USB接口是现在计算机系统中通用的一种接口，这里介绍USB控制器驱动的移植，以U盘驱动为例。 FS4412通过usb hub芯片将一个usb口扩展为多个接口如图：

所以为了能够使用usb口接入usb设备还需要移植usb hub驱动。

设备树添加内容：$ vim arch/arm/boot/dts/exynos4412-fs4412.dts

添加如下内容：
        usbphy: usbphy@125B0000 {
        #address-cells = < 1>;
        #size-cells = < 1>;
        compatible = "samsung,exynos4x12-usb2phy";
        reg = < 0x125B0000 0x100>;
        ranges;
        clocks = < &clock 2>, < &clock 305>;
        clock-names = "xusbxti", "otg";
        usbphy-sys {
        reg = < 0x10020704 0x8 0x1001021c 0x4>;
        };
        };
        ehci@12580000 {
        status = "okay";
        usbphy = < &usbphy>;
        };
        usb3503@08 {
        compatible = "smsc,usb3503";
        reg = < 0x08 0x4>;
        connect-gpios = < &gpm3 3 1>;
        intn-gpios = < &gpx2 3 1>;
        reset-gpios = < &gpm2 4 1>;
        initial-mode = < 1>;
        };

usbphy相关内容参考：Documentation/devicetree/bindings/usb/samsung-usbphy.txt

usb hub芯片几个关键管脚连接如下：

所以：
        USB3503_RESET 对应 GPM2_4
        USB3503_CONNECT 对应 GPM3_3
        HUB_INT_N 对应 GPX2_3

所以
        usb3503@08 {
        compatible = "smsc,usb3503";
        reg = < 0x08 0x4>;
        connect-gpios = < &gpm3 3 1>;
        intn-gpios = < &gpx2 3 1>;
        reset-gpios = < &gpm2 4 1>;
        initial-mode = < 1>;
        };

参考内容：Documentation/devicetree/bindings/usb/usb3503.txt

配置内核：
        make menuconfig
        Device Drivers --->
        [*] USB support --->
        <*> EHCI HCD (USB 2.0) support
        <*> EHCI support for Samsung S5P/EXYNOS SoC Series
        <*> USB Mass Storage support
        <*> USB3503 HSIC to USB20 Driver
        USB Physical Layer drivers --->
        <*> Samsung USB 2.0 PHY controller Driver
        SCSI device support --->
        <*> SCSI device support
        <*> SCSI disk support
        <*> SCSI generic support
        File systems --->
        DOS/FAT/NT Filesystems --->
        <*> MSDOS fs support
        <*> VFAT (Windows-95) fs support
        (437) Default codepage for FAT
        (iso8859-1) Default iocharset for FAT
        -*- Native language support --->
        <*> Codepage 437 (United States, Canada)
        <*> Simplified Chinese charset (CP936, GB2312)
        <*> ASCII (United States)
        <*> NLS ISO 8859-1 (Latin 1; Western European Languages)
        <*> NLS UTF-8

重新编译内核，插入U盘看到如下内容表示移植成功：
        [ 72.695000] usb 1-3.2: USB disconnect, device number 3
        [ 74.435000] usb 1-3.2: new high-speed USB device number 4 using exynos-ehci
        [ 74.555000] usb-storage 1-3.2:1.0: USB Mass Storage device detected
        [ 74.560000] scsi1 : usb-storage 1-3.2:1.0
        [ 75.645000] scsi 1:0:0:0: Direct-Access Kingston DataTraveler 160 PMAP PQ: 0 ANSI: 4
        [ 75.660000] sd 1:0:0:0: Attached scsi generic sg0 type 0
        [ 76.695000] sd 1:0:0:0: [sda] 15556608 512-byte logical blocks: (7.96 GB/7.41 GiB)
        [ 76.700000] sd 1:0:0:0: [sda] Write Protect is off
        [ 76.705000] sd 1:0:0:0: [sda] No Caching mode page found
        [ 76.710000] sd 1:0:0:0: [sda] Assuming drive cache: write through
        [ 76.725000] sd 1:0:0:0: [sda] No Caching mode page found
        [ 76.730000] sd 1:0:0:0: [sda] Assuming drive cache: write through
        [ 76.760000] sda: sda1 (sda是设备名 sda1是分区名)
        [ 76.770000] sd 1:0:0:0: [sda] No Caching mode page found
        [ 76.770000] sd 1:0:0:0: [sda] Assuming drive cache: write through
        [ 76.780000] sd 1:0:0:0: [sda] Attached SCSI removable disk

然后执行如下操作

# mount -t vfat /dev/sda1 /mnt
        # ls