will also cause the pin to go low.
+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"
+
+ 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.
+Load: dtoverlay=gpio-shutdown,<param>=<val>
+Params: gpio_pin GPIO pin to trigger on (default 3)
+
+ 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.
+
+
Name: hifiberry-amp
Info: Configures the HifiBerry Amp and Amp+ audio cards
Load: dtoverlay=hifiberry-amp
--- /dev/null
+// 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. 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,bcm2708";
+
+ 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 {
+ 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 {
+ // 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>;
+ };
+ };
+ };
+ };
+
+ // 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",
+ <&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).
+ gpio_pull = <&pin_state>,"brcm,pull:0";
+
+ // Allow setting the active_low flag. 0 = active high, 1 = active low
+ active_low = <&button>,"gpios:8";
+ };
+
+};
projects / linux-4.9.git / commitdiff