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

   1 Bindings for the Generic PWM Regulator
   2 ======================================
   3
   4 Currently supports 2 modes of operation:
   5
   6 Voltage Table:          When in this mode, a voltage table (See below) of
   7                         predefined voltage <=> duty-cycle values must be
   8                         provided via DT. Limitations are that the regulator can
   9                         only operate at the voltages supplied in the table.
  10                         Intermediary duty-cycle values which would normally
  11                         allow finer grained voltage selection are ignored and
  12                         rendered useless.  Although more control is given to
  13                         the user if the assumptions made in continuous-voltage
  14                         mode do not reign true.
  15
  16 Continuous Voltage:     This mode uses the regulator's maximum and minimum
  17                         supplied voltages specified in the
  18                         regulator-{min,max}-microvolt properties to calculate
  19                         appropriate duty-cycle values.  This allows for a much
  20                         more fine grained solution when compared with
  21                         voltage-table mode above.  This solution does make an
  22                         assumption that a %50 duty-cycle value will cause the
  23                         regulator voltage to run at half way between the
  24                         supplied max_uV and min_uV values.
  25
  26 Required properties:
  27 --------------------
  28 - compatible:           Should be "pwm-regulator"
  29
  30 - pwms:                 PWM specification (See: ../pwm/pwm.txt)
  31
  32 Only required for Voltage Table Mode:
  33 - voltage-table:        Voltage and Duty-Cycle table consisting of 2 cells
  34                             First cell is voltage in microvolts (uV)
  35                             Second cell is duty-cycle in percent (%)
  36
  37 Optional properties for Continuous mode:
  38 - pwm-dutycycle-unit:   Integer value encoding the duty cycle unit. If not
  39                         defined, <100> is assumed, meaning that
  40                         pwm-dutycycle-range contains values expressed in
  41                         percent.
  42
  43 - pwm-dutycycle-range:  Should contain 2 entries. The first entry is encoding
  44                         the dutycycle for regulator-min-microvolt and the
  45                         second one the dutycycle for regulator-max-microvolt.
  46                         Duty cycle values are expressed in pwm-dutycycle-unit.
  47                         If not defined, <0 100> is assumed.
  48
  49 NB: To be clear, if voltage-table is provided, then the device will be used
  50 in Voltage Table Mode.  If no voltage-table is provided, then the device will
  51 be used in Continuous Voltage Mode.
  52
  53 Optional properties:
  54 --------------------
  55 - enable-gpios:         GPIO to use to enable/disable the regulator
  56
  57 Any property defined as part of the core regulator binding can also be used.
  58 (See: ../regulator/regulator.txt)
  59
  60 Continuous Voltage With Enable GPIO Example:
  61         pwm_regulator {
  62                 compatible = "pwm-regulator;
  63                 pwms = <&pwm1 0 8448 0>;
  64                 enable-gpios = <&gpio0 23 GPIO_ACTIVE_HIGH>;
  65                 regulator-min-microvolt = <1016000>;
  66                 regulator-max-microvolt = <1114000>;
  67                 regulator-name = "vdd_logic";
  68                 /* unit == per-mille */
  69                 pwm-dutycycle-unit = <1000>;
  70                 /*
  71                  * Inverted PWM logic, and the duty cycle range is limited
  72                  * to 30%-70%.
  73                  */
  74                 pwm-dutycycle-range <700 300>; /* */
  75         };
  76
  77 Voltage Table Example:
  78         pwm_regulator {
  79                 compatible = "pwm-regulator;
  80                 pwms = <&pwm1 0 8448 0>;
  81                 regulator-min-microvolt = <1016000>;
  82                 regulator-max-microvolt = <1114000>;
  83                 regulator-name = "vdd_logic";
  84
  85                               /* Voltage Duty-Cycle */
  86                 voltage-table = <1114000 0>,
  87                                 <1095000 10>,
  88                                 <1076000 20>,
  89                                 <1056000 30>,
  90                                 <1036000 40>,
  91                                 <1016000 50>;
  92         };