android电池充电以及电量检测驱动分析

前段时间比较烦躁，各种不想学习不想工作，于是休息了几天。这几天又下来任务了--调试充电电路和电池电量检测电路，于是又开始工作，顺便把调试过程记录下来。

平台： cpu        飞思卡尔imx6q 4核

充电芯片     MAX8903

电量检测芯片  MAX11801

android版本  android4.0

一、电量检测

我们用的电池电量检测芯片MAX11801其实是一款电阻触摸屏的驱动芯片，它外带一个AD采集引脚，因此我们用这个引脚来检测电池电压。MAX11801电源为3.3V而电池电压范围可能是0~4.2V，因此我们需要给电池电压分压。我们所用的电路如下

知道了硬件电路下面来 添加这个芯片的驱动，这是一个i2c的芯片，因此首先在board文件中添加i2c设备

		I2C_BOARD_INFO("max11801", 0x48),
		.platform_data = (void *)&max11801_mode,
		.irq = gpio_to_irq(SABRESD_TS_INT),
	},

然后添加这个芯片的驱动文件放在/drivers/input/touchiscreen/max11801_ts.c

对于这个驱动文件我们只要读取出AD的值就可以了，对于触摸屏部分我们并不需要，因此主要是下面几个函数

static u32 max11801_dcm_sample_aux(struct i2c_client *client)
{
	u8 temp_buf;
	int ret;
	int aux = 0;
	u32 sample_data = 0;
	/* AUX_measurement*/
	max11801_dcm_write_command(client, AUX_measurement);//发送AD采集命令
	mdelay(5);
	ret = i2c_smbus_read_i2c_block_data(client, FIFO_RD_AUX_MSB, //读取高字节数据
						1, &temp_buf);
	if (ret < 1)
		printk(KERN_DEBUG "FIFO_RD_AUX_MSB read fails\n");
	else
		aux_buf[0] = temp_buf;
	mdelay(5);
	ret = i2c_smbus_read_i2c_block_data(client, FIFO_RD_AUX_LSB,    //读取低字节数据
						1, &temp_buf);
	if (ret < 1)
		printk(KERN_DEBUG "FIFO_RD_AUX_LSB read fails\n");
	else
		aux_buf[1] = temp_buf;
	aux = (aux_buf[0] << 4) +           //视最低4位无效并去掉
					(aux_buf[1] >> 4);

	/*
	10k和18.7k并联后电阻
	R=18.7*10/(18.7+10)=6.516
	V(aux) = V(bat)*6.516/(6.516+18.7)
	V(aux) = aux*3300/0xfff
	V(bat) = aux*1386880/444717
	*/
	sample_data = (aux*1386880)/444717;	//计算出电池电压
	return sample_data;
}

u32  max11801_read_adc(void)
{
	u32 adc_data;
	adc_data = max11801_dcm_sample_aux(max11801_client);
//	printk("----%s %d\n",__func__,adc_data);	//lijianzhang
	return adc_data;
}
EXPORT_SYMBOL_GPL(max11801_read_adc);

由于电池电量检测的驱动非常简单，而且和充电驱动关系非常密切，因此一般都卸载充电驱动里面，我们也是这么做的。下面的代码都是从充电驱动中摘出来的，因此当大家看到，一些设备文件和函数参数类型 都是充电驱动中的  时候不要太奇怪。

通过上面的max11801_read_adc函数我们已经得到了理论计算的电池的电压，但实际应用中由于分压电阻误差，焊接问题等，这个电压会有一定的误差因此需要一个校正函数

u32 calibration_voltage(struct max8903_data *data)
{
	int volt[ADC_SAMPLE_COUNT];
	u32 voltage_data;
	int i;
		for (i = 0; i < ADC_SAMPLE_COUNT; i++) {    //多次采样，防止AD误差
			if (data->charger_online == 0 && data->usb_charger_online == 0) {
				/* ADC offset when battery is discharger*/
				volt[i] = max11801_read_adc()-offset_discharger;    //没有充电情况下 电压误差
				} else {
						if (data->charger_online == 1)
						volt[i] = max11801_read_adc()-offset_charger;//DC充电式 电压误差
						else if (data->usb_charger_online == 1)
						volt[i] = max11801_read_adc()-offset_usb_charger;//usb充电  电压误差
						else if (data->charger_online == 1 && data->usb_charger_online == 1)
						volt[i] = max11801_read_adc()-offset_charger;
				}

	}
	sort(volt, i, 4, cmp_func, NULL);//对电压排序
	for (i = 0; i < ADC_SAMPLE_COUNT; i++)
		pr_debug("volt_sorted[%2d]: %d\n", i, volt[i]);
	/* get the average of second max/min of remained. */
	voltage_data = (volt[2] + volt[ADC_SAMPLE_COUNT - 3]) / 2;//去掉最大值最小值 并对剩余数据求平均
	return voltage_data;
}

从上面函数我们读取到了正确的电压值。电池电压是随时变化的，我们要检测电池电量，必须随时采集，因此用一个定时器来做这件事情，代码如下：

INIT_DELAYED_WORK(&data->work, max8903_battery_work);
	schedule_delayed_work(&data->work, data->interval);

电压采集完成后就是将电压上报出去，上报的过程是：我们读取到电压变化->告诉android端电池电压变化了->android会通过power_supply设备文件来读取具体的电压值。
我们来看定时器回调函数

static void max8903_battery_work(struct work_struct *work)
{
	struct max8903_data *data;
	data = container_of(work, struct max8903_data, work.work);
	data->interval = HZ * BATTERY_UPDATE_INTERVAL;
	max8903_charger_update_status(data);    //检测充电状态
	max8903_battery_update_status(data);    //检测电池状态
	/* reschedule for the next time */
	schedule_delayed_work(&data->work, data->interval);//定时器继续
}

检测电池状态函数

static void max8903_battery_update_status(struct max8903_data *data)
{
	int temp;
	static int temp_last;
	bool changed_flag;
	changed_flag = false;
	mutex_lock(&data->work_lock);
	temp = calibration_voltage(data);
	if (temp_last == 0) {
		data->voltage_uV = temp;
		temp_last = temp;
	}
	if (data->charger_online == 0 && temp_last != 0) {//DC充电状态
		if (temp < temp_last) {
		temp_last = temp;
		data->voltage_uV = temp;
		} else {
		data->voltage_uV = temp_last;
		}
	}
	if (data->charger_online == 1 || data->usb_charger_online == 1) {//USB充电状态和DC充电状态
		data->voltage_uV = temp;
		temp_last = temp;
	}
	data->percent = calibrate_battery_capability_percent(data);//计算电量的百分比
	if (data->percent != data->old_percent) {   //电池电压有变化
		data->old_percent = data->percent;
		changed_flag = true;
	}
	if (changed_flag) {         //如果有变化
		changed_flag = false;
		power_supply_changed(&data->bat);//告诉android端 电池电量改变了
	}
	/*
	    because boot time gap between led framwork and charger
	    framwork,when system boots with charger attatched, charger
	    led framwork loses the first charger online event,add once extra
	    power_supply_changed can fix this issure
	*/
	if (data->first_delay_count < 200) {
		data->first_delay_count = data->first_delay_count + 1 ;
		power_supply_changed(&data->bat);
	}

	mutex_unlock(&data->work_lock);
}

这里我们看到了 power_supply_changed(&data->bat);告诉android端 电池电量改变了，那么下一步android来读取具体电压，就涉及到了power_supply设备文件。
来看设备文件的建立过程

	data->bat.name = "max8903-charger";
	data->bat.type = POWER_SUPPLY_TYPE_BATTERY;
	data->bat.properties = max8903_battery_props;
	data->bat.num_properties = ARRAY_SIZE(max8903_battery_props);
	data->bat.get_property = max8903_battery_get_property;
	data->bat.use_for_apm = 1;
	retval = power_supply_register(&pdev->dev, &data->bat);//注册设备文件
	if (retval) {
		dev_err(data->dev, "failed to register battery\n");
		goto battery_failed;
	}

这里注册了一个名为max8903-charger的 power_supply设备文件，这个设备文件包含了ARRAY_SIZE(max8903_battery_props)个操作分别为

static enum power_supply_property max8903_battery_props[] = {
	POWER_SUPPLY_PROP_VOLTAGE_NOW,//当前电压
	POWER_SUPPLY_PROP_STATUS,       //当前充电状态
	POWER_SUPPLY_PROP_PRESENT,      //不太清除
	POWER_SUPPLY_PROP_CAPACITY,     //电量百分比
	POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN,//电池极限电压 最大值
	POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN,//电池极限电压 最小值
	POWER_SUPPLY_PROP_HEALTH,       //电池健康状态
	POWER_SUPPLY_PROP_CAPACITY_LEVEL,//电量水平，low或者normal
};

这些状态是通过max8903_battery_get_property()这个函数来读取的

static int max8903_battery_get_property(struct power_supply *bat,
				       enum power_supply_property psp,
				       union power_supply_propval *val)
{
	struct max8903_data *di = container_of(bat,
			struct max8903_data, bat);
	switch (psp) {
	case POWER_SUPPLY_PROP_STATUS:
		val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
				if (gpio_get_value(di->pdata->chg) == 0) {
					di->battery_status = POWER_SUPPLY_STATUS_CHARGING;  //正在充电
				} else if (di->ta_in &&
					gpio_get_value(di->pdata->chg) == 1) {
					if (di->percent >= 99)
						di->battery_status = POWER_SUPPLY_STATUS_FULL;//电量大于99就充满了
					else
						di->battery_status = POWER_SUPPLY_STATUS_NOT_CHARGING;
					}
				  else if (di->usb_in &&
					gpio_get_value(di->pdata->chg) == 1) {
					if (di->percent >= 99)
					    di->battery_status = POWER_SUPPLY_STATUS_FULL;
					else
					  di->battery_status = POWER_SUPPLY_STATUS_NOT_CHARGING;
					}
		val->intval = di->battery_status;
		return 0;
	default:
		break;
	}

	switch (psp) {
	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
		val->intval = di->voltage_uV;
		break;
	case POWER_SUPPLY_PROP_CHARGE_NOW:
		val->intval = 0;
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_MAX_DESIGN:
		val->intval = HIGH_VOLT_THRESHOLD;
		break;
	case POWER_SUPPLY_PROP_VOLTAGE_MIN_DESIGN:
		val->intval = LOW_VOLT_THRESHOLD;
		break;
	case POWER_SUPPLY_PROP_PRESENT:
		val->intval = 1;
		break;
	case POWER_SUPPLY_PROP_CAPACITY:
		val->intval = di->percent < 0 ? 0 :
				(di->percent > 100 ? 100 : di->percent);
		break;
	case POWER_SUPPLY_PROP_HEALTH:
		val->intval = POWER_SUPPLY_HEALTH_GOOD;
		if (di->fault)
			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
		break;
	case POWER_SUPPLY_PROP_CAPACITY_LEVEL:
		if (di->battery_status == POWER_SUPPLY_STATUS_FULL)
			val->intval = POWER_SUPPLY_CAPACITY_LEVEL_FULL;
		else if (di->percent <= 15)
			val->intval = POWER_SUPPLY_CAPACITY_LEVEL_LOW;//电量小于15%就报低电量
		else
			val->intval = POWER_SUPPLY_CAPACITY_LEVEL_NORMAL;//否则就报正常
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

当我们注册设备文件以后，可以在/sys/devices/platform/max8903-charger.1/power_supply/max8903-charger目录下找到其设备文件如下

我们通过cat命令就可以随时查看电池状态。

二、电池电压校正参数

上面我们知道根据硬件实际情况不同，AD采集出来的电池电压需要校正参数。也就是

static int offset_discharger;
   static int offset_charger;
   static int offset_usb_charger;

对于这三个参数，当然我们可以在驱动力写死，但是为了以后的兼容性我们可以通过android上层来设置，当我们设备出厂时候，通过一配置文件方便的来修改这三个参数，下面我们就来介绍一下，怎么用设备文件和脚本，来修改者三个参数：

我们用的是sys文件系统的设备文件，创建代码为

	ret = device_create_file(&pdev->dev, &max8903_discharger_dev_attr);
	if (ret)
		dev_err(&pdev->dev, "create device file failed!\n");
	ret = device_create_file(&pdev->dev, &max8903_charger_dev_attr);
	if (ret)
		dev_err(&pdev->dev, "create device file failed!\n");
	ret = device_create_file(&pdev->dev, &max8903_usb_charger_dev_attr);
	if (ret)
		dev_err(&pdev->dev, "create device file failed!\n");

设备文件的实现代码为

static ssize_t max8903_voltage_offset_discharger_show(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "read offset_discharger:%04d\n",
		offset_discharger);
}

static ssize_t max8903_voltage_offset_discharger_store(struct device *dev,
			     struct device_attribute *attr, const char *buf,
			     size_t count)
{
	offset_discharger = simple_strtoul(buf, NULL, 10);
	pr_info("read offset_discharger:%04d\n", offset_discharger);
	return count;
}

static ssize_t max8903_voltage_offset_charger_show(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "read offset_charger:%04d\n",
		offset_charger);
}

static ssize_t max8903_voltage_offset_charger_store(struct device *dev,
			     struct device_attribute *attr, const char *buf,
			     size_t count)
{
	offset_charger = simple_strtoul(buf, NULL, 10);
	pr_info("read offset_charger:%04d\n", offset_charger);
	return count;
}

static ssize_t max8903_voltage_offset_usb_charger_show(struct device *dev,
			    struct device_attribute *attr, char *buf)
{
	return sprintf(buf, "read offset_usb_charger:%04d\n",
		offset_usb_charger);
}

static ssize_t max8903_voltage_offset_usb_charger_store(struct device *dev,
			     struct device_attribute *attr, const char *buf,
			     size_t count)
{
	offset_usb_charger = simple_strtoul(buf, NULL, 10);
	pr_info("read offset_charger:%04d\n", offset_usb_charger);
	return count;
}

static struct device_attribute max8903_discharger_dev_attr = {
	.attr = {
		 .name = "max8903_ctl_offset_discharger",
		 .mode = S_IRUSR | S_IWUSR,
		 },
	.show = max8903_voltage_offset_discharger_show,
	.store = max8903_voltage_offset_discharger_store,
};

static struct device_attribute max8903_charger_dev_attr = {
	.attr = {
		 .name = "max8903_ctl_offset_charger",
		 .mode = S_IRUSR | S_IWUSR,
		 },
	.show = max8903_voltage_offset_charger_show,
	.store = max8903_voltage_offset_charger_store,
};

static struct device_attribute max8903_usb_charger_dev_attr = {
	.attr = {
		 .name = "max8903_ctl_offset_usb_charger",
		 .mode = S_IRUSR | S_IWUSR,
		 },
	.show = max8903_voltage_offset_usb_charger_show,
	.store = max8903_voltage_offset_usb_charger_store,
};

这样，我们就可以在/sys/devices/platform/max8903-charger.1目录下看到这样三个设备文件

我们用cat命令可以读出当前值，用echo "500">>max8903_ctl_offset_charger 可以修改当前值

这样我们就可以在系统启动的时候，用脚本来自动修改者三个值，我用的办法是在init.rc的on boot阶段增加这么三行

#battery charge
    write /sys/devices/platform/max8903-charger.1/max8903_ctl_offset_charger 150
    write /sys/devices/platform/max8903-charger.1/max8903_ctl_offset_discharger 200
    write /sys/devices/platform/max8903-charger.1/max8903_ctl_offset_usb_charger 250

当然大家也可以把这三行命令写在另外一个脚本里，然后init.rc中调用

三、电池充电

电池充电的电路

一共有4个引脚输出到cpu中：

CHG_FLT1_B    电池检测错误

UOK_B              usb插入

DOK_BDC插入

CHG_STATUS1_B 充电状态

对于充电状态的检测过程，和电量检测基本相同， 检测到状态变化->告诉android层发生变化->android层通过设备文件来读取变化值

知道了这些我们来看驱动，首先在board文件中添加max8903设备

static struct max8903_pdata charger1_data = {
	.dok = SABRESD_CHARGE_DOK_B,
	.uok = SABRESD_CHARGE_UOK_B,
	.chg = CHARGE_STATE2,
	.flt = CHARGE_STATE1,
	.dcm_always_high = true,
	.dc_valid = true,
	.usb_valid = true,
};

static struct platform_device sabresd_max8903_charger_1 = {
	.name	= "max8903-charger",
	.id	= 1,

	.dev	= {
		.platform_data = &charger1_data,
	},
};

platform_device_register(&sabresd_max8903_charger_1);

然后在/derivers/power/目录下添加驱动文件。充电状态的变化都是IO电平的变化，我们来看驱动是怎么处理这4个io的，首先在probe函数中

申请IO

if (pdata->dc_valid) {
		if (pdata->dok && gpio_is_valid(pdata->dok)) {
			gpio = pdata->dok; /* PULL_UPed Interrupt */
			/* set DOK gpio input */
			ret = gpio_request(gpio, "max8903-DOK");
			if (ret) {
				printk(KERN_ERR"request max8903-DOK error!!\n");
				goto err;
			} else {
				gpio_direction_input(gpio);
			}
			ta_in = gpio_get_value(gpio) ? 0 : 1;
		} else if (pdata->dok && gpio_is_valid(pdata->dok) && pdata->dcm_always_high) {
			ta_in = pdata->dok; /* PULL_UPed Interrupt */
			ta_in = gpio_get_value(gpio) ? 0 : 1;
		} else {
			dev_err(dev, "When DC is wired, DOK and DCM should"
					" be wired as well."
					" or set dcm always high\n");
			ret = -EINVAL;
			goto err;
		}
	}
	if (pdata->usb_valid) {
		if (pdata->uok && gpio_is_valid(pdata->uok)) {
			gpio = pdata->uok;
			/* set UOK gpio input */
			ret = gpio_request(gpio, "max8903-UOK");
			if (ret) {
				printk(KERN_ERR"request max8903-UOK error!!\n");
				goto err;
			} else {
				gpio_direction_input(gpio);
			}
			usb_in = gpio_get_value(gpio) ? 0 : 1;
		} else {
			dev_err(dev, "When USB is wired, UOK should be wired."
					"as well.\n");
			ret = -EINVAL;
			goto err;
		}
	}
	if (pdata->chg) {
		if (!gpio_is_valid(pdata->chg)) {
			dev_err(dev, "Invalid pin: chg.\n");
			ret = -EINVAL;
			goto err;
		}
		/* set CHG gpio input */
		ret = gpio_request(pdata->chg, "max8903-CHG");
		if (ret) {
			printk(KERN_ERR"request max8903-CHG error!!\n");
			goto err;
		} else {
			gpio_direction_input(pdata->chg);
		}
	}
	if (pdata->flt) {
		if (!gpio_is_valid(pdata->flt)) {
			dev_err(dev, "Invalid pin: flt.\n");
			ret = -EINVAL;
			goto err;
		}
		/* set FLT gpio input */
		ret = gpio_request(pdata->flt, "max8903-FLT");
		if (ret) {
			printk(KERN_ERR"request max8903-FLT error!!\n");
			goto err;
		} else {
			gpio_direction_input(pdata->flt);
		}
	}
	if (pdata->usus) {
		if (!gpio_is_valid(pdata->usus)) {
			dev_err(dev, "Invalid pin: usus.\n");
			ret = -EINVAL;
			goto err;
		}
	}

注册DC充电的设备文件

mutex_init(&data->work_lock);
	data->fault = false;
	data->ta_in = ta_in;
	data->usb_in = usb_in;
	data->psy.name = "max8903-ac";
	data->psy.type = POWER_SUPPLY_TYPE_MAINS;
	data->psy.get_property = max8903_get_property;
	data->psy.properties = max8903_charger_props;
	data->psy.num_properties = ARRAY_SIZE(max8903_charger_props);
	ret = power_supply_register(dev, &data->psy);
	if (ret) {
		dev_err(dev, "failed: power supply register.\n");
		goto err_psy;
	}

注册USB充电的设备文件

data->usb.name = "max8903-usb";
	data->usb.type = POWER_SUPPLY_TYPE_USB;
	data->usb.get_property = max8903_get_usb_property;
	data->usb.properties = max8903_charger_props;
	data->usb.num_properties = ARRAY_SIZE(max8903_charger_props);
	ret = power_supply_register(dev, &data->usb);
	if (ret) {
		dev_err(dev, "failed: power supply register.\n");
		goto err_psy;
	}

这两个设备文件都只有一个操作：检测充电器是否在线

static enum power_supply_property max8903_charger_props[] = {
	POWER_SUPPLY_PROP_ONLINE,
};

操作函数也很简单

static int max8903_get_property(struct power_supply *psy,
		enum power_supply_property psp,
		union power_supply_propval *val)
{
	struct max8903_data *data = container_of(psy,
			struct max8903_data, psy);

	switch (psp) {
	case POWER_SUPPLY_PROP_ONLINE:
		val->intval = 0;
		if (data->ta_in)
			val->intval = 1;
		data->charger_online = val->intval;
		break;
	default:
		return -EINVAL;
	}
	return 0;
}
static int max8903_get_usb_property(struct power_supply *usb,
		enum power_supply_property psp,
		union power_supply_propval *val)
{
	struct max8903_data *data = container_of(usb,
			struct max8903_data, usb);

	switch (psp) {
	case POWER_SUPPLY_PROP_ONLINE:
		val->intval = 0;
		if (data->usb_in)
			val->intval = 1;
		data->usb_charger_online = val->intval;
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

我们可以通过/sys/devices/platform/max8903-charger.1/power_supply/max8903-ac 目录和/sys/devices/platform/max8903-charger.1/power_supply/max8903-usb目录下的设备文件来访问充电器的状态

接下来是IO中断

if (pdata->dc_valid) {
		ret = request_threaded_irq(gpio_to_irq(pdata->dok),
				NULL, max8903_dcin,
				IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
				"MAX8903 DC IN", data);
		if (ret) {
			dev_err(dev, "Cannot request irq %d for DC (%d)\n",
					gpio_to_irq(pdata->dok), ret);
			goto err_usb_irq;
		}
	}

	if (pdata->usb_valid) {
		ret = request_threaded_irq(gpio_to_irq(pdata->uok),
				NULL, max8903_usbin,
				IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
				"MAX8903 USB IN", data);
		if (ret) {
			dev_err(dev, "Cannot request irq %d for USB (%d)\n",
					gpio_to_irq(pdata->uok), ret);
			goto err_dc_irq;
		}
	}

	if (pdata->flt) {
		ret = request_threaded_irq(gpio_to_irq(pdata->flt),
				NULL, max8903_fault,
				IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
				"MAX8903 Fault", data);
		if (ret) {
			dev_err(dev, "Cannot request irq %d for Fault (%d)\n",
					gpio_to_irq(pdata->flt), ret);
			goto err_flt_irq;
		}
	}

	if (pdata->chg) {
		ret = request_threaded_irq(gpio_to_irq(pdata->chg),
				NULL, max8903_chg,
				IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING,
				"MAX8903 Fault", data);
		if (ret) {
			dev_err(dev, "Cannot request irq %d for Fault (%d)\n",
					gpio_to_irq(pdata->flt), ret);
			goto err_chg_irq;
		}
	}

这4个IO的中断处理函数很类似

static irqreturn_t max8903_dcin(int irq, void *_data)
{
	struct max8903_data *data = _data;
	struct max8903_pdata *pdata = data->pdata;
	bool ta_in;

	ta_in = gpio_get_value(pdata->dok) ? false : true;   //保存当前dok值

	if (ta_in == data->ta_in)
		return IRQ_HANDLED;

	data->ta_in = ta_in;
	pr_info("TA(DC-IN) Charger %s.\n", ta_in ?
			"Connected" : "Disconnected");
	max8903_charger_update_status(data);
	max8903_battery_update_status(data);
	power_supply_changed(&data->psy);   //报告状态改变
	power_supply_changed(&data->bat);
	return IRQ_HANDLED;
}
static irqreturn_t max8903_usbin(int irq, void *_data)
{
	struct max8903_data *data = _data;
	struct max8903_pdata *pdata = data->pdata;
	bool usb_in;
	usb_in = gpio_get_value(pdata->uok) ? false : true; //保存当前uok值
	if (usb_in == data->usb_in)
		return IRQ_HANDLED;

	data->usb_in = usb_in;
	max8903_charger_update_status(data);
	max8903_battery_update_status(data);
	pr_info("USB Charger %s.\n", usb_in ?
			"Connected" : "Disconnected");
	power_supply_changed(&data->bat);
	power_supply_changed(&data->usb);  //报告状态改变
	return IRQ_HANDLED;
}

static irqreturn_t max8903_fault(int irq, void *_data)
{
	struct max8903_data *data = _data;
	struct max8903_pdata *pdata = data->pdata;
	bool fault;

	fault = gpio_get_value(pdata->flt) ? false : true;  //保存当前电池错误值

	if (fault == data->fault)
		return IRQ_HANDLED;

	data->fault = fault;

	if (fault)
		dev_err(data->dev, "Charger suffers a fault and stops.\n");
	else
		dev_err(data->dev, "Charger recovered from a fault.\n");
	max8903_charger_update_status(data);
	max8903_battery_update_status(data);
	power_supply_changed(&data->psy);
	power_supply_changed(&data->bat);
	power_supply_changed(&data->usb);   //报告状态改变
	return IRQ_HANDLED;
}

static irqreturn_t max8903_chg(int irq, void *_data)
{
	struct max8903_data *data = _data;
	struct max8903_pdata *pdata = data->pdata;
	int chg_state;

	chg_state = gpio_get_value(pdata->chg) ? false : true;//保存电池充电状态

	if (chg_state == data->chg_state)
		return IRQ_HANDLED;

	data->chg_state = chg_state;
	max8903_charger_update_status(data);
	max8903_battery_update_status(data);
	power_supply_changed(&data->psy);
	power_supply_changed(&data->bat);
	power_supply_changed(&data->usb);//报告状态改变
	return IRQ_HANDLED;
}

到了这里电池充电的流程就走完了。