* ARM architected timer

ARM Cortex-A7 and Cortex-A15 have a per-core architected timer, which
provides a per-cpu local timer.

The timer is attached to a GIC to deliver its two per-processor
interrupts (one for the secure mode, one for the non-secure mode).

** CP15 Timer node properties:

- compatible : Should be "arm,armv7-timer"

- interrupts : One or two interrupts for secure and non-secure mode

- clock-frequency : The frequency of the main counter, in Hz. Optional.

Example:

	timer {
		compatible = "arm,armv7-timer"";
		interrupts = <1 13 0xf08 1 14 0xf08>;
		clock-frequency = <100000000>;
	};

** Memory mapped timer node properties:

- compatible : Should at least contain "arm,armv7-timer-mem".

- clock-frequency : The frequency of the main counter, in Hz. Optional.

- reg : The control frame base address.

Note that #address-cells, #size-cells, and ranges shall be present to ensure
the CPU can address the frame's registers.

Each timer node has up to 8 frame sub-nodes with the following properties:

- frame-number: 0 to 7.

- interrupts : Interrupt list for physical and virtual timers in that order.
  The virtual timer interrupt is optional.

- reg : The first and second view base addresses in that order. The second view
  base address is optional.

- status : "disabled" indicates the frame is not available for use. Optional.

Example:

	timer@f0000000 {
		compatible = "arm,armv7-timer-mem";
		#address-cells = <1>;
		#size-cells = <1>;
		ranges;
		reg = <0xf0000000 0x1000>;
		clock-frequency = <50000000>;

		frame0@f0001000 {
			frame-number = <0>
			interrupts = <0 13 0x8>,
				     <0 14 0x8>;
			reg = <0xf0001000 0x1000>,
			      <0xf0002000 0x1000>;
		};

		frame1@f0003000 {
			frame-number = <1>
			interrupts = <0 15 0x8>;
			reg = <0xf0003000 0x1000>;
			status = "disabled";
		};
	};