dt-bindings: cpufreq: Document allwinner,sun50i-h6-operating-points

Allwinner Process Voltage Scaling Tables defines the voltage and
frequency value based on the speedbin blown in the efuse combination.
The sunxi-cpufreq-nvmem driver reads the efuse value from the SoC to
provide the OPP framework with required information.
This is used to determine the voltage and frequency value for each
OPP of operating-points-v2 table when it is parsed by the OPP framework.

The "allwinner,sun50i-h6-operating-points" DT extends the
"operating-points-v2"
with following parameters:
- nvmem-cells (NVMEM area containig the speedbin information)
- opp-microvolt-<name>: voltage in micro Volts.
  At runtime, the platform can pick a <name> and matching
  opp-microvolt-<name> property.
                        HW:             <name>:
                        sun50i-h6      speed0 speed1 speed2
Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

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>;
+		};
+        };
+};