drivers: ethernet: Add Intel i226 Ethernet MAC device driver

The Intel i226 Ethernet Controller is a PCIe Gen 2 one-lane modular
endpoint device that integrates a GbE Media Access Control (MAC) and
Physical Layer (PHY) port. This driver provides support for MAC and
DMA-specific initialization and runtime TX/RX operations.

Key features supported by the driver:
- Full duplex support for 10/100/1000 Mbps.
- Half duplex support for 10/100 Mbps.
- MSI-X interrupts for TX/RX DMA channels.
- MSI-X interrupts for link status change detection.
- Multiple TX/RX DMA channel support with exclusive bottom-half
  processing.
- Auto-negotiation for 10/100/1000 Mbps.
- MTU customization for flexible packet sizes.
- MAC address filtering based on:
  - Pre-programmed MAC addresses.
  - MAC addresses specified in the device tree.
- Support for multiple Ethernet interface instances.

Signed-off-by: Vijayakannan Ayyathurai <vijayakannan.ayyathurai@intel.com>
Signed-off-by: Ling Pei Lee <pei.lee.ling@intel.com>

Author: Vijayakannan

drivers/ethernet/intel/CMakeLists.txt

@@ -2,3 +2,4 @@
 # SPDX-License-Identifier: Apache-2.0
 
 zephyr_library_sources_ifdef(CONFIG_ETH_INTEL_PLAT	eth_intel_plat.c)
+zephyr_library_sources_ifdef(CONFIG_ETH_INTEL_IGC	eth_intel_igc.c)

drivers/ethernet/intel/Kconfig

@@ -8,3 +8,4 @@ config ETH_INTEL_PLAT
 	  Enable Platform driver to retrieve the MMIO mapping details and
 	  share them with all the child devices such as MDIO, PHY, MAC
 	  and PTP_CLOCK.
+source "drivers/ethernet/intel/Kconfig.intel_igc"

drivers/ethernet/intel/Kconfig.intel_igc

@@ -0,0 +1,29 @@
+# Copyright (c) 2025 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+menuconfig ETH_INTEL_IGC
+	bool "Intel IGC MAC driver"
+	default y
+	depends on DT_HAS_INTEL_IGC_MAC_ENABLED
+	select MDIO
+	select PCIE_MSI_MULTI_VECTOR
+	select PCIE_MSI_X
+	help
+	  Ethernet device driver for Intel i226 MAC.
+
+if ETH_INTEL_IGC
+
+config ETH_INTEL_IGC_INT_PRIORITY
+	int "Interrupt priority"
+	default 6
+	help
+	  MSI-X vectors priority for IGC interrupts.
+
+config ETH_INTEL_IGC_NET_MTU
+	int "MTU size"
+	default 1500
+	range 64 1522
+	help
+	  Maximum Transmission Unit (MTU) size configuration.
+
+endif # ETH_INTEL_IGC