linux/linux-5.4.31/Documentation/devicetree/bindings/opp/sun50i-nvmem-cpufreq.txt

Allwinner Technologies, Inc. NVMEM CPUFreq and OPP bindings
===================================

For some SoCs, the CPU frequency subset and voltage value of each OPP
varies based on the silicon variant in use. Allwinner Process Voltage
Scaling Tables defines the voltage and frequency value based on the
speedbin blown in the efuse combination. The sun50i-cpufreq-nvmem driver
reads the efuse value from the SoC to provide the OPP framework with
required information.

Required properties:
--------------------
In 'cpus' nodes:
- operating-points-v2: Phandle to the operating-points-v2 table to use.

In 'operating-points-v2' table:
- compatible: Should be
	- 'allwinner,sun50i-h6-operating-points'.
- nvmem-cells: A phandle pointing to a nvmem-cells node representing the
		efuse registers that has information about the speedbin
		that is used to select the right frequency/voltage value
		pair. Please refer the for nvmem-cells bindings
		Documentation/devicetree/bindings/nvmem/nvmem.txt and
		also examples below.

In every OPP node:
- opp-microvolt-<name>: Voltage in micro Volts.
			At runtime, the platform can pick a <name> and
			matching opp-microvolt-<name> property.
			[See: opp.txt]
			HW:		<name>:
			sun50i-h6	speed0 speed1 speed2

Example 1:
---------

	cpus {
		#address-cells = <1>;
		#size-cells = <0>;

		cpu0: cpu@0 {
			compatible = "arm,cortex-a53";
			device_type = "cpu";
			reg = <0>;
			enable-method = "psci";
			clocks = <&ccu CLK_CPUX>;
			clock-latency-ns = <244144>; /* 8 32k periods */
			operating-points-v2 = <&cpu_opp_table>;
			#cooling-cells = <2>;
		};

		cpu1: cpu@1 {
			compatible = "arm,cortex-a53";
			device_type = "cpu";
			reg = <1>;
			enable-method = "psci";
			clocks = <&ccu CLK_CPUX>;
			clock-latency-ns = <244144>; /* 8 32k periods */
			operating-points-v2 = <&cpu_opp_table>;
			#cooling-cells = <2>;
		};

		cpu2: cpu@2 {
			compatible = "arm,cortex-a53";
			device_type = "cpu";
			reg = <2>;
			enable-method = "psci";
			clocks = <&ccu CLK_CPUX>;
			clock-latency-ns = <244144>; /* 8 32k periods */
			operating-points-v2 = <&cpu_opp_table>;
			#cooling-cells = <2>;
		};

		cpu3: cpu@3 {
			compatible = "arm,cortex-a53";
			device_type = "cpu";
			reg = <3>;
			enable-method = "psci";
			clocks = <&ccu CLK_CPUX>;
			clock-latency-ns = <244144>; /* 8 32k periods */
			operating-points-v2 = <&cpu_opp_table>;
			#cooling-cells = <2>;
		};
        };

        cpu_opp_table: opp_table {
                compatible = "allwinner,sun50i-h6-operating-points";
                nvmem-cells = <&speedbin_efuse>;
                opp-shared;

                opp@480000000 {
                        clock-latency-ns = <244144>; /* 8 32k periods */
                        opp-hz = /bits/ 64 <480000000>;

                        opp-microvolt-speed0 = <880000>;
                        opp-microvolt-speed1 = <820000>;
                        opp-microvolt-speed2 = <800000>;
                };

                opp@720000000 {
                        clock-latency-ns = <244144>; /* 8 32k periods */
                        opp-hz = /bits/ 64 <720000000>;

                        opp-microvolt-speed0 = <880000>;
                        opp-microvolt-speed1 = <820000>;
                        opp-microvolt-speed2 = <800000>;
                };

                opp@816000000 {
                        clock-latency-ns = <244144>; /* 8 32k periods */
                        opp-hz = /bits/ 64 <816000000>;

                        opp-microvolt-speed0 = <880000>;
                        opp-microvolt-speed1 = <820000>;
                        opp-microvolt-speed2 = <800000>;
                };

                opp@888000000 {
                        clock-latency-ns = <244144>; /* 8 32k periods */
                        opp-hz = /bits/ 64 <888000000>;

                        opp-microvolt-speed0 = <940000>;
                        opp-microvolt-speed1 = <820000>;
                        opp-microvolt-speed2 = <800000>;
                };

                opp@1080000000 {
                        clock-latency-ns = <244144>; /* 8 32k periods */
                        opp-hz = /bits/ 64 <1080000000>;

                        opp-microvolt-speed0 = <1060000>;
                        opp-microvolt-speed1 = <880000>;
                        opp-microvolt-speed2 = <840000>;
                };

                opp@1320000000 {
                        clock-latency-ns = <244144>; /* 8 32k periods */
                        opp-hz = /bits/ 64 <1320000000>;

                        opp-microvolt-speed0 = <1160000>;
                        opp-microvolt-speed1 = <940000>;
                        opp-microvolt-speed2 = <900000>;
                };

                opp@1488000000 {
                        clock-latency-ns = <244144>; /* 8 32k periods */
                        opp-hz = /bits/ 64 <1488000000>;

                        opp-microvolt-speed0 = <1160000>;
                        opp-microvolt-speed1 = <1000000>;
                        opp-microvolt-speed2 = <960000>;
                };
        };
....
soc {
....
	sid: sid@3006000 {
		compatible = "allwinner,sun50i-h6-sid";
		reg = <0x03006000 0x400>;
		#address-cells = <1>;
		#size-cells = <1>;
		....
		speedbin_efuse: speed@1c {
			reg = <0x1c 4>;
		};
        };
};