@@ -1,27 +1,71 @@
-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";
};
* 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: Lee Jones <lee.jones@linaro.org> --- .../bindings/regulator/pwm-regulator.txt | 68 ++++++++++++++++++---- 1 file changed, 56 insertions(+), 12 deletions(-)