Android P在wifi这块改动挺大的,Wifi到AndoidO之后不再使用jni,所以AndroidP也一样不再使用jni来实现Java代码与本地的C/C++代码交互,而是使用HIDL,Hardware Interface Define Language。摒弃了以前的hardware/libhardware_legacy/wifi/wifi.c作为底层接口,所以得重新梳理下整个wifi流程。
点击Wifi开关到Android的Java框架层,可以参考这个Wifi模块—源码分析Wifi启动1(Android P)
这里只记录下 HIDL—WPA适配层—wpa_supplicant—linux kernel
1.Java框架层
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java
/**
* Setup an interface for Client mode operations.
*
* * This method configures an interface in STA mode in all the native daemons
* (wificond, wpa_supplicant & vendor HAL).
*
* @param lowPrioritySta The requested STA has a low request priority (lower probability of
* getting created, higher probability of getting destroyed).
* @param interfaceCallback Associated callback for notifying status changes for the iface.
* @return Returns the name of the allocated interface, will be null on failure.
*/
public String setupInterfaceForClientMode(boolean lowPrioritySta,
@NonNull InterfaceCallback interfaceCallback) {
synchronized (mLock) {
if (!startHal()) {
Log.e(TAG, "Failed to start Hal");
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToHal();
return null;
}
if (!startSupplicant()) {
Log.e(TAG, "Failed to start supplicant");
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToSupplicant();
return null;
}
Iface iface = mIfaceMgr.allocateIface(Iface.IFACE_TYPE_STA);
if (iface == null) {
Log.e(TAG, "Failed to allocate new STA iface");
return null;
}
iface.externalListener = interfaceCallback;
iface.name = createStaIface(iface, lowPrioritySta);
if (TextUtils.isEmpty(iface.name)) {
Log.e(TAG, "Failed to create STA iface in vendor HAL");
mIfaceMgr.removeIface(iface.id);
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToHal();
return null;
}
if (mWificondControl.setupInterfaceForClientMode(iface.name) == null) {
Log.e(TAG, "Failed to setup iface in wificond on " + iface);
teardownInterface(iface.name);
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToWificond();
return null;
}
if (!mSupplicantStaIfaceHal.setupIface(iface.name)) {
Log.e(TAG, "Failed to setup iface in supplicant on " + iface);
teardownInterface(iface.name);
mWifiMetrics.incrementNumSetupClientInterfaceFailureDueToSupplicant();
return null;
}
iface.networkObserver = new NetworkObserverInternal(iface.id);
if (!registerNetworkObserver(iface.networkObserver)) {
Log.e(TAG, "Failed to register network observer on " + iface);
teardownInterface(iface.name);
return null;
}
mWifiMonitor.startMonitoring(iface.name);
// Just to avoid any race conditions with interface state change callbacks,
// update the interface state before we exit.
onInterfaceStateChanged(iface, isInterfaceUp(iface.name));
initializeNwParamsForClientInterface(iface.name);
Log.i(TAG, "Successfully setup " + iface);
return iface.name;
}
}
看一些关键性的操作:
启动Hal:startHal()
启动supplicant:startSupplicant()
先分析startHAL
/** Helper method invoked to start supplicant if there were no ifaces */
private boolean startHal() {
synchronized (mLock) {
if (!mIfaceMgr.hasAnyIface()) {
if (mWifiVendorHal.isVendorHalSupported()) {
if (!mWifiVendorHal.startVendorHal()) {
Log.e(TAG, "Failed to start vendor HAL");
return false;
}
} else {
Log.i(TAG, "Vendor Hal not supported, ignoring start.");
}
}
return true;
}
}
看mWifiVendorHal.startVendorHal()
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiVendorHal.java
/**
* Bring up the HIDL Vendor HAL.
* @return true on success, false otherwise.
*/
public boolean startVendorHal() {
synchronized (sLock) {
if (!mHalDeviceManager.start()) {
mLog.err("Failed to start vendor HAL").flush();
return false;
}
mLog.info("Vendor Hal started successfully").flush();
return true;
}
}
看mHalDeviceaManager.start()
frameworks/opt/net/wifi/service/java/com/android/server/wifi/HalDeviceManager.java
/**
* Attempts to start Wi-Fi (using HIDL). Returns the success (true) or failure (false) or
* the start operation. Will also dispatch any registered ManagerStatusCallback.onStart() on
* success.
*
* Note: direct call to HIDL.
*/
public boolean start() {
return startWifi();
}
继续看startWifi()
private boolean startWifi() {
if (VDBG) Log.d(TAG, "startWifi");
synchronized (mLock) {
try {
if (mWifi == null) {
Log.w(TAG, "startWifi called but mWifi is null!?");
return false;
} else {
int triedCount = 0;
while (triedCount <= START_HAL_RETRY_TIMES) {
WifiStatus status = mWifi.start();
if (status.code == WifiStatusCode.SUCCESS) {
initIWifiChipDebugListeners();
managerStatusListenerDispatch();
if (triedCount != 0) {
Log.d(TAG, "start IWifi succeeded after trying "
+ triedCount + " times");
}
return true;
} else if (status.code == WifiStatusCode.ERROR_NOT_AVAILABLE) {
// Should retry. Hal might still be stopping.
Log.e(TAG, "Cannot start IWifi: " + statusString(status)
+ ", Retrying...");
try {
Thread.sleep(START_HAL_RETRY_INTERVAL_MS);
} catch (InterruptedException ignore) {
// no-op
}
triedCount++;
} else {
// Should not retry on other failures.
Log.e(TAG, "Cannot start IWifi: " + statusString(status));
return false;
}
}
Log.e(TAG, "Cannot start IWifi after trying " + triedCount + " times");
return false;
}
} catch (RemoteException e) {
Log.e(TAG, "startWifi exception: " + e);
return false;
}
}
}
主要看WifiStatus status = mWifi.start(),先看下mWifi是什么
import android.hardware.wifi.V1_0.IWifi;
private IWifi mWifi;
/**
* Wrapper function to access the HIDL services. Created to be mockable in unit-tests.
*/
protected IWifi getWifiServiceMockable() {
try {
return IWifi.getService();
} catch (RemoteException e) {
Log.e(TAG, "Exception getting IWifi service: " + e);
return null;
}
}
IWifi的定义就需要用到HIDL
2.HIDL
HIDL 读作 hide-l,Wifi到Andoid O之后所以Android P也一样不再使用jni,而是使用HIDL,Hardware Interface Define Language。
2.1 hardware/interfaces/wifi/1.0/IWifi.hal
/**
* Perform any setup that is required to make use of the module. If the module
* is already started then this must be a noop.
* Must trigger |IWifiEventCallback.onStart| on success.
*
* @return status WifiStatus of the operation.
* Possible status codes:
* |WifiStatusCode.SUCCESS|,
* |WifiStatusCode.NOT_AVAILABLE|,
* |WifiStatusCode.UNKNOWN|
*/
@entry
@callflow(next={"registerEventCallback", "start", "stop", "getChip"})
start() generates (WifiStatus status);
系统编译的时候会自动产生IWifi.java文件。
out/soong/.intermediates/hardware/interfaces/wifi/1.0/android.hardware.wifi_V1.0-java_gen_java/gen/android/hardware/wifi/V1_0/IWifi.java
IWifi.java的getService方法
public static IWifi getService(String serviceName) throws android.os.RemoteException {
return IWifi.asInterface(android.os.HwBinder.getService("[email protected]::IWifi",serviceName));
}
再看一下 IWifi.java的asInterface方法
IWifi.asInterface(android.os.HwBinder.getService("[email protected]::IWifi",serviceName));
从而我们就可以知道IWifi对应的服务端了
2.2 在hardware/interfaces/wifi/有三个版本,分别是1.0 /1.1 /1.2,使用哪个版本是可以设置的,wpa_supplicant和hostapd同理
device/fsl/imx8m/evk_8mq/manifest.xml
android.hardware.wifi
hwbinder
1.2
IWifi
default
android.hardware.wifi.supplicant
hwbinder
1.1
ISupplicant
default
android.hardware.wifi.hostapd
hwbinder
1.0
IHostapd
default
hardware/interfaces/wifi/1.2/default/wifi.cpp
Return Wifi::start(start_cb hidl_status_cb) {
return validateAndCall(this, WifiStatusCode::ERROR_UNKNOWN,
&Wifi::startInternal, hidl_status_cb);
}
看startInternal()
WifiStatus Wifi::startInternal() {
if (run_state_ == RunState::STARTED) {
return createWifiStatus(WifiStatusCode::SUCCESS);
} else if (run_state_ == RunState::STOPPING) {
return createWifiStatus(WifiStatusCode::ERROR_NOT_AVAILABLE,
"HAL is stopping");
}
WifiStatus wifi_status = initializeModeControllerAndLegacyHal();
if (wifi_status.code == WifiStatusCode::SUCCESS) {
// Create the chip instance once the HAL is started.
chip_ = new WifiChip(kChipId, legacy_hal_, mode_controller_,
feature_flags_);
run_state_ = RunState::STARTED;
for (const auto& callback : event_cb_handler_.getCallbacks()) {
if (!callback->onStart().isOk()) {
LOG(ERROR) << "Failed to invoke onStart callback";
};
}
LOG(INFO) << "Wifi HAL started";
} else {
for (const auto& callback : event_cb_handler_.getCallbacks()) {
if (!callback->onFailure(wifi_status).isOk()) {
LOG(ERROR) << "Failed to invoke onFailure callback";
}
}
LOG(ERROR) << "Wifi HAL start failed";
}
return wifi_status;
}
WifiStatus Wifi::initializeModeControllerAndLegacyHal() {
if (!mode_controller_->initialize()) {
LOG(ERROR) << "Failed to initialize firmware mode controller";
return createWifiStatus(WifiStatusCode::ERROR_UNKNOWN);
}
legacy_hal::wifi_error legacy_status = legacy_hal_->initialize();
if (legacy_status != legacy_hal::WIFI_SUCCESS) {
LOG(ERROR) << "Failed to initialize legacy HAL: "
<< legacyErrorToString(legacy_status);
return createWifiStatusFromLegacyError(legacy_status);
}
return createWifiStatus(WifiStatusCode::SUCCESS);
}
接着看wifi_mode_controller.cpp得initialize()方法
2.3 hardware/interfaces/wifi/1.2/default/wifi_mode_controller.cpp
bool WifiModeController::initialize() {
if (!driver_tool_->LoadDriver()) {
LOG(ERROR) << "Failed to load WiFi driver";
return false;
}
return true;
}
再继续看driver_tool.cpp这里开始走到WPA适配层了
HAL 可定义一个标准接口以供硬件供应商实现,这可让 Android 忽略较低级别的驱动程序实现。借助 HAL,可以顺利实现相关功能,而不会影响或更改更高级别的系统。HAL 实现会被封装成模块,并由 Android 系统适时地加载。
wpa_supplicant适配层是通用的wpa_supplicant的封装,在Android中作为WiFi部分的硬件抽象层来使用。wpa_supplicant适配层主要用于与wpa_supplicant守护进程的通信,以提供给Android框架使用,它实现了加载、控制和消息监控等功能。
3.1frameworks/opt/net/wifi/libwifi_hal/driver_tool.cpp
bool DriverTool::LoadDriver() {
return ::wifi_load_driver() == 0;
}
2.2 frameworks/opt/net/wifi/libwifi_hal/wifi_hal_common.cpp
int wifi_load_driver() {
#ifdef WIFI_DRIVER_MODULE_PATH
if (is_wifi_driver_loaded()) {
return 0;
}
if (insmod(DRIVER_MODULE_PATH, DRIVER_MODULE_ARG) < 0) return -1;
#endif
#ifdef WIFI_DRIVER_STATE_CTRL_PARAM
if (is_wifi_driver_loaded()) {
return 0;
}
if (wifi_change_driver_state(WIFI_DRIVER_STATE_ON) < 0) return -1;
#endif
property_set(DRIVER_PROP_NAME, "ok");
return 0;
}
到这里Wifi驱动就加载完成了
现在回到文章的最开始分析完了startHal(),接下来就该分析startSupplicant()
4.1 frameworks/opt/net/wifi/service/java/com/android/server/wifi/WifiNative.java
/** Helper method invoked to start supplicant if there were no STA ifaces */
private boolean startSupplicant() {
synchronized (mLock) {
if (!mIfaceMgr.hasAnyStaIface()) {
if (!mWificondControl.enableSupplicant()) {
Log.e(TAG, "Failed to enable supplicant");
return false;
}
if (!waitForSupplicantConnection()) {
Log.e(TAG, "Failed to connect to supplicant");
return false;
}
if (!mSupplicantStaIfaceHal.registerDeathHandler(
new SupplicantDeathHandlerInternal())) {
Log.e(TAG, "Failed to register supplicant death handler");
return false;
}
}
return true;
}
}
看mWificondControl.enableSupplicant()
frameworks/opt/net/wifi/service/java/com/android/server/wifi/WificondControl.java
/**
* Enable wpa_supplicant via wificond.
* @return Returns true on success.
*/
public boolean enableSupplicant() {
if (!retrieveWificondAndRegisterForDeath()) {
return false;
}
try {
return mWificond.enableSupplicant();
} catch (RemoteException e) {
Log.e(TAG, "Failed to enable supplicant due to remote exception");
}
return false;
}
看 mWificond.enableSupplicant()
private IWificond mWificond;
import android.net.wifi.IWificond;
4.2 IWificond的方法
system/connectivity/wificond/server.cpp
Status Server::enableSupplicant(bool* success) {
*success = supplicant_manager_->StartSupplicant();
return Status::ok();
}
4.3 frameworks/opt/net/wifi/libwifi_system/supplicant_manager.cpp
bool SupplicantManager::StartSupplicant() {
char supp_status[PROPERTY_VALUE_MAX] = {'\0'};
int count = 200; /* wait at most 20 seconds for completion */
const prop_info* pi;
unsigned serial = 0;
/* Check whether already running */
if (property_get(kSupplicantInitProperty, supp_status, NULL) &&
strcmp(supp_status, "running") == 0) {
return true;
}
/*
* Get a reference to the status property, so we can distinguish
* the case where it goes stopped => running => stopped (i.e.,
* it start up, but fails right away) from the case in which
* it starts in the stopped state and never manages to start
* running at all.
*/
pi = __system_property_find(kSupplicantInitProperty);
if (pi != NULL) {
serial = __system_property_serial(pi);
}
property_set("ctl.start", kSupplicantServiceName);
sched_yield();
while (count-- > 0) {
if (pi == NULL) {
pi = __system_property_find(kSupplicantInitProperty);
}
if (pi != NULL) {
/*
* property serial updated means that init process is scheduled
* after we sched_yield, further property status checking is based on this
*/
if (__system_property_serial(pi) != serial) {
__system_property_read(pi, NULL, supp_status);
if (strcmp(supp_status, "running") == 0) {
return true;
} else if (strcmp(supp_status, "stopped") == 0) {
return false;
}
}
}
usleep(100000);
}
return false;
}
namespace {
const char kSupplicantInitProperty[] = "init.svc.wpa_supplicant";
const char kSupplicantServiceName[] = "wpa_supplicant";
} // namespace
以前wifi.c的start_supplicant就搬到这儿来了
到此wifi驱动已经加载,wpa_supplicant服务也已经启动了,wifi的启动流程也就分析完了