dt-bindings: power: avs: Add support for CPR (Core Power Reduction)

Add DT bindings to describe the CPR HW found on certain Qualcomm SoCs.
Co-developed-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>
Signed-off-by: Niklas Cassel <niklas.cassel@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Documentation/devicetree/bindings/power/avs/qcom,cpr.txt

+QCOM CPR (Core Power Reduction)
+
+CPR (Core Power Reduction) is a technology to reduce core power on a CPU
+or other device. Each OPP of a device corresponds to a "corner" that has
+a range of valid voltages for a particular frequency. While the device is
+running at a particular frequency, CPR monitors dynamic factors such as
+temperature, etc. and suggests adjustments to the voltage to save power
+and meet silicon characteristic requirements.
+
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: should be "qcom,qcs404-cpr", "qcom,cpr" for qcs404
+
+- reg:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: base address and size of the rbcpr register region
+
+- interrupts:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: should specify the CPR interrupt
+
+- clocks:
+	Usage: required
+	Value type: <prop-encoded-array>
+	Definition: phandle to the reference clock
+
+- clock-names:
+	Usage: required
+	Value type: <stringlist>
+	Definition: must be "ref"
+
+- vdd-apc-supply:
+	Usage: required
+	Value type: <phandle>
+	Definition: phandle to the vdd-apc-supply regulator
+
+- #power-domain-cells:
+	Usage: required
+	Value type: <u32>
+	Definition: should be 0
+
+- operating-points-v2:
+	Usage: required
+	Value type: <phandle>
+	Definition: A phandle to the OPP table containing the
+		    performance states supported by the CPR
+		    power domain
+
+- acc-syscon:
+	Usage: optional
+	Value type: <phandle>
+	Definition: phandle to syscon for writing ACC settings
+
+- nvmem-cells:
+	Usage: required
+	Value type: <phandle>
+	Definition: phandle to nvmem cells containing the data
+		    that makes up a fuse corner, for each fuse corner.
+		    As well as the CPR fuse revision.
+
+- nvmem-cell-names:
+	Usage: required
+	Value type: <stringlist>
+	Definition: should be "cpr_quotient_offset1", "cpr_quotient_offset2",
+		    "cpr_quotient_offset3", "cpr_init_voltage1",
+		    "cpr_init_voltage2", "cpr_init_voltage3", "cpr_quotient1",
+		    "cpr_quotient2", "cpr_quotient3", "cpr_ring_osc1",
+		    "cpr_ring_osc2", "cpr_ring_osc3", "cpr_fuse_revision"
+		    for qcs404.
+
+Example:
+
+	cpr_opp_table: cpr-opp-table {
+		compatible = "operating-points-v2-qcom-level";
+
+		cpr_opp1: opp1 {
+			opp-level = <1>;
+			qcom,opp-fuse-level = <1>;
+		};
+		cpr_opp2: opp2 {
+			opp-level = <2>;
+			qcom,opp-fuse-level = <2>;
+		};
+		cpr_opp3: opp3 {
+			opp-level = <3>;
+			qcom,opp-fuse-level = <3>;
+		};
+	};
+
+	power-controller@b018000 {
+		compatible = "qcom,qcs404-cpr", "qcom,cpr";
+		reg = <0x0b018000 0x1000>;
+		interrupts = <0 15 IRQ_TYPE_EDGE_RISING>;
+		clocks = <&xo_board>;
+		clock-names = "ref";
+		vdd-apc-supply = <&pms405_s3>;
+		#power-domain-cells = <0>;
+		operating-points-v2 = <&cpr_opp_table>;
+		acc-syscon = <&tcsr>;
+
+		nvmem-cells = <&cpr_efuse_quot_offset1>,
+			<&cpr_efuse_quot_offset2>,
+			<&cpr_efuse_quot_offset3>,
+			<&cpr_efuse_init_voltage1>,
+			<&cpr_efuse_init_voltage2>,
+			<&cpr_efuse_init_voltage3>,
+			<&cpr_efuse_quot1>,
+			<&cpr_efuse_quot2>,
+			<&cpr_efuse_quot3>,
+			<&cpr_efuse_ring1>,
+			<&cpr_efuse_ring2>,
+			<&cpr_efuse_ring3>,
+			<&cpr_efuse_revision>;
+		nvmem-cell-names = "cpr_quotient_offset1",
+			"cpr_quotient_offset2",
+			"cpr_quotient_offset3",
+			"cpr_init_voltage1",
+			"cpr_init_voltage2",
+			"cpr_init_voltage3",
+			"cpr_quotient1",
+			"cpr_quotient2",
+			"cpr_quotient3",
+			"cpr_ring_osc1",
+			"cpr_ring_osc2",
+			"cpr_ring_osc3",
+			"cpr_fuse_revision";
+	};