dt-bindings: regulator: Document regulators coupling of NVIDIA Tegra20/30 SoCs

There is voltage coupling between three regulators on Tegra20 boards and
between two on Tegra30. The voltage coupling is a SoC-level feature and
thus it is mandatory and common for all of the Tegra boards.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Thierry Reding <treding@nvidia.com>
This commit is contained in:
Dmitry Osipenko 2019-07-25 18:18:30 +03:00 committed by Thierry Reding
parent cdc2d6685c
commit db45f0f05c

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NVIDIA Tegra Regulators Coupling
================================
NVIDIA Tegra SoC's have a mandatory voltage-coupling between regulators.
Thus on Tegra20 there are 3 coupled regulators and on NVIDIA Tegra30
there are 2.
Tegra20 voltage coupling
------------------------
On Tegra20 SoC's there are 3 coupled regulators: CORE, RTC and CPU.
The CORE and RTC voltages shall be in a range of 170mV from each other
and they both shall be higher than the CPU voltage by at least 120mV.
Tegra30 voltage coupling
------------------------
On Tegra30 SoC's there are 2 coupled regulators: CORE and CPU. The CORE
and CPU voltages shall be in a range of 300mV from each other and CORE
voltage shall be higher than the CPU by N mV, where N depends on the CPU
voltage.
Required properties:
- nvidia,tegra-core-regulator: Boolean property that designates regulator
as the "Core domain" voltage regulator.
- nvidia,tegra-rtc-regulator: Boolean property that designates regulator
as the "RTC domain" voltage regulator.
- nvidia,tegra-cpu-regulator: Boolean property that designates regulator
as the "CPU domain" voltage regulator.
Example:
pmic {
regulators {
core_vdd_reg: core {
regulator-name = "vdd_core";
regulator-min-microvolt = <950000>;
regulator-max-microvolt = <1300000>;
regulator-coupled-with = <&rtc_vdd_reg &cpu_vdd_reg>;
regulator-coupled-max-spread = <170000 550000>;
nvidia,tegra-core-regulator;
};
rtc_vdd_reg: rtc {
regulator-name = "vdd_rtc";
regulator-min-microvolt = <950000>;
regulator-max-microvolt = <1300000>;
regulator-coupled-with = <&core_vdd_reg &cpu_vdd_reg>;
regulator-coupled-max-spread = <170000 550000>;
nvidia,tegra-rtc-regulator;
};
cpu_vdd_reg: cpu {
regulator-name = "vdd_cpu";
regulator-min-microvolt = <750000>;
regulator-max-microvolt = <1125000>;
regulator-coupled-with = <&core_vdd_reg &rtc_vdd_reg>;
regulator-coupled-max-spread = <550000 550000>;
nvidia,tegra-cpu-regulator;
};
};
};