RK3399 Android7.1实时读取当前cpu频率

1，cpu频率可在/sys下读取
/sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq
/sys/devices/system/cpu/cpu1/cpufreq/cpuinfo_cur_freq
/sys/devices/system/cpu/cpu2/cpufreq/cpuinfo_cur_freq
/sys/devices/system/cpu/cpu3/cpufreq/cpuinfo_cur_freq
/sys/devices/system/cpu/cpu4/cpufreq/cpuinfo_cur_freq
/sys/devices/system/cpu/cpu5/cpufreq/cpuinfo_cur_freq

默认权限为400,需要修改权限为444
修改位置在内核中：
kernel/drivers/cpufreq/cpufreq.c

@@ -649,7 +649,7 @@ static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
        return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
 }
 
-cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
+cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0444);

2,apk开发
循环读取文件中的频率数值然后显示到界面

//cpufreq_path 为cpufreq在sys中对应的节点路径
public String readCpuCurFreq(String cpufreq_path) {
        String prop = "";
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new FileReader(cpufreq_path));
            prop = reader.readLine();
        } catch (IOException e) {
            e.printStackTrace();
            Log.e(TAG, "error:" + e.getMessage());
        } finally {
            if(reader != null){
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return prop;
    }