Commit | Line | Data |
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5343527b AL |
1 | Driver a GPIO line that can be used to turn the power off. |
2 | ||
3 | The driver supports both level triggered and edge triggered power off. | |
4 | At driver load time, the driver will request the given gpio line and | |
5 | install a pm_power_off handler. If the optional properties 'input' is | |
6 | not found, the GPIO line will be driven in the inactive | |
7 | state. Otherwise its configured as an input. | |
8 | ||
9 | When the pm_power_off is called, the gpio is configured as an output, | |
10 | and drive active, so triggering a level triggered power off | |
11 | condition. This will also cause an inactive->active edge condition, so | |
12 | triggering positive edge triggered power off. After a delay of 100ms, | |
13 | the GPIO is set to inactive, thus causing an active->inactive edge, | |
14 | triggering negative edge triggered power off. After another 100ms | |
15 | delay the GPIO is driver active again. If the power is still on and | |
16 | the CPU still running after a 3000ms delay, a WARN_ON(1) is emitted. | |
96ff0f5c JL |
17 | |
18 | Required 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 | ||
25 | Optional 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 | ||
96ff0f5c JL |
31 | Examples: |
32 | ||
33 | gpio-poweroff { | |
34 | compatible = "gpio-poweroff"; | |
5343527b | 35 | gpios = <&gpio 4 0>; |
96ff0f5c | 36 | }; |