在 Android 2.2上移植了2个wifi模块，vt6656和rt2070，总结一下要点。

首先，将wifi linux驱动编译成模块，并将驱动（vntwusb.ko或rt3070sta.ko放到/system/lib/modules/中。

然后，做如下修改：

1。修改 init.rc：很多文章都有描述，但还是有些说明不清的地方，我先列出增加项，然后作些说明。

增加： mkdir /system/etc/wifi 0771 wifi wifi            chmod 0771 /system/etc/wifi            chmod 0660 /system/etc/wifi/wpa_supplicant.conf            chown wifi wifi /system/etc/wifi/wpa_supplicant.conf  ＃wifi的原始配置文件            # wpa_supplicant socket            mkdir /data/system/wpa_supplicant 0771 wifi wifi            chmod 0771 /data/system/wpa_supplicant  ＃放置wifi interface的地方            mkdir /data/misc/wifi 0771 wifi wifi           chmod 0771 /data/misc/wifi

          chmod 0660 /data/misc/wifi/wpa_supplicant.conf  ＃wifi的配置文件，将由wpa_supplicant根据实际配置写入该文件

          mkdir /data/misc/wifi/sockets 0777 wifi wifi  ＃与上层通过socket通信的路径            # Prepare for wifi            setprop wifi.interface ra0  ＃intreface名称设置，这在framework/base/wifi/java/android/net/wifi /WifiStateTracker.java中会用到，以处理dhcp。rt2070用ra0，而vt6656使用eth1。 这里0771对 目录权限的处理是为了所有用户能对下一级进行搜索，而红字特别提醒的权限配置，是因为/data/misc/wifi/sockets目录不仅为wifi拥有者服务，还因为通信的原因要和其他用户联系，要不然，将会出现Unable to open connection to supplicant on "/data/system/wpa_supplicant/ra0": Connection refused，或permission denied的错误。很多人干脆将上述所有的权限都设为0777，当然也行，但总觉得有些粗糙。 service的修改： service wpa_supplicant /system/bin/logwrapper /system/bin/wpa_supplicant /     -Dwext -ira0 -c/data/misc/wifi/wpa_supplicant.conf  #也可以用/system/etc/wifi/wpa_supplicant.conf代替     user root     group system wifi inet #    socket wpa_wlan0 dgram 660 wifi wifi   ＃屏蔽该项是因为这项是用于UDP连接的     disable     oneshot service dhcpcd /system/bin/logwrapper /system/bin/dhcpcd -d -B ra0     group system dhcp wifi     disabled     oneshot 2。修改system/etc/wifi/wpa_supplicant.conf （在源码中是修改external/wpa_supplicant/wpa_supplicant.conf）将ctrl_interface=wlan0改成ctrl_interface=DIR=/data/system/wpa_supplicant GROUP=wifi  ＃这个路径在wifi.c中用到。 3。修改system/etc/dhcpcd/dhcpcd.conf将其中的interface名称改成ra0 4。修改芯片厂商的配置 BoardConfig.mk。 例如，Freeescale 是在device/fsl/imx51_bbg/BoardConfig.mk，加入： HAVE_CUSTOM_WIFI_DRIVER_2 := true

BOARD_WPA_SUPPLICANT_DRIVER := WEXT 5。修改hardware/libhardware_legacy/wifi/wifi.c

已经定义的wifi驱动的路径我感到还是屏蔽为好，直接在wifi.c中修改不是更直观些。

ifndef WIFI_DRIVER_MODULE_PATH #define WIFI_DRIVER_MODULE_PATH         "/system/lib/modules/rt3070sta.ko" #endif #ifndef WIFI_DRIVER_MODULE_NAME #define WIFI_DRIVER_MODULE_NAME         "rt3070sta" #endif 在 文件中还可以看到其他一些信息，如IFACE_DIR[]           = "/data/system/wpa_supplicant"， 就是interface的安放的路径。MODULE_FILE[]         = "/proc/modules"，这是insmod安放module的路径。在调试时可以查询是否已经安装了模块，接口是否启动。 6。源码修改 修改 external/wpa_supplicant/wpa_ctrl.c: 找到chmod那行，将 chmod(ctrl->local.sun_path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);改成chmod(ctrl->local.sun_path, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH);  #增加权限这是为了防止出现ioctl 写message的错误。

修改 external/wpa_supplicant/driver_wext.c：这 是为了避免wpa_supplicant与 下层驱动 通讯时出现ioctl[SIOCSIWPRIV]错误，因为现在大部分wifi模块对 SIOCSIWPRIV命令不处理，而这个命令要用于侦测wifi强度RSSI的，比较简单的方法是在wifi驱动中增加个空函数。例如，对于 rt2070，有一个sta_ioctl.c，找到SIOCSIWPRIV，将其对应个空函数

static int handler_SIOCSIWPRIV(struct net_device *dev, struct iw_request_info *info,

                         union iwreq_data *wrqu, char *extra) {        return 0; } 不过，这样做就有些信息，如RSSI，MAC地址等就没法在上层显示了。比较好的方法如下： 在struct wpa_driver_wext_data 中增加     u8 ssid[32];     unsigned int ssid_len; 2个变量。将原来的wpa_driver_priv_driver_cmd函数改成如下函数（我从Porting wifi driver to Android抄来稍作修改）： static int wpa_driver_priv_driver_cmd(void *priv, char *cmd, char *buf, size_t buf_len) {     struct wpa_driver_wext_data *drv = priv;     int ret = -1;     wpa_printf(MSG_DEBUG, "AWEXT: %s %s", __func__, cmd);     if (os_strcasecmp(cmd, "start") == 0) {         wpa_printf(MSG_DEBUG,"Start command");         return (ret);     }     if (os_strcasecmp(cmd, "stop") == 0) {         wpa_printf(MSG_DEBUG,"Stop command");     }     else if (os_strcasecmp(cmd, "macaddr") == 0) {         struct ifreq ifr;         os_memset(&ifr, 0, sizeof(ifr));         os_strncpy(ifr.ifr_name, drv->ifname, IFNAMSIZ);         if (ioctl(drv->ioctl_sock, SIOCGIFHWADDR, &ifr) < 0) {             perror("ioctl[SIOCGIFHWADDR]");             ret = -1;         } else {             u8 *macaddr = (u8 *) ifr.ifr_hwaddr.sa_data;             ret = snprintf(buf, buf_len, "Macaddr = " MACSTR "/n",                            MAC2STR(macaddr));         }     }     else if (os_strcasecmp(cmd, "scan-passive") == 0) {         wpa_printf(MSG_DEBUG,"Scan Passive command");     }     else if (os_strcasecmp(cmd, "scan-active") == 0) {         wpa_printf(MSG_DEBUG,"Scan Active command");     }     else if (os_strcasecmp(cmd, "linkspeed") == 0) {         struct iwreq wrq;         unsigned int linkspeed;         os_strncpy(wrq.ifr_name, drv->ifname, IFNAMSIZ);         wpa_printf(MSG_DEBUG,"Link Speed command");         if (ioctl(drv->ioctl_sock, SIOCGIWRATE, &wrq) < 0) {             perror("ioctl[SIOCGIWRATE]");             ret = -1;         } else {             linkspeed = wrq.u.bitrate.value / 1000000;             ret = snprintf(buf, buf_len, "LinkSpeed %d/n", linkspeed);         }     }     else if (os_strncasecmp(cmd, "scan-channels", 13) == 0) {     }     else if ((os_strcasecmp(cmd, "rssi") == 0) || (os_strcasecmp(cmd, "rssi-approx") == 0)) {         struct iwreq wrq;         struct iw_statistics stats;         signed int rssi;         wpa_printf(MSG_DEBUG, ">>>. DRIVER AWEXT RSSI ");         wrq.u.data.pointer = (caddr_t) &stats;         wrq.u.data.length = sizeof(stats);         wrq.u.data.flags = 1; /* Clear updated flag */         strncpy(wrq.ifr_name, drv->ifname, IFNAMSIZ);         if (ioctl(drv->ioctl_sock, SIOCGIWSTATS, &wrq) < 0) {             perror("ioctl[SIOCGIWSTATS]");             ret = -1;         } else {             if (stats.qual.updated & IW_QUAL_DBM) {                 /* Values in dBm, stored in u8 with range 63 : -192 */                 rssi = ( stats.qual.level > 63 ) ?                     stats.qual.level - 0x100 :                     stats.qual.level;             } else {                 rssi = stats.qual.level;             }             if (drv->ssid_len != 0 && drv->ssid_len < buf_len) {                 os_memcpy((void *) buf, (void *) (drv->ssid),                         drv->ssid_len );                 ret = drv->ssid_len;                 ret += snprintf(&buf[ret], buf_len-ret,                         " rssi %d/n", rssi);                 if (ret < (int)buf_len) {                     return( ret );                 }                 ret = -1;             }         }     }     else if (os_strncasecmp(cmd, "powermode", 9) == 0) {     }     else if (os_strncasecmp(cmd, "getpower", 8) == 0) {     }     else if (os_strncasecmp(cmd, "get-rts-threshold", 17) == 0) {         struct iwreq wrq;         unsigned int rtsThreshold;         strncpy(wrq.ifr_name, drv->ifname, IFNAMSIZ);         if (ioctl(drv->ioctl_sock, SIOCGIWRTS, &wrq) < 0) {             perror("ioctl[SIOCGIWRTS]");             ret = -1;         } else {             rtsThreshold = wrq.u.rts.value;             wpa_printf(MSG_DEBUG,"Get RTS Threshold command = %d",                 rtsThreshold);             ret = snprintf(buf, buf_len, "rts-threshold = %u/n",                 rtsThreshold);             if (ret < (int)buf_len) {                 return( ret );             }         }     }     else if (os_strncasecmp(cmd, "set-rts-threshold", 17) == 0) {         struct iwreq wrq;         unsigned int rtsThreshold;         char *cp = cmd + 17;         char *endp;         strncpy(wrq.ifr_name, drv->ifname, IFNAMSIZ);         if (*cp != '/0') {             rtsThreshold = (unsigned int)strtol(cp, &endp, 0);             if (endp != cp) {                 wrq.u.rts.value = rtsThreshold;                 wrq.u.rts.fixed = 1;                 wrq.u.rts.disabled = 0;                 if (ioctl(drv->ioctl_sock, SIOCSIWRTS, &wrq) < 0) {                     perror("ioctl[SIOCGIWRTS]");                     ret = -1;                 } else {                     rtsThreshold = wrq.u.rts.value;                     wpa_printf(MSG_DEBUG,"Set RTS Threshold command = %d", rtsThreshold);                     ret = 0;                 }             }         }     }     else if (os_strcasecmp(cmd, "btcoexscan-start") == 0) {     }     else if (os_strcasecmp(cmd, "btcoexscan-stop") == 0) {     }     else if (os_strcasecmp(cmd, "rxfilter-start") == 0) {         wpa_printf(MSG_DEBUG,"Rx Data Filter Start command");     }     else if (os_strcasecmp(cmd, "rxfilter-stop") == 0) {         wpa_printf(MSG_DEBUG,"Rx Data Filter Stop command");     }     else if (os_strcasecmp(cmd, "rxfilter-statistics") == 0) {     }     else if (os_strncasecmp(cmd, "rxfilter-add", 12) == 0 ) {     }     else if (os_strncasecmp(cmd, "rxfilter-remove",15) == 0) {     }     else if (os_strcasecmp(cmd, "snr") == 0) {         struct iwreq wrq;         struct iw_statistics stats;         int snr, rssi, noise;         wrq.u.data.pointer = (caddr_t) &stats;         wrq.u.data.length = sizeof(stats);         wrq.u.data.flags = 1; /* Clear updated flag */         strncpy(wrq.ifr_name, drv->ifname, IFNAMSIZ);         if (ioctl(drv->ioctl_sock, SIOCGIWSTATS, &wrq) < 0) {             perror("ioctl[SIOCGIWSTATS]");             ret = -1;         } else {             if (stats.qual.updated & IW_QUAL_DBM) {                 /* Values in dBm, stored in u8 with range 63 : -192 */                 rssi = ( stats.qual.level > 63 ) ?                     stats.qual.level - 0x100 :                     stats.qual.level;                 noise = ( stats.qual.noise > 63 ) ?                     stats.qual.noise - 0x100 :                     stats.qual.noise;             } else {                 rssi = stats.qual.level;                 noise = stats.qual.noise;             }             snr = rssi - noise;             ret = snprintf(buf, buf_len, "snr = %u/n", (unsigned int)snr);             if (ret < (int)buf_len) {                 return( ret );             }         }     }     else if (os_strncasecmp(cmd, "btcoexmode", 10) == 0) {     }     else if( os_strcasecmp(cmd, "btcoexstat") == 0 ) {     }     else {         wpa_printf(MSG_DEBUG,"Unsupported command");     }     return (ret); } 经过这些修改后，wifi应该可以上去了。问题留存：  1。这次修改的是5.x版本的wpa_supplicant，android已经出了6.x版本，我在那里没有发现driver_wext.c！，那我上面的修改如何实现？看来还要研究。 2。修改好的driver_wext.c可以显示MAC地址，在上层的设置界面也能显示信号强度，但在主页面上却没有显示强度，估计还要在java程序中找找原因。 3。在设置界面，如果将wifi关闭后再打开，wifi连不上，需要手工在调试终端打ifconfig ra0 up才能触发连接上。估计是java程序在关闭wifi时没有将wifi设置进行初始化操作，要去看看设置的数据库修改情况。