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


On Fri, 23 Sep 2022, Ilpo Järvinen wrote:

> On Fri, 23 Sep 2022, matthew.gerlach@linux.intel.com wrote:
>
>> From: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>>
>> Add documentation describing the extensions provided by Version
>> 1 of the Device Feature Header (DFHv1).
>>
>> Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
>> ---
>> 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"
>
> ?


I was hesitant to have a picture because the description would then be in
two places. I suspect my picture is not clear, but it does line up with
the offset definitions:

DFH offset 0x0
GUID offsets 0x8 and 0x10
CSR_START offset 0x18
CSR_SIZE offset 0x20
First PARAM_HDR, if it exists, is 0x28,
First PARAM_DATA, if it exists, is 0x30.

>
>> + |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.
>
>
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