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32 .Nd GPIO LED generic device driver
34 To compile this driver into the kernel,
35 place the following lines in your
36 kernel configuration file:
37 .Bd -ragged -offset indent
44 driver provides glue to attach a
46 compatible device to a GPIO pin.
47 Each LED in the system has a
49 which is used to export a device as
51 The GPIO pin can then be controlled by writing to this device as described
59 these values are configurable for
61 .Bl -tag -width ".Va hint.gpioiic.%d.atXXX"
62 .It Va hint.gpioled.%d.at
63 The gpiobus you are attaching to.
64 Normally assigned to gpiobus0.
65 .It Va hint.gpioled.%d.name
66 Arbitrary name of device in
70 .It Va hint.gpioled.%d.pins
71 Which pin on the GPIO interface to map to this instance.
72 Please note that this mask should only ever have one bit set
73 (any other bits - i.e., pins - will be ignored).
74 .It Va hint.gpioled.%d.invert
75 If set to 1, the pin will be set to 0 to light the LED, and 1 to clear it.
76 .It Va hint.gpioled.%d.state
77 The initial state of the LED when the driver takes control over it.
78 If set to 1 or 0, the LED will be on or off correspondingly.
79 If set to -1, the LED will be kept in its original state.
88 device usually looks like:
96 compatible = "gpioled";
97 gpios = <&gpio 16 2 0>; /* GPIO pin 16. */
102 compatible = "gpioled";
103 gpios = <&gpio 17 2 0>; /* GPIO pin 17. */
109 Optionally, you can choose to combine all the LEDs under a single
118 compatible = "gpio-leds";
121 gpios = <&gpio 16 2 0>;
126 gpios = <&gpio 17 2 0>;
133 Both methods are equally supported and it is possible to have the LEDs
134 defined with any sort of mix between the methods.
135 The only restriction is that a GPIO pin cannot be mapped by two different
138 For more details about the
140 property, please consult
141 .Pa /usr/src/sys/dts/bindings-gpio.txt .
145 is the arbitrary name of the device in
157 manual page first appeared in
161 manual page was written by
162 .An Luiz Otavio O Souza .