kernel部分添加键值:
1.在dts中(kernel/arch/arm64/boot/dts/rockchip/px30-hyperlcd-core.dtsi)添加键值属性，可以仿照power按键配置
gpio_keys: gpio-keys {status = "okay";compatible = "gpio-keys";autorepeat;pinctrl-names = "default";pinctrl-0 = <&leds_keys_gpio>;key_sw1 {debounce-interval = <100>;gpios = <&gpio1 19 GPIO_ACTIVE_LOW>;label = "GPIO Key sw1";linux,code = <KEY_FRONT>;// wakeup-source;gpio-key,wakeup;};};&pinctrl {gpio-keys {leds_keys_gpio: leds_keys-gpio {rockchip,pins = <1 RK_PC3 RK_FUNC_GPIO &pcfg_pull_none>;};};
};因我们使用的键值操作是通过gpio触发的，则配置成gpio-key。
kernel/drivers/input/keyboard/gpio_keys.c
kernel/include/dt-bindings/input/rk-input.h
关于linux,code = <KEY_FRONT>;里的KEY_FRONT，可以在rk-input.h查看
这里KEY_FRONT为132，后面的onkeydown onkeyup中的返回事件中ScanCode，也是132
测试验证
通过调试串口或者ADB进入系统，执行getevent -l命令测试GPIO按键，命令如下：
130|console:/ # getevent -l
add device 1: /dev/input/event3name: "gpio_keys"
add device 2: /dev/input/event1name: "rk805 pwrkey"
add device 3: /dev/input/event2name: "adc-keys"
add device 4: /dev/input/event0name: "fdd70030.pwm"
add device 5: /dev/input/event4name: "rk-headset"
执行后，将GPIO4_A4对应的引脚短接到GND即可触发，如下所示：
当成功返回键值即可测试成功。
配置onkeydown onkeyUP
1.由于按键是先down后up，这个流程逻辑在frameworks/native/services/inputflinger/reader/mapper/KeyboardInputMapper.cpp里可以配置
void KeyboardInputMapper::processKey(nsecs_t when, bool down, int32_t scanCode, } else {// Remove key down.ssize_t keyDownIndex = findKeyDown(scanCode);if (keyDownIndex >= 0) {// key up, be sure to use same keycode as before in case of rotationkeyCode = mKeyDowns[keyDownIndex].keyCode;mKeyDowns.erase(mKeyDowns.begin() + (size_t)keyDownIndex);} else if (scanCode == 132) {//特殊处理} else {// key was not actually downALOGI("Dropping key up from device %s because the key was not down. ""keyCode=%d, scanCode=%d",getDeviceName().c_str(), keyCode, scanCode);return;}}从这里可以看到，当先收到某个scanCode的keyup，但是在表里没找到对应的keydown数据，就会直接return，不会再走下面的onkeyup方法，提示如下
Dropping key up from device %s because the key was not down. ""keyCode=%d, scanCode=%d"这里要注意下配置的这个gpio默认状态是不是就已经是down状态了（比如gpio默认就是低电平，默认已经按下了，就是down操作），这个时候拉高gpio电位，从framework认为是up操作，但由于framework没收到过down，所以系统会直接return掉，这个地方记得改下就可以了
2.可通过调用frameworks/base/core/java/android/view/KeyEvent.java中的接口去拦截键值
public final boolean dispatch(Callback receiver, DispatcherState state,Object target) {
这里是我添加的，是针对某个特殊功能，让这个gpio在按下和抬起时，都发送onekydown指令所以改动的，如果有其它onkeydown onkeyup事件拦截 也应该在这里
3.frameworks/base/core/java/android/view/View.java
这里是下发onkeydown onkeyup回调的地方
