regulator: Add driver for voltage controlled regulators

The output voltage of a voltage controlled regulator can be controlled
through the voltage of another regulator. The current version of this
driver assumes that the output voltage is a linear function of the control
voltage.

Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 49 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/regulator/vctrl.txt b/Documentation/devicetree/bindings/regulator/vctrl.txt
new file mode 100644
index 000000000000..601328d7fdbb
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/vctrl.txt
@@ -0,0 +1,49 @@
+Bindings for Voltage controlled regulators
+==========================================
+
+Required properties:
+--------------------
+- compatible		  : must be "vctrl-regulator".
+- regulator-min-microvolt : smallest voltage consumers may set
+- regulator-max-microvolt : largest voltage consumers may set
+- ctrl-supply		  : The regulator supplying the control voltage.
+- ctrl-voltage-range	  : an array of two integer values describing the range
+			    (min/max) of the control voltage. The values specify
+			    the control voltage needed to generate the corresponding
+			    regulator-min/max-microvolt output voltage.
+
+Optional properties:
+--------------------
+- ovp-threshold-percent	: overvoltage protection (OVP) threshold of the
+			  regulator in percent. Some regulators have an OVP
+			  circuitry which shuts down the regulator when the
+			  actual output voltage deviates beyond a certain
+			  margin from the expected value for a given control
+			  voltage. On larger voltage decreases this can occur
+			  undesiredly since the output voltage does not adjust
+			  inmediately to changes in the control voltage. To
+			  avoid this situation the vctrl driver breaks down
+			  larger voltage decreases into multiple steps, where
+			  each step is within the OVP threshold.
+- min-slew-down-rate	: Describes how slowly the regulator voltage will decay
+			  down in the worst case (lightest expected load).
+			  Specified in uV / us (like main regulator ramp rate).
+			  This value is required when ovp-threshold-percent is
+			  specified.
+
+Example:
+
+	vctrl-reg {
+		compatible = "vctrl-regulator";
+		regulator-name = "vctrl_reg";
+
+		ctrl-supply = <&ctrl_reg>;
+
+		regulator-min-microvolt = <800000>;
+		regulator-max-microvolt = <1500000>;
+
+		ctrl-voltage-range = <200000 500000>;
+
+		min-slew-down-rate = <225>;
+		ovp-threshold-percent = <16>;
+	};