42 lines
1.5 KiB
Text
42 lines
1.5 KiB
Text
* HDMI CEC GPIO driver
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The HDMI CEC GPIO module supports CEC implementations where the CEC line
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is hooked up to a pull-up GPIO line and - optionally - the HPD line is
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hooked up to another GPIO line.
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Please note: the maximum voltage for the CEC line is 3.63V, for the HPD and
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5V lines it is 5.3V. So you may need some sort of level conversion circuitry
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when connecting them to a GPIO line.
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Required properties:
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- compatible: value must be "cec-gpio".
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- cec-gpios: gpio that the CEC line is connected to. The line should be
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tagged as open drain.
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If the CEC line is associated with an HDMI receiver/transmitter, then the
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following property is also required:
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- hdmi-phandle - phandle to the HDMI controller, see also cec.txt.
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If the CEC line is not associated with an HDMI receiver/transmitter, then
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the following property is optional and can be used for debugging HPD changes:
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- hpd-gpios: gpio that the HPD line is connected to.
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This property is optional and can be used for debugging changes on the 5V line:
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- v5-gpios: gpio that the 5V line is connected to.
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Example for the Raspberry Pi 3 where the CEC line is connected to
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pin 26 aka BCM7 aka CE1 on the GPIO pin header, the HPD line is
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connected to pin 11 aka BCM17 and the 5V line is connected to pin
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15 aka BCM22 (some level shifter is needed for the HPD and 5V lines!):
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#include <dt-bindings/gpio/gpio.h>
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cec-gpio {
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compatible = "cec-gpio";
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cec-gpios = <&gpio 7 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN)>;
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hpd-gpios = <&gpio 17 GPIO_ACTIVE_HIGH>;
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v5-gpios = <&gpio 22 GPIO_ACTIVE_HIGH>;
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};
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