Add Secure Offload Engine (SOE) support for the Airoha EN7581 Ethernet
driver. SOE provides inline ESP packet offload for native ESP and NAT-T
traffic, with the Ethernet/QDMA path used to submit packets to the SOE
block and the PPE path used to bind eligible ESP flows. NETIF_F_GSO_ESP
and NETIF_F_HW_ESP_TX_CSUM are intentionally left out for now and will be
revisited separately for feasibility.

This is posted as RFC because the code was originally developed and tested
against an OpenWrt 6.18 Airoha tree, not against the current upstream
net-next driver. The original OpenWrt commit used as the source for this
RFC is available at:
https://github.com/hurryman2212/OpenW1700k-test/commit/7c1b5e662f7790b3d23ed143beadc1dcbf6d15f7

The SOE part is intentionally linked into the airoha Ethernet module
instead of being exposed as an independent crypto or platform driver. The
user-visible ESP offload control is a netdev capability: xfrmdev_ops and
NETIF_F_HW_ESP live on the target netdev, and the feature can be controlled
through the usual netdev feature path. SOE also shares the FE/QDMA/PPE
datapath, private queues, DSA conduit handling and netdev lifetime owned by
airoha_eth.

Patch 1 adds xdo_dev_packet_xmit() because the existing XFRM packet
offload transmit path does not provide a hook for hardware whose ESP engine
is reached through device-specific packet forwarding. SOE needs to consume
the skb, add a hardware hop descriptor, steer it to a private QDMA path and
return the final transmit status. Drivers that do not implement the
optional callback keep the existing XFRM output behavior.

Jihong Min (7):
  xfrm: allow packet offload drivers to own transmit
  dt-bindings: net: airoha: add EN7581 SOE
  arm64: dts: airoha: add EN7581 SOE node
  net: airoha: add SOE registers and driver state
  net: airoha: add QDMA support for SOE packets
  net: airoha: add PPE support for SOE flows
  net: airoha: add SOE XFRM packet offload support

 .../bindings/net/airoha,en7581-soe.yaml       |   48 +
 MAINTAINERS                                   |    1 +
 arch/arm64/boot/dts/airoha/en7581.dtsi        |    6 +
 drivers/net/ethernet/airoha/Kconfig           |   13 +
 drivers/net/ethernet/airoha/Makefile          |    1 +
 drivers/net/ethernet/airoha/airoha_eth.c      |  668 +++++-
 drivers/net/ethernet/airoha/airoha_eth.h      |   40 +
 drivers/net/ethernet/airoha/airoha_ppe.c      |  606 +++++-
 drivers/net/ethernet/airoha/airoha_regs.h     |   16 +
 drivers/net/ethernet/airoha/airoha_soe.c      | 1896 +++++++++++++++++
 drivers/net/ethernet/airoha/airoha_soe.h      |  126 ++
 include/linux/netdevice.h                     |    8 +
 include/linux/soc/airoha/airoha_offload.h     |    5 +
 net/xfrm/xfrm_output.c                        |   11 +
 14 files changed, 3342 insertions(+), 103 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/net/airoha,en7581-soe.yaml
 create mode 100644 drivers/net/ethernet/airoha/airoha_soe.c
 create mode 100644 drivers/net/ethernet/airoha/airoha_soe.h

-- 
2.53.0