linux/Documentation/devicetree/bindings/gpio/gpio_lpc32xx.txt
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   1NXP LPC32xx SoC GPIO controller
   2
   3Required properties:
   4- compatible: must be "nxp,lpc3220-gpio"
   5- reg: Physical base address and length of the controller's registers.
   6- gpio-controller: Marks the device node as a GPIO controller.
   7- #gpio-cells: Should be 3:
   8   1) bank:
   9      0: GPIO P0
  10      1: GPIO P1
  11      2: GPIO P2
  12      3: GPIO P3
  13      4: GPI P3
  14      5: GPO P3
  15   2) pin number
  16   3) optional parameters:
  17      - bit 0 specifies polarity (0 for normal, 1 for inverted)
  18- reg: Index of the GPIO group
  19
  20Example:
  21
  22        gpio: gpio@40028000 {
  23                compatible = "nxp,lpc3220-gpio";
  24                reg = <0x40028000 0x1000>;
  25                gpio-controller;
  26                #gpio-cells = <3>; /* bank, pin, flags */
  27        };
  28
  29        leds {
  30                compatible = "gpio-leds";
  31
  32                led0 {
  33                        gpios = <&gpio 5 1 1>; /* GPO_P3 1, active low */
  34                        linux,default-trigger = "heartbeat";
  35                        default-state = "off";
  36                };
  37
  38                led1 {
  39                        gpios = <&gpio 5 14 1>; /* GPO_P3 14, active low */
  40                        linux,default-trigger = "timer";
  41                        default-state = "off";
  42                };
  43        };
  44