igc: Add support for Frame Preemption feature in IGC

Introduces support for the FPE feature in the IGC driver.

The patches aligns with the upstream FPE API:
https://patchwork.kernel.org/project/netdevbpf/cover/2023...
https://patchwork.kernel.org/project/netdevbpf/cover/2023...

It builds upon earlier work:
https://patchwork.kernel.org/project/netdevbpf/cover/2022...

The patch series adds the following functionalities to the IGC driver:
a) Configure FPE using `ethtool --set-mm`.
b) Display FPE settings via `ethtool --show-mm`.
c) View FPE statistics using `ethtool --include-statistics --show-mm'.
e) Block setting preemptible tc in taprio since it is not supported yet.
   Existing code already blocks it in mqprio.

Tested:
Enabled CONFIG_PROVE_LOCKING, CONFIG_DEBUG_ATOMIC_SLEEP, CONFIG_DMA_API_DEBUG, and CONFIG_KASAN
1) selftests
2) netdev down/up cycles
3) suspend/resume cycles
4) fpe verification

No bugs or unusual dmesg logs were observed.
Ran 1), 2) and 3) with and without the patch series, compared dmesg and selftest logs — no differences found.

Change Log:
v5 -> v6:
- Added Tested-by: Furong Xu for patch 1/9 (Vladimir, Furong Xu)
- Updated logic in ethtool_mmsv_link_state_handle() (Vladimir, Furong Xu)
- Swap sequence of function call in stmmac_set_mm() (Furong Xu)
- Log an error if igc_enable_empty_addr_recv() fails (Vladimir)
- Move the patch ".. Block setting preemptible traffic .." before ".. Add support to get MAC Merge data .." (Vladimir)
- Move mmsv function kernel-doc from .h to .c file (Vladimir)

v4 -> v5:
- Remove "igc: Add support for preemptible traffic class in taprio" patch (Vladimir)
- Add a new patch "igc: Block setting preemptible traffic classes in taprio" (Vladimir)
- Add kernel-doc for mmsv api (Vladimir)
- olininfo_status to use host byte order (Simon)
- status_error should host byte type (Simon)
- Some code was misplaced in the wrong patch (Vladimir)
- Mix of tabs and spaces in patch description (Vladimir)
- Created igc_is_pmac_enabled() to reduce code repetition (Vladimir)

v3 -> v4:
- Fix compilation warnings introduced by this patch series

v2 -> v3:
- Implement configure_tx() mmsv callback (Vladimir)
- Use static_branch_inc() and static_branch_dec() (Vladimir)
- Add adapter->fpe.mmsv.pmac_enabled as extra check (Vladimir)
- Remove unnecessary error check in igc_fpe_init_tx_descriptor() (Vladimir)
- Additional places to use FIELD_PREP() instead of manual bit manipulation (Vladimir)
- IGC_TXD_POPTS_SMD_V and IGC_TXD_POPTS_SMD_R type change to enum (Vladimir)
- Remove unnecessary netif_running() check in igc_fpe_xmit_frame (Vladimir)
- Rate limit print in igc_fpe_send_mpacket (Vladimir)

v1 -> v2:
- Extract the stmmac verification logic into a common library (Vladimir)
- igc to use common library for verification (Vladimir)
- Fix syntax for kernel-doc to use "Return:" (Vladimir)
- Use FIELD_GET instead of manual bit masking (Vladimir)
- Don't assign 0 to statistics counter in igc_ethtool_get_mm_stats() (Vladimir)
- Use pmac-enabled as a condition to allow MAC address value 0 (Vladimir)
- Define macro register value in increasing value order (Vladimir)
- Fix tx-min-frag-size handling for igc (Vladimir)
- Handle link state changes with verification in igc (Vladimir)
- Add static key for fast path code (Vladimir)
- rx_min_frag_size get from constant (Vladimir)

v1: https://patchwork.kernel.org/project/netdevbpf/cover/2024...
v2: https://patchwork.kernel.org/project/netdevbpf/cover/2025...
v3: https://patchwork.kernel.org/project/netdevbpf/cover/2025...
v4: https://patchwork.kernel.org/project/netdevbpf/cover/2025...
v5: https://patchwork.kernel.org/project/netdevbpf/cover/2025...

Faizal Rahim (8):
  igc: Rename xdp_get_tx_ring() for non-xdp usage
  igc: Optimize the TX packet buffer utilization
  igc: Set the RX packet buffer size for TSN mode
  igc: Add support for frame preemption verification
  igc: Add support to set tx-min-frag-size
  igc: Block setting preemptible traffic class in taprio
  igc: Add support to get MAC Merge data via ethtool
  igc: Add support to get frame preemption statistics via ethtool

Vladimir Oltean (1):
  net: ethtool: mm: extract stmmac verification logic into common
    library

 drivers/net/ethernet/intel/igc/igc.h          |  15 +-
 drivers/net/ethernet/intel/igc/igc_base.h     |   1 +
 drivers/net/ethernet/intel/igc/igc_defines.h  |  15 +-
 drivers/net/ethernet/intel/igc/igc_ethtool.c  |  76 +++++
 drivers/net/ethernet/intel/igc/igc_main.c     |  67 ++++-
 drivers/net/ethernet/intel/igc/igc_regs.h     |  16 +
 drivers/net/ethernet/intel/igc/igc_tsn.c      | 193 +++++++++++-
 drivers/net/ethernet/intel/igc/igc_tsn.h      |  52 ++++
 drivers/net/ethernet/stmicro/stmmac/stmmac.h  |  16 +-
 .../ethernet/stmicro/stmmac/stmmac_ethtool.c  |  41 +--
 .../net/ethernet/stmicro/stmmac/stmmac_fpe.c  | 174 +++--------
 .../net/ethernet/stmicro/stmmac/stmmac_fpe.h  |   5 -
 .../net/ethernet/stmicro/stmmac/stmmac_main.c |   8 +-
 include/linux/ethtool.h                       |  73 +++++
 net/ethtool/mm.c                              | 281 +++++++++++++++++-
 15 files changed, 816 insertions(+), 217 deletions(-)

--
2.34.1