Wi-Fi原始碼分析之WifiService操作Wi-Fi(一)

分析Wifi.c中的wifi_load_driver()函式

int wifi_load_driver()
{
    ALOGD("============wifi_load_driver================");
    /* WIFI_DRIVER_MODULE_PATH定義wlan driver的檔案路徑名. 我這裡並沒有定義 */
#ifdef WIFI_DRIVER_MODULE_PATH
     ALOGD("============wifi_load_driver:WIFI_DRIVER_MODULE_PATH================"
 
);
    char driver_status[PROPERTY_VALUE_MAX];
    int count = 100; /* wait at most 20 seconds for completion */

    if (is_wifi_driver_loaded()) {
        return 0;
    }

    /* DRIVER_MODULE_PATH裡儲存WIFI_DRIVER_MODULE_PATH巨集定義的檔案路徑名;
     * 如果WIFI_DRIVER_MODULE_PATH定義了就在此處通過       insmod向核心新增wlan driver*/
 

    if (insmod(DRIVER_MODULE_PATH, DRIVER_MODULE_ARG) < 0)
        return -1;

    /* FIRMWARE_LOADER 變數指向 WIFI_FIRMWARE_LOADER巨集定義的 wlan 韌體載入程式檔案路徑名
     * DRIVER_PROP_NAME 的值為"wlan.driver.status";
     * 如果沒有指定 wlan 韌體載入程式,則直接設定"wlan.driver.status"的屬性為"ok"
     * 否則                                   通過"ctl.start"方式來啟動 wlan 韌體載入程式
     * */
 

    if (strcmp(FIRMWARE_LOADER,"") == 0) {
        /* usleep(WIFI_DRIVER_LOADER_DELAY); */
        property_set(DRIVER_PROP_NAME, "ok");
    }
    else {
        property_set("ctl.start", FIRMWARE_LOADER);
    }
    sched_yield();
    while (count-- > 0) {
        if (property_get(DRIVER_PROP_NAME, driver_status, NULL)) {
            if (strcmp(driver_status, "ok") == 0)
                return 0;
            else if (strcmp(DRIVER_PROP_NAME, "failed") == 0) {
                wifi_unload_driver();
                return -1;
            }
        }
        usleep(200000);
    }
    property_set(DRIVER_PROP_NAME, "timeout");
    wifi_unload_driver();
    return -1;
#else
    /*如果沒有定義巨集WIFI_DRIVER_MODULE_PATH,則直接設定"wlan.driver.status"的屬性為"ok"*/
    property_set(DRIVER_PROP_NAME, "ok");
    return 0;
#endif
}