BCM2835 System Timer

The System Timer peripheral provides four 32-bit timer channels and a
single 64-bit free running counter. Each channel has an output compare
register, which is compared against the 32 least significant bits of the
free running counter values, and generates an interrupt.

Required properties:

- compatible : should be "brcm,bcm2835-system-timer"
- reg : Specifies base physical address and size of the registers.
- interrupts : A list of 4 interrupt sinks; one per timer channel.
- clock-frequency : The frequency of the clock that drives the counter, in Hz.

Example:

timer {
	compatible = "brcm,bcm2835-system-timer";
	reg = <0x7e003000 0x1000>;
	interrupts = <1 0>, <1 1>, <1 2>, <1 3>;
	clock-frequency = <1000000>;
};
