MTK Battery系统

转自：http://www.voidcn.com/blog/bsxiaomage/article/p-4091451.html

MTK方案的电池充电过程分为预充、恒流充电（CC模式）、恒压充电（CV模式）三种模式，整个充电过程如下充电状态图所示：



从充电状态图看出来，刚开始充电的时候，代码先判断是插USB充电还是插ac充电，电池在进入充电阶段分为快速充电、CC（恒流充电）、CV（恒压充电）。而从CC模式切换到CV模式在代码中的alps/mediatek/kernel/drivers/power/linear_charging.c和alps/mediatek/kernel/drivers/power/ switch_charging.c。

MTK Battery系统驱动的大致流程主要是通过系统platform总线注册device和driver，然后在probe函数里面创建了一个线程，然后创建一个hrtimer定时器，定时器没10s运行一次，同时在probe函数里面会创建一些设备节点，通过这些设备节点，系统将每10s更新的数据上传给上层供上层调用显示。

1、battery硬件原理图

首先先介绍几个电压值：

VCHG：USB正极

VCDT：充电电压检测脚

ISENSE：充电电流检测电阻的正极

BATSNS：充电电流检测电阻的负极

BAT：电池正极引脚

BAT_ON：电池NTC（热敏电阻）引脚

通过三极管可以开启，关闭充电功能，开启充电的时候调节三极管的基级电流可以控制流过三极管CE端的电流从而实现充电电流大小的设置。

Rsense采样电阻:对于软件来说可以测量充电电流的大小：电流计算方法：（ISENSE – VBAT）/Rsense。对于PMU来说通过Rsense可以实现电流控制。比如要实现1A的充电电流，Rsense为0.2欧。PMU实现该电流的方法就是设法一直保证Rsense两端的电压是0.2V。



BAT_ON在充电中的作用：

1，检测电池是否存在。电压必须小于1.062V，否则认为电池不存在不能充电，硬件行为，软件无法关闭此功能

2，高温检测，电池电压必须大于0.2V，否则认为电池温度过高不能充电，硬件行为，软件可以关闭此功能

3，软件检测电池温度。
上图中NTC电阻会串联一个24k的电阻，这个会在后面源代码分析时起作用。

2、Battery架构简析

MTK电池显示的具体过程为：硬件ADC读取Battery的各路信息：包括温度，电压等。然后利用MTK开发的电量算法分析得到的数据。Kernel层将电量信息通过写文件节点的方式更新,并通过UEVENT通知上层。上层Service开启UEVENT LISTENER，监听到UEVENT后，读取battery相关文件节点，获取电量信息。Service更新数据后，通过Broadcast通知所有开启了相关listener的activities。
根据不同的电量读取和计算的策略，第一步的读取和第二步的算法部分会有比较大的差异，而后面的数据更新和事件通知部分一致性较高。

3、MTK电池驱动分析

在分析源代码前，先来看看PMU_ChargerStruct这个结构体。

<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">146</span> <span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">typedef</span> <span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">struct</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">147</span> {
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">148</span>         kal_bool                        bat_exist;  <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 判断电池是否存在</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">149</span>         kal_bool                        bat_full;  <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//判断电池是否充满</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">150</span>         INT32                   bat_charging_state; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//判断充电状态</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">151</span>         UINT32                  bat_vol; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//电池平均电压</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">152</span>         kal_bool                        bat_in_recharging_state; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//电池是否在回充</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">153</span>         kal_uint32              Vsense; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 电池瞬间电压</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">154</span>         kal_bool                        charger_exist; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// Charger是否存在Charger电压</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">155</span>         UINT32                  charger_vol;  <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// Charger电压</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">156</span>         INT32                   charger_protect_status; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//充电保护状态，过流或者过压保护状态</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">157</span>         INT32                   ICharging; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 充电电流</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">158</span>         INT32                   IBattery;
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">159</span>         INT32                   temperature; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 电池温度</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">160</span>         INT32                   temperatureR;
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">161</span>         INT32                   temperatureV;
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">162</span>         UINT32                  total_charging_time; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//总的充电时间</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">163</span>         UINT32                  PRE_charging_time; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// Pre cc充电时间</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">164</span>         UINT32                  CC_charging_time; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//cc充电时间</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">165</span>         UINT32                  TOPOFF_charging_time; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//TOPOFF充电时间</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">166</span>         UINT32                  POSTFULL_charging_time; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//Postfull充电时间</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">167</span>         UINT32                  charger_type; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//充电器类型</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">168</span>         INT32                   SOC; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//底层的电量</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">169</span>         INT32                   UI_SOC; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 上层的电量</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">170</span>         UINT32                  nPercent_ZCV;
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">171</span>         UINT32                  nPrecent_UI_SOC_check_point; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//N%同步点对应的开路电压以及UI电量</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">172</span>         UINT32                  ZCV; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//电池当前开路电压</span>
<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">173</span> } PMU_ChargerStruct;

结构体中个变量定义可参考注释，PMU_ChargerStruct记录了整个充电代码的所有充电的变化情况，包括上报给上层的电量值，可以说整个充电的过程就是围绕这这个结构体进行数值的变化，所以这个结构体在整个充电过程中起着非常重要的作用。

下面来看看代码的具体实现。
MTK的battery的注册是通过platform总线实现的，在mediatek/kernel/drivers/power/battery_common.c中，我们会看到对battery的device和driver进行注册的函数，device和driver通过name进行匹配，device和driver注册后，就是执行battery_driver结构体里面的函数，执行battery_driver里面的函数首先运行的是battery_probe函数，在battery_probe函数里面，先对battery进行字符设备的注册，注册的字符设备名为MT_pmic_adc_cali。

在注册完字符设备后，probe会执行get_charging_control();这个函数，这个函数在整个充电过程中起着很重要的作用，该函数就一行代码：

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;"><span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">static</span> <span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span> <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">get_charging_control</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span>)</span>
</span>{
battery_charging_control = chr_control_interface;
}
<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;">kal_int32 <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">chr_control_interface</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(CHARGING_CTRL_CMD cmd, <span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span> *data)</span>
</span>{
kal_int32 status;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(cmd < CHARGING_CMD_NUMBER)
status = charging_func[cmd](data);
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">else</span>
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> STATUS_UNSUPPORTED;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> status;
}

在get_charging_control函数里面，就是将chr_control_interface函数指向battery_charging_control，在后面会有很多对battery_charging_control函数的调用，而所有的调用都是传递一个参数进来，然后对比charging_func数组里面的函数指正，在对其他函数进行调用。下面看看battery_charging_control(CHARGING_CMD_GET_PLATFORM_BOOT_MODE,&g_platform_boot_mode);这个语句的调用，就可以知道battery_charging_control函数是怎样运行的。

<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">typedef</span> <span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">enum</span>
{
CHARGING_CMD_INIT,
CHARGING_CMD_DUMP_REGISTER,
CHARGING_CMD_ENABLE,
CHARGING_CMD_SET_CV_VOLTAGE,
CHARGING_CMD_GET_CURRENT,
CHARGING_CMD_SET_CURRENT,
CHARGING_CMD_SET_INPUT_CURRENT,
CHARGING_CMD_GET_CHARGING_STATUS,
CHARGING_CMD_RESET_WATCH_DOG_TIMER,
CHARGING_CMD_SET_HV_THRESHOLD,
CHARGING_CMD_GET_HV_STATUS,
CHARGING_CMD_GET_BATTERY_STATUS,
CHARGING_CMD_GET_CHARGER_DET_STATUS,
CHARGING_CMD_GET_CHARGER_TYPE,
CHARGING_CMD_GET_IS_PCM_TIMER_TRIGGER,
CHARGING_CMD_SET_PLATFORM_RESET,
CHARGING_CMD_GET_PLATFORM_BOOT_MODE,
CHARGING_CMD_SET_POWER_OFF,
CHARGING_CMD_NUMBER
} CHARGING_CTRL_CMD;

CHARGING_CMD_GET_PLATFORM_BOOT_MODE定义在一个枚举型变量中，并且在枚举类型中的是第十七个元素，而枚举类型如果没有初始化第一参数时第一个参数就为0，所以CHARGING_CMD_GET_PLATFORM_BOOT_MODE的值就为16，而battery_charging_control函数是通过chr_control_interface函数指向相同的地址的，所以，调用battery_charging_control函数并传递参数实际就是对chr_control_interface函数进行操作，在chr_control_interface函数中，会直接将cmd参数直接给charging_func结构体，而charging_func结构体的定义为：

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;"><span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">static</span> <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">kal_uint32</span> <span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(*charging_func[CHARGING_CMD_NUMBER])</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span> *data)</span></span>=
{
charging_hw_init
,charging_dump_register
,charging_enable
,charging_set_cv_voltage
,charging_get_current
,charging_set_current
,charging_set_input_current             <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// not support, empty function</span>
,charging_get_charging_status   <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// not support, empty function</span>
,charging_reset_watch_dog_timer
,charging_set_hv_threshold
,charging_get_hv_status
,charging_get_battery_status
,charging_get_charger_det_status
,charging_get_charger_type
,charging_get_is_pcm_timer_trigger
,charging_set_platform_reset
,charging_get_platfrom_boot_mode
,charging_set_power_off
};

CHARGING_CMD_GET_PLATFORM_BOOT_MODE在CHARGING_CTRL_CMD枚举类型中的值为17，所以执行status
= charging_func[cmd](data)语句的时候就直接调用到charging_func中的第十七个参数，并且返回值直接跟data指向相同的地址，所以返回值会在data。所以，对于battery_charging_control(CHARGING_CMD_GET_PLATFORM_BOOT_MODE,&g_platform_boot_mode)这类函数的调用，首先就是确定CHARGING_CMD_GET_PLATFORM_BOOT_MODE在CHARGING_CTRL_CMD枚举中的位置，然后到charging_func结构体中相对应的位置查询相对应的函数执行，最后将执行函数后的返回值通过data这个指针变量传给调用函数。

当probe函数注册完了字符设备后，函数进行的随后的进行的操作是在sys下面建立设备节点，总共建立了四个设备节点，分别为ac_main、usb_main、wireless_main和battery_main，这四个节点分别为使用适配器、USB、无线充电以及使用电池供电。电池电量发生变化的时候，会通过这些节点将数据上报给上层，也就是说上层是通过这些节点来读取底层电池电量变化的数据的。

当初始化完成后，probe函数会创建一个hrtimer定时器，定时器启动bat_thread_kthread函数，bat_thread_kthread函数中的while(1)里面包含了BAT_thread()函数，BAT_thread()就是充电的核心函数。

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;"><span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">int</span> <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">bat_thread_kthread</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span> *x)</span>
</span>{
ktime_t ktime = ktime_set(<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">3</span>, <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>);  <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 10s, 10* 1000 ms	</span>

<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">/* Run on a process content */</span>
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">while</span> (<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1</span>) {
mutex_lock(&bat_mutex);
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>((chargin_hw_init_done == KAL_TRUE) && (battery_suspended == KAL_FALSE))
BAT_thread();
mutex_unlock(&bat_mutex);
battery_xlog_printk(BAT_LOG_FULL, <span class="hljs-string" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(33, 145, 97); background: transparent;">"wait event \n"</span> );
wait_event(bat_thread_wq, (bat_thread_timeout == KAL_TRUE));
bat_thread_timeout = KAL_FALSE;
hrtimer_start(&battery_kthread_timer, ktime, HRTIMER_MODE_REL);
ktime = ktime_set(BAT_TASK_PERIOD, <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>);  <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 10s, 10* 1000 ms</span>
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>( chr_wake_up_bat == KAL_TRUE && g_smartbook_update != <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1</span>) <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// for charger plug in/ out</span>
{
g_smartbook_update = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
battery_meter_reset();
chr_wake_up_bat = KAL_FALSE;
battery_xlog_printk(BAT_LOG_CRTI, <span class="hljs-string" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(33, 145, 97); background: transparent;">"[BATTERY] Charger plug in/out, Call battery_meter_reset. (%d)\n"</span>, BMT_status.UI_SOC);
}
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
}

bat_thread_kthread函数作为定时器的触发函数，在函数中通过ktime =ktime_set(BAT_TASK_PERIOD,
0);将定时触发时间设置为10s，所以每10s就将会对该函数进行触发，该函数的核心函数为BAT_thread()，基本上整个充电过程都在这个函数里面实现。

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;"><span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span> <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">BAT_thread</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span>)</span>
</span>{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">static</span> kal_bool  battery_meter_initilized = KAL_FALSE;
_g_bat_sleep_total_time = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(battery_meter_initilized == KAL_FALSE)
{
battery_meter_initial();	<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//move from battery_probe() to decrease booting time</span>
BMT_status.nPercent_ZCV = battery_meter_get_battery_nPercent_zcv();
battery_meter_initilized = KAL_TRUE;
}
mt_battery_charger_detect_check();
mt_battery_GetBatteryData();
mt_battery_thermal_check();
mt_battery_notify_check();
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>( BMT_status.charger_exist == KAL_TRUE )
{
mt_battery_CheckBatteryStatus();
mt_battery_charging_algorithm();
}
mt_battery_update_status();
}

当系统第一次启动的时候battery_meter_initilized为KAL_FALSE，所以BAT_thread会调用battery_meter_initial函数。

battery_meter_initial函数为系统启动时运行的，也电池充电做一些初始化操作。MTK有AUXADC、SW_FG、HW_FG三种不同的电池算法方案，这三种方案分别初始化，因为82平台采用的SW_FG，所以接下去先主要分析SW_FG的流程。而SW_FG中主要是利用线性插值算法来重构zcv表格，利用积分算法求电池的当前电量。

先来看看系统是如何利用线性插值的方法来求电池的温度，重构zcv表格，在table_init函数中：

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;"><span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span> <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">table_init</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span>)</span>
</span>{
..........
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">int</span> temperature = force_get_tbat(); <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//求电池的温度</span>

<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// Re-constructure r-table profile according to current temperature</span>
profile_p_r_table = fgauge_get_profile_r_table(TEMPERATURE_T);
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span> (profile_p_r_table == NULL)
{
bm_print(BM_LOG_CRTI, <span class="hljs-string" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(33, 145, 97); background: transparent;">"[FGADC] fgauge_get_profile_r_table : create table fail !\r\n"</span>);
}
fgauge_construct_r_table_profile(temperature, profile_p_r_table);

<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// Re-constructure battery profile according to current temperature</span>
profile_p = fgauge_get_profile(TEMPERATURE_T);
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span> (profile_p == NULL)
{
bm_print(BM_LOG_CRTI, <span class="hljs-string" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(33, 145, 97); background: transparent;">"[FGADC] fgauge_get_profile : create table fail !\r\n"</span>);
}
fgauge_construct_battery_profile(temperature, profile_p);
}

table_init首先获取系统的温度int temperature =force_get_tbat()，这里是通过读NTC电阻的电压，然后通过查表来求电阻的。

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;"><span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">int</span> <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">force_get_tbat</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span>)</span>
</span>{
……………
bat_temperature_volt = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">2</span>;
<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//求的NTC电阻的电压，也就是原理图中的BAT_ON</span>
ret = battery_meter_ctrl(BATTERY_METER_CMD_GET_ADC_V_BAT_TEMP, &bat_temperature_volt);
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(bat_temperature_volt != <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>)
{
……………
bat_temperature_val = BattVoltToTemp(bat_temperature_volt);
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> bat_temperature_val;
<span class="hljs-preprocessor" style="border: 0px; margin: 0px; padding: 0px; font-weight: bold; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(153, 153, 153); background: transparent;">#<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">endif</span>    </span>
}

BattVoltToTemp函数就是任何将ADC读出的电压值转换为温度值，该函数其实就是做了两个运算，运算的原理如下图所示：



NTC电阻就是通过与电阻的串联跟并联并且通过电压值来得到的。计算出系统当前NTC电阻的电阻值后，然后就调用BattThermistorConverTemp函数进行查表，对比出当前系统的温度。而BattThermistorConverTemp函数是通过alps/mediatek/custom/mt6582/kernel/battery/battery/cust_battery_meter_table.h中的Batt_Temperature_Table结构体，然后根据电阻值落在哪个区间，根据线性插值的方法求出当前电池的温度。
然后在回到table_init函数，MTK的zcv电池参数表格会预先测得的在-100 25 50 摄氏度开路电量跟放电深度之间的关系。结合真实的温度值，系统会自己构建一张当前温度值的ZCV电池曲线表格。

<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// Re-constructure r-table profile according to current temperature</span>
profile_p_r_table = fgauge_get_profile_r_table(TEMPERATURE_T); <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//返回NTC电阻跟电压表格</span>
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span> (profile_p_r_table == NULL)
{
bm_print(BM_LOG_CRTI, <span class="hljs-string" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(33, 145, 97); background: transparent;">"[FGADC] fgauge_get_profile_r_table : create table fail !\r\n"</span>);
}
<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//动态构建一个NTC电阻跟电压关系的表格</span>
fgauge_construct_r_table_profile(temperature, profile_p_r_table);

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;">R_PROFILE_STRUC_P <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">fgauge_get_profile_r_table</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(kal_uint32 temperature)</span>
</span>{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">switch</span> (temperature)
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">case</span> TEMPERATURE_T0:
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> &r_profile_t0[g_fg_battery_id][<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>];
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">break</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">case</span> TEMPERATURE_T1:
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> &r_profile_t1[g_fg_battery_id][<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>];
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">break</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">case</span> TEMPERATURE_T2:
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> &r_profile_t2[g_fg_battery_id][<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>];
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">break</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">case</span> TEMPERATURE_T3:
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> &r_profile_t3[g_fg_battery_id][<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>];
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">break</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">case</span> TEMPERATURE_T:
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> &r_profile_temperature[<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>];
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">break</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">default</span>:
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> NULL;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">break</span>;
}
}

调用fgauge_get_profile_r_table函数会根据上面读取到的温度来返回相对应的r_profile_t数组，r_profile_t数组在alps/mediatek/custom/mt6582/kernel/battery/battery/cust_battery_meter_table.h中，而随后调用的fgauge_construct_r_table_profile函数也是先根据当前电池的温度确定是落入哪个温度范围，假如当前电池温度是落入打0到25度之间，然后根据开路电压值和NTC电阻值的不同采用线性平均法分别构建出两个数值，并以这两个值在构造出一个新的开路电压跟NTC电阻的动态的结构体。

<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">for</span> (i = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>; i < saddles; i++) <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 构建表格中的电压值</span>
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>( ((high_profile_p + i)->voltage) > ((low_profile_p + i)->voltage) )
{
temp_v_1 = (high_profile_p + i)->voltage;
temp_v_2 = (low_profile_p + i)->voltage;
(temp_profile_p + i)->voltage = temp_v_2 + <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//采用线性平均法求电压</span>
(
(
(temperature - low_temperature) *
(temp_v_1 - temp_v_2)
) /
(high_temperature - low_temperature)
);
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">else</span>
{
temp_v_1 = (low_profile_p + i)->voltage;
temp_v_2 = (high_profile_p + i)->voltage;
(temp_profile_p + i)->voltage = temp_v_2 +
(
(
(high_temperature - temperature) *
(temp_v_1 - temp_v_2)
) /
(high_temperature - low_temperature)
);
}
}
<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">/* Interpolation for R_BAT */</span>
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">for</span> (i = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>; i < saddles; i++) <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 构建表格中的NTC电阻值</span>
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>( ((high_profile_p + i)->resistance) > ((low_profile_p + i)->resistance) )
{
temp_r_1 = (high_profile_p + i)->resistance;
temp_r_2 = (low_profile_p + i)->resistance;
(temp_profile_p + i)->resistance = temp_r_2 + <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//采用线性平均法求电阻</span>
(
(
(temperature - low_temperature) *
(temp_r_1 - temp_r_2)
) /
(high_temperature - low_temperature)
);
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">else</span>
{
temp_r_1 = (low_profile_p + i)->resistance;
temp_r_2 = (high_profile_p + i)->resistance;
(temp_profile_p + i)->resistance = temp_r_2 +
(
(
(high_temperature - temperature) *
(temp_r_1 - temp_r_2)
) /
(high_temperature - low_temperature)
);
}
}

重构ZCV表格的方法是通过线性插值的方法重构的，具体原理如下图：



table_init后面利用同样的原理，动态生成了一个开路电压与放电深度关系的结构体，这里就不介绍了。
当table_init函数后系统会对一些变量进行初始化操作，包括在dod_init函数中对oam_v_ocv_1和oam_v_ocv_2进行初始化赋值，读取RTC实时时钟芯片的电量值等等，经过这一系列操作后，就会进入battery系统一个最重要的部分，利用积分的方式来求电池的当前电量。

MTK系统是通过battery_meter_get_battery_percentage函数来读取当前电池的电量的，然后在通过设备结点，通过给上层调用。battery_meter_get_battery_percentage函数主要就是调用oam_run函数来实现电流的库伦算法。积分法是利用电流计算公式 I = Q/t来求的，它的优点时适用于各种电池，但缺点是初始电量无法获取。



而整个积分过程可参考下图：

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;"><span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span> <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">oam_run</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">void</span>)</span>
</span>{
……
<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//now_time = rtc_read_hw_time();</span>
getrawmonotonic(&now_time); <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//获取系统当前时间</span>
delta_time = now_time.tv_sec - last_oam_run_time.tv_sec;

last_oam_run_time = now_time;

<span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// Reconstruct table if temp changed;</span>
fgauge_construct_table_by_temp(); <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">// 当电压表发生改变了的时候，重构电压表</span>

vol_bat = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">15</span>; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//set avg times</span>
ret = battery_meter_ctrl(BATTERY_METER_CMD_GET_ADC_V_BAT_SENSE, &vol_bat); <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//得到闭路电压</span>

oam_i_1 = (((oam_v_ocv_1-vol_bat)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1000</span>)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>) / oam_r_1;    <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mA </span>
oam_i_2 = (((oam_v_ocv_2-vol_bat)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1000</span>)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>) / oam_r_2;    <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mA </span>

oam_car_1 = (oam_i_1*delta_time/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">3600</span>) + oam_car_1; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mAh </span>
oam_car_2 = (oam_i_2*delta_time/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">3600</span>) + oam_car_2; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mAh</span>

oam_d_1 = oam_d0 + (oam_car_1*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>)/gFG_BATT_CAPACITY_aging; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//gFG_BATT_CAPACITY_aging is Q_MAX</span>
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_1 < <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>)   oam_d_1 = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_1 > <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>) oam_d_1 = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>;

oam_d_2 = oam_d0 + (oam_car_2*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>)/gFG_BATT_CAPACITY_aging;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_2 < <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>)   oam_d_2 = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_2 > <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>) oam_d_2 = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>;

oam_v_ocv_1 = vol_bat + mtk_imp_tracking(vol_bat, oam_i_2, <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">5</span>);

oam_d_3 = fgauge_read_d_by_v(oam_v_ocv_1);
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_3 < <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>)   oam_d_3 = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_3 > <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>) oam_d_3 = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">100</span>;

oam_r_1 = fgauge_read_r_bat_by_v(oam_v_ocv_1);

oam_v_ocv_2 = fgauge_read_v_by_d(oam_d_2);
oam_r_2 = fgauge_read_r_bat_by_v(oam_v_ocv_2);

oam_run函数中算法的大致思路为：系统当前的电量通过最终的开路电压oam_v_ocv_1查ZCV表得到当前的电量值，而最终开路电压需要通过闭路电压v_bat和闭路电流oam_i_2 去回溯电池内阻，逐次逼近，而oam_i_2 通过另一种方式即电量积分更新的电压oam_v_ocv_2来得到。

下面看看具体代码的实现。

vol_bat = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">15</span>; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//set avg times</span>
ret = battery_meter_ctrl(BATTERY_METER_CMD_GET_ADC_V_BAT_SENSE, &vol_bat);

首先是闭路电压的更新，这里求的是V_BAT的电压，不需要算法支持直接通过读寄存器实现，注意vol_bat这个参数被复用，返回的平均次数时为最终的v_bat电压值。

oam_i_1 = (((oam_v_ocv_1-vol_bat)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1000</span>)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>) / oam_r_1;    <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mA</span>
oam_i_2 = (((oam_v_ocv_2-vol_bat)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1000</span>)*<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>) / oam_r_2;    <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mA</span>

oam_car_1 = (oam_i_1*delta_time/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">3600</span>) + oam_car_1; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mAh</span>
oam_car_2 = (oam_i_2*delta_time/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">3600</span>) + oam_car_2; <span class="hljs-comment" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: italic; font-family: inherit; vertical-align: baseline; color: rgb(64, 128, 128); background: transparent;">//0.1mAh</span>

oam_v_ocv_1的值会在oam_init函数里面赋值，oam_init里给的值是hw_ocv的电压值，即系统刚起来时电流很小的时候的电压值。ocv_1和ocv_2是通过两种不同的方式来更新电压。这里是通过内阻压降即IR drop来求电流。如下图所示，图中R为电池内阻。


这里的关键是oam_i_2，这边的I2 有几个作用：

1、因为电流是通过上图的内阻IR drop得到的，而方式一内阻回溯逼近开路电压本质也是IR drop，如果使用oam_i_1 则没有意义，只能使用不同体系的I2.

2、方式二 电流积分求电量查表 同样依赖 oam_i_2 这个体系是累积积分不需要引用其他体系的参数

3、I2的方向作为充电还是放电的依据

而oam_i_1只有作用3。这里还要注意的是oam_i_1和oam_i_2的单位是0.1mA。而oam_car_1和oam_car_2 是累积电量，同样对应的单位是0.1mAh，显然oam_car_2是算法的有效参数。

oam_v_ocv_1 = vol_bat + mtk_imp_tracking(vol_bat, oam_i_2, <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">5</span>);

求oam_v_ocv_1电压的思路是闭路电压加上电池内阻消耗的电压，而mtk_imp_tracking函数是利用内阻回溯电池内阻压降，即回溯IR
drop，然后逐渐比较开路电压。

<span class="hljs-function" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; background: transparent;">kal_int32 <span class="hljs-title" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(25, 70, 157); background: transparent;">mtk_imp_tracking</span><span class="hljs-params" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(0, 0, 255); background: transparent;">(kal_int32 ori_voltage, kal_int32 ori_current, kal_int32 recursion_time)</span>
</span>{
kal_int32 ret_compensate_value = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
kal_int32 temp_voltage_1 = ori_voltage;
kal_int32 temp_voltage_2 = temp_voltage_1;
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">int</span> i = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;

<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">for</span>(i=<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span> ; i < recursion_time ; i++)
{
gFG_resistance_bat = fgauge_read_r_bat_by_v(temp_voltage_2);
ret_compensate_value = ( (ori_current) * (gFG_resistance_bat + R_FG_VALUE)) / <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1000</span>;
ret_compensate_value = (ret_compensate_value+(<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">2</span>)) / <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>;
temp_voltage_2 = temp_voltage_1 + ret_compensate_value;

bm_print(BM_LOG_FULL, <span class="hljs-string" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(33, 145, 97); background: transparent;">"[mtk_imp_tracking] temp_voltage_2=%d,temp_voltage_1=%d,ret_compensate_value=%d,gFG_resistance_bat=%d\n"</span>,
temp_voltage_2,temp_voltage_1,ret_compensate_value,gFG_resistance_bat);
}

gFG_resistance_bat = fgauge_read_r_bat_by_v(temp_voltage_2);
ret_compensate_value = ( (ori_current) * (gFG_resistance_bat + R_FG_VALUE + FG_METER_RESISTANCE)) / <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1000</span>;
ret_compensate_value = (ret_compensate_value+(<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>/<span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">2</span>)) / <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>;

gFG_compensate_value = ret_compensate_value;

bm_print(BM_LOG_FULL, <span class="hljs-string" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(33, 145, 97); background: transparent;">"[mtk_imp_tracking] temp_voltage_2=%d,temp_voltage_1=%d,ret_compensate_value=%d,gFG_resistance_bat=%d\n"</span>,
temp_voltage_2,temp_voltage_1,ret_compensate_value,gFG_resistance_bat);

<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">return</span> ret_compensate_value;
}

mtk_imp_tracking函数主要是在for循环实现逼近。首先通过闭路电压vol_bat去查表得到电池的内阻gFG_resistance_bat，然后通过U=I*R来算出内阻分去的电压ret_compensate_value，这里要注意的是调用mtk_imp_tracking函数时第二个参数传递的参数为oam_i_2，为oam_i_2的单位为0.1mA，所以这里算出来的内阻分去的电压值ret_compensate_value的单位为0.1mV。然后利用闭路电压加上内阻分去的电压值来获取开路电压。这里求开路电压不是一次进行一次直接求出，而是通过for循环进行5次逼近，这样反复就能更真实的逼近电池的开路电压。这里还需注意两点，首先是这条语句ret_compensate_value
= (ret_compensate_value+(10/2)) / 10;因为ret_compensate_value为int型变量，而int型变量在进行整除的时候往往小数点后面的会被去掉，会引入较大误差，这里做的目的就是起到四舍五入的目的。另外一点需要注意的是R_FG_VALUE，R_FG_VALUE是指硬件FG使用的FG电阻（一般是20毫欧）这边是SW_FG所以为0。

oam_r_1 = fgauge_read_r_bat_by_v(oam_v_ocv_1);
oam_v_ocv_2 = fgauge_read_v_by_d(oam_d_2);
oam_r_2 = fgauge_read_r_bat_by_v(oam_v_ocv_2);

然后函数会根据之前读出来的oam_v_ocv_1和oam_d_2在去求出oam_r_1和oam_r_2这也是为下次积分做准备，因为系统每10s会调用这个函数。MTK为了增加用户的体验感，在D3的问题上针对电量跳变的情况 又做了步优化得到D5；

<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(d5_count >= d5_count_time)
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(gFG_Is_Charging == KAL_FALSE)
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>( oam_d_3 > oam_d_5 )
{
oam_d_5 = oam_d_5 + <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1</span>;
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">else</span>
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_4 > oam_d_5)
{
oam_d_5 = oam_d_5 + <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1</span>;
}
}
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">else</span>
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>( oam_d_5 > oam_d_3 )
{
oam_d_5 = oam_d_5 - <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1</span>;
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">else</span>
{
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">if</span>(oam_d_4 < oam_d_5)
{
oam_d_5 = oam_d_5 - <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">1</span>;
}
}
}
d5_count = <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">0</span>;
oam_d_3_pre = oam_d_3;
oam_d_4_pre = oam_d_4;
}
<span class="hljs-keyword" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(149, 65, 33); background: transparent;">else</span>
{
d5_count = d5_count + <span class="hljs-number" style="border: 0px; margin: 0px; padding: 0px; font-weight: inherit; font-style: inherit; font-family: inherit; vertical-align: baseline; color: rgb(64, 160, 112); background: transparent;">10</span>;
}

这部分代码比较简单，1分钟内电量值不会改变，且每分钟电量的变化不会大于1%，这样用户体验会比较好。防止因为低电压时陡峭的电量曲线，以及比较耗电的应用，或突然的大电流引起的电量跳变。当然特殊应用下应该取消这个功能，否则会带来电量变化延时等问题。