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diff --git a/Documentation/devicetree/bindings/regulator/pwm-regulator.txt b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt new file mode 100644 index 000000000..3d78d507e --- /dev/null +++ b/Documentation/devicetree/bindings/regulator/pwm-regulator.txt @@ -0,0 +1,92 @@ +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: PWM specification (See: ../pwm/pwm.txt) + +Only required for Voltage Table Mode: +- 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 (%) + +Optional properties for Continuous mode: +- pwm-dutycycle-unit: Integer value encoding the duty cycle unit. If not + defined, <100> is assumed, meaning that + pwm-dutycycle-range contains values expressed in + percent. + +- pwm-dutycycle-range: Should contain 2 entries. The first entry is encoding + the dutycycle for regulator-min-microvolt and the + second one the dutycycle for regulator-max-microvolt. + Duty cycle values are expressed in pwm-dutycycle-unit. + If not defined, <0 100> is assumed. + +NB: To be clear, if voltage-table is provided, then the device will be used +in Voltage Table Mode. If no voltage-table is provided, then the device will +be used in Continuous Voltage Mode. + +Optional properties: +-------------------- +- enable-gpios: GPIO to use to enable/disable the regulator + +Any property defined as part of the core regulator binding can also be used. +(See: ../regulator/regulator.txt) + +Continuous Voltage With Enable GPIO Example: + pwm_regulator { + compatible = "pwm-regulator"; + pwms = <&pwm1 0 8448 0>; + enable-gpios = <&gpio0 23 GPIO_ACTIVE_HIGH>; + regulator-min-microvolt = <1016000>; + regulator-max-microvolt = <1114000>; + regulator-name = "vdd_logic"; + /* unit == per-mille */ + pwm-dutycycle-unit = <1000>; + /* + * Inverted PWM logic, and the duty cycle range is limited + * to 30%-70%. + */ + pwm-dutycycle-range = <700 300>; /* */ + }; + +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>; + }; |