dt-bindings: opp: Introduce ti-opp-supply bindings

Document the devicetree bindings that describe Texas Instruments
opp-supply which allow a platform to describe multiple regulators and
additional information, such as registers containing data needed to
program aforementioned regulators.
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/devicetree/bindings/opp/ti-omap5-opp-supply.txt

+Texas Instruments OMAP compatible OPP supply description
+
+OMAP5, DRA7, and AM57 family of SoCs have Class0 AVS eFuse registers which
+contain data that can be used to adjust voltages programmed for some of their
+supplies for more efficient operation. This binding provides the information
+needed to read these values and use them to program the main regulator during
+an OPP transitions.
+
+Also, some supplies may have an associated vbb-supply which is an Adaptive Body
+Bias regulator which much be transitioned in a specific sequence with regards
+to the vdd-supply and clk when making an OPP transition. By supplying two
+regulators to the device that will undergo OPP transitions we can make use
+of the multi regulator binding that is part of the OPP core described here [1]
+to describe both regulators needed by the platform.
+
+[1] Documentation/devicetree/bindings/opp/opp.txt
+
+Required Properties for Device Node:
+- vdd-supply: phandle to regulator controlling VDD supply
+- vbb-supply: phandle to regulator controlling Body Bias supply
+	      (Usually Adaptive Body Bias regulator)
+
+Required Properties for opp-supply node:
+- compatible: Should be one of:
+	"ti,omap-opp-supply" - basic OPP supply controlling VDD and VBB
+	"ti,omap5-opp-supply" - OMAP5+ optimized voltages in efuse(class0)VDD
+			    along with VBB
+	"ti,omap5-core-opp-supply" - OMAP5+ optimized voltages in efuse(class0) VDD
+			    but no VBB.
+- reg: Address and length of the efuse register set for the device (mandatory
+	only for "ti,omap5-opp-supply")
+- ti,efuse-settings: An array of u32 tuple items providing information about
+	optimized efuse configuration. Each item consists of the following:
+	volt: voltage in uV - reference voltage (OPP voltage)
+	efuse_offseet: efuse offset from reg where the optimized voltage is stored.
+- ti,absolute-max-voltage-uv: absolute maximum voltage for the OPP supply.
+
+Example:
+
+/* Device Node (CPU)  */
+cpus {
+	cpu0: cpu@0 {
+		device_type = "cpu";
+
+		...
+
+		vdd-supply = <&vcc>;
+		vbb-supply = <&abb_mpu>;
+	};
+};
+
+/* OMAP OPP Supply with Class0 registers */
+opp_supply_mpu: opp_supply@4a003b20 {
+	compatible = "ti,omap5-opp-supply";
+	reg = <0x4a003b20 0x8>;
+	ti,efuse-settings = <
+	/* uV   offset */
+	1060000 0x0
+	1160000 0x4
+	1210000 0x8
+	>;
+	ti,absolute-max-voltage-uv = <1500000>;
+};