WiFi on Android

Take the following blog information as a Referrence:

Http://blog.csdn.net/hongjiujing/archive/2010/05/07/5565431.aspx

 

 

Android WiFi state: Disabled, disabling, enabled, enabling, unknown.

 

1. Porting WiFi driver on Android

--> # Create filesystem for WiFi & DHCP (add this in the init. RC file)

++

Mkdir/data/MISC/WiFi 0771 WiFi system

Chown WiFi system/data/MISC/WiFi

Chmod 0771/data/MISC/WiFi

 

Mkdir/data/MISC/WiFi/sockets 0771 WiFi system

Chown WiFi system/data/MISC/WiFi/sockets

Chmod 07771/data/MISC/WiFi/sockets

Mkdir/data/MISC/DHCP 0770 DHCP

Chown DHCP/data/MISC/DHCP

Chmod 0770/data/MISC/DHCP

++

2. WPA and wpa2 implement

--> Init. RC configuration

++

Mkdir/data/system/wpa_supplicant 0771 WiFi system

Chown WiFi system/data/system/wpa_supplicant

Chmod 0771/data/eth0

Setprop wifi. Interface mlan0

 

Service wpa_supplicant/system/bin/wpa_supplicant-dwext-imlan0-C/data/MISC/WiFi/wpa_supplicant.conf

User Root

Group system WiFi

Disabled

 

Service dhcpcd/system/bin/dhcpcd-BKL mlan0

Disabled

One shot

++

 

--> Useful tool: wpa_cli

--> Requirement: driver_wext.c expects the WiFi kernel driver to implement the siocsiwpriv ioctrl and respond to Android commands like Arg, macaddr, linkspeed and etc.

--> Implement: add the upper IOCTL to kernel WiFi driver. (In wlan_wext.c). The following is the detail implement source code.

Add the "board_wpa_supplicant_driver: = wext" in boardconfig. mk

 

++

/**
* @ Brief set priv command
*
* @ Param Dev a pointer to net_device Structure
* @ Param info a pointer to iw_request_info Structure
* @ Param dwrq a pointer to iw_point Structure
* @ Param extra a pointer to extra data Buf
*
* @ Return 0 -- success, otherwise fail
*/
Static int wlan_set_priv (struct net_device * Dev, struct iw_request_info * info,
Struct iw_point * dwrq, char * extra)
{
Int ret = 0;
Wlan_private * priv = (wlan_private *) netdev_priv (Dev );
Char * Buf = NULL;
Int Len = 0;
Int EAP = 0;
Bssdescriptor_t * pbssdesc = NULL;

Enter ();
If (! (BUF = kmalloc (dwrq-> length, gfp_kernel ))){
Ret =-enomem;
Goto done;
}
If (copy_from_user (BUF, dwrq-> pointer, dwrq-> length )){
Ret =-efault;
Goto done;
}
Printm (Cmnd, "siocsiwpriv requst = % s/n", Buf );
If (strncmp (BUF, "reported", strlen ("reported") = 0 ){
If (priv-> adapter-> mediaconnectstatus = wlanmediastateconnected ){
If (wlan_prepare_cmd (priv,
Host1__assist_rssi_info,
Host1__act_gen_get, host1__option_waitforrsp,
0, null )){
Ret =-efault;
Goto done;
}
Http: // service.ap-southeast-1.maxcompute.aliyun-inc.com/api;
Pbssdesc = & priv-> adapter-> curbssparams. bssdescriptor;
Len = sprintf (BUF, "% s Arg % d/N", pbssdesc-> SSID. SSID, ARG) + 1;
}
}
Else if (strncmp (BUF, "linkspeed", strlen ("linkspeed") = 0 ){
If (wlan_prepare_cmd (priv, host1__802_11_tx_rate_query,
Host1__act_gen_get, host1__option_waitforrsp,
0, null )){
Ret =-efault;
Goto done;
}
Printm (Cmnd, "TX rate = % d/N", (INT) priv-> adapter-> txrate );
Len = sprintf (BUF, "linkspeed % d/N", (INT) (index_to_data_rate (priv-> adapter-> txrate) * 500000/1000000) + 1;
}
Else if (strncmp (BUF, "macaddr", strlen ("macaddr") = 0 ){
Len = sprintf (BUF, "macaddr = % 02x: % 02x: % 02x: % 02x: % 02x: % 02x/N ", priv-> adapter-> currentaddr [0],
Priv-> adapter-> currentaddr [1], priv-> adapter-> currentaddr [2], priv-> adapter-> currentaddr [3],
Priv-> adapter-> currentaddr [4], priv-> adapter-> currentaddr [5]);
}
Else {
Len = sprintf (BUF, "OK/N") + 1;
Printm (warn, "unknow private command: % s, ignored/N", Buf );
}
Printm (Cmnd, "priv command return: % s, length = % d/N", Buf, Len );
Dwrq-> length = Len;
If (copy_to_user (dwrq-> pointer, Buf, dwrq-> length )){
Ret =-efault;
}
Done:
If (BUF)
Kfree (BUF );
Leave ();
Return ret;
}

 

(Iw_handler) wlan_set_priv,/* siocsiwpriv */

++

 

3. WiFi Service

--> Android/frameworks/base/services/Java/COM/Android/Server/wifiservice. Java

 

4. WiFi Power Management

--> Take the following webpage for a reference

Http://www.cnmsdn.com/html/201003/1268408234ID1814.html

 

5. Problem:

--> After successfully connect to AP with wpa2 encryption, then disconnect with this AP, and reconnect with it, then it can not connect with this AP successfully.

Workaroud: Turn off the WiFi and then turn on it.