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