Re: [PATCH v2 1/6] Documentation: fpga: dfl: Add documentation for DFHv1

From: Ilpo Järvinen
Date: Fri Sep 23 2022 - 10:34:38 EST


On Fri, 23 Sep 2022, matthew.gerlach@xxxxxxxxxxxxxxx wrote:

> From: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
>
> Add documentation describing the extensions provided by Version
> 1 of the Device Feature Header (DFHv1).
>
> Signed-off-by: Matthew Gerlach <matthew.gerlach@xxxxxxxxxxxxxxx>
> ---
> v2: s/GUILD/GUID/
> add picture
> ---
> Documentation/fpga/dfl.rst | 49 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 49 insertions(+)
>
> diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> index 15b670926084..7c786b75b498 100644
> --- a/Documentation/fpga/dfl.rst
> +++ b/Documentation/fpga/dfl.rst
> @@ -561,6 +561,55 @@ new DFL feature via UIO direct access, its feature id should be added to the
> driver's id_table.
>
>
> +Extending the Device Feature Header - DFHv1
> +===========================================
> +The current 8 bytes of the Device Feature Header, hereafter referred to as
> +to DFHv0, provide very little opportunity for the hardware to describe itself
> +to software. Version 1 of the Device Feature Header (DFHv1) is being introduced
> +to provide increased flexibility and extensibility to hardware designs using
> +Device Feature Lists. The list below describes some of the goals behind the
> +changes in DFHv1:
> +
> +* Provide a standardized mechanism for features to describe
> + parameters/capabilities to software.
> +* Standardize the use of a GUID for all DFHv1 types.
> +* Decouple the location of the DFH from the register space of the feature itself.
> +
> +Modeled after PCI Capabilities, DFHv1 Parameters provide a mechanism to associate
> +a list of parameter values to a particular feature.
> +
> +With DFHv0, not all features types contained a GUID. DFHv1 makes the GUID standard
> +across all types.
> +
> +With DFHv0, the register map of a given feature is located immediately following
> +the DFHv0 in the memory space. With DFHv1, the location of the feature register
> +map can be specified as an offset to the DFHv1 or as an absolute address. The DFHv1
> +structure is shown below:
> +
> + +-----------------------------------------------------------------------+
> + |63 Type 60|59 DFH VER 52|51 Rsvd 41|40 EOL|39 Next 16|15 VER 12|11 ID 0|
> + +-----------------------------------------------------------------------+
> + |63 GUID_L 0|
> + +-----------------------------------------------------------------------+
> + |63 GUID_H 0|
> + +-----------------------------------------------------------------------+
> + |63 Address/Offset 1| Rel 0|
> + +-----------------------------------------------------------------------+

Is something missing here given the layout is claimed (in 2/6) to be:

"DFHv1 Register Offset definitons
In DHFv1, DFH + GUID + CSR_START + CSR_SIZE_GROUP + PARAM_HDR + PARAM_DATA"

?

> + |63 Size of register set 32|Params 31|30 Group 16|15 Instance 0|
> + +-----------------------------------------------------------------------+
> + |63 Next parameter offset 32|31 Param Version 16|15 Param ID 0|
> + +-----------------------------------------------------------------------+
> + |63 Parameter Data 0|
> + +-----------------------------------------------------------------------+
> +
> + ...
> +
> + +-----------------------------------------------------------------------+
> + |63 Next parameter offset 32|31 Param Version 16|15 Param ID 0|
> + +-----------------------------------------------------------------------+
> + |63 Parameter Data 0|
> + +-----------------------------------------------------------------------+
> +
> Open discussion
> ===============
> FME driver exports one ioctl (DFL_FPGA_FME_PORT_PR) for partial reconfiguration
>

--
i.