framboise314.fr

Code : Tout sélectionner

Name:   gpio-shutdown
Info:   Initiates a shutdown when GPIO pin changes. The given GPIO pin
        is configured as an input key that generates KEY_POWER events.

        This event is handled by systemd-logind by initiating a
        shutdown. Systemd versions older than 225 need an udev rule
        enable listening to the input device:

                ACTION!="REMOVE", SUBSYSTEM=="input", KERNEL=="event*", \
                        SUBSYSTEMS=="platform", DRIVERS=="gpio-keys", \
                        ATTRS{keys}=="116", TAG+="power-switch"

        Alternatively this event can be handled also on systems without
        systemd, just by traditional SysV init daemon. KEY_POWER event
        (keycode 116) needs to be mapped to KeyboardSignal on console
        and then kb::kbrequest inittab action which is triggered by
        KeyboardSignal from console can be configured to issue system
        shutdown. Steps for this configuration are:

            Add following lines to the /etc/console-setup/remap.inc file:

                # Key Power as special keypress
                keycode 116 = KeyboardSignal

            Then add following lines to /etc/inittab file:

                # Action on special keypress (Key Power)
                kb::kbrequest:/sbin/shutdown -t1 -a -h -P now

            And finally reload configuration by calling following commands:

                # dpkg-reconfigure console-setup
                # service console-setup reload
                # init q

        This overlay only handles shutdown. After shutdown, the system
        can be powered up again by driving GPIO3 low. The default
        configuration uses GPIO3 with a pullup, so if you connect a
        button between GPIO3 and GND (pin 5 and 6 on the 40-pin header),
        you get a shutdown and power-up button. Please note that
        Raspberry Pi 1 Model B rev 1 uses GPIO1 instead of GPIO3.
Load:   dtoverlay=gpio-shutdown,<param>=<val>
Params: gpio_pin                GPIO pin to trigger on (default 3)
                                For Raspberry Pi 1 Model B rev 1 set this
                                explicitly to value 1, e.g.:

                                    dtoverlay=gpio-shutdown,gpio_pin=1

        active_low              When this is 1 (active low), a falling
                                edge generates a key down event and a
                                rising edge generates a key up event.
                                When this is 0 (active high), this is
                                reversed. The default is 1 (active low).

        gpio_pull               Desired pull-up/down state (off, down, up)
                                Default is "up".

                                Note that the default pin (GPIO3) has an
                                external pullup. Same applies for GPIO1
                                on Raspberry Pi 1 Model B rev 1.

        debounce                Specify the debounce interval in milliseconds
                                (default 100)

Code : Tout sélectionner

// Definitions for gpio-poweroff module
/dts-v1/;
/plugin/;

// This overlay sets up an input device that generates KEY_POWER events
// when a given GPIO pin changes. It defaults to using GPIO3, which can
// also be used to wake up (start) the Rpi again after shutdown.
// Raspberry Pi 1 Model B rev 1 can be wake up only by GPIO1 pin, so for
// these boards change default GPIO pin to 1 via gpio_pin parameter. Since
// wakeup is active-low, this defaults to active-low with a pullup
// enabled, but all of this can be changed using overlay parameters (but
// note that GPIO3 has an external pullup on at least some boards).

/ {
	compatible = "brcm,bcm2835";

	fragment@0 {
		// Configure the gpio pin controller
		target = <&gpio>;
		__overlay__ {
			// Define a pinctrl state, that sets up the gpio
			// as an input with a pullup enabled. This does
			// not take effect by itself, only when referenced
			// by a "pinctrl client", as is done below. See:
			//   https://www.kernel.org/doc/Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
			//   https://www.kernel.org/doc/Documentation/devicetree/bindings/pinctrl/brcm,bcm2835-gpio.txt
			pin_state: shutdown_button_pins@3 {
				brcm,pins = <3>; // gpio number
				brcm,function = <0>; // 0 = input, 1 = output
				brcm,pull = <2>; // 0 = none, 1 = pull down, 2 = pull up
			};
		};
	};
	fragment@1 {
		// Add a new device to the /soc devicetree node
		target-path = "/soc";
		__overlay__ {
			shutdown_button: shutdown_button@3 {
				// Let the gpio-keys driver handle this device. See:
				// https://www.kernel.org/doc/Documentation/devicetree/bindings/input/gpio-keys.txt
				compatible = "gpio-keys";

				// Declare a single pinctrl state (referencing the one declared above) and name it
				// default, so it is activated automatically.
				pinctrl-names = "default";
				pinctrl-0 = <&pin_state>;

				// Enable this device
				status = "okay";

				// Define a single key, called "shutdown" that monitors the gpio and sends KEY_POWER
				// (keycode 116, see
				// https://github.com/torvalds/linux/blob/v4.12/include/uapi/linux/input-event-codes.h#L190)
				button: shutdown {
					label = "shutdown";
					linux,code = <116>; // KEY_POWER
					gpios = <&gpio 3 1>;
					debounce-interval = <100>; // ms
				};
			};
		};
	};

	// This defines parameters that can be specified when loading
	// the overlay. Each foo = line specifies one parameter, named
	// foo. The rest of the specification gives properties where the
	// parameter value is inserted into (changing the values above
	// or adding new ones).
	__overrides__ {
		// Allow overriding the GPIO number.
		gpio_pin = <&button>,"gpios:4",
			   <&shutdown_button>,"reg:0",
			   <&pin_state>,"reg:0",
		           <&pin_state>,"brcm,pins:0";

		// Allow changing the internal pullup/down state. 0 = none, 1 = pulldown, 2 = pullup
		// Note that GPIO3 and GPIO2 are the I2c pins and have an external pullup (at least
		// on some boards). Same applies for GPIO1 on Raspberry Pi 1 Model B rev 1.
		gpio_pull = <&pin_state>,"brcm,pull:0";

		// Allow setting the active_low flag. 0 = active high, 1 = active low
		active_low = <&button>,"gpios:8";
		debounce = <&button>,"debounce-interval:0";
	};

};