Android Wifi software layers

root

　　//based on Android2.3 QCom MSM7227A AR6003-v806 source.
　　learning by wifi sta enabling
　　Load driver:

• com.android.server.WifiService.setWifiEnabled(true)
  
• android.net.wifi.WifiStateTracker.loadDriver()
  
• hardware/libhardware_legacy/wifi/wifi.c: wifi_load_driver()
  
  
  
  • start init service "init.svc.wlan_tool" with parameter "load" to load driver
    
  • check value of  property wlan.driver.status to make sure driver is loaded
    
  
  
• check /init.rc. service wlan_tool: /system/bin/wlan_tool :system/wlan/atheros/AR6kSDK.build_3.1_RC.806/host/tools/wlan_tool/wlan_tool. it is a linux shell script
  
  
  
  • it is a onshot service
    
  • loaddriver():reload():do_insmod():insmod /system/wifi/ar6000.ko
    
  
  

　　Start supplicant:

• see "Load driver" step 1
  
• see "Load driver" step 2
  
• see "Load driver" step 3
  
• check /init.rc. service "wpa_supplicant" : /system/bin/wpa_supplicant -Dwext -iwlan0 -c/data/misc/wifi/wpa_supplicant.conf
  
  
  
  • wpa_supplicant now running.
    
  
  

　　Connect to wpa_supplicant and monitor wifi states:

• android.net.wifi.WifiStateTracker.startEventLoop()
  
• android.net.wifi.WifiMonitor.MonitorThread.run()
  
• MonitorThread.connectToSupplicant()
  
  
  
  • hardware/libhardware_legacy/wifi/wifi.c:wifi_connect_to_supplicant():wpa_ctrl_open()
    
  
  
• MonitorThread.handleSupplicantStateChange():MonitorThread.handleDriverEvent()
  
• if driver state change to "STARTED", start scan:andorid.net.wifi.WifiStateTracker.scan()
  

　　Scan AP:

• andorid.net.wifi.WifiStateTracker.scan()
  
• android.net.wifi.WifiStateTracker.android_net_wifi_scanCommand():
  
  
  
  • doCommand("DRIVER SCAN-ACTIVE");
    
  • doCommand("SCAN")
    
  
  
• hardware/libhardware_legacy/wifi/wifi.c:wifi_send_command()
  
  
  
  • wpa_ctrl_request