Introduce flowtable hw offloading in airoha_eth driver

Introduce netfilter flowtable integration in airoha_eth driver to
offload 5-tuple flower rules learned by the PPE module if the user
accelerates them using a nft configuration similar to the one reported
below:

table inet filter {
	flowtable ft {
		hook ingress priority filter
		devices = { lan1, lan2, lan3, lan4, eth1 }
		flags offload;
	}
	chain forward {
		type filter hook forward priority filter; policy accept;
		meta l4proto { tcp, udp } flow add @ft
	}
}

Packet Processor Engine (PPE) module available on EN7581 SoC populates
the PPE table with 5-tuples flower rules learned from traffic forwarded
between the GDM ports connected to the Packet Switch Engine (PSE) module.
airoha_eth driver configures and collects data from the PPE module via a
Network Processor Unit (NPU) RISC-V module available on the EN7581 SoC.
Move airoha_eth driver in a dedicated folder
(drivers/net/ethernet/airoha).

---
Changes in v8:
- Remove unnecessary GFP_ZERO flag in dmam_alloc_coherent()
- Fix 802.1q offloading support
- Link to v7: https://lore.kernel.org/r/20250224-airoha-en7581-flowtabl...

Changes in v7:
- Fix Coccicheck warnings
- Add missing request_module
- Introduce ops in airoha_npu struct
- Add missing wlan interrupt to airoha_npu binding
- Link to v6: https://lore.kernel.org/r/20250221-airoha-en7581-flowtabl...

Changes in v6:
- Fix Smatch errors.
- Remove unnecessary GFP_DMA allocating NPU buffers
- Remove wrong dma coherent mask
- Rely on skb_cow_head() instead of skb_ensure_writable() in
  airoha_get_dsa_tag()
- Unregister net_device before deallocating metadata_dst
- Link to v5: https://lore.kernel.org/r/20250217-airoha-en7581-flowtabl...

Changes in v5:
- Fix uninitialized variable in airoha_ppe_setup_tc_block_cb()
- Rebase on top of net-next
- Link to v4: https://lore.kernel.org/r/20250213-airoha-en7581-flowtabl...

Changes in v4:
- Add dedicated driver for the Airoha NPU module
- Move airoha npu binding in net
- Link to v3: https://lore.kernel.org/r/20250209-airoha-en7581-flowtabl...

Changes in v3:
- Fix TSO support for header cloned skbs
- Do not use skb_pull_rcsum() in airoha_get_dsa_tag()
- Fix head lean computation after running airoha_get_dsa_tag() in
  airoha_dev_xmit()
- Link to v2: https://lore.kernel.org/r/20250207-airoha-en7581-flowtabl...

Changes in v2:
- Add airoha-npu document binding
- Enable Rx SPTAG on MT7530 dsa switch for EN7581 SoC.
- Fix warnings in airoha_npu_run_firmware()
- Fix sparse warnings
- Link to v1: https://lore.kernel.org/r/20250205-airoha-en7581-flowtabl...

---
Lorenzo Bianconi (15):
      net: airoha: Move airoha_eth driver in a dedicated folder
      net: airoha: Move definitions in airoha_eth.h
      net: airoha: Move reg/write utility routines in airoha_eth.h
      net: airoha: Move register definitions in airoha_regs.h
      net: airoha: Move DSA tag in DMA descriptor
      net: dsa: mt7530: Enable Rx sptag for EN7581 SoC
      net: airoha: Enable support for multiple net_devices
      net: airoha: Move REG_GDM_FWD_CFG() initialization in airoha_dev_init()
      net: airoha: Rename airoha_set_gdm_port_fwd_cfg() in airoha_set_vip_for_gdm_port()
      dt-bindings: net: airoha: Add the NPU node for EN7581 SoC
      dt-bindings: net: airoha: Add airoha,npu phandle property
      net: airoha: Introduce Airoha NPU support
      net: airoha: Introduce flowtable offload support
      net: airoha: Add loopback support for GDM2
      net: airoha: Introduce PPE debugfs support

 .../devicetree/bindings/net/airoha,en7581-eth.yaml |   10 +
 .../devicetree/bindings/net/airoha,en7581-npu.yaml |   84 ++
 drivers/net/dsa/mt7530.c                           |    5 +
 drivers/net/dsa/mt7530.h                           |    4 +
 drivers/net/ethernet/Kconfig                       |    2 +
 drivers/net/ethernet/Makefile                      |    1 +
 drivers/net/ethernet/airoha/Kconfig                |   27 +
 drivers/net/ethernet/airoha/Makefile               |    9 +
 .../net/ethernet/{mediatek => airoha}/airoha_eth.c | 1277 +++++---------------
 drivers/net/ethernet/airoha/airoha_eth.h           |  551 +++++++++
 drivers/net/ethernet/airoha/airoha_npu.c           |  520 ++++++++
 drivers/net/ethernet/airoha/airoha_npu.h           |   34 +
 drivers/net/ethernet/airoha/airoha_ppe.c           |  910 ++++++++++++++
 drivers/net/ethernet/airoha/airoha_ppe_debugfs.c   |  181 +++
 drivers/net/ethernet/airoha/airoha_regs.h          |  798 ++++++++++++
 drivers/net/ethernet/mediatek/Kconfig              |    8 -
 drivers/net/ethernet/mediatek/Makefile             |    1 -
 17 files changed, 3422 insertions(+), 1000 deletions(-)
---
base-commit: 56794b5862c5a9aefcf2b703257c6fb93f76573e
change-id: 20250205-airoha-en7581-flowtable-offload-e3a11b3b34ad

Best regards,
-- 
Lorenzo Bianconi <lorenzo@kernel.org>