Nuvoton NAU8824 audio codec This device supports I2C only. Required properties: - compatible : Must be "nuvoton,nau8824" - reg : the I2C address of the device. This is either 0x1a (CSB=0) or 0x1b (CSB=1). Optional properties: - nuvoton,jkdet-polarity: JKDET pin polarity. 0 - active high, 1 - active low. - nuvoton,vref-impedance: VREF Impedance selection 0 - Open 1 - 25 kOhm 2 - 125 kOhm 3 - 2.5 kOhm - nuvoton,micbias-voltage: Micbias voltage level. 0 - VDDA 1 - VDDA 2 - VDDA * 1.1 3 - VDDA * 1.2 4 - VDDA * 1.3 5 - VDDA * 1.4 6 - VDDA * 1.53 7 - VDDA * 1.53 - nuvoton,sar-threshold-num: Number of buttons supported - nuvoton,sar-threshold: Impedance threshold for each button. Array that contains up to 8 buttons configuration. SAR value is calculated as SAR = 255 * MICBIAS / SAR_VOLTAGE * R / (2000 + R) where MICBIAS is configured by 'nuvoton,micbias-voltage', SAR_VOLTAGE is configured by 'nuvoton,sar-voltage', R - button impedance. Refer datasheet section 10.2 for more information about threshold calculation. - nuvoton,sar-hysteresis: Button impedance measurement hysteresis. - nuvoton,sar-voltage: Reference voltage for button impedance measurement. 0 - VDDA 1 - VDDA 2 - VDDA * 1.1 3 - VDDA * 1.2 4 - VDDA * 1.3 5 - VDDA * 1.4 6 - VDDA * 1.53 7 - VDDA * 1.53 - nuvoton,sar-compare-time: SAR compare time 0 - 500 ns 1 - 1 us 2 - 2 us 3 - 4 us - nuvoton,sar-sampling-time: SAR sampling time 0 - 2 us 1 - 4 us 2 - 8 us 3 - 16 us - nuvoton,short-key-debounce: Button short key press debounce time. 0 - 30 ms 1 - 50 ms 2 - 100 ms - nuvoton,jack-eject-debounce: Jack ejection debounce time. 0 - 0 ms 1 - 1 ms 2 - 10 ms Example: headset: nau8824@1a { compatible = "nuvoton,nau8824"; reg = <0x1a>; interrupt-parent = <&gpio>; interrupts = ; nuvoton,vref-impedance = <2>; nuvoton,micbias-voltage = <6>; // Setup 4 buttons impedance according to Android specification nuvoton,sar-threshold-num = <4>; nuvoton,sar-threshold = <0xc 0x1e 0x38 0x60>; nuvoton,sar-hysteresis = <0>; nuvoton,sar-voltage = <6>; nuvoton,sar-compare-time = <1>; nuvoton,sar-sampling-time = <1>; nuvoton,short-key-debounce = <0>; nuvoton,jack-eject-debounce = <1>; };