Synopsys DesignWare AXI DMA Controller

Required properties:
- compatible: "snps,axi-dma-1.01a"
- reg: Address range of the DMAC registers. This should include
  all of the per-channel registers.
- interrupt: Should contain the DMAC interrupt number.
- interrupt-parent: Should be the phandle for the interrupt controller
  that services interrupts for this device.
- dma-channels: Number of channels supported by hardware.
- snps,dma-masters: Number of AXI masters supported by the hardware.
- snps,data-width: Maximum AXI data width supported by hardware.
  (0 - 8bits, 1 - 16bits, 2 - 32bits, ..., 6 - 512bits)
- snps,priority: Priority of channel. Array size is equal to the number of
  dma-channels. Priority value must be programmed within [0:dma-channels-1]
  range. (0 - minimum priority)
- snps,block-size: Maximum block size supported by the controller channel.
  Array size is equal to the number of dma-channels.

Optional properties:
- snps,axi-max-burst-len: Restrict master AXI burst length by value specified
  in this property. If this property is missing the maximum AXI burst length
  supported by DMAC is used. [1:256]

Example:

dmac: dma-controller@80000 {
	compatible = "snps,axi-dma-1.01a";
	reg = <0x80000 0x400>;
	clocks = <&core_clk>, <&cfgr_clk>;
	clock-names = "core-clk", "cfgr-clk";
	interrupt-parent = <&intc>;
	interrupts = <27>;

	dma-channels = <4>;
	snps,dma-masters = <2>;
	snps,data-width = <3>;
	snps,block-size = <4096 4096 4096 4096>;
	snps,priority = <0 1 2 3>;
	snps,axi-max-burst-len = <16>;
};
