net: airoha: Introduce ethernet support for EN7581 SoC

Add airoha_eth driver in order to introduce ethernet support for
Airoha EN7581 SoC available on EN7581 development board (en7581-evb).
EN7581 mac controller is mainly composed by the Frame Engine (PSE+PPE)
and QoS-DMA (QDMA) modules. FE is used for traffic offloading (just
basic functionalities are currently supported) while QDMA is used for
DMA operations and QOS functionalities between the mac layer and the
external modules conncted to the FE GDM ports (e.g MT7530 DSA switch
or external phys).
A general overview of airoha_eth architecture is reported below:

               ┌───────┐                                     ┌───────┐
               │ QDMA2 │                                     │ QDMA1 │
               └───┬───┘                                     └───┬───┘
                   │                                             │
           ┌───────▼─────────────────────────────────────────────▼────────┐
           │                                                              │
           │       P5                                            P0       │
           │                                                              │
           │                                                              │
           │                                                              │    ┌──────┐
           │                                                           P3 ├────► GDM3 │
           │                                                              │    └──────┘
           │                                                              │
           │                                                              │
┌─────┐    │                                                              │
│ PPE ◄────┤ P4                          PSE                              │
└─────┘    │                                                              │
           │                                                              │
           │                                                              │
           │                                                              │    ┌──────┐
           │                                                           P9 ├────► GDM4 │
           │                                                              │    └──────┘
           │                                                              │
           │                                                              │
           │                                                              │
           │        P2                                           P1       │
           └─────────┬───────────────────────────────────────────┬────────┘
                     │                                           │
                 ┌───▼──┐                                     ┌──▼───┐
                 │ GDM2 │                                     │ GDM1 │
                 └──────┘                                     └──┬───┘
                                                                 │
                                                            ┌────▼─────┐
                                                            │  MT7530  │
                                                            └──────────┘

Currently only hw LAN features (QDMA1+GDM1) are available while hw WAN
(QDMA2+GDM{2,3,4}) ones will be added with subsequent patches introducing
traffic offloading support.
Tested-by: Benjamin Larsson <benjamin.larsson@genexis.eu>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/274945d2391c195098ab180a46d0617b18b9e42c.1720818878.git.lorenzo@kernel.orgSigned-off-by: Jakub Kicinski <kuba@kernel.org>

MAINTAINERS

@@ -682,6 +682,15 @@ S:	Supported
 F:	fs/aio.c
 F:	include/linux/*aio*.h
 
+AIROHA ETHERNET DRIVER
+M:	Lorenzo Bianconi <lorenzo@kernel.org>
+L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
+L:	linux-mediatek@lists.infradead.org (moderated for non-subscribers)
+L:	netdev@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/net/airoha,en7581-eth.yaml
+F:	drivers/net/ethernet/mediatek/airoha_eth.c
+
 AIROHA SPI SNFI DRIVER
 M:	Lorenzo Bianconi <lorenzo@kernel.org>
 M:	Ray Liu <ray.liu@airoha.com>

drivers/net/ethernet/mediatek/Kconfig

 # SPDX-License-Identifier: GPL-2.0-only
 config NET_VENDOR_MEDIATEK
 	bool "MediaTek devices"
-	depends on ARCH_MEDIATEK || SOC_MT7621 || SOC_MT7620 || COMPILE_TEST
+	depends on ARCH_MEDIATEK || ARCH_AIROHA || SOC_MT7621 || SOC_MT7620 || COMPILE_TEST
 	help
 	  If you have a Mediatek SoC with ethernet, say Y.
 
 if NET_VENDOR_MEDIATEK
 
+config NET_AIROHA
+	tristate "Airoha SoC Gigabit Ethernet support"
+	depends on NET_DSA || !NET_DSA
+	select PAGE_POOL
+	help
+	  This driver supports the gigabit ethernet MACs in the
+	  Airoha SoC family.
+
 config NET_MEDIATEK_SOC_WED
 	depends on ARCH_MEDIATEK || COMPILE_TEST
 	def_bool NET_MEDIATEK_SOC != n

drivers/net/ethernet/mediatek/Makefile

@@ -11,3 +11,4 @@ mtk_eth-$(CONFIG_NET_MEDIATEK_SOC_WED) += mtk_wed_debugfs.o
 endif
 obj-$(CONFIG_NET_MEDIATEK_SOC_WED) += mtk_wed_ops.o
 obj-$(CONFIG_NET_MEDIATEK_STAR_EMAC) += mtk_star_emac.o
+obj-$(CONFIG_NET_AIROHA) += airoha_eth.o