[移动开发]Android 开机自动加载新wifi模块驱动

在android ROM 开发中经常会遇到产品更换wifi模块的情况，一般常见的wifi驱动android内核中自带都有，无需过多调试，要是碰上内核中没有的就需要根据厂商提供的驱动进行移植。

wifi驱动移植过程不多说，根据厂商提供的文档说明进行移植编译出驱动文件xxx.ko即可。

在成功编译出驱动ko文件后，手动insmod 加载驱动是可以的，但是开机时不会自动加载，这时可按以下步骤进行调整，让设备开机自动加载新模块的驱动。以USB类型模块为例：

1.通过adb shell lsusb 命令查看wifi的设备名称。

λ adb shell
Hi3798MV200:/ # lsusb
Bus 001 Device 002: ID 1a40:0101
Bus 001 Device 003: ID 1a40:0101
Bus 004 Device 002: ID 1d5c:2000
Bus 001 Device 001: ID 1d6b:0002
Bus 002 Device 001: ID 1d6b:0001
Bus 003 Device 001: ID 1d6b:0002
Bus 004 Device 001: ID 1d6b:0003
Bus 001 Device 004: ID 1a40:0101
Bus 001 Device 005: ID 1a86:7523
Bus 001 Device 006: ID 046d:c534
Bus 001 Device 007: ID 248a:8367
Bus 001 Device 008: ID 174c:55aa
Bus 001 Device 009: ID 0bda:8152

可通过拔插排除无关usb设备或查看usb设备的具体信息来判断是哪一个，比如我目前用的rtl8188fu模块的设备名称为：0bda:f179

2.添加该设备名称到系统支持的wifi设备列表中:hardware\libhardware_legacy\wifi\wifi.c

每个模块名称与设备名称一一对应{WIFI_REALTEK_RTL8188FU, "0bda:f179"},

/* Product ID of supported WiFi devices */
static wifi_device_s devices[] = {
    {WIFI_RALINK_MT7601U, "148f:7601"},
    {WIFI_REALTEK_RTL8188EUS, "0bda:8179"},
    {WIFI_REALTEK_RTL8188ETV, "0bda:0179"},
    {WIFI_REALTEK_RTL8192EU, "0bda:818b"},
    {WIFI_REALTEK_RTL8812AU, "0bda:8812"},
    {WIFI_REALTEK_RTL8723BU, "0bda:b720"},
    {WIFI_MEDIATEK_MT7632U, "0e8d:7632"},
    {WIFI_MEDIATEK_MT7662U, "0e8d:7662"},
    {WIFI_MEDIATEK_MT7612U, "0e8d:7612"},
    {WIFI_REALTEK_RTL8821AU, "0bda:0823"},
    {WIFI_ATHEROS_QCA6174, "168c:003e"},
    {WIFI_REALTEK_RTL8822BU, "0bda:b82c"},
    {WIFI_REALTEK_RTL8822BE, "10ec:b822"},
    {WIFI_HISI_HI1131C, "0296:5347"},
    {WIFI_AMPAK_AP6356S, "02D0:4356"},
    {WIFI_REALTEK_RTL8188FU, "0bda:f179"},
    {WIFI_MEDIATEK_MT7662TE, "14c3:7662"},
    {WIFI_MEDIATEK_MT7662TU, "0e8d:76a0"},
    {WIFI_REALTEK_RTL8821CU, "0bda:c811"}
};

WIFI_REALTEK_RTL8188FU是我们自定义的名称，需要先在头文件的模块名称列表中声明：

\hardware\libhardware_legacy\include\hardware_legacy\wifi.h

/* ID of supported WiFi devices */
typedef enum {
    WIFI_RALINK_MT7601U,
    WIFI_REALTEK_RTL8188EUS,
    WIFI_REALTEK_RTL8188ETV,
    WIFI_REALTEK_RTL8192EU,
    WIFI_REALTEK_RTL8812AU,
    WIFI_REALTEK_RTL8723BU,
    WIFI_MEDIATEK_MT7632U,
    WIFI_MEDIATEK_MT7662U,
    WIFI_MEDIATEK_MT7612U,
    WIFI_REALTEK_RTL8821AU,
    WIFI_ATHEROS_QCA6174,
    WIFI_REALTEK_RTL8822BU,
    WIFI_REALTEK_RTL8822BE,
    WIFI_HISI_HI1131C,
    WIFI_AMPAK_AP6356S,
    WIFI_REALTEK_RTL8188FU,
    WIFI_MEDIATEK_MT7662TE,
    WIFI_MEDIATEK_MT7662TU,
    WIFI_REALTEK_RTL8821CU,
    WIFI_INVALID_DEVICE = ~0x0 ,
} wifi_id_e;

3.声明wifi新模块要加载的驱动名称rtl8188fu.ko和位置：wifi.c中

#define DRIVER_MODULE_RTL8188FU   2, \
{ \
    {"cfg80211",MODULE_PATH"cfg80211.ko","","cfg80211 "}, \
    {"rtl8188fu",MODULE_PATH"rtl8188fu.ko","rtw_channel_plan=0x0C ifname=wlan0 if2name=p2p0","rtl8188fu "} \
}

4.将声明的新驱动模块DRIVER_MODULE_RTL8188FU添加到系统对应的驱动列表中：wifi.c

static wifi_modules_s sta_drivers[] = {
    {DRIVER_MODULE_MT7601U_STA},      // MediaTek MT7601U
    {DRIVER_MODULE_RTL8188EUS},       // RealTek RTL8188EUS
    {DRIVER_MODULE_RTL8188EUS},       // RealTek RTL8188ETV
    {DRIVER_MODULE_RTL8192EU},        // RealTek RTL8192EU
    {DRIVER_MODULE_RTL8812AU},        // RealTek RTL8812AU
    {DRIVER_MODULE_RTL8723BU},        // RealTek RTL8723BU
    {DRIVER_MODULE_MT7632U},          // MediaTek MT7632U
    {DRIVER_MODULE_MT7632U},          // MediaTek MT7662U
    {DRIVER_MODULE_MT7632U},          // MediaTek MT7612U
    {DRIVER_MODULE_RTL8821AU},        // RealTek RTL8821AU
    {DRIVER_MODULE_QCA6174},          // Atheros QCA6174
    {DRIVER_MODULE_RTL8822BU},        // RealTek RTL8822BU
    {DRIVER_MODULE_RTL8822BE},        // RealTek RTL8822BE
    {DRIVER_MODULE_HI1131C},          // Hisi Hi1131C
    {DRIVER_MODULE_AP6356S_STA},     // AMPAK AP6356S
    {DRIVER_MODULE_RTL8188FU},       // RealTek RTL8188FTV
    {DRIVER_MODULE_MT7662TE},         //MediaTek MT7662TE
    {DRIVER_MODULE_MT7662TU},          //MediaTek MT7662TU
    {DRIVER_MODULE_RTL8821CU}          //RealTek RTL8821CU
};

注意sta_drivers[] 中的名称位置顺序需要跟步骤2中的devices[]一一对应。

5.编译hardware\libhardware_legacy得到libhardware_legacy.so,adb push 到 system/lib/，至此开机后就会自动加载、system/lib/modules/rtl8188fu.ko 新WiFi模块的驱动了。

最后，梳理一下wifi驱动自动加载流程：

1.libhardware_legacy会遍历所有的usb设备名称，与devices[]中的wifi模块名称进行对比，有匹配到的话，就会记住该名称的索引位置

2.寻找sta_drivers[]中对应步骤1记住的索引位置指向的驱动名称

3.根据步骤2中找到的驱动名称，自动加载该名称声明时配置的驱动名称和位置进行insmod