diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devicetree/bindings/gpio/gpio-poweroff.txt | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt b/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt index 558cdf3c9ab..d4eab9227ea 100644 --- a/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt +++ b/Documentation/devicetree/bindings/gpio/gpio-poweroff.txt @@ -1,4 +1,19 @@ -GPIO line that should be set high/low to power off a device +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". @@ -13,10 +28,9 @@ Optional properties: 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>; /* GPIO 4 Active Low */ + gpios = <&gpio 4 0>; }; |