* 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.
- snps,pbl		Programmable Burst Length
- 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

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,
  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".
- 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.
- snps,burst_len: The AXI burst lenth value of the AXI BUS MODE register.

Examples:

	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>;
		clocks = <&clock>;
		clock-names = "stmmaceth";
	};
