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     1 Microchip AT42QT1050 Five-channel Touch Sensor IC
    2 
    3 The AT42QT1050 (QT1050) is a QTouchADC sensor device. The device can sense from
    4 one to five keys, dependent on mode. The QT1050 includes all signal processing
    5 functions necessary to provide stable sensing under a wide variety of changing
    6 conditions, and the outputs are fully debounced.
    7 
    8 The touchkey device node should be placed inside an I2C bus node.
    9 
   10 Required properties:
   11 - compatible: Must be "microchip,qt1050"
   12 - reg: The I2C address of the device
   13 - interrupts: The sink for the touchpad's IRQ output,
   14   see ../interrupt-controller/interrupts.txt
   15 
   16 Optional properties:
   17 - wakeup-source: touch keys can be used as a wakeup source
   18 
   19 Each button (key) is represented as a sub-node:
   20 
   21 Each not specified key or key with linux,code set to KEY_RESERVED gets disabled
   22 in HW.
   23 
   24 Subnode properties:
   25 - linux,code: Keycode to emit.
   26 - reg: The key number. Valid values: 0, 1, 2, 3, 4.
   27 
   28 Optional subnode-properties:
   29 
   30 If a optional property is missing or has a invalid value the default value is
   31 taken.
   32 
   33 - microchip,pre-charge-time-ns:
   34   Each touchpad need some time to precharge. The value depends on the mechanical
   35   layout.
   36   Valid value range: 0 - 637500; values must be a multiple of 2500;
   37   default is 0.
   38 - microchip,average-samples:
   39   Number of data samples which are averaged for each read.
   40   Valid values: 1, 4, 16, 64, 256, 1024, 4096, 16384; default is 1.
   41 - microchip,average-scaling:
   42   The scaling factor which is used to scale the average-samples.
   43   Valid values: 1, 2, 4, 8, 16, 32, 64, 128; default is 1.
   44 - microchip,threshold:
   45   Number of counts to register a touch detection.
   46   Valid value range: 0 - 255; default is 20.
   47 
   48 Example:
   49 QT1050 with 3 non continuous keys, key2 and key4 are disabled.
   50 
   51 touchkeys@41 {
   52         compatible = "microchip,qt1050";
   53         reg = <0x41>;
   54         interrupt-parent = <&gpio0>;
   55         interrupts = <17 IRQ_TYPE_EDGE_FALLING>;
   56 
   57         up@0 {
   58                 reg = <0>;
   59                 linux,code = <KEY_UP>;
   60                 microchip,average-samples = <64>;
   61                 microchip,average-scaling = <16>;
   62                 microchip,pre-charge-time-ns = <10000>;
   63         };
   64 
   65         right@1 {
   66                 reg = <1>;
   67                 linux,code = <KEY_RIGHT>;
   68                 microchip,average-samples = <64>;
   69                 microchip,average-scaling = <8>;
   70         };
   71 
   72         down@3 {
   73                 reg = <3>;
   74                 linux,code = <KEY_DOWN>;
   75                 microchip,average-samples = <256>;
   76                 microchip,average-scaling = <16>;
   77         };
   78 };
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