regulator: pwm-regulator: Re-write bindings

* Add support for continuous-voltage mode
* Put more meat on the bones with regards to voltage-table mode
* Sort out formatting for ease of consumption

Cc: devicetree@vger.kernel.org
Signed-off-by: NLee Jones <lee.jones@linaro.org>
Signed-off-by: NMark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/pwm-regulator.txt

-pwm regulator bindings
+Bindings for the Generic PWM Regulator
+======================================
+
+Currently supports 2 modes of operation:
+
+voltage-table:		When in this mode, a voltage table (See below) of
+			predefined voltage <=> duty-cycle values must be
+			provided via DT. Limitations are that the regulator can
+			only operate at the voltages supplied in the table.
+			Intermediary duty-cycle values which would normally
+			allow finer grained voltage selection are ignored and
+			rendered useless.  Although more control is given to
+			the user if the assumptions made in continuous-voltage
+			mode do not reign true.
+
+continuous-voltage:	This mode uses the regulator's maximum and minimum
+			supplied voltages specified in the
+			regulator-{min,max}-microvolt properties to calculate
+			appropriate duty-cycle values.  This allows for a much
+			more fine grained solution when compared with
+			voltage-table mode above.  This solution does make an
+			assumption that a %50 duty-cycle value will cause the
+			regulator voltage to run at half way between the
+			supplied max_uV and min_uV values.
 
 Required properties:
-- compatible: Should be "pwm-regulator"
-- pwms: OF device-tree PWM specification (see PWM binding pwm.txt)
-- voltage-table: voltage and duty table, include 2 members in each set of
-  brackets, first one is voltage(unit: uv), the next is duty(unit: percent)
+--------------------
+- compatible:		Should be "pwm-regulator"
+
+- pwms:			PWM specification (See: ../pwm/pwm.txt)
+
+One of these must be provided:
+- voltage-table: 	Voltage and Duty-Cycle table consisting of 2 cells
+			    First cell is voltage in microvolts (uV)
+			    Second cell is duty-cycle in percent (%)
+
+- max-duty-cycle:	Maximum Duty-Cycle value -- this will normally be
+  			255 (0xff) for an 8 bit PWM device
 
-Any property defined as part of the core regulator binding defined in
-regulator.txt can also be used.
+If both are provided, the current default is voltage-table mode.
 
-Example:
+Any property defined as part of the core regulator binding can also be used.
+(See: ../regulator/regulator.txt)
+
+Continuous Voltage Example:
 	pwm_regulator {
 		compatible = "pwm-regulator;
 		pwms = <&pwm1 0 8448 0>;
+		regulator-min-microvolt = <1016000>;
+		regulator-max-microvolt = <1114000>;
+		regulator-name = "vdd_logic";
+
+		max-duty-cycle = <255>; /* 8bit PWM */
+	};
 
+Voltage Table Example:
+	pwm_regulator {
+		compatible = "pwm-regulator;
+		pwms = <&pwm1 0 8448 0>;
+		regulator-min-microvolt = <1016000>;
+		regulator-max-microvolt = <1114000>;
+		regulator-name = "vdd_logic";
+
+			      /* Voltage Duty-Cycle */
 		voltage-table = <1114000 0>,
 				<1095000 10>,
 				<1076000 20>,
 				<1056000 30>,
 				<1036000 40>,
 				<1016000 50>;
-
-		regulator-min-microvolt = <1016000>;
-		regulator-max-microvolt = <1114000>;
-		regulator-name = "vdd_logic";
 	};