基於Qualcom 8960/8921平台
一，軟件分析
1. USB charger types & Power supply types
USB_INVALID_CHARGER Invalid USB charger.
USB_SDP_CHARGER Standard downstream port. Refers to a downstream port on USB2.0 compliant host/hub.
USB_DCP_CHARGER Dedicated charger port (AC charger/ Wall charger).
USB_CDP_CHARGER Charging downstream port. Enumeration can happen and IDEV_CHG_MAX can be drawn irrespective of USB state.
USB_ACA_A_CHARGER B-device is connected on accessory port with charger connected on charging port. This configuration allows charging in host mode.
USB_ACA_B_CHARGER No device (or A-device without VBUS) is connected on accessory port with charger connected on charging port.
USB_ACA_C_CHARGER A-device (with VBUS) is connected on accessory port with charger connected on charging port.
USB_ACA_DOCK_CHARGER A docking station that has one upstream port and one or more downstream ports. Capable of supplying IDEV_CHG_MAX irrespective of devices connected on
accessory ports.
USB_PROPRIETARY_CHARGER A proprietary charger pull DP and DM to specific voltages between 2.0-3.3v for identification.
POWER_SUPPLY_TYPE_USB, /* Standard Downstream Port */
POWER_SUPPLY_TYPE_USB_DCP, /* Dedicated Charging Port */
POWER_SUPPLY_TYPE_USB_CDP, /* Charging Downstream Port */
POWER_SUPPLY_TYPE_USB_ACA, /* Accessory Charger Adapters */
POWER_SUPPLY_TYPE_BMS, /* Battery Monitor System */
2. How to classify or identify charger?
USB_SDP_CHARGER |
POWER_SUPPLY_TYPE_USB |
USB Charger |
USB_CDP_CHARGER |
POWER_SUPPLY_TYPE_USB_CDP |
|
USB_ACA_DOCK_CHARGER |
POWER_SUPPLY_TYPE_USB_ACA |
|
USB_ACA_A_CHARGER |
||
USB_ACA_B_CHARGER |
||
USB_ACA_C_CHARGER |
||
USB_DCP_CHARGER |
POWER_SUPPLY_TYPE_USB_DCP |
AC Charger |
USB_PROPRIETARY_CHARGER |
As for the DMS, refer to bold font items, so it is USB charger.
3. Analysis about source codes
*******************************************************************
###用戶空間的分析如下：
1. 檢查 /sys/class/power_supply/pm8921-dc/online和 /sys/class/power_supply/usb/online 的值,可以知道是何充電器類型
@frameworks/base/services/jni/com_android_server_batteryservice.cpp中有
int register_android_server_BatteryService(JNIEnv* env)
｛
if (strcmp(buf, "Mains") == 0) { ///sys/class/power_supply/pm8921-dc/type == Mains
snprintf(path, sizeof(path), "%s/%s/online", POWER_SUPPLY_PATH, name);
if (access(path, R_OK) == 0)
gPaths.acOnlinePath = strdup(path);
}
｝
如果/sys/class/power_supply/pm8921-dc/online==1,則插入的充電器是wall
charger
/sys/class/power_supply/usb/online==1, 則插入的充電器是usb charger
調試路徑：/sys/kernel/debug/msm_otg
2. 分析frameworks/base/services/jni/com_android_server_batteryservice.cpp
a.函數register_android_server_BatteryService將為被frameworks/base/services/jni/onload.cpp中的JNI_OnLoad調用，用於關聯java和C++之間的變量
b.jclass clazz = env->FindClass("com/android/server/BatteryService"); //根據java的路徑找到batteryservice.java對應的jclass
gFieldIds.mAcOnline = env->GetFieldID(clazz, "mAcOnline", "Z");
gFieldIds.mUsbOnline = env->GetFieldID(clazz, "mUsbOnline", "Z"); //用於關聯batteryservice.java中變量private
boolean mAcOnline和gFieldIds.mAcOnline
c. android_server_BatteryService_update
static JNINativeMethod sMethods[] = {
/* name, signature, funcPtr */
{"native_update", "()V", (void*)android_server_BatteryService_update},
};
關聯到native_update@frameworks/base/services/java/com/android/server/batteryservice.java
3. 分析frameworks/base/services/java/com/android/server/batteryservice.java
a. mPowerSupplyObserver.startObserving("SUBSYSTEM=power_supply"); //注冊監聽該uevent
b. private UEventObserver mPowerSupplyObserver = new UEventObserver() {
public void onUEvent(UEventObserver.UEvent event) { //如果就收到來自kernel的uevent,觸發該函數
update(); //-->native_update();和processValues();
}
};
c. native_update函數會通過JNI調用得到更新的mAcOnline和mUsbOnline值
d. processValues會根據mAcOnline和mUsbOnline值對mPlugType賦值
if (mAcOnline) {
mPlugType = BatteryManager.BATTERY_PLUGGED_AC;
} else if (mUsbOnline) {
mPlugType = BatteryManager.BATTERY_PLUGGED_USB;
} else {
mPlugType = BATTERY_PLUGGED_NONE;
}
e. sendIntent函數會准備Intent並且broadcast這個Intent
Intent intent = new Intent(Intent.ACTION_BATTERY_CHANGED); //public static final String ACTION_BATTERY_CHANGED = "android.intent.action.BATTERY_CHANGED";@batteryservice.java
intent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY
| Intent.FLAG_RECEIVER_REPLACE_PENDING);
intent.putExtra(BatteryManager.EXTRA_PLUGGED, mPlugType);
ActivityManagerNative.broadcastStickyIntent(intent, null);
4. 分析vendor/semc/packages/apps/debugmenu/src/com/sonyericsson/debugmenu/battery.java
a. 接收intent
private BroadcastReceiver mBatteryInfoReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context arg0, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)) {
mPowerInformation.parseIntent(intent);
updateViews();
}
}
};
public void registerBroadcastReceivers() {
IntentFilter mIntentFilter;
mIntentFilter = new IntentFilter();
mIntentFilter.addAction(Intent.ACTION_BATTERY_CHANGED); //只接收Intent.ACTION_BATTERY_CHANGED的intent
// Register battery receiver.
registerReceiver(mBatteryInfoReceiver, mIntentFilter);
}
b. parseIntent 得到最新的"plugged"值賦給mPlugged
c. updateViews 更新charger類型顯示
###內核空間
1. 插入充電器觸發的過程@kernel/drivers/usb/otg/msm_otg.c
a. CONFIG_PM_RUNTIME 定義 @kernel/arch/arm/configs/viskan_huashan_defconfig
b.msm_otg_runtime_resume-->msm_otg_resume-->??-->msm_otg_sm_work
c.msm_otg_sm_work,先進入OTG_STATE_UNDEFINED case，然后進入OTG_STATE_B_IDLE
case-->motg->chg_state=USB_CHG_STATE_UNDEFINED-->啟動msm_chg_detect_work
d.msm_chg_detect_work 該函數主要完成USB charger類型的識別
USB_CHG_STATE_UNDEFINED //其中psy = power_supply_get_by_name("usb");很關鍵，表明只是獲取usb的power_supply,實際上就是chip->usb_psy@pm8921-charger.c
USB_CHG_STATE_WAIT_FOR_DCD //Waiting for Data pins contact.
然后多次(MSM_CHG_DCD_MAX_RETRIES=6)檢測USB狀態，啟動queue_delayed_work(motg->wq,
&motg->chg_work, delay); //motg->chg_work=msm_chg_detect_work
USB_CHG_STATE_DETECTED //最后USB charge類型檢測完畢
e. 啟動queue_work(motg->wq, &motg->sm_work); //motg->sm_work=msm_otg_sm_work
f. 由於motg->chg_state==USB_CHG_STATE_DETECTED,
motg->chg_type==USB_DCP_CHARGER -->msm_otg_notify_charger(motg,IDEV_CHG_MAX);//IDEV_CHG_MAX=1500
2. 發送uevent到用戶層
a. msm_otg_notify_charger@kernel/drivers/usb/otg/msm_otg.c
b. -->msm_otg_notify_chg_type@msm_otg.c,該函數中充電類型只歸納成4種：POWER_SUPPLY_TYPE_USB,POWER_SUPPLY_TYPE_USB_CDP,POWER_SUPPLY_TYPE_USB_DCP,POWER_SUPPLY_TYPE_USB_ACA,POWER_SUPPLY_TYPE_BATTERY
c. -->power_supply_set_supply_type@power_supply_core.c // set type of
the power supply
d. -->psy->set_property(psy, POWER_SUPPLY_PROP_TYPE,&ret);
那么在用usb_psy.get_property和dc_psy.get_property
(在函數中pm8921_charger_probe)讀取property時
如果是USB type,則在pm_power_get_property_usb讀取POWER_SUPPLY_PROP_ONLINE的值,其中POWER_SUPPLY_TYPE_USB，POWER_SUPPLY_TYPE_USB_CDP和POWER_SUPPLY_TYPE_USB_ACA都被歸納成USB
charger
如果是AC type,則在pm_power_get_property_mains讀取POWER_SUPPLY_PROP_ONLINE的值，只有POWER_SUPPLY_TYPE_USB_DCP為AC
charger.
e. psy=chip->usb_psy@pm8921-charger.c,所以繼續調用的是pm_power_set_property_usb@pm8921-charger.c
f. -->pm8921_set_usb_power_supply_type(val->intval)@pm8921-charger.c
-->power_supply_changed(&the_chip->usb_psy);
-->power_supply_changed(&the_chip->dc_psy);
g. power_supply_changed@pm8921-charger.c , 就會馬上發送uevent給user
space,然后user space通過sysfs得到USB
type變化后的信息，參考用戶空間的分析
二、硬件分析
主要是通過特殊設計的電路，檢測不同的pin的狀態，從而確定是何種類型的Charger. 更details的內容省略。