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。
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_B DC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。