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

[Jonathan Cameron <Jonathan.Cameron@huawei.com>]

On Fri, 28 Feb 2025 17:35:54 -0800
Shannon Nelson <shannon.nelson@amd.com> wrote:

> Add pds_fwctl to the driver and fwctl documentation pages.
> 
> Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Really minor stuff inline.

Thanks,

Jonathan

> ---
>  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

fwctl is a class not a bus though here I'd be tempted to say subsystem.

> +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.
requests from the firmware both a list of endpoints and a list of operations for
each endpoint. 

As currently written the sentence suggest that we are asking for something
unspecified from the "firmware list of endpoints..."

> +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.