net: lan966x: add PCIe FDMA support

Add PCIe FDMA support for lan966x. The PCIe FDMA path uses contiguous
DMA buffers mapped through the endpoint's ATU, with memcpy-based frame
transfer instead of per-page DMA mappings.

With PCIe FDMA, throughput increases from ~33 Mbps (register-based I/O)
to ~620 Mbps on an Intel x86 host with a lan966x PCIe card.

The RX path uses its own copy of lan966x_hw_offload() that reports back
when skb_vlan_untag() frees the skb, so the caller can drop the frame
instead of touching it.

XDP is not supported on this path yet, so do not advertise xdp_features
and reject program attach for PCIe instances.

Tested-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260928-lan966x-pci-fdma-v9-11-a17caf60f89a@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions