add gpio-key overlay (#2329)

An overlay that allows a Linux key to be bound to a GPIO.

diff --git a/arch/arm/boot/dts/overlays/Makefile b/arch/arm/boot/dts/overlays/Makefile
index fb576ea2e925e588ee669979a386ee131569a249..b1f2ec2fdb3e97a9893ef37bfaa51e07fb0a1e7c 100644 (file)
--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -30,6 +30,7 @@ dtbo-$(CONFIG_ARCH_BCM2835) += \
        goodix.dtbo \
        googlevoicehat-soundcard.dtbo \
        gpio-ir.dtbo \
+       gpio-key.dtbo \
        gpio-poweroff.dtbo \
        gpio-shutdown.dtbo \
        hifiberry-amp.dtbo \

diff --git a/arch/arm/boot/dts/overlays/README b/arch/arm/boot/dts/overlays/README
index 92e7f0ff3c3205e5864f5dfd9d59033a4535ba22..52a9304acb182edff66d51fd8192b0a11dddf6fe 100644 (file)
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -504,6 +504,27 @@ Params: gpio_pin                Input pin number. Default is 18.
                                 ir-keytable), defaults to "rc-rc6-mce"
 
 
+Name:   gpio-key
+Info:   This is a generic overlay for activating GPIO keypresses using
+        the gpio-keys library and this dtoverlay. Multiple keys can be
+        set up using multiple calls to the overlay for configuring
+        additional buttons or joysticks. You can see available keycodes
+        at https://github.com/torvalds/linux/blob/v4.12/include/uapi/
+        linux/input-event-codes.h#L64
+Load:   dtoverlay=gpio-key,<param>=<val>
+Params: gpio                    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
+        label                   Set a label for the key
+        keycode                 Set the key code for the button
+
+
 Name:   gpio-poweroff
 Info:   Drives a GPIO high or low on poweroff (including halt). Enabling this
         overlay will prevent the ability to boot by driving GPIO3 low.

diff --git a/arch/arm/boot/dts/overlays/gpio-key-overlay.dts b/arch/arm/boot/dts/overlays/gpio-key-overlay.dts
new file mode 100644 (file)
index 0000000..333d016
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/gpio-key-overlay.dts
@@ -0,0 +1,48 @@
+// Definitions for gpio-key module
+/dts-v1/;
+/plugin/;
+
+/ {
+       compatible = "brcm,bcm2708";
+
+       fragment@0 {
+               // Configure the gpio pin controller
+               target = <&gpio>;
+               __overlay__ {
+                       pin_state: button_pins@0 {
+                               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 {
+               target-path = "/";
+               __overlay__ {
+                       button: button@0 {
+                               compatible = "gpio-keys";
+                               pinctrl-names = "default";
+                               pinctrl-0 = <&pin_state>;
+                               status = "okay";
+
+                               key: key {
+                                       linux,code = <116>;
+                                       gpios = <&gpio 3 1>;
+                                       label = "KEY_POWER";
+                               };
+                       };
+               };
+       };
+
+       __overrides__ {
+               gpio =       <&key>,"gpios:4",
+                            <&button>,"reg:0",
+                            <&pin_state>,"brcm,pins:0",
+                            <&pin_state>,"reg:0";
+               label =      <&key>,"label";
+               keycode =    <&key>,"linux,code:0";
+               gpio_pull =  <&pin_state>,"brcm,pull:0";
+               active_low = <&key>,"gpios:8";
+       };
+
+};