Texas Instruments clkctrl clock binding

Texas Instruments SoCs can have a clkctrl clock controller for each
interconnect target module. The clkctrl clock controller manages functional
and interface clocks for each module. Each clkctrl controller can also
gate one or more optional functional clocks for a module, and can have one
or more clock muxes. There is a clkctrl clock controller typically for each
interconnect target module on omap4 and later variants.

The clock consumers can specify the index of the clkctrl clock using
the hardware offset from the clkctrl instance register space. The optional
clocks can be specified by clkctrl hardware offset and the index of the
optional clock.

For more information, please see the Linux clock framework binding at
Documentation/devicetree/bindings/clock/clock-bindings.txt.

Required properties :
- compatible : shall be "ti,clkctrl" or a clock domain specific name:
	       "ti,clkctrl-l4-cfg"
	       "ti,clkctrl-l4-per"
	       "ti,clkctrl-l4-secure"
	       "ti,clkctrl-l4-wkup"
- clock-output-names : from common clock binding
- #clock-cells : shall contain 2 with the first entry being the instance
		 offset from the clock domain base and the second being the
		 clock index
- reg : clock registers

Example: Clock controller node on omap 4430:

&cm2 {
	l4per: cm@1400 {
		cm_l4per@0 {
			cm_l4per_clkctrl: clock@20 {
				compatible = "ti,clkctrl";
				clock-output-names = "l4_per";
				reg = <0x20 0x1b0>;
				#clock-cells = <2>;
			};
		};
	};
};

Example: Preprocessor helper macros in dt-bindings/clock/ti-clkctrl.h

#define OMAP4_CLKCTRL_OFFSET		0x20
#define OMAP4_CLKCTRL_INDEX(offset)	((offset) - OMAP4_CLKCTRL_OFFSET)
#define MODULEMODE_HWCTRL		1
#define MODULEMODE_SWCTRL		2

#define OMAP4_GPTIMER10_CLKTRL		OMAP4_CLKCTRL_INDEX(0x28)
#define OMAP4_GPTIMER11_CLKTRL		OMAP4_CLKCTRL_INDEX(0x30)
#define OMAP4_GPTIMER2_CLKTRL		OMAP4_CLKCTRL_INDEX(0x38)
...
#define OMAP4_GPIO2_CLKCTRL		OMAP_CLKCTRL_INDEX(0x60)

Example: Clock consumer node for GPIO2:

&gpio2 {
       clocks = <&cm_l4per_clkctrl OMAP4_GPIO2_CLKCTRL 0
		 &cm_l4per_clkctrl OMAP4_GPIO2_CLKCTRL 8>;
};
