RK3288_Android7.1调试RTC总结（二）

RK3288_Android7.1调试RTC总结（一）主要是讲解rtc的调试和驱动框架浅析，
RK3288_Android7.1调试RTC总结（二）主要讲解看门狗方面的内容。
我这里主要是基于rtc芯片：am1805的驱动来说明。

rtc1805驱动跑起来就默认看门狗是kernel feeddog，每隔2s feeddog一次（feeddog就是向特定的寄存器写入值），如果没有feeddog就会触发系统强制复位而重启系统。

/*
 *	am1805_watchdog_feeddog- set up the watchdog timer   
 *
 *	Inputs:
 *	period - timeout period in ms (65 to 124,000)
 *	pin - pin to generate the watchdog signal
 *		0 => disable WDT
 *		1 => generate an interrupt on FOUT/nIRQ
 *		2 => generate an interrupt on PSW/nIRQ2
 *		3 => generate a reset on nRST (AM18xx only)
 *
 */

am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_PIN_RST);//设置feeddog，并且使能reset pin，发送feeddog信号
am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_DISABLE); //设置disabled feeddog

rtc_am1805看门狗验证

首先确认有以下两个节点：

sys/class/rtc_am1805/feeddog //feddog 操作
sys/class/rtc_am1805/timer //设置disabled feeddog之后，然后重新使能kernel feeddog在time之后系统重启

feeddog节点对应代码实现：

static ssize_t am1805_show_feeddog(struct class *class,
			struct class_attribute *attr,	char *buf)
{
	int ret;

	if (rtc_info->watchdog_enable==TYPE_DISABLE)
	{
		ret = sprintf(buf, "0 -- disable\n");
	}
	else if(rtc_info->watchdog_enable==TYPE_KERNLE)
	{
		ret = sprintf(buf, "1 -- kernel feed\n");
	}
	else{
		ret = sprintf(buf, "2 -- user feed\n");
	}

	return ret;
}

static ssize_t am1805_store_feeddog(struct class *class,
	struct class_attribute *attr, const char *buf, size_t count)
{
	int type;

  RTC_DBG(RTC_DBG_VAL, "%s ,run \n",__func__);

  sscanf(buf,"%i",&type);

  if(type==0){
	 rtc_info->watchdog_enable = TYPE_DISABLE;
	 am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_DISABLE);
  }
  else if(type==1){
	 rtc_info->watchdog_enable = TYPE_KERNLE;
	 am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_PIN_RST);
  }
  else{
	 rtc_info->watchdog_enable = TYPE_USER;
	 am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_PIN_RST);
  }

  return count;
}

static struct class_attribute rtc_class_attrs[] = {
	__ATTR(show_all_reg, S_IRUGO | S_IWUSR, show_all_reg, NULL),
	__ATTR(time, S_IRUGO | S_IWUSR, show_time, store_time),
	__ATTR(regwrite, S_IRUGO | S_IWUSR, NULL, store_reg),
	__ATTR(regread, S_IRUGO | S_IWUSR, NULL,show_reg),
	__ATTR(feeddog, S_IRUGO | S_IWUSR, am1805_show_feeddog,am1805_store_feeddog),
	__ATTR(timer, S_IRUGO | S_IWUSR, aml1805_show_timer, am1805_store_timer),
	__ATTR(setalarm, S_IRUGO | S_IWUSR, am1805_set_alarm,NULL),
	__ATTR_NULL
};

static struct class rtc_am1805_class = {
	.name = "rtc_am1805",
	.class_attrs = rtc_class_attrs,
};

probe函数中调用以下接口创建class节点[这里只节选部分代码]：

static int rtc_am1805_probe(struct platform_device *pdev)
{
...
ret = class_register(&rtc_am1805_class);
	if (ret){
		pr_info(" class register rtc_class fail!\n");
		return -1;
	}
...
}

---

查看看门狗（WDT）的状态：

root@stvs912:/ # cat sys/class/rtc_am1805/feeddog                              
1 -- kernel feed //驱动默认起来就是kernel feeddog状态

root@stvs912:/ # echo 0 > sys/class/rtc_am1805/feeddog //关闭看门狗功能
root@stvs912:/ # echo 1 > sys/class/rtc_am1805/feeddog //kernel feeddog，kernel有定时器设置，每隔一定时间（feeddog time）kernel会自动feeddog，这里时间是2s
root@stvs912:/ # echo 2 > sys/class/rtc_am1805/feeddog //user feeddog，需要用户每隔一定时间feeddog一次（shell-env下执行echo 2 > sys/class/rtc_am1805/feeddog），否则会自动复位重启系统

对应代码如下：

static ssize_t am1805_show_feeddog(struct class *class,
			struct class_attribute *attr,	char *buf)
{
	int ret;

	if (rtc_info->watchdog_enable==TYPE_DISABLE)
	{
		ret = sprintf(buf, "0 -- disable\n");
	}
	else if(rtc_info->watchdog_enable==TYPE_KERNLE)
	{
		ret = sprintf(buf, "1 -- kernel feed\n");
	}
	else{
		ret = sprintf(buf, "2 -- user feed\n");
	}

	return ret;
}

通过以下节点可以设置feeddog time验证看门狗功能：

rk3399_all:/ # ls -l sys/class/rtc_am1805/timer
-rw-r--r-- 1 root root 4096 2019-11-13 09:19 sys/class/rtc_am1805/timer

例如feeddog设置disabled feeddog之后，然后重新使能kernel feeddog在time（10s）之后系统重启可以这样验证：

rk3399_all:/ # echo 0 > sys/class/rtc_am1805/feeddog //disabled feeddog
rk3399_all:/ # echo 10000 > sys/class/rtc_am1805/timer //设置feeddog = 10s，除非在10s到达之前重新执行这句指令，否则会重启
rk3399_all:/ # cat sys/class/rtc_am1805/timer                                
10000

对应代码实现如下[节选部分]：

static ssize_t aml1805_show_timer(struct class* class,
	struct class_attribute *att, char* buf)
{
  RTC_DBG(RTC_DBG_VAL, "%s ,run \n",__func__);

	return sprintf(buf, "%d\n", rtc_info->watchdog_timer);
}

static ssize_t am1805_store_timer(struct class* class,
	struct class_attribute* att, const char* buf, size_t count)
{
	int value;

  RTC_DBG(RTC_DBG_VAL, "%s ,run \n",__func__);

  sscanf(buf,"%i",&value);
  RTC_DBG(RTC_DBG_VAL, "value = %d \n", value);

  rtc_info->watchdog_timer = value;
	am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_PIN_RST);

  return count;
}

真待机导致机器在进入休眠之后会重启

原因分析：
目前我们的板子都是做的假待机，所以feeddog不会受影响，如果是真待机情况下[kernel进入休眠，不跑kernel]，kernel就不自动feeddog就会导致系统重启，所以需要在suspend的情况下关闭feeddog，在唤醒系统的时候再重新打开，以下是feeddog的接口函数。

解决方法：添加休眠唤醒的处理函数，当机器进入休眠的时候，disabled掉watchdog功能，在机器唤醒之后，重新使能watchdog功能即可。

具体代码实现（代码来自rk3399 7.1）：

+static int rtc_am1805_suspend(struct device *dev)
+{
+       pr_info("%s,line(%d): enter suspend\n", __func__, __LINE__);
+       //rtc_info->watchdog_enable = TYPE_DISABLE;
+       am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_DISABLE);
+
+       return 0;
+}
+
+static int rtc_am1805_resume(struct device *dev)
+{
+
+       pr_info("%s,line(%d): enter resume\n", __func__, __LINE__);
+       if(rtc_info->watchdog_enable != TYPE_DISABLE)
+               am1805_watchdog_feeddog(rtc_info->watchdog_timer,WATCHDOG_INT_PIN_RST);
+       return 0;
+}
+
 static void rtc_am1805_shutdown(struct i2c_client * client)
 {
        unsigned char val=0;
@@ -1374,6 +1392,9 @@ static void rtc_am1805_shutdown(struct i2c_client * client)
        rtc_am1805_i2c_write(&val, WDT_REG, 0x01);
 }

+static SIMPLE_DEV_PM_OPS(rtc_am1805_pm_ops, rtc_am1805_suspend,
+                                               rtc_am1805_resume);
+
 static const struct i2c_device_id am1805_id[] = {
        { "rtc_am1805", 0 },
        { }
@@ -1389,6 +1410,7 @@ struct i2c_driver rtc_am1805_driver = {
                .name = "rtc_am1805",
                .owner = THIS_MODULE,
                .of_match_table = am1805_rtc_dt_match,
+               .pm = &rtc_am1805_pm_ops,
        },
        .probe = rtc_am1805_probe,
        .remove = (rtc_am1805_remove),