Cirrus Logic Tacna class audio codecs extcon driver

The extcon configuration settings are a child node of the parent MFD driver
binding.
See Documentation/devicetree/bindings/mfd/tacna.txt

This node contains one or more child nodes to describe the configuration for
each accessory detect.

Mandatory properties:
  - compatible : must be "cirrus,tacna-extcon"
  - #address-cells : must be 1
  - #size-cells : must be 0

Optional properties:
  - cirrus,gpsw : Settings for the general purpose switches, set as per the
    SWn_MODE bits in the GP_SWITCH register. If given must be 2 cells.
    First cell is the value for the GPSW1_MODE
    Second cell is the value for the GPSW2_MODE

Child node mandatory properties:
  - reg : output number this configuration applies to, must be 1

Child node optional properties:
  - cirrus,micd-detect-debounce-ms : Additional software microphone detection
    debounce specified in milliseconds

  - cirrus,micd-manual-debounce : Additional software button detection
    debounce specified as a number

  - cirrus,micd-bias-start-time : Time allowed for MICBIAS to startup prior to
    performing microphone detection, specified as per the MICDn_DELAY
    bits in the register MICDET_CONTROL1

  - cirrus,micd-pol-gpio : GPIO specifier for the GPIO controlling the headset
    polarity if one exists

  - cirrus,micd-rate : Delay between successive microphone detection
    measurements, specified as per the MICDn_RATE bits in the register
    MICDETn_CONTROL1

  - cirrus,micd-dbtime : Microphone detection hardware debounce level, specified
    as per the MICDn_DBTIME bits in the register MICDET_CONTROL1

  - cirrus,micd-timeout-ms : Timeout for microphone detection, specified in
    milliseconds

  - cirrus,micd-software-compare : Use a software comparison to determine mic
    presence

  - cirrus,fixed-hpdet-imp : Do not perform any headphone detection, just use
    the fixed value specified here as the headphone impedance. Value is in
    hundredths-of-an-ohm (ohms * 100)

  - cirrus,hpdet-ext-res : Impedance of external series resistor on hpdet.
    Value is in hundredths-of-an-ohm (ohms * 100)

  - cirrus,hpdet-short-circuit-imp : Specifies the maximum impedance in ohms
    that will be considered as a short circuit

  - cirrus,hpdet-channel : Set which channel is used for headphone impedance
    measurement. 0 = left, 1 = right

  - cirrus,micd-clamp-mode : Specifies the logic of the micdetect clamp block

  - cirrus,hpd-pins : 4 cells specifying the clamp and sense pins to use.
	<clamp_left sense_left clamp_right sense_right>
    where clamp_x is the clamp pin for channel x and sense_x is the impedance
    sense pin for channel x, as per the HPD_OUT_SEL field of HPDET1_CONTROL1
    register. A value >0xFFFF means use the default.

  - cirrus,micd-configs : Headset polarity configurations, variable length but
    must be a multiple of 5 cells, each 5-cell group represents one
    polarity configuration
    first cell is the value of MICDn_SENSE_SEL register field
    second cell is the accessory detection ground as per the MICDn_GND_SEL
      register field
    the third cell is the MICBIAS to be used as per the MICDn_BIAS_SRC register
      field
    fourth cell is the value of the micd-pol-gpio pin, a non-zero value
      indicates this should be on
    fifth cell is the value of HPn_GND_SEL register field

  - cirrus,accdet-dbtime : Set accessory detection hardware debounce level,
    as per the ACCDET_DBTIME bits in the register TACNA_ACCDET_DEBOUNCE

Example:

codec: cs47l96@0 {
	compatible = "cirrus,cs47l96";

	accdet {
		compatible = "cirrus,tacna-extcon";
		#address-cells = <1>;
		#size-cells = <0>;

		cirrus,gpsw = <3 0>;

		cirrus,micd-pol-gpios = <&gpio 0>

		acc@1 {
			reg = <1>;

			cirrus,micd-detect-debounce-ms = <10>;
			cirrus,micd-bias-start-time = <0x1>;
			cirrus,micd-rate = <0x1>;
			cirrus,micd-dbtime = <0x1>;
			cirrus,micd-timeout-ms = <10>;
			cirrus,micd-configs = <
				0x1 0 1 0 2
				0x0 0 2 1 2
			>;
			cirrus,accdet-dbtime =<0x1>;
		};
	};
};