[经验]

DragonBoard 410c的按键添加

2018-9-27 16:50:24

2641 Qualcomm DragonBoard

今天给大家介绍一下如何运用Android已有的框架去添加按键.首先,我们来看一下按键的现象!

将DragonBoard 410c开发板连接到ubuntu, 输入以下命令:

$ adb root

$ adb shell

# getevent

在板子上分别按下电源键,音量+, 音量- 时,会看到有事件上报,如图1所示:

图1

现在来给大家详细介绍下如何在410c板子上添加一个按键,当输入上面的命令时按下该按键也能看到有事件上报.

1) 根据410c硬件原理图,如图2所示,选择一个合适的GPIO(支持中断),如GPIO_13.

图2

2)在msm8916-pinctrl.dtsi中添加GPIO13

      tlmm_gpio_key {

//    qcom,pins = <&gp 107>, <&gp 108>, <&gp 109>;

         qcom,pins = <&gp 107>, <&gp 108>, <&gp 109>, <&gp 13>;

         qcom,pin-func = <0>;

//    qcom,num-grp-pins = <3>;

         qcom,num-grp-pins = <4>;

         label = "tlmm_gpio_key";

         gpio_key_active: gpio_key_active {

            drive-strength = <2>;

            bias-pull-up;

         };

         gpio_key_suspend: gpio_key_suspend {

            drive-strength = <2>;

            bias-pull-up;

         };

      };

3) 查看kernel/include/uapi/linux/input.h文件,选择一个合适的键值(未被使用),如147,然后在apq8016-***c.dtsi中添加相应的节点,如:

gpio_keys {

      compatible = "gpio-keys";

      input-name = "gpio-keys";

      pinctrl-names = "tlmm_gpio_key_active","tlmm_gpio_key_suspend";

      pinctrl-0 = <&gpio_key_active>;

      pinctrl-1 = <&gpio_key_suspend>;

      camera_focus {

         label = "camera_focus";

         gpios = <&msm_gpio 108 0x1>;

         linux,input-type = <1>;

         linux,code = <0x210>;

         gpio-key,wakeup;

         debounce-interval = <15>;

      };

      camera_snapshot {

         label = "camera_snapshot";

         gpios = <&msm_gpio 109 0x1>;

         linux,input-type = <1>;

         linux,code = <0x2fe>;

         gpio-key,wakeup;

         debounce-interval = <15>;

      };

      vol_up {

         label = "volume_up";

         gpios = <&msm_gpio 107 0x1>;

         linux,input-type = <1>;

         linux,code = <115>;

         gpio-key,wakeup;

         debounce-interval = <15>;

      };

      my_key {

         label = "my_key";

         gpios = <&msm_gpio 13 0x1>;

         linux,input-type = <1>;

         linux,code = <147>;

         gpio-key,wakeup;

         debounce-interval = <15>;

      };

};

4) 编译bootimage,并烧写到开发板就可以实现了,按下所添加的按键会看到有事件上报,如图3所示:

图3

以上就是添加按键的全部过程.至于上报的 0001 0093 00000001 表示什么含义,我将会在往后的blog进行讲解,敬请期待!