regulator: palmas: add support for external control of rails

Palmas rails like LDOs, SMPSs, REGENs, SYSENs can be enable and disable
by register programming through I2C communication as well as it can be
enable/disable with the external control input ENABLE1, ENABLE2 and NSLEEP.

Add support for configuring these rails to be controlled by external control
inputs. This is require to configure the rail's control register as well as
configuration of resource register.

Provide the external input names through parameter "roof-floor". Updated the
DT binding document to details different value of the roof-floor.
Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/regulator/palmas-pmic.txt

@@ -26,11 +26,17 @@ Optional nodes:
 
 	       For ti,palmas-pmic - smps12, smps123, smps3 depending on OTP,
 	       smps45, smps457, smps7 depending on variant, smps6, smps[8-9],
-	       smps10_out2, smps10_out1, do[1-9], ldoln, ldousb.
+	       smps10_out2, smps10_out1, ldo[1-9], ldoln, ldousb.
 
 	       Optional sub-node properties:
 	       ti,warm-reset - maintain voltage during warm reset(boolean)
-	       ti,roof-floor - control voltage selection by pin(boolean)
+	       ti,roof-floor - This takes as optional argument on platform supporting
+	       the rail from desired external control. If there is no argument then
+	       it will be assume that it is controlled by NSLEEP pin.
+	       The valid value for external pins are:
+			ENABLE1 then 1,
+			ENABLE2 then 2 or
+			NSLEEP then 3.
 	       ti,mode-sleep - mode to adopt in pmic sleep 0 - off, 1 - auto,
 	       2 - eco, 3 - forced pwm
 	       ti,smps-range - OTP has the wrong range set for the hardware so override
@@ -61,7 +67,7 @@ pmic {
 			regulator-always-on;
 			regulator-boot-on;
 			ti,warm-reset;
-			ti,roof-floor;
+			ti,roof-floor = <1>; /* ENABLE1 control */
 			ti,mode-sleep = <0>;
 			ti,smps-range = <1>;
 		};