Xilinx OPB/XPS HWICAP FPGA self-reconfiguration interface
An on-chip interface that lets a MicroBlaze soft-CPU running Linux read and rewrite parts of its own FPGA bitstream at runtime, used on Xilinx Virtex-II Pro, Virtex-4, Virtex-5, Virtex-6 and Spartan-6 boards built around the older OPB and XPS buses through roughly 2011. It enabled partial reconfiguration features on embedded FPGA systems before Xilinx moved to the AXI-based HWICAP cores.
recommendation
Worth keeping but documenting as legacy, because it only binds to the older OPB/XPS HWICAP cores used in Virtex-II Pro through Virtex-6 era MicroBlaze designs (last specified in 2011), while AMD/Xilinx have since moved new designs to the AXI HWICAP v3.0 IP that this code does not target. Upstream activity in 2024 (a NULL-pointer bugfix and a treewide API update) shows it is still being maintained rather than dismantled, so removal would be premature even though deployments today are sparse.
repository signals
sources
- lore.kernel.org
Upstream still takes functional fixes for this driver; a NULL-vs-IS_ERR bugfix was posted in February 2024.
- lore.kernel.org
The driver also received treewide API adaptation in April 2024, indicating it is still kept buildable in mainline.
- docs.amd.com
The XPS HWICAP product spec is an older PLB-based core (DS586, June 22 2011) for Spartan-6 and Virtex-4/5/6-class devices, matching the Linux driver's legacy OPB/XPS bindings rather than current AMD FPGA flows.
- docs.amd.com
AMD still documents HWICAP in 2025, but as AXI HWICAP v3.0; this suggests current new designs use AXI-era IP, not the OPB/XPS cores this Linux driver binds.
codex reasoning notes (technical)
Local source inspection via shell showed only legacy OF compatibles (xlnx,opb-hwicap-1.00.b and xlnx,xps-hwicap-1.00.a) and family strings up to virtex6 in xilinx_hwicap.c. Activity evidence came from lore_file_timeline on drivers/char/xilinx_hwicap/xilinx_hwicap.c, which showed 2024-2025 fixes/treewide churn rather than removal. Product URLs were obtained by web search on docs.amd.com; DS586 identifies the older XPS HWICAP core, while PG134 shows the modern AXI HWICAP line. Conclusion: legacy hardware/IP with low present-day deployment, but still enough upstream maintenance that deprecate/remove would be premature; annotate as legacy instead.