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diff --git a/Documentation/userspace-api/fwctl/pds_fwctl.rst b/Documentation/userspace-api/fwctl/pds_fwctl.rst new file mode 100644 index 000000000000..b5a31f82c883 --- /dev/null +++ b/Documentation/userspace-api/fwctl/pds_fwctl.rst @@ -0,0 +1,46 @@ +.. 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 +================== + +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. |