Qualcomm MSM Clock controller

Qualcomm MSM Clock controller devices contain PLLs, root clock generators
and other clocking hardware blocks that provide stable, low power clocking to
hardware blocks on Qualcomm SOCs. The clock controller device node lists the
power supplies needed to be scaled using the vdd_*-supply property.

Minor differences between hardware revisions are handled in code by re-using
the compatible string to indicate the revision.

Required properties:
- compatible:		Must be one of following,
			"qcom,gcc-8916"
			"qcom,gcc-8936"
			"qcom,gcc-8909"
			"qcom,gcc-8992"
			"qcom,gcc-8994"
			"qcom,gcc-8994v2"
			"qcom,gcc-8952"
			"qcom,gcc-spm-8952"
			"qcom,gcc-fsm9010"
			"qcom,gcc-8996"
			"qcom,gcc-8996-v2"
			"qcom,gcc-8996-v3"
			"qcom,gcc-8937"
			"qcom,gcc-gold"
			"qcom,gcc-spm-8937"
			"qcom,gcc-titanium"
			"qcom,rpmcc-8994"
			"qcom,rpmcc-8992"
			"qcom,rpmcc-8916"
			"qcom,rpmcc-8936"
			"qcom,rpmcc-8909"
			"qcom,cc-debug-8916"
			"qcom,cc-debug-8936"
			"qcom,cc-debug-8909"
			"qcom,cc-debug-8992"
			"qcom,cc-debug-8994"
			"qcom,cc-debug-8952"
			"qcom,cc-debug-titanium"
			"qcom,cc-debug-fsm9010"
			"qcom,cc-debug-8996"
			"qcom,cc-debug-8996-v2"
			"qcom,cc-debug-8996-v3"
			"qcom,cc-debug-8937"
			"qcom,cc-debug-gold"
			"qcom,gcc-mdss-8936"
			"qcom,gcc-mdss-8909"
			"qcom,gcc-mdss-8916"
			"qcom,gcc-mdss-8952"
			"qcom,gcc-mdss-8937"
			"qcom,gcc-mdss-gold"
			"qcom,gcc-mdss-titanium"
			"qcom,mmsscc-8994v2"
			"qcom,mmsscc-8994"
			"qcom,mmsscc-8992"
			"qcom,mmsscc-8996"
			"qcom,mmsscc-8996-v2"
			"qcom,mmsscc-8996-v3"
			"qcom,gpucc-8996"
			"qcom,gpucc-8996-v2"
			"qcom,gpucc-8996-v3"
			"qcom,gpucc-8996-v3.0"
			"qcom,gcc-gfx-titanium"
			"qcom,gcc-californium"
			"qcom,cc-debug-californium"
			"qcom,gcc-mdm9607"
			"qcom,cc-debug-mdm9607"
			"qcom,gcc-cobalt"
			"qcom,cc-debug-cobalt"

- reg:			Pairs of physical base addresses and region sizes of
			memory mapped registers.
- reg-names:		Names of the bases for the above registers. Currently,
			there is one expected base: "cc_base". Optional
			reg-names are "apcs_base", "meas", "mmss_base",
			"lpass_base", "apcs_c0_base", "apcs_c1_base",
			"apcs_cci_base".

Optional properties:
- vdd_dig-supply:	The digital logic rail supply.
- <pll>_dig-supply:	Some PLLs might have separate digital supply on some
			targets. These properties will be provided on those
			targets for specific PLLs.
- <pll>_analog-supply:	Some PLLs might have separate analog supply on some
			targets. These properties will be provided on those
			targets for specific PLLs.
- vdd_gpu_mx-supply:	MX rail supply for the GPU core.
- #clock_cells:		If this device will also be providing controllable
			clocks, the clock_cells property needs to be specified.
			This will allow the common clock device tree framework
			to recognize _this_ device node as a clock provider.
- qcom,<clk>-corner-<vers>: List of frequency voltage pairs that the clock can
			    operate at. Drivers can use the OPP library API to
			    operate on the list of OPPs registered using these
			    values.
- qcom,<clk>-speedbinX: A table of frequency (Hz) to voltage (corner) mapping
			that represents the max frequency possible for each
			supported voltage level for the clock.
			'X' is the speed bin into which the device falls into -
			a bin will have unique frequency-voltage relationships.
			The value 'X' is read from efuse registers, and the right
			table is picked from multiple possible tables.
- qcom,<clock-name>-opp-handle: phandle references to the devices for which OPP
			table is filled with the clock frequency and voltage
			values.
- qcom,<clock-name>-opp-store-vcorner: phandle references to the devices for
			which OPP table is filled with the clock frequency
			 and voltage corner/level.

Example:
	clock_rpm: qcom,rpmcc@fc4000000 {
		compatible = "qcom,rpmcc-8974";
		reg = <0xfc400000 0x4000>;
		reg-names = "cc_base";
		#clock-cells = <1>;
	};

	clock_gcc: qcom,gcc@fc400000 {
		compatible = "qcom,gcc-8974";
		reg = <0xfc400000 0x4000>;
		reg-names = "cc_base";
		vdd_dig-supply = <&pm8841_s2_corner>;
		#clock-cells = <1>;
	};