strsep(&data,","); //字符串切割函数
kstrtoint(first,10,&duty_cycle);//字符串转整形 10:十进制
sprintf(data,"%d,%d",duty_cycle,fan_freq);//整型数转字符串

示例代码：
ssize_t dcfan_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{int ret;char *data;char *first,*second;printk(KERN_EMERG "%s,line:%d: enter\n",__FUNCTION__,__LINE__);if(!copy_from_user((char *)data, buf, count)){first	= strsep(&data,",");	//字符串切割函数second	= data;ret = kstrtoint(first,10,&duty_cycle);//字符串转整形 10:十进制if(ret)	return -1;ret = kstrtoint(second,10,&fan_freq);if(ret)	return -1;printk(KERN_EMERG "App write duty_cycle=%d,fan_freq=%d\n",duty_cycle,fan_freq);return count;}elsereturn -1;
}ssize_t dcfan_read(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{size_t cnt;char data[10]={0};printk(KERN_EMERG "%s-line:%d: enter\n",__FUNCTION__,__LINE__);printk(KERN_EMERG "%s,duty_cycle=%d,fan_freq=%d\n",__FUNCTION__,duty_cycle,fan_freq);sprintf(data,"%d,%d",duty_cycle,fan_freq);//整型数转字符串cnt = strlen(data);if(!copy_to_user((char *)buf, data, cnt))return 0;elsereturn -1;
}