1.概述

本文基于qcom msm8953 android7.1.2平台，最近硬件改版需要新增一个MODE的按键，目的是发送一个广播供用户层使用。

2.实现（由下往上->(kernel->frameworks)）

先列举下该功能实现所涉及到的文件
device/qcom/msm8953_64/gpio-keys.kl
frameworks/base/core/java/android/view/KeyEvent.java
frameworks/base/core/res/res/values/attrs.xml
frameworks/base/services/core/java/com/android/server/policy/PhoneWindowManager.java
frameworks/native/include/android/keycodes.h b/include/android/keycodes.h
frameworks/native/include/input/InputEventLabels.h
kernel/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi
kernel/msm-3.18/include/uapi/linux/input.h

2.1 kernel注册gpio_key 上报的key_value

1.找到平台对应内核dtsi配置文件。我这里是kernel/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi

diff --git a/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi b/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsiindex 87c248f..254b677 100755--- a/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi+++ b/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi@@ -288,13 +288,24 @@ debounce-interval = <15>; };*/+//key mode 249+mode_button {+label = "mode_button";+gpios = <&tlmm 33 0x1>;+linux,input-type = <1>;+linux,code = <249>;  //驱动上报的值，该值是新增，默认没有，该值不是frameworks中keyevents中的值，具体后面说明+gpio-key,wakeup;+debounce-interval = <15>; }; };

2.新增key value
kernel/msm-3.18/include/uapi/linux/input.h

+#define KEY_SYSTEM_MODE249/*add by hogo@wmz for system_key_mode 20190805 */

2.2 frameworks native层转换 kernel上报的key value值

frameworks/native/include/android/keycodes.h b/include/android/keycodes.h

+    /** fingerprint mode key, mode. */+    AKEYCODE_SYSTEM_KEY_MODE = 284

frameworks/native/include/input/InputEventLabels.h

+    DEFINE_KEYCODE(SYSTEM_KEY_MODE), /*add by hogo@wmz for mode key 20190805*/

完成这两步后，驱动上报的key value值249经过frameworks native层的处理到frameworks java层就会是我们在keyevent中得到的值了，这里不研究是怎么处理的。留个坑，后面分析Android input的时候再补上。

2.3 frameworks java层 配置keyevent 值，并且修改gpio_keys.kl映射文件

frameworks/base/core/res/res/values/attrs.xml

++        

frameworks/base/core/java/android/view/KeyEvent.java

+    /** fingerprint mode key, mode. */+    AKEYCODE_SYSTEM_KEY_MODE = 284

device/qcom/msm8953_64/gpio-keys.kl

+#add by hogo@wmz for mode key 20190805+key 249  SYSTEM_KEY_MODE

ps:这里说明下怎么找到本平台对应使用的kl文件？
1.可以先确定key在kernel注册的是什么节点（如果知道，可直接略过）
cat proc/bus/input/devices 可以查看
简单点：直接getevent 按按钮就知道是哪个，如图：

2.查看对应kl文件 dumpsys input | grep “gpio-keys”

2.4 frameworks java层根据keyevent事件处理新增按键事件

这里实现方式是可变多样的，可自行调整

+import java.io.DataInputStream;+import java.io.DataOutputStream;+import java.io.IOException;+    //add by hogo@wmz for mode key 20190805+            case KeyEvent.KEYCODE_SYSTEM_KEY_MODE: {+                result &= ~ACTION_PASS_TO_USER;+if(down)+{+            //Slog.e(TAG, "if ");+}+else+{+            //Slog.e(TAG, "else ");+Intent intent = new Intent(ACTION_ENG_MODE_SWITCH);+mContext.sendBroadcast(intent);+//mContext.sendBroadcastAsUser(intent, UserHandle.CURRENT);+//mContext.sendOrderedBroadcastAsUser(intent, UserHandle.CURRENT,+                            //null, null, null, 0, null, null);+}+                break;+            }

2.5 实现功能 git diff 一览

project device/diff --git a/qcom/msm8953_64/gpio-keys.kl b/qcom/msm8953_64/gpio-keys.klindex 0e02155..ced3ca5 100755--- a/qcom/msm8953_64/gpio-keys.kl+++ b/qcom/msm8953_64/gpio-keys.kl@@ -25,9 +25,12 @@ # OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN # IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. -#key 115   VOLUME_UP+key 115   VOLUME_UP key 114   VOLUME_DOWN-#key 102   HOME+key 102   HOME key 528   FOCUS key 766   CAMERA key 158  BACK++#add by hogo@wmz for mode key 20190805+key 249  SYSTEM_KEY_MODEproject frameworks/base/diff --git a/api/current.txt b/api/current.txtold mode 100644new mode 100755index 3466b04..95ac6f3--- a/api/current.txt+++ b/api/current.txt@@ -41602,6 +41602,7 @@ package android.view {     field public static final int KEYCODE_SWITCH_CHARSET = 95; // 0x5f     field public static final int KEYCODE_SYM = 63; // 0x3f     field public static final int KEYCODE_SYSRQ = 120; // 0x78+    field public static final int KEYCODE_SYSTEM_KEY_MODE = 284; // 0x11c     field public static final int KEYCODE_SYSTEM_NAVIGATION_DOWN = 281; // 0x119     field public static final int KEYCODE_SYSTEM_NAVIGATION_LEFT = 282; // 0x11a     field public static final int KEYCODE_SYSTEM_NAVIGATION_RIGHT = 283; // 0x11bdiff --git a/api/system-current.txt b/api/system-current.txtindex 2f5cb2f..761c0b0 100644--- a/api/system-current.txt+++ b/api/system-current.txt@@ -44780,6 +44780,7 @@ package android.view {     field public static final int KEYCODE_SWITCH_CHARSET = 95; // 0x5f     field public static final int KEYCODE_SYM = 63; // 0x3f     field public static final int KEYCODE_SYSRQ = 120; // 0x78+    field public static final int KEYCODE_SYSTEM_KEY_MODE = 284; // 0x11c     field public static final int KEYCODE_SYSTEM_NAVIGATION_DOWN = 281; // 0x119     field public static final int KEYCODE_SYSTEM_NAVIGATION_LEFT = 282; // 0x11a     field public static final int KEYCODE_SYSTEM_NAVIGATION_RIGHT = 283; // 0x11bdiff --git a/api/test-current.txt b/api/test-current.txtindex 77e36ab..0f5154d 100644--- a/api/test-current.txt+++ b/api/test-current.txt@@ -41688,6 +41688,7 @@ package android.view {     field public static final int KEYCODE_SWITCH_CHARSET = 95; // 0x5f     field public static final int KEYCODE_SYM = 63; // 0x3f     field public static final int KEYCODE_SYSRQ = 120; // 0x78+    field public static final int KEYCODE_SYSTEM_KEY_MODE = 284; // 0x11c     field public static final int KEYCODE_SYSTEM_NAVIGATION_DOWN = 281; // 0x119     field public static final int KEYCODE_SYSTEM_NAVIGATION_LEFT = 282; // 0x11a     field public static final int KEYCODE_SYSTEM_NAVIGATION_RIGHT = 283; // 0x11bdiff --git a/core/java/android/view/KeyEvent.java b/core/java/android/view/KeyEvent.javaindex b73acda..1c1a4e3 100644--- a/core/java/android/view/KeyEvent.java+++ b/core/java/android/view/KeyEvent.java@@ -804,8 +804,10 @@ public class KeyEvent extends InputEvent implements Parcelable {     public static final int KEYCODE_SYSTEM_NAVIGATION_LEFT = 282;     /** Key code constant: Consumed by the system for navigation right */     public static final int KEYCODE_SYSTEM_NAVIGATION_RIGHT = 283;+    /** Key code constant: Consumed by the system for mode key add by hogo@wmz 20190805 */+    public static final int KEYCODE_SYSTEM_KEY_MODE = 284; -    private static final int LAST_KEYCODE = KEYCODE_SYSTEM_NAVIGATION_RIGHT;+    private static final int LAST_KEYCODE = KEYCODE_SYSTEM_KEY_MODE;      // NOTE: If you add a new keycode here you must also add it to:     //  isSystem()@@ -1857,6 +1859,7 @@ public class KeyEvent extends InputEvent implements Parcelable {             case KeyEvent.KEYCODE_SYSTEM_NAVIGATION_DOWN:             case KeyEvent.KEYCODE_SYSTEM_NAVIGATION_LEFT:             case KeyEvent.KEYCODE_SYSTEM_NAVIGATION_RIGHT:+            case KeyEvent.KEYCODE_SYSTEM_KEY_MODE:                 return true;         } diff --git a/core/res/res/values/attrs.xml b/core/res/res/values/attrs.xmlindex 066a538..7112b75 100644--- a/core/res/res/values/attrs.xml+++ b/core/res/res/values/attrs.xml@@ -1839,6 +1839,8 @@ i                           ++                   diff --git a/services/core/java/com/android/server/policy/PhoneWindowManager.java b/services/core/java/com/android/server/policy/PhoneWindowManager.javaindex 33e20a8..a167a1d 100644--- a/services/core/java/com/android/server/policy/PhoneWindowManager.java+++ b/services/core/java/com/android/server/policy/PhoneWindowManager.java@@ -161,6 +161,9 @@ import java.io.PrintWriter; import java.util.HashSet; import java.util.List; +import java.io.DataInputStream;+import java.io.DataOutputStream;+import java.io.IOException; /**  * WindowManagerPolicy implementation for the Android phone UI.  This  * introduces a new method suffix, Lp, for an internal lock of the@@ -3503,7 +3506,13 @@ public class PhoneWindowManager implements WindowManagerPolicy {                 dispatchDirectAudioEvent(event);                 return -1;             }-        }+        } +//add by hogo@wmz for mode key 20190805+/*else if(keyCode == KeyEvent.KEYCODE_SYSTEM_KEY_MODE)+{+execRootCmd("am broadcast -a android.intent.action.ENG_MODE_SWITCH");+return -1;+}*/          // Toggle Caps Lock on META-ALT.         boolean actionTriggered = false;@@ -5798,6 +5807,49 @@ public class PhoneWindowManager implements WindowManagerPolicy {         mContext.sendBroadcastAsUser(errorIntent, UserHandle.CURRENT);     } +    // 执行命令并且输出结果+    public String execRootCmd(String cmd) {+        String result = "";+        DataOutputStream dos = null;+        DataInputStream dis = null;++        try {+            java.lang.Process p = Runtime.getRuntime().exec("su");+            dos = new DataOutputStream(p.getOutputStream());+            dis = new DataInputStream(p.getInputStream());++            dos.writeBytes(cmd + "\n");+            dos.flush();+            dos.writeBytes("exit\n");+            dos.flush();+            String line = null;+            while ((line = dis.readLine()) != null) {+                result += line;+            }+            p.waitFor();+        } catch (Exception e) {+            e.printStackTrace();+        } finally {+            if (dos != null) {+                try {+                    dos.close();+                } catch (IOException e) {+                    e.printStackTrace();+                }+            }+            if (dis != null) {+                try {+                    dis.close();+                } catch (IOException e) {+                    e.printStackTrace();+                }+            }+        }+        return result;+    }++    int cnt = 0;+     /** {@inheritDoc} */     @Override     public int interceptKeyBeforeQueueing(KeyEvent event, int policyFlags) {@@ -5811,6 +5863,18 @@ public class PhoneWindowManager implements WindowManagerPolicy {         final boolean canceled = event.isCanceled();         final int keyCode = event.getKeyCode(); +//wmz+/*if(KeyEvent.KEYCODE_VOLUME_DOWN == keyCode)+{+cnt++;+if(cnt == 2)+{+execRootCmd("am broadcast -a android.intent.action.ENG_MODE_SWITCH");+cnt = 0;+}+return 0;+}*/+         final boolean isInjected = (policyFlags & WindowManagerPolicy.FLAG_INJECTED) != 0;          // If screen is off then we treat the case where the keyguard is open but hidden@@ -5884,6 +5948,21 @@ public class PhoneWindowManager implements WindowManagerPolicy {          // Handle special keys.         switch (keyCode) {+    //add by hogo@wmz for mode key 20190805+            case KeyEvent.KEYCODE_SYSTEM_KEY_MODE: {+                result &= ~ACTION_PASS_TO_USER;+if(down)+{+            //Slog.e(TAG, "if ");+}+else+{+            //Slog.e(TAG, "else ");+Intent intent = new Intent(ACTION_ENG_MODE_SWITCH);+mContext.sendBroadcast(intent);+//mContext.sendBroadcastAsUser(intent, UserHandle.CURRENT);+//mContext.sendOrderedBroadcastAsUser(intent, UserHandle.CURRENT,+                            //null, null, null, 0, null, null);+}+                break;+            }             case KeyEvent.KEYCODE_BACK: {                 if (down) {                     interceptBackKeyDown();project frameworks/native/diff --git a/include/android/keycodes.h b/include/android/keycodes.hindex e202060..67a4e63 100644--- a/include/android/keycodes.h+++ b/include/android/keycodes.h@@ -765,7 +765,9 @@ enum {     /** fingerprint navigation key, left. */     AKEYCODE_SYSTEM_NAVIGATION_LEFT = 282,     /** fingerprint navigation key, right. */-    AKEYCODE_SYSTEM_NAVIGATION_RIGHT = 283+    AKEYCODE_SYSTEM_NAVIGATION_RIGHT = 283,+    /** fingerprint mode key, mode. */+    AKEYCODE_SYSTEM_KEY_MODE = 284      // NOTE: If you add a new keycode here you must also add it to several other files.     //       Refer to frameworks/base/core/java/android/view/KeyEvent.java for the full list.diff --git a/include/input/InputEventLabels.h b/include/input/InputEventLabels.hindex 0bd14ea..170ef47 100644--- a/include/input/InputEventLabels.h+++ b/include/input/InputEventLabels.h@@ -323,6 +323,7 @@ static const InputEventLabel KEYCODES[] = {     DEFINE_KEYCODE(SYSTEM_NAVIGATION_DOWN),     DEFINE_KEYCODE(SYSTEM_NAVIGATION_LEFT),     DEFINE_KEYCODE(SYSTEM_NAVIGATION_RIGHT),+    DEFINE_KEYCODE(SYSTEM_KEY_MODE), /*add by hogo@wmz for mode key 20190805*/      { NULL, 0 } };project kernel/diff --git a/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi b/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsiindex 87c248f..254b677 100755--- a/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi+++ b/msm-3.18/arch/arm/boot/dts/qcom/msm8953-mtp.dtsi@@ -288,13 +288,24 @@ debounce-interval = <15>; };*/ -back_button {+//158 back+/*back_button { label = "back_button"; gpios = <&tlmm 33 0x1>; linux,input-type = <1>; linux,code = <158>; gpio-key,wakeup; debounce-interval = <15>;+};*/++//key mode 249+mode_button {+label = "mode_button";+gpios = <&tlmm 33 0x1>;+linux,input-type = <1>;+linux,code = <249>;+gpio-key,wakeup;+debounce-interval = <15>; }; };diff --git a/msm-3.18/include/uapi/linux/input.h b/msm-3.18/include/uapi/linux/input.hindex 7082516..be564da 100644--- a/msm-3.18/include/uapi/linux/input.h+++ b/msm-3.18/include/uapi/linux/input.h@@ -481,6 +481,8 @@ struct input_keymap_entry {  #define KEY_MICMUTE248/* Mute / unmute the microphone */ +#define KEY_SYSTEM_MODE249/*add by hogo@wmz for system_key_mode 20190805 */+ /* Code 255 is reserved for special needs of AT keyboard driver */  #define BTN_MISC0x100

3.总结

若单纯的只是对Android input 做些简单的修修补补，add new 之类的操作，想必是很简单的，但我们能这样简单轻松的在Android input中做些简单的新增就能实现我们想要的功能，这肯定是离不开Android系统内部对input的实现的，本文这里不对Android input作分析，留个坑给自己，后面分析input再来补上。
ps:本文好像留了两个坑，这里统计下。

4.参考

https://blog.csdn.net/weixin_42193691/article/details/82874476
https://blog.csdn.net/dkbdkbdkb/article/details/53667216
https://www.jianshu.com/p/dcd0e030fbf5
https://blog.csdn.net/tt11212/article/details/87608373

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