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pds_fwctl: add Documentation entries
Add pds_fwctl to the driver and fwctl documentation pages.
Link: https://patch.msgid.link/r/20250320194412.67983-7-shannon.nelson@amd.com
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
authored by
Shannon Nelson
and committed by
Jason Gunthorpe
40325707
92c66ee8
+48
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Documentation/userspace-api/fwctl/fwctl.rst
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Documentation/userspace-api/fwctl/fwctl.rst
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Documentation/userspace-api/fwctl/pds_fwctl.rst
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Documentation/userspace-api/fwctl/pds_fwctl.rst
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.. SPDX-License-Identifier: GPL-2.0
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================
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fwctl pds driver
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================
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:Author: Shannon Nelson
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Overview
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========
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The PDS Core device makes a fwctl service available through an
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auxiliary_device named pds_core.fwctl.N. The pds_fwctl driver binds to
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this device and registers itself with the fwctl subsystem. The resulting
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userspace interface is used by an application that is a part of the
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AMD Pensando software package for the Distributed Service Card (DSC).
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The pds_fwctl driver has little knowledge of the firmware's internals.
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It only knows how to send commands through pds_core's message queue to the
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firmware for fwctl requests. The set of fwctl operations available
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depends on the firmware in the DSC, and the userspace application
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version must match the firmware so that they can talk to each other.
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When a connection is created the pds_fwctl driver requests from the
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firmware a list of firmware object endpoints, and for each endpoint the
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driver requests a list of operations for that endpoint.
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Each operation description includes a firmware defined command attribute
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that maps to the FWCTL scope levels. The driver translates those firmware
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values into the FWCTL scope values which can then be used for filtering the
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scoped user requests.
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pds_fwctl User API
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==================
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Each RPC request includes the target endpoint and the operation id, and in
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and out buffer lengths and pointers. The driver verifies the existence
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of the requested endpoint and operations, then checks the request scope
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against the required scope of the operation. The request is then put
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together with the request data and sent through pds_core's message queue
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to the firmware, and the results are returned to the caller.
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The RPC endpoints, operations, and buffer contents are defined by the
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particular firmware package in the device, which varies across the
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available product configurations. The details are available in the
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specific product SDK documentation.