Android 10 应用层如何操作设备节点/sys/devices
功能：应用层去访问驱动给的一个设备节点
1、在init.uis8581a2h10.rc文件中添加该设备的权限
on post-fs-data
setprop fpga.target.enable 1
setprop debug.delaytime.min 10
setprop debug.delaytime.mid 100
setprop debug.delaytime.max 1000
setprop debug.android_watchdog.disable 1
chmod 666 /sys/devices/virtual/power_state
chmod 666 /sys/devices/virtual/tunetoch
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验证是否添加成功：
整编译软件在out目录下面搜索该文件:find -name init.uis8581a2h10.rc,如果该文件中存在添加加节点的代码，那就说明添加成功了
2、应用层向该设备节点写入值
public static final String FM_POWER_PATH = “/sys/devices/virtual/power_state”;
public static final String FM_TUNETOCH_PATH = “/sys/devices/virtual/tunetoch”;
private void setFmOn() {
String frequency = getFmFrequency();
if(DEBUG) Log.i(TAG, "setFmOn() frequency = " + frequency);
try {
Writer fm_tunetoc