The NXP i.MX8M Nano CPU has one 10/100/1000 Ethernet MAC.

On the ConnectCore 8M Nano Development Kit:

  • Ethernet port is connected to a 10/100/1000 Atheros AR8031 PHY.

Kernel configuration

You can manage the Ethernet driver and PHY Device support through the following kernel configuration options:

  • FEC Ethernet controller (of ColdFire and some i.MX CPUs) (CONFIG_FEC)

  • PHY device support for AT803x (CONFIG_AT803X_PHY)

These options are enabled as built-in on the default ConnectCore 8M Nano kernel configuration file.

Kernel driver

The driver for the Ethernet interface is located at:

File Description

drivers/net/ethernet/freescale/fec_main.c

i.MX FEC driver

drivers/net/phy/at803x.c

Driver for Atheros 8031 PHY

Device tree bindings and customization

The i.MX8M Nano Ethernet interface device tree binding is documented at Documentation/devicetree/bindings/net/fsl-fec.txt. The Ethernet interface is defined in the i.MX8M Nano CPU and ConnectCore 8M Nano Development Kit device tree files.

Example: FEC1 on ConnectCore 8M Nano Development Kit

Definition of the FEC

i.MX8M Nano device tree
fec1: ethernet@30be0000 {
	compatible = "fsl,imx8mm-fec", "fsl,imx8mq-fec", "fsl,imx6sx-fec";
	reg = <0x30be0000 0x10000>;
	interrupts = <GIC_SPI 118 IRQ_TYPE_LEVEL_HIGH>,
		     <GIC_SPI 119 IRQ_TYPE_LEVEL_HIGH>,
		     <GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&clk IMX8MN_CLK_ENET1_ROOT>,
		 <&clk IMX8MN_CLK_ENET1_ROOT>,
		 <&clk IMX8MN_CLK_ENET_TIMER>,
		 <&clk IMX8MN_CLK_ENET_REF>,
		 <&clk IMX8MN_CLK_ENET_PHY_REF>;
	clock-names = "ipg", "ahb", "ptp",
			"enet_clk_ref", "enet_out";
	assigned-clocks = <&clk IMX8MN_CLK_ENET_AXI>,
			  <&clk IMX8MN_CLK_ENET_TIMER>,
			  <&clk IMX8MN_CLK_ENET_REF>,
			  <&clk IMX8MN_CLK_ENET_TIMER>;
	assigned-clock-parents = <&clk IMX8MN_SYS_PLL1_266M>,
				 <&clk IMX8MN_SYS_PLL2_100M>,
				 <&clk IMX8MN_SYS_PLL2_125M>;
	assigned-clock-rates = <0>, <0>, <125000000>, <100000000>;
	fsl,num-tx-queues = <3>;
	fsl,num-rx-queues = <3>;
	nvmem-cells = <&fec_mac_address>;
	nvmem-cell-names = "mac-address";
	nvmem_macaddr_swap;
	stop-mode = <&gpr 0x10 3>;
	fsl,wakeup_irq = <2>;
	status = "disabled";
};

IOMUX configuration

ConnectCore 8M Nano Development Kit device tree
pinctrl_fec1_gpio: fec1gpiogrp {
	fsl,pins = <
		/* PHY reset */
		MX8MN_IOMUXC_SPDIF_TX_GPIO5_IO3		0x19
		/* PHY interrupt */
		MX8MN_IOMUXC_SAI3_MCLK_GPIO5_IO2	0x19
	>;
};

pinctrl_fec1: fec1grp {
	fsl,pins = <
		MX8MN_IOMUXC_ENET_MDC_ENET1_MDC		0x3
		MX8MN_IOMUXC_ENET_MDIO_ENET1_MDIO	0x3
		MX8MN_IOMUXC_ENET_TD3_ENET1_RGMII_TD3	0x1f
		MX8MN_IOMUXC_ENET_TD2_ENET1_RGMII_TD2	0x1f
		MX8MN_IOMUXC_ENET_TD1_ENET1_RGMII_TD1	0x1f
		MX8MN_IOMUXC_ENET_TD0_ENET1_RGMII_TD0	0x1f
		MX8MN_IOMUXC_ENET_RD3_ENET1_RGMII_RD3	0x91
		MX8MN_IOMUXC_ENET_RD2_ENET1_RGMII_RD2	0x91
		MX8MN_IOMUXC_ENET_RD1_ENET1_RGMII_RD1	0x91
		MX8MN_IOMUXC_ENET_RD0_ENET1_RGMII_RD0	0x91
		MX8MN_IOMUXC_ENET_TXC_ENET1_RGMII_TXC	0x1f
		MX8MN_IOMUXC_ENET_RXC_ENET1_RGMII_RXC	0x91
		MX8MN_IOMUXC_ENET_RX_CTL_ENET1_RGMII_RX_CTL	0x91
		MX8MN_IOMUXC_ENET_TX_CTL_ENET1_RGMII_TX_CTL	0x1f
	>;
};

Ethernet enabling and PHY parameters

ConnectCore 8M Nano Development Kit device tree
&fec1 {
	pinctrl-names = "default";
	pinctrl-0 = <&pinctrl_fec1_gpio>,
		    <&pinctrl_fec1>;
	phy-mode = "rgmii-id";
	phy-handle = <&ethphy0>;
	digi,mdio-lt-supply = <&reg_1v8_ext>;
	phy-supply = <&reg_3v3_eth0>;
	phy-reset-gpios = <&gpio5 3 GPIO_ACTIVE_LOW>;
	phy-reset-duration = <1>;
	digi,phy-reset-in-suspend;
	fsl,magic-packet;
	status = "okay";

	mdio {
		#address-cells = <1>;
		#size-cells = <0>;

		ethphy0: ethernet-phy@0 {
			compatible = "ethernet-phy-ieee802.3-c22";
			reg = <0>;
			at803x,eee-disabled;
			at803x,vddio-1p8v;
		};
	};
};

MAC address

The MAC address of the i.MX8M Nano Ethernet interface is programmed in the U-Boot environment (variable ethaddr) on the ConnectCore 8M Nano eMMC. The MAC address is also printed on the module label. U-Boot writes the MAC address in the ethaddr environment variable into its respective device tree fec node under the local-mac-address property. For more information, see Environment variables.

Ethernet user space usage

In the Linux system, the Ethernet interface is known as eth0. The Ethernet (FEC) driver exposes device data through the sysfs at /sys/class/net/eth0. You can use NetworkManager to configure Ethernet settings such as IP and netmask.