* Samsung Exynos PPMU (Platform Performance Monitoring Unit) device

The Samsung Exynos SoC has PPMU (Platform Performance Monitoring Unit) for
each IP. PPMU provides the primitive values to get performance data. These
PPMU events provide information of the SoC's behaviors so that you may
use to analyze system performance, to make behaviors visible and to count
usages of each IP (DMC, CPU, RIGHTBUS, LEFTBUS, CAM interface, LCD, G3D, MFC).
The Exynos PPMU driver uses the devfreq-event class to provide event data
to various devfreq devices. The devfreq devices would use the event data when
derterming the current state of each IP.

Required properties:
- compatible: Should be "samsung,exynos-ppmu".
- reg: physical base address of each PPMU and length of memory mapped region.

Optional properties:
- clock-names : the name of clock used by the PPMU, "ppmu"
- clocks : phandles for clock specified in "clock-names" property
- #clock-cells: should be 1.

Example1 : PPMU nodes in exynos3250.dtsi are listed below.

		ppmu_dmc0: ppmu_dmc0@106a0000 {
			compatible = "samsung,exynos-ppmu";
			reg = <0x106a0000 0x2000>;
			status = "disabled";
		};

		ppmu_dmc1: ppmu_dmc1@106b0000 {
			compatible = "samsung,exynos-ppmu";
			reg = <0x106b0000 0x2000>;
			status = "disabled";
		};

		ppmu_cpu: ppmu_cpu@106c0000 {
			compatible = "samsung,exynos-ppmu";
			reg = <0x106c0000 0x2000>;
			status = "disabled";
		};

		ppmu_rightbus: ppmu_rightbus@112a0000 {
			compatible = "samsung,exynos-ppmu";
			reg = <0x112a0000 0x2000>;
			clocks = <&cmu CLK_PPMURIGHT>;
			clock-names = "ppmu";
			status = "disabled";
		};

		ppmu_leftbus: ppmu_leftbus0@116a0000 {
			compatible = "samsung,exynos-ppmu";
			reg = <0x116a0000 0x2000>;
			clocks = <&cmu CLK_PPMULEFT>;
			clock-names = "ppmu";
			status = "disabled";
		};

Example2 : Events of each PPMU node in exynos3250-rinato.dts are listed below.

	&ppmu_dmc0 {
		status = "okay";

		events {
			ppmu_dmc0_3: ppmu-event3-dmc0 {
				event-name = "ppmu-event3-dmc0";
			};

			ppmu_dmc0_2: ppmu-event2-dmc0 {
				event-name = "ppmu-event2-dmc0";
			};

			ppmu_dmc0_1: ppmu-event1-dmc0 {
				event-name = "ppmu-event1-dmc0";
			};

			ppmu_dmc0_0: ppmu-event0-dmc0 {
				event-name = "ppmu-event0-dmc0";
			};
		};
	};

	&ppmu_dmc1 {
		status = "okay";

		events {
			ppmu_dmc1_3: ppmu-event3-dmc1 {
				event-name = "ppmu-event3-dmc1";
			};
		};
	};

	&ppmu_leftbus {
		status = "okay";

		events {
			ppmu_leftbus_3: ppmu-event3-leftbus {
				event-name = "ppmu-event3-leftbus";
			};
		};
	};

	&ppmu_rightbus {
		status = "okay";

		events {
			ppmu_rightbus_3: ppmu-event3-rightbus {
				event-name = "ppmu-event3-rightbus";
			};
		};
	};