* Texas Instruments TRF7970A RFID/NFC/15693 Transceiver

Required properties:
- compatible: Should be "ti,trf7970a".
- spi-max-frequency: Maximum SPI frequency (<= 2000000).
- interrupts: A single interrupt specifier.
- ti,enable-gpios: One or two GPIO entries used for 'EN' and 'EN2' pins on the
  TRF7970A. EN2 is optional.
- vin-supply: Regulator for supply voltage to VIN pin

Optional SoC Specific Properties:
- pinctrl-names: Contains only one value - "default".
- pintctrl-0: Specifies the pin control groups used for this controller.
- autosuspend-delay: Specify autosuspend delay in milliseconds.
- irq-status-read-quirk: Specify that the trf7970a being used has the
  "IRQ Status Read" erratum.
- en2-rf-quirk: Specify that the trf7970a being used has the "EN2 RF"
  erratum.
- vdd-io-supply: Regulator specifying voltage for vdd-io
- clock-frequency: Set to specify that the input frequency to the trf7970a is 13560000Hz or 27120000Hz

Example (for ARM-based BeagleBone with TRF7970A on SPI1):

&spi1 {

	nfc@0 {
		compatible = "ti,trf7970a";
		reg = <0>;
		pinctrl-names = "default";
		pinctrl-0 = <&trf7970a_default>;
		spi-max-frequency = <2000000>;
		interrupt-parent = <&gpio2>;
		interrupts = <14 0>;
		ti,enable-gpios = <&gpio2 2 GPIO_ACTIVE_HIGH>,
				  <&gpio2 5 GPIO_ACTIVE_HIGH>;
		vin-supply = <&ldo3_reg>;
		vdd-io-supply = <&ldo2_reg>;
		autosuspend-delay = <30000>;
		irq-status-read-quirk;
		en2-rf-quirk;
		clock-frequency = <27120000>;
	};
};