SpacemiT K1 has two gigabit Ethernet MACs with RGMII and RMII support.
Add devicetree bindings, driver, and DTS for it.

Tested primarily on BananaPi BPI-F3. Basic TX/RX functionality also
tested on Milk-V Jupiter.

I would like to note that even though some bit field names superficially
resemble that of DesignWare MAC, all other differences point to it in
fact being a custom design.

Based on SpacemiT drivers [1]. These patches are also available at:

https://github.com/dramforever/linux/tree/k1/ethernet/v9

[1]: https://github.com/spacemit-com/linux-k1x

---
Changes in v9:
- Refactor to use phy_interface_mode_is_rgmii
- Minor changes
  - Use netdev_err in more places
  - Print phy-mode by name on unsupported phy-mode
- Link to v8: https://lore.kernel.org/r/20250828-net-k1-emac-v8-0-e9075dd2ca90@iscas.ac.cn (local)

Changes in v8:
- Use devres to do of_phy_deregister_fixed_link on probe failure or
  remove
- Simplified control flow in a few places with early return or continue
- Minor changes
  - Removed some unneeded parens in emac_configure_{tx,rx}
- Link to v7: https://lore.kernel.org/r/20250826-net-k1-emac-v7-0-5bc158d086ae@iscas.ac.cn (local)

Changes in v7:
- Removed scoped_guard usage
- Renamed error handling path labels after destinations
- Fix skb free error handling path in emac_start_xmit and emac_tx_mem_map
- Cancel tx_timeout_task to prevent schedule_work lifetime problems
- Minor changes:
  - Remove unnecessary timer_delete_sync in emac_down
  - Use dev_err_ratelimited in a few more places
  - Cosmetic fixes in error messages
- Link to v6: https://lore.kernel.org/r/20250820-net-k1-emac-v6-0-c1e28f2b8be5@iscas.ac.cn (local)

Changes in v6:
- Implement pause frame support
- Minor changes:
  - Convert comment for emac_stats_update() into assert_spin_locked()
  - Cosmetic fixes for some comments and whitespace
  - emac_set_mac_addr() is now refactored
- Link to v5: https://lore.kernel.org/r/20250812-net-k1-emac-v5-0-dd17c4905f49@iscas.ac.cn (local)

Changes in v5:
- Rebased on v6.17-rc1, add back DTS now that they apply cleanly
- Use standard statistics interface, handle 32-bit statistics overflow
- Minor changes:
  - Fix clock resource handling in emac_resume
  - Ratelimit the message in emac_rx_frame_status
  - Add ndo_validate_addr = eth_validate_addr
  - Remove unnecessary parens in emac_set_mac_addr
  - Change some functions that never fail to return void instead of int
  - Minor rewording
- Link to v4: https://lore.kernel.org/r/20250703-net-k1-emac-v4-0-686d09c4cfa8@iscas.ac.cn (local)

Changes in v4:
- Resource handling on probe and remove: timer_delete_sync and
  of_phy_deregister_fixed_link
- Drop DTS changes and dependencies (will send through SpacemiT tree)
- Minor changes:
  - Remove redundant phy_stop() and setting of ndev->phydev
  - Fix error checking for emac_open in emac_resume
  - Fix one missed dev_err -> dev_err_probe
  - Fix type of emac_start_xmit
  - Fix one missed reverse xmas tree formatting
  - Rename some functions for consistency between emac_* and ndo_*
- Link to v3: https://lore.kernel.org/r/20250702-net-k1-emac-v3-0-882dc55404f3@iscas.ac.cn (local)

Changes in v3:
- Refactored and simplified emac_tx_mem_map
- Addressed other minor v2 review comments
- Removed what was patch 3 in v2, depend on DMA buses instead
- DT nodes in alphabetical order where appropriate
- Link to v2: https://lore.kernel.org/r/20250618-net-k1-emac-v2-0-94f5f07227a8@iscas.ac.cn (local)

Changes in v2:
- dts: Put eth0 and eth1 nodes under a bus with dma-ranges
- dts: Added Milk-V Jupiter
- Fix typo in emac_init_hw() that broke the driver (Oops!)
- Reformatted line lengths to under 80
- Addressed other v1 review comments
- Link to v1: https://lore.kernel.org/r/20250613-net-k1-emac-v1-0-cc6f9e510667@iscas.ac.cn (local)

---
Vivian Wang (5):
      dt-bindings: net: Add support for SpacemiT K1
      net: spacemit: Add K1 Ethernet MAC
      riscv: dts: spacemit: Add Ethernet support for K1
      riscv: dts: spacemit: Add Ethernet support for BPI-F3
      riscv: dts: spacemit: Add Ethernet support for Jupiter

 .../devicetree/bindings/net/spacemit,k1-emac.yaml  |   81 +
 arch/riscv/boot/dts/spacemit/k1-bananapi-f3.dts    |   46 +
 arch/riscv/boot/dts/spacemit/k1-milkv-jupiter.dts  |   46 +
 arch/riscv/boot/dts/spacemit/k1-pinctrl.dtsi       |   48 +
 arch/riscv/boot/dts/spacemit/k1.dtsi               |   22 +
 drivers/net/ethernet/Kconfig                       |    1 +
 drivers/net/ethernet/Makefile                      |    1 +
 drivers/net/ethernet/spacemit/Kconfig              |   29 +
 drivers/net/ethernet/spacemit/Makefile             |    6 +
 drivers/net/ethernet/spacemit/k1_emac.c            | 2183 ++++++++++++++++++++
 drivers/net/ethernet/spacemit/k1_emac.h            |  426 ++++
 11 files changed, 2889 insertions(+)
---
base-commit: 062b3e4a1f880f104a8d4b90b767788786aa7b78
change-id: 20250606-net-k1-emac-3e181508ea64

Best regards,
-- 
Vivian "dramforever" Wang