1Driver a GPIO line that can be used to turn the power off.
2
3The driver supports both level triggered and edge triggered power off.
4At driver load time, the driver will request the given gpio line and
5install a pm_power_off handler. If the optional properties 'input' is
6not found, the GPIO line will be driven in the inactive
7state. Otherwise its configured as an input.
8
9When the pm_power_off is called, the gpio is configured as an output,
10and drive active, so triggering a level triggered power off
11condition. This will also cause an inactive->active edge condition, so
12triggering positive edge triggered power off. After a delay of 100ms,
13the GPIO is set to inactive, thus causing an active->inactive edge,
14triggering negative edge triggered power off. After another 100ms
15delay the GPIO is driver active again. If the power is still on and
16the CPU still running after a 3000ms delay, a WARN_ON(1) is emitted.
17
18Required properties:
19- compatible : should be "gpio-poweroff".
20- gpios : The GPIO to set high/low, see "gpios property" in
21  Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be
22  low to power down the board set it to "Active Low", otherwise set
23  gpio to "Active High".
24
25Optional properties:
26- input : Initially configure the GPIO line as an input. Only reconfigure
27  it to an output when the pm_power_off function is called. If this optional
28  property is not specified, the GPIO is initialized as an output in its
29  inactive state.
30
31Examples:
32
33gpio-poweroff {
34	compatible = "gpio-poweroff";
35	gpios = <&gpio 4 0>;
36};
37