37 lines
1.5 KiB
Plaintext
37 lines
1.5 KiB
Plaintext
|
Driver a GPIO line that can be used to turn the power off.
|
||
|
|
|
||
|
|
The driver supports both level triggered and edge triggered power off.
|
||
|
|
At driver load time, the driver will request the given gpio line and
|
||
|
|
install a pm_power_off handler. If the optional properties 'input' is
|
||
|
|
not found, the GPIO line will be driven in the inactive
|
||
|
|
state. Otherwise its configured as an input.
|
||
|
|
|
||
|
|
When the pm_power_off is called, the gpio is configured as an output,
|
||
|
|
and drive active, so triggering a level triggered power off
|
||
|
|
condition. This will also cause an inactive->active edge condition, so
|
||
|
|
triggering positive edge triggered power off. After a delay of 100ms,
|
||
|
|
the GPIO is set to inactive, thus causing an active->inactive edge,
|
||
|
|
triggering negative edge triggered power off. After another 100ms
|
||
|
|
delay the GPIO is driver active again. If the power is still on and
|
||
|
|
the CPU still running after a 3000ms delay, a WARN_ON(1) is emitted.
|
||
|
|
|
||
|
|
Required properties:
|
||
|
|
- compatible : should be "gpio-poweroff".
|
||
|
|
- gpios : The GPIO to set high/low, see "gpios property" in
|
||
|
|
Documentation/devicetree/bindings/gpio/gpio.txt. If the pin should be
|
||
|
|
low to power down the board set it to "Active Low", otherwise set
|
||
|
|
gpio to "Active High".
|
||
|
|
|
||
|
|
Optional properties:
|
||
|
|
- input : Initially configure the GPIO line as an input. Only reconfigure
|
||
|
|
it to an output when the pm_power_off function is called. If this optional
|
||
|
|
property is not specified, the GPIO is initialized as an output in its
|
||
|
|
inactive state.
|
||
|
|
|
||
|
|
Examples:
|
||
|
|
|
||
|
|
gpio-poweroff {
|
||
|
|
compatible = "gpio-poweroff";
|
||
|
|
gpios = <&gpio 4 0>;
|
||
|
|
};
|