Broadcom's PWM Controller Device Tree bindings

Broadcom's Kona PWM Controller has 6 channels

Required Properties :
- compatible: should be "brcm,kona-pwm"
- reg: physical base address and length of the controller's registers
- clocks: clock specifier for the kona pwm external clock
- #pwm-cells: should be 2.  The first cell specifies the per-chip index
  of the PWM to use and the second cell is the period in nanoseconds.

Refer to pwm/pwm.txt for generic pwm controller node properties.

Refer to clocks/clock-bindings.txt for generic clock consumer
properties

Example:

pwm: pwm@3e01a000 {
	compatible = "brcm,bcm11351-pwm", "brcm,kona-pwm";
	reg = <0x3e01a000 0xc4>;
	clocks = <&pwm_clk>;
	#pwm-cells = <2>;
};