* STMicroelectronics 10/100/1000 Ethernet driver (GMAC)

Required properties:
- compatible: Should be "snps,dwmac-<ip_version>" "snps,dwmac"
	For backwards compatibility: "st,spear600-gmac" is also supported.
- reg: Address and length of the register set for the device
- interrupt-parent: Should be the phandle for the interrupt controller
  that services interrupts for this device
- interrupts: Should contain the STMMAC interrupts
- interrupt-names: Should contain the interrupt names "macirq"
  "eth_wake_irq" if this interrupt is supported in the "interrupts"
  property
- phy-mode: See ethernet.txt file in the same directory.
- snps,reset-gpio 	gpio number for phy reset.
- snps,reset-active-low boolean flag to indicate if phy reset is active low.
- snps,reset-delays-us  is triplet of delays
	The 1st cell is reset pre-delay in micro seconds.
	The 2nd cell is reset pulse in micro seconds.
	The 3rd cell is reset post-delay in micro seconds.

Optional properties:
- resets: Should contain a phandle to the STMMAC reset signal, if any
- reset-names: Should contain the reset signal name "stmmaceth", if a
	reset phandle is given
- max-frame-size: See ethernet.txt file in the same directory
- clocks: If present, the first clock should be the GMAC main clock and
  the second clock should be peripheral's register interface clock. Further
  clocks may be specified in derived bindings.
- clock-names: One name for each entry in the clocks property, the
  first one should be "stmmaceth" and the second one should be "pclk".
- clk_ptp_ref: this is the PTP reference clock; in case of the PTP is
  available this clock is used for programming the Timestamp Addend Register.
  If not passed then the system clock will be used and this is fine on some
  platforms.
- tx-fifo-depth: See ethernet.txt file in the same directory
- rx-fifo-depth: See ethernet.txt file in the same directory
- snps,pbl		Programmable Burst Length
- snps,aal		Address-Aligned Beats
- snps,fixed-burst	Program the DMA to use the fixed burst mode
- snps,mixed-burst	Program the DMA to use the mixed burst mode
- snps,force_thresh_dma_mode	Force DMA to use the threshold mode for
				both tx and rx
- snps,force_sf_dma_mode	Force DMA to use the Store and Forward
				mode for both tx and rx. This flag is
				ignored if force_thresh_dma_mode is set.
- snps,multicast-filter-bins:	Number of multicast filter hash bins
				supported by this device instance
- snps,perfect-filter-entries:	Number of perfect filter entries supported
				by this device instance
- snps,ps-speed: port selection speed that can be passed to the core when
		 PCS is supported. For example, this is used in case of SGMII
		 and MAC2MAC connection.
- AXI BUS Mode parameters: below the list of all the parameters to program the
			   AXI register inside the DMA module:
	- snps,lpi_en: enable Low Power Interface
	- snps,xit_frm: unlock on WoL
	- snps,wr_osr_lmt: max write outstanding req. limit
	- snps,rd_osr_lmt: max read outstanding req. limit
	- snps,kbbe: do not cross 1KiB boundary.
	- snps,axi_all: align address
	- snps,blen: this is a vector of supported burst length.
	- snps,fb: fixed-burst
	- snps,mb: mixed-burst
	- snps,rb: rebuild INCRx Burst
	- snps,tso: this enables the TSO feature otherwise it will be managed by
	    MAC HW capability register.
- mdio: with compatible = "snps,dwmac-mdio", create and register mdio bus.

Examples:

	stmmac_axi_setup: stmmac-axi-config {
		snps,wr_osr_lmt = <0xf>;
		snps,rd_osr_lmt = <0xf>;
		snps,blen = <256 128 64 32 0 0 0>;
	};

	gmac0: ethernet@e0800000 {
		compatible = "st,spear600-gmac";
		reg = <0xe0800000 0x8000>;
		interrupt-parent = <&vic1>;
		interrupts = <24 23>;
		interrupt-names = "macirq", "eth_wake_irq";
		mac-address = [000000000000]; /* Filled in by U-Boot */
		max-frame-size = <3800>;
		phy-mode = "gmii";
		snps,multicast-filter-bins = <256>;
		snps,perfect-filter-entries = <128>;
		rx-fifo-depth = <16384>;
		tx-fifo-depth = <16384>;
		clocks = <&clock>;
		clock-names = "stmmaceth";
		snps,axi-config = <&stmmac_axi_setup>;
		mdio0 {
			#address-cells = <1>;
			#size-cells = <0>;
			compatible = "snps,dwmac-mdio";
			phy1: ethernet-phy@0 {
			};
		};
	};