[PATCH v7 17/24] mfd: max77686: Add documentation for DVS bindings

[Javier Martinez Canillas <javier.martinez@collabora.co.uk>]

The MAX77686 PMIC submodule has Dynamic Voltage Scaling (DVS)
support on some regulators. Now that the regulator driver has
bindings to configure it, these bindings have to be documented.

Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
---
 Documentation/devicetree/bindings/mfd/max77686.txt | 34 ++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/Documentation/devicetree/bindings/mfd/max77686.txt b/Documentation/devicetree/bindings/mfd/max77686.txt
index 678f3cf..daf1c07 100644
--- a/Documentation/devicetree/bindings/mfd/max77686.txt
+++ b/Documentation/devicetree/bindings/mfd/max77686.txt
@@ -10,12 +10,38 @@ PMIC submodule.
 Binding for the built-in 32k clock generator block is defined separately
 in bindings/clk/maxim,max77686.txt file.
 
+Buck regulators 2, 3 and 4 include Dynamic Voltage Scaling (DVS) that allows
+each output voltage to change dynamically. Each Buck output voltage is selected
+using a set of external inputs: DVS1-3 and SELB2, 3 and 4.
+
+There are 8 DVS registers that can be used to configure the output voltage
+for each Buck regulator and which one is active is controled by DVSx lines.
+
+SELBx lines are used to control if individual Buck lines are ON or OFF.
+
 Required properties:
 - compatible : Must be "maxim,max77686";
 - reg : Specifies the i2c slave address of PMIC block.
 - interrupts : This i2c device has an IRQ line connected to the main SoC.
 - interrupt-parent : The parent interrupt controller.
 
+Optional properties:
+- max77686,pmic-buck-default-dvs-idx: We'll always write this DVS index in the
+  PMIC for Bucks with DVS.
+  NOTE: at the moment these bindings don't include enough details for actual
+  GPIO-DVS--this just lets you choose which single slot to use.
+
+- max77686,pmic-buck-dvs-gpios: A GPIO array where each GPIO is connected to a
+  DVS line. We'll try to set these GPIOs to match pmic-buck-default-dvs-idx at
+  probe time if they are defined. If some or all of these GPIOs are not defined
+  it's assumed that the board has any missing GPIOs hardwired to match
+  pmic-buck-default-dvs-idx.
+
+- max77686,pmic-buck-selb-gpios: A GPIO array where each GPIO is connected to a
+  SELBx line. Should be three values: 2, 3 and 4. It is strongly suggested to
+  include these GPIOs if there's any chance that changing DVS GPIOs one line at
+  a time might glitch your DVS values.
+
 Optional node:
 - voltage-regulators : The regulators of max77686 have to be instantiated
   under subnode named "voltage-regulators" using the following format.
@@ -42,6 +68,14 @@ Example:
 		interrupts = <26 0>;
 		reg = <0x09>;
 
+		max77686,pmic-buck-default-dvs-idx = <1>;
+		max77686,pmic-buck-dvs-gpios = <&gpy7 6 0>,
+					       <&gpj4 2 0>,
+					       <&gpj4 3 0>;
+		max77686,pmic-buck-selb-gpios = <&gph0 1 0>,
+						<&gph0 2 0>,
+						<&gph0 3 0>,
+
 		voltage-regulators {
 			ldo11_reg {
 				regulator-compatible = "LDO11";
-- 
2.0.0.rc2