net: add ethernet driver for MediaTek MT7620 SoC

This patch adds  ethernet driver for MediaTek MT7620 SoC.

The MT7620 SoC has a built-in ethernet (Frame Engine) and a built-in
7-port switch and two xMII interfaces (can be MII/RMII/RGMII).

The port 0-3 of the switch connects to intergrited FE PHYs. Port 4 can be
configured to connect to either the intergrited FE PHY, or the xMII.
Port 5 always connects to the xMII. Port 6 is the CPU port.

This driver supports MT7530 giga switch connects to port 5.

Reviewed-by: Stefan Roese <sr@denx.de>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>

drivers/net/Kconfig

@@ -399,6 +399,18 @@ config MACB_ZYNQ
 	  The Cadence MACB ethernet interface was used on Zynq platform.
 	  Say Y to enable support for the MACB/GEM in Zynq chip.
 
+config MT7620_ETH
+	bool "MediaTek MT7620 Ethernet Interface"
+	depends on SOC_MT7620
+	select PHYLIB
+	select DM_RESET
+	select DM_GPIO
+	select CLK
+	help
+	  The MediaTek MT7620 ethernet interface is used on MT7620 based
+	  boards. It has a built-in switch with two configurable ports which
+	  can connect to external PHY/MACs.
+
 config MT7628_ETH
 	bool "MediaTek MT7628 Ethernet Interface"
 	depends on SOC_MT7628

drivers/net/Makefile

@@ -44,6 +44,7 @@ obj-$(CONFIG_MDIO_IPQ4019) += mdio-ipq4019.o
 obj-$(CONFIG_MDIO_MUX_I2CREG) += mdio_mux_i2creg.o
 obj-$(CONFIG_MDIO_MUX_SANDBOX) += mdio_mux_sandbox.o
 obj-$(CONFIG_MPC8XX_FEC) += mpc8xx_fec.o
+obj-$(CONFIG_MT7620_ETH) += mt7620-eth.o
 obj-$(CONFIG_MT7628_ETH) += mt7628-eth.o
 obj-$(CONFIG_MVGBE) += mvgbe.o
 obj-$(CONFIG_MVMDIO) += mvmdio.o