linux-kernel - [RFC PATCH v2 03/17] dt-bindings: cpufreq: Add binding for NVIDIA Tegra20/30

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Message-Id: <20181021205501.23943-4-digetx@gmail.com>
Date:   Sun, 21 Oct 2018 23:54:47 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>
Cc:     linux-tegra@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH v2 03/17] dt-bindings: cpufreq: Add binding for NVIDIA Tegra20/30

Add device-tree binding that describes CPU frequency-scaling hardware
found on NVIDIA Tegra20/30 SoC's.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 .../cpufreq/nvidia,tegra20-cpufreq.txt        | 96 +++++++++++++++++++
 1 file changed, 96 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/cpufreq/nvidia,tegra20-cpufreq.txt

diff --git a/Documentation/devicetree/bindings/cpufreq/nvidia,tegra20-cpufreq.txt b/Documentation/devicetree/bindings/cpufreq/nvidia,tegra20-cpufreq.txt
new file mode 100644
index 000000000000..a8023ea7a99f
--- /dev/null
+++ b/Documentation/devicetree/bindings/cpufreq/nvidia,tegra20-cpufreq.txt
@@ -0,0 +1,96 @@
+Binding for NVIDIA Tegra20 CPUFreq
+==================================
+
+Required properties:
+- clocks: Must contain an entry for each entry in clock-names.
+  See ../clocks/clock-bindings.txt for details.
+- clock-names: Must include the following entries:
+  - pll_x: main-parent for CPU clock, must be the first entry
+  - intermediate: intermediate-parent for CPU clock
+  - cclk: the CPU clock
+- operating-points-v2: See ../bindings/opp/opp.txt for details.
+- #cooling-cells: Should be 2. See ../thermal/thermal.txt for details.
+
+For each opp entry in 'operating-points-v2' table:
+- opp-supported-hw: Two bitfields indicating:
+	On Tegra20:
+	1. CPU process ID mask
+	2. SoC speedo ID mask
+
+	On Tegra30:
+	1. CPU process ID mask
+	2. CPU speedo ID mask
+
+	A bitwise AND is performed against these values and if any bit
+	matches, the OPP gets enabled.
+
+- opp-microvolt: CPU voltage triplet.
+
+Optional properties:
+- cpu-supply: Phandle to the CPU power supply.
+- core-supply: Phandle to the CORE power supply.
+- rtc-supply: Phandle to the RTC power supply, required only for Tegra20.
+
+Voltage supply requirements:
+- Tegra20:
+	CORE and RTC regulators must be coupled using the regulator-coupled-with
+	property and regulator-coupled-max-spread property must be set to no
+	more than 170mV.
+
+	See ../regulator/regulator.txt for more detail about the properties.
+
+- Tegra30:
+	CORE and CPU regulators must be coupled using the regulator-coupled-with
+	property and regulator-coupled-max-spread property must be set to no
+	more than 300mV. Each of CORE and CPU regulators must set
+	regulator-max-step-microvolt property to no more than 100mV.
+
+	See ../regulator/regulator.txt for more detail about the properties.
+
+
+Example:
+	regulators {
+		cpu_reg: regulator0 {
+			regulator-name = "vdd_cpu";
+		};
+
+		core_reg: regulator1 {
+			regulator-name = "vdd_core";
+			regulator-coupled-with = <&rtc_reg>;
+			regulator-coupled-max-spread = <170000>;
+		};
+
+		rtc_reg: regulator2 {
+			regulator-name = "vdd_rtc";
+			regulator-coupled-with = <&core_reg>;
+			regulator-coupled-max-spread = <170000>;
+		};
+	};
+
+	cpu0_opp_table: opp_table0 {
+		compatible = "operating-points-v2";
+
+		opp@...000000 {
+			clock-latency-ns = <125000>;
+			opp-microvolt = <825000 825000 1125000>;
+			opp-supported-hw = <0x03 0x0001>;
+			opp-hz = /bits/ 64 <456000000>;
+		};
+
+		...
+	};
+
+	cpus {
+		cpu@0 {
+			compatible = "arm,cortex-a9";
+			clocks = <&tegra_car TEGRA20_CLK_PLL_X>,
+				 <&tegra_car TEGRA20_CLK_PLL_P>,
+				 <&tegra_car TEGRA20_CLK_CCLK>;
+			clock-names = "pll_x", "intermediate", "cclk";
+			operating-points-v2 = <&cpu0_opp_table>;
+			cpu-supply = <&cpu_reg>;
+			core-supply = <&core_reg>;
+			rtc-supply = <&rtc_reg>;
+			#cooling-cells = <2>;
+		};
+	};
-- 
2.19.0