USB port 如何识别不同的Charger类型

tianpu0501 · 发表于 2015-9-11 22:40

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USB port 如何识别不同的Charger类型
2013年10月03日 ⁄ 综合 ⁄ 共 8924字 ⁄ 字号 [url=]小[/url] [url=]中[/url] [url=]大[/url] ⁄ 评论关闭

一，软件分析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 : v1 Y8 a# F8 u2 {# m8 `7 N2 p	POWER_SUPPLY_TYPE_USB % g& g7 _; r) [5 t. e2 a) Z! b	USB Charger
USB_CDP_CHARGER' i9 K" @ U, ^5 x6 f	POWER_SUPPLY_TYPE_USB_CDP ) \; I" n5 b* G
USB_ACA_DOCK_CHARGER 3 \|; i \, _% L3 a( \|6 b/ F u	POWER_SUPPLY_TYPE_USB_ACA
USB_ACA_A_CHARGER - V& X1 m: f$ n A+ n# G
USB_ACA_B_CHARGER 7 i. [ p7 X( T# ^% [
USB_ACA_C_CHARGER & M2 X# _0 U) c$ j, V# F+ H
USB_DCP_CHARGER 5 M s) i( s( d# \	POWER_SUPPLY_TYPE_USB_DCP	AC Charger
USB_PROPRIETARY_CHARGER ) u' X, K% M. ^7 J; t1 L7 k	POWER_SUPPLY_TYPE_USB_DCP	AC Charger

As for the DMS, refer to bold font items, so it is USB charger.

3. Analysis about source codes
*******************************************************************
###用户空间的分析如下：
1. 检查 /sys/class/power_supply/pm8921-dc/online和
/sys/class/power_supply/usb/online 的值,可以知道是何充电器类型
            @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,则插入的充电器是wall
6 b( Z" Q! j. I4 k9 s# }charger
   /sys/class/power_supply/usb/online==1, & I( V5 q# H' l1 A; Q
则插入的充电器是usb charger
调试路径：/sys/kernel/debug/msm_otg
2. 分析frameworks/base/services/jni/com_android_server_batteryservice.cpp
            a.函数register_android_server_BatteryService将为被frameworks/base/services/jni/onload.cpp中的JNI_OnLoad调用，用于关联java和C++之间的变量
            b.jclass clazz = env->FindClass("com/android/server/BatteryService"); //根据java的路径找到batteryservice.java对应的jclass
               gFieldIds.mAcOnline = env->GetFieldID(clazz, "mAcOnline", "Z");
               gFieldIds.mUsbOnline = env->GetFieldID(clazz, "mUsbOnline", "Z"); //用于关联batteryservice.java中变量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},
                              };
               关联到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"); //注册监听该uevent
            b.    private UEventObserver mPowerSupplyObserver = new UEventObserver() {
                              public void onUEvent(UEventObserver.UEvent event) { //如果就收到来自kernel的uevent,触发该函数
                                 update(); //-->native_update();和processValues();
                              }
                     };
            c. native_update函数会通过JNI调用得到更新的mAcOnline和mUsbOnline值
            d. processValues会根据mAcOnline和mUsbOnline值对mPlugType赋值
                              if (mAcOnline) {
                                 mPlugType = BatteryManager.BATTERY_PLUGGED_AC;
                              } else if (mUsbOnline) {
                                 mPlugType = BatteryManager.BATTERY_PLUGGED_USB;
                              } else {
                                 mPlugType = BATTERY_PLUGGED_NONE;
                              }
            e. sendIntent函数会准备Intent并且broadcast这个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"值赋给mPlugged
            c. updateViews 更新charger类型显示
###内核空间
1. 插入充电器触发的过程@kernel/drivers/usb/otg/msm_otg.c
            a. CONFIG_PM_RUNTIME 定义 @kernel/arch/arm/configs/viskan_huashan_defconfig
            b.msm_otg_runtime_resume-->msm_otg_resume-->??-->msm_otg_sm_work
            c.msm_otg_sm_work,先进入OTG_STATE_UNDEFINED case，然后进入OTG_STATE_B_IDLE
case-->motg->chg_state=USB_CHG_STATE_UNDEFINED-->启动msm_chg_detect_work
            d.msm_chg_detect_work 该函数主要完成USB charger类型的识别
                              USB_CHG_STATE_UNDEFINED //其中psy = power_supply_get_by_name("usb");很关键，表明只是获取usb的power_supply,实际上就是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)检测USB状态，启动queue_delayed_work(motg->wq,
&motg->chg_work, delay); //motg->chg_work=msm_chg_detect_work
                              USB_CHG_STATE_DETECTED //最后USB charge类型检测完毕
            e. 启动queue_work(motg->wq, &motg->sm_work); //motg->sm_work=msm_otg_sm_work
            f. 由于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. 发送uevent到用户层
            a. msm_otg_notify_charger@kernel/drivers/usb/otg/msm_otg.c
            b. -->msm_otg_notify_chg_type@msm_otg.c,该函数中充电类型只归纳成4种：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
(在函数中pm8921_charger_probe)读取property时
                              如果是USB type,则在pm_power_get_property_usb读取POWER_SUPPLY_PROP_ONLINE的值,其中POWER_SUPPLY_TYPE_USB，POWER_SUPPLY_TYPE_USB_CDP和POWER_SUPPLY_TYPE_USB_ACA都被归纳成USB
charger
                              如果是AC type,则在pm_power_get_property_mains读取POWER_SUPPLY_PROP_ONLINE的值，只有POWER_SUPPLY_TYPE_USB_DCP为AC
charger.
            e. psy=chip->[url=http://www.16rd.com/mailto:usb_psy@pm8921-charger.c,%E6%89%80%E4%BB%A5%E7%BB%A7%E7%BB%AD%E8%B0%83%E7%94%A8%E7%9A%84%E6%98%AFpm_power_set_property_usb@pm8921-charger.c]usb_psy@pm8921-charger.c,所以继续调用的是[/url]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 , 就会马上发送uevent给user
space,然后user space通过sysfs得到USB
type变化后的信息，参考用户空间的分析

二、硬件分析

主要是通过特殊设计的电路，检测不同的pin的状态，从而确定是何种类型的Charger. 更details的内容省略。