firmware in the DSC, and the userspace application
+version must match the firmware so that they can talk to each other.
+
+This set of available operations is not known to the pds_fwctl driver.
+When a connection is created the pds_fwctl driver requests from the
+firmware list of endpoints and a list of operations for each endpoint.
+This list of operations includes a minimum scope level that the pds_fwctl
+driver can use for filtering privilege levels.
+
+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 current 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.
-- 
2.17.1