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>
---
v3: no change
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|
+ +-----------------------------------------------------------------------+
+ |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
--
2.25.1
