[PATCH net-next v3 0/2] net: stmmac: dwxgmac2: timestamp interrupt + Agilex5 fix

[Zxyan Zhu <zxyan0222@gmail.com>]

This series adds auxiliary snapshot (EXTTS) interrupt support to
DWXGMAC2/DWXLGMAC2 and fixes a regression it would introduce on the
Agilex5 cross-timestamp path.

Patch 1 wires up a dedicated DWXGMAC2 timestamp interrupt handler.
Before this change the XGMAC hwif entries used the generic stmmac_ptp
ops, whose timestamp_interrupt callback read the dwmac4 offset
GMAC_TIMESTAMP_STATUS (0xb20) instead of the XGMAC register at 0xd20,
and XGMAC_TSIE was never enabled, so auxiliary snapshot events were
never reported on XGMAC platforms.

Patch 1 also unmasks XGMAC_TSIE in XGMAC_INT_DEFAULT_EN.  That makes the
new handler run from hardirq on every XGMAC timestamp event, which races
with the Agilex5 smtg_crosststamp() poll loop: the handler clears TSIS
by reading XGMAC_TIMESTAMP_STATUS before the poll loop in process
context can observe it, so getcrosststamp() times out.  Patch 2 fixes
this by masking XGMAC_TSIE for the duration of the cross-timestamp so
the handler cannot steal TSIS while smtg_crosststamp() owns the
snapshot FIFO.

Patch 2 has been verified on Agilex5 hardware: with both patches
applied, smtg_crosststamp() no times out (no "Wait for time sync
operation timeout" in dmesg) and the PTP clock registers and operates
normally.

v1: https://lore.kernel.org/netdev/20260806-dwxgmac2-timestamp-irq-v1-1-c051c79c9d90@gmail.com/
v2: https://lore.kernel.org/netdev/20260810100221.9166-1-zxyan0222@gmail.com/
v3:
- Add patch 2 to mask XGMAC_TSIE during the Agilex5 cross-timestamp, so
  enabling XGMAC_TSIE in patch 1 does not break getcrosststamp() on
  Agilex5 XGMAC (reported by the netdev sashiko review, fixed approach
  discussed with Maxime).
- Patch 2 verified on Agilex5 by Nazim Amirul (Tested-by tag carried on
  patch 2).

Zxyan Zhu (2):
  net: stmmac: dwxgmac2: add XGMAC timestamp interrupt support
  net: stmmac: dwmac-socfpga: mask XGMAC_TSIE during cross-timestamp

 .../ethernet/stmicro/stmmac/dwmac-socfpga.c   | 11 +++++
 .../net/ethernet/stmicro/stmmac/dwxgmac2.h    |  2 +-
 .../ethernet/stmicro/stmmac/dwxgmac2_core.c   | 43 +++++++++++++++++++
 drivers/net/ethernet/stmicro/stmmac/hwif.c    |  4 +-
 drivers/net/ethernet/stmicro/stmmac/hwif.h    |  1 +
 .../ethernet/stmicro/stmmac/stmmac_hwtstamp.c | 12 ++++++
 .../net/ethernet/stmicro/stmmac/stmmac_ptp.h  |  1 +
 7 files changed, 71 insertions(+), 3 deletions(-)

--
2.34.1