[PATCH v3 1/3] dt-bindings: hwmon: pmbus: Add Maxim MAX31785 documentation

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Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
---
 .../devicetree/bindings/hwmon/pmbus/max31785.txt   | 158 +++++++++++++++++++++
 1 file changed, 158 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/pmbus/max31785.txt

diff --git a/Documentation/devicetree/bindings/hwmon/pmbus/max31785.txt b/Documentation/devicetree/bindings/hwmon/pmbus/max31785.txt
new file mode 100644
index 000000000000..af9578e7742c
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/pmbus/max31785.txt
@@ -0,0 +1,158 @@
+Bindings for the Maxim MAX31785 Intelligent Fan Controller
+==========================================================
+
+Reference:
+
+https://datasheets.maximintegrated.com/en/ds/MAX31785.pdf
+
+Required properties:
+- compatible     : One of "maxim,max31785" or "maxim,max31785a"
+- reg            : I2C address, one of 0x52, 0x53, 0x54, 0x55.
+- #address-cells : Must be 1
+- #size-cells    : Must be 0
+- #thermal-sensor-cells  : Should be 1. The device supports:
+                           - One internal sensor
+                           - Four external I2C digital sensors
+                           - Six external thermal diodes
+
+Optional properties:
+- use-stored-presence    : Do not treat the devicetree description as canon for
+                           fan presence (the 'installed' bit of FAN_CONFIG_*).
+                           Instead, rely on the on the default value store of
+                           the device to populate it.
+
+Capabilities are configured through subnodes of the controller's node.
+
+Fans
+----
+
+Only fans with subnodes present will be considered as installed. If
+use-stored-presence is present in the parent node, then only fans that are both
+defined in the devicetree and have their installed bit set are considered
+installed.
+
+Required subnode properties:
+- compatible             : Must be "pmbus-fan"
+- reg                    : The PMBus page the properties apply to.
+- #cooling-cells         : Should be 2. See the thermal bindings at [1].
+- maxim,fan-rotor-input  : The type of rotor measurement provided to the
+                           controller. Must be either "tach" for tachometer
+                           pulses or "lock" for a locked-rotor signal.
+- maxim,fan-lock-polarity: Required iff maxim,fan-rotor-input is "lock". Valid
+                           values are "low" for active low, "high" for active
+                           high.
+
+Optional subnode properties:
+- fan-mode               : "rpm" or "pwm". Default value is "pwm".
+- tach-pulses            : Tachometer pulses per revolution. Valid values are
+                           1, 2, 3 or 4. The default is 1.
+- cooling-min-level      : Smallest cooling state accepted. See [1].
+- cooling-max-level      : Largest cooling state accepted. See [1].
+- maxim,fan-no-fault-ramp: Do not ramp the fan to 100% PWM duty on detecting a
+                           fan fault
+- maxim,fan-startup      : The number of rotations required before taking
+                           emergency action for an unresponsive fan and driving
+                           it with 100% or 0% PWM duty, depending on the state
+                           of maxim,fan-no-fault-ramp. Valid values are 0
+                           (automatic spin-up disabled), 2, 4, or 8. Default
+                           value is 0.
+- maxim,fan-health       : Enable automated fan health check
+- maxim,fan-ramp         : Configures how fast the device ramps the PWM duty
+                           cycle from one value to another. Valid values are 0
+                           to 7 inclusive, with values 0 - 2 configuring a
+                           1000ms update rate and 1 - 3% duty respective duty
+                           increase, and 3 - 7 a 200ms update rate with a 1 -
+                           5% respective duty increase. Default value is 0.
+- maxim,fan-no-watchdog  : Do not ramp fan to 100% PWM duty on failure to
+                           update desired fan rate inside 10s. This implies
+                           maxim,tmp-no-fault-ramp
+- maxim,tmp-no-fault-ramp: Do not ramp fan to 100% PWM duty on temperature
+                           sensor fault detection. This implies
+                           maxim,fan-no-watchdog
+- maxim,tmp-hysteresis   : The temperature hysteresis used to determine
+                           transitions to lower fan speed bands in the
+                           temperature/fan rate lookup table. Valid values are
+                           2, 4, 6 or 8 (degrees celcius). Default value is 2.
+- maxim,fan-dual-tach    : Enable dual tachometer functionality
+- maxim,fan-pwm-freq     : The PWM frequency. Valid values are 30, 50, 100, 150
+                           and 25000 (Hz). Default value is 30Hz.
+- maxim,fan-lookup-table : A 16-element cell array of alternating temperature
+                           and rate values representing the look up table. The
+                           rate units are set through the fan-mode property.
+- maxim,fan-fault-pin-mon: Ramp fans to 100% PWM duty when the FAULT pin is
+                           asserted
+
+Temperature
+-----------
+
+Required subnode properties:
+- compatible    : Must be "pmbus-temperature"
+- reg           : The PMBus page the properties apply to.
+
+Optional subnode properties:
+- maxim,tmp-offset      : Valid values are 0 - 30 (degrees celcius) inclusive.
+                          Default value is 0.
+- maxim,tmp-fans        : An array of phandles to fans controlled by the
+                          current temperature sensor.
+
+[1] Documentation/devicetree/bindings/thermal/thermal.txt
+
+Example:
+	fan-max31785: max31785@52 {
+		reg = <0x52>;
+		compatible = "maxim,max31785";
+                #address-cells = <1>;
+                #size-cells = <0>;
+                #thermal-sensor-cells = <1>;
+
+                fan@0 {
+                        compatible = "pmbus-fan";
+                        reg = <0>;
+                        mode = "rpm";
+                        tach-pulses = <1>;
+
+                        #cooling-cells = <2>;
+                        cooling-min-level = <0>;
+                        cooling-max-level = <9>;
+
+                        maxim,fan-rotor-input = "tach";
+                        maxim,fan-dual-tach;
+                };
+
+                /*
+                 * Hardware controlled fan: Fan speed is controlled by a
+                 * temperature sensor feeding values into the lookup table. The
+                 * fan association is done in the temperature sensor node. One
+                 * sensor can drive multiple fans.
+                 */
+                cpu_fan: fan@1 {
+                        compatible = "pmbus-fan";
+                        reg = <1>;
+                        mode = "rpm";
+                        tach-pulses = <1>;
+
+                        #cooling-cells = <2>;
+
+                        maxim,fan-rotor-input = "tach";
+                        maxim,tmp-hysteresis = <2>;
+                        maxim,fan-lookup-table = <
+                        /*  Temperature    RPM  */
+                                 0        1000
+                                10        2000
+                                20        3000
+                                30        4000
+                                40        5000
+                                50        6000
+                                60        7000
+                                70        8000
+                        >;
+                };
+
+                cpu_temp: sensor@6 {
+                        compatible = "pmbus-temperature";
+                        reg = <6>;
+
+                        maxim,tmp-offset = <0>;
+                        maxim,tmp-fans = <&cpu_fan>;
+                };
+	};
-- 
2.11.0

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