Some boards, in order to power devices that have a quite high power
consumption, wire multiple regulators in parallel.

In such a case, the regulators need to be kept in sync, all of them being
enabled or disabled in parallel.

This also requires to expose only the voltages that are common to all the
regulators.

Eventually support for changing the voltage in parallel should be added
too, possibly with delays between each other to avoid having a too brutal
peak consumption.

Signed-off-by: Maxime Ripard <redacted>
---
 .../bindings/regulator/coupled-voltage.txt         |  18 ++
 drivers/regulator/Kconfig                          |   8 +
 drivers/regulator/Makefile                         |   1 +
 drivers/regulator/coupled-voltage-regulator.c      | 299 +++++++++++++++++++++
 4 files changed, 326 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/regulator/coupled-voltage.txt
 create mode 100644 drivers/regulator/coupled-voltage-regulator.c

diff --git a/Documentation/devicetree/bindings/regulator/coupled-voltage.txt b/Documentation/devicetree/bindings/regulator/coupled-voltage.txt
new file mode 100644
index 000000000000..f5401aab52f2
--- /dev/null
+++ b/Documentation/devicetree/bindings/regulator/coupled-voltage.txt

@@ -0,0 +1,18 @@
+Coupled voltage regulators
+
+Required properties:
+- compatible		: Must be "coupled-voltage-regulator".
+
+Optional properties:
+- vinX-supply		: Phandle to the regulators it aggregates
+
+Any property defined as part of the core regulator binding defined in
+regulator.txt can also be used.
+
+Example:
+	vcc_wifi: wifi_reg {
+		compatible = "coupled-voltage-regulator";
+		regulator-name = "vcc-wifi";
+		vin0-supply = <&reg_ldo3>;
+		vin1-supply = <&reg_ldo4>;
+	};