Android wifi系统分析

Android wifi系统分析

一、wifiManager

1. wifi 操作的一些api 接口；

二、 wifiservice

1. 创建WifiStateMachine；其中wifinative、wifiMonitor 都在WifiStateMachine中创建

三、 wifiMonitor

1. 负责从wpa_supplicant接收事件通知。

四、 wifiNative

1. 提供与hardware 交互接口

五、wifi hardware

、加载wifi 驱动；
int rk_wifi_load_driver(int enable)
{
    int sz, fd = -;
    int ret = -;
    char buffer = '0';

    ALOGE("rk_wifi_load_driver:(%s)", enable? "insmod":"rmmod");
    switch(enable)
    {
        case :
            buffer = '0';
            break;

        case :
            buffer = '1';
            break;
    }

    fd = open(WIFI_DRIVER_INF, O_WRONLY);
    if (fd < )
    {
        ALOGE("rk_wifi_load_driver: open(%s) for write failed: %s (%d)",
            WIFI_DRIVER_INF, strerror(errno), errno);
        return ret;
    }

    sz = write(fd, &buffer, );

    if (sz < ) {
        ALOGE("rk_wifi_load_driver: write(%s) failed: %s (%d)",
            &buffer, strerror(errno),errno);
    }
    else {
        ret = ;
        usleep(*1000);
    }

    if (fd >= )
        close(fd);

    return ret;
}
           

2、启动wpa服务

property_set("ctl.start", supplicant_name);
           

3、和wpa 通信的一对socket；收发命令—位于data/misc/wifi/wpa_ctrl-**

这两个socket 非常重要，控制整个wifi 命令的下发和信息的收取
int wifi_connect_on_socket_path(const char *path)
{
    char supp_status[PROPERTY_VALUE_MAX] = {'\0'};

    /* Make sure supplicant is running */
    if (!property_get(supplicant_prop_name, supp_status, NULL)
            || strcmp(supp_status, "running") != ) {
        ALOGE("Supplicant not running, cannot connect");
        return -;
    }

    ctrl_conn = wpa_ctrl_open(path);
    if (ctrl_conn == NULL) {
        ALOGE("Unable to open connection to supplicant on \"%s\": %s",
             path, strerror(errno));
        return -;
    }
    monitor_conn = wpa_ctrl_open(path);
    if (monitor_conn == NULL) {
        wpa_ctrl_close(ctrl_conn);
        ctrl_conn = NULL;
        return -;
    }
    if (wpa_ctrl_attach(monitor_conn) != ) {
        wpa_ctrl_close(monitor_conn);
        wpa_ctrl_close(ctrl_conn);
        ctrl_conn = monitor_conn = NULL;
        return -;
    }

    if (socketpair(AF_UNIX, SOCK_STREAM, , exit_sockets) == -) {
        wpa_ctrl_close(monitor_conn);
        wpa_ctrl_close(ctrl_conn);
        ctrl_conn = monitor_conn = NULL;
        return -;
    }

    return ;
}
           

wpa_ctrl_request();发送命令给wpa；
         wifi_ctrl_recv();监听消息；
           

六、wpaSuppliant

在init.connectivity.rc 中定义

service wpa_supplicant /system/bin/wpa_supplicant \
    -iwlan -Dnl80211 -c/data/misc/wifi/wpa_supplicant.conf \
    -I/system/etc/wifi/wpa_supplicant_overlay.conf \
    -e/data/misc/wifi/entropy.bin -g@android:wpa_wlan0
    class main
    socket wpa_wlan0 dgram 660 wifi wifi
    disabled
    oneshot
           

wpa_wlan0 位置在dev/socket/wpa_wlan0 
1、和kernel 通信，扫描、监听、加入wifi 信息
           

7、wifi kernel （rk 平台 AP6335）

rk wifi驱动调用流程

下章再详细分析博通wifi 驱动