[PATCH v6 0/5] Support multi-channel IRQs in stmmac platform drivers

The stmmac core supports two interrupt modes, controlled by the
flag STMMAC_FLAG_MULTI_MSI_EN:

- When the flag is set, the driver uses multi-channel IRQ mode (Multi-IRQ).
- Otherwise, a single IRQ line is requested (aka MAC-IRQ):

static int stmmac_request_irq(struct net_device *dev)
{
        /* Request the IRQ lines */
        if (priv->plat->flags & STMMAC_FLAG_MULTI_MSI_EN)
                ret = stmmac_request_irq_multi_msi(dev);
        else
                ret = stmmac_request_irq_single(dev);
}

At present, only PCI drivers (Intel and Loongson) make use of the Multi-IRQ
mode. This concept can be extended to DT-based embedded glue drivers
(dwmac-xxx.c).

This series adds support for reading per-channel IRQs from the DT node and
reuses the existing STMMAC_FLAG_MULTI_MSI_EN flag to enable multi-IRQ
operation in platform drivers.

The final decision if Multi-IRQ gets enabled remains on glue driver
to allow implementing any reguirements/limitions the focused platform
needs.

NXP S32G2/S32G3/S32R SoCs integrate the DWMAC IP with multi-channel
interrupt support. The dwmac-s32.c driver change is provided as an example of
enabling multi-IRQ mode for non-PCI drivers.

Signed-off-by: Jan Petrous (OSS) <jan.petrous@oss.nxp.com>
---
Changes in v6:
- Added helper macro for loop over queue-based arrays (inspired by AI
  review)
- Added full validation on all channel IRQs
- Link to v5: https://lore.kernel.org/r/20260223-dwmac_multi_irq-v5-0-8fc699a5fac4@oss.nxp.com (local)

Changes in v5:
- fixed typo in "symetrical"
- cleaned negative return value on platform_get_irq_byname_optional()
  in stmmac_get_platform_resources()
- rebased on v7.0-rc1
- Link to v4: https://lore.kernel.org/r/20260128-dwmac_multi_irq-v4-0-82fa34fcf2f2@oss.nxp.com (local)

Changes in v4:
- Fixed IRQ reading check
- Made cleaner the IRQ validity (to get AI reviewer happy)
- Fixed minItems of interrupts property in yaml
- Link to v3: https://lore.kernel.org/r/20260123-dwmac_multi_irq-v3-0-cc53f2be8961@oss.nxp.com (local)

Changes in v3:
- removed RFC prefix
- rebased on v6.19-rc6
- fixed forgotten extra line setting to Multi-IRQ unconditionally
- fixed yaml
- Link to v2: https://lore.kernel.org/r/20260121-dwmac_multi_irq-v2-0-3b829230d071@oss.nxp.com (local)

Changes in v2:
- Fixed incorrect buffer len for 'rx-queue-%d' property check
- Added backward compatibility to not break old settings
- Fixed DT example in yaml
- Link to v1: https://lore.kernel.org/r/20251214-dwmac_multi_irq-v1-0-36562ab0e9f7@oss.nxp.com (local)

---
Jan Petrous (OSS) (5):
      net: stmmac: Use helper macro for loop over queue-based arrays
      net: stmmac: platform: read channels irq
      dt-bindings: net: nxp,s32-dwmac: Declare per-queue interrupts
      arm64: dts: s32: set Ethernet channel irqs
      stmmac: s32: enable support for Multi-IRQ mode

 .../devicetree/bindings/net/nxp,s32-dwmac.yaml     | 44 +++++++++++++++++++---
 arch/arm64/boot/dts/freescale/s32g2.dtsi           | 26 +++++++++++--
 arch/arm64/boot/dts/freescale/s32g3.dtsi           | 26 +++++++++++--
 drivers/net/ethernet/stmicro/stmmac/dwmac-s32.c    | 36 +++++++++++++++++-
 .../net/ethernet/stmicro/stmmac/dwxgmac2_core.c    |  2 +-
 drivers/net/ethernet/stmicro/stmmac/stmmac.h       |  3 ++
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c  | 16 ++++----
 .../net/ethernet/stmicro/stmmac/stmmac_platform.c  | 40 +++++++++++++++++++-
 8 files changed, 171 insertions(+), 22 deletions(-)
---
base-commit: 6de23f81a5e08be8fbf5e8d7e9febc72a5b5f27f
change-id: 20251209-dwmac_multi_irq-9d8f60462cc1

Best regards,
-- 
Jan Petrous (OSS) [off-list ref]