usb的設置

背景

設置usb0爲host模式，支持u盤的熱插拔。設置usb1爲otg模式，支持設備作爲u盤連接到電腦。
我對usb沒有研究，但是linux內核對usb的支持非常強大，不需要修改代碼，只需配置就可以實現。

設備樹

首先，查看並設置usb的設備樹，其中具體設置在am33xx.dtsi中。
am33xx.dtsi

usb: usb@47400000 {
            compatible = "ti,am33xx-usb";
            reg = <0x47400000 0x1000>;
            ranges;
            #address-cells = <1>;
            #size-cells = <1>;
            ti,hwmods = "usb_otg_hs";
            status = "disabled";

            usb_ctrl_mod: control@44e10000 {
                compatible = "ti,am335x-usb-ctrl-module";
                reg = <0x44e10620 0x10
                    0x44e10648 0x4>;
                reg-names = "phy_ctrl", "wakeup";
                status = "disabled";
            };

            usb0_phy: usb-phy@47401300 {
                compatible = "ti,am335x-usb-phy";
                reg = <0x47401300 0x100>;
                reg-names = "phy";
                status = "disabled";
                ti,ctrl_mod = <&usb_ctrl_mod>;
            };

            usb0: usb@47401000 {
                compatible = "ti,musb-am33xx";
                status = "disabled";
                reg = <0x47401400 0x400
                    0x47401000 0x200>;
                reg-names = "mc", "control";

                interrupts = <18>;
                interrupt-names = "mc";
                dr_mode = "otg";
                mentor,multipoint = <1>;
                mentor,num-eps = <16>;
                mentor,ram-bits = <12>;
                mentor,power = <500>;
                phys = <&usb0_phy>;

                dmas = <&cppi41dma  0 0 &cppi41dma  1 0
                    &cppi41dma  2 0 &cppi41dma  3 0
                    &cppi41dma  4 0 &cppi41dma  5 0
                    &cppi41dma  6 0 &cppi41dma  7 0
                    &cppi41dma  8 0 &cppi41dma  9 0
                    &cppi41dma 10 0 &cppi41dma 11 0
                    &cppi41dma 12 0 &cppi41dma 13 0
                    &cppi41dma 14 0 &cppi41dma  0 1
                    &cppi41dma  1 1 &cppi41dma  2 1
                    &cppi41dma  3 1 &cppi41dma  4 1
                    &cppi41dma  5 1 &cppi41dma  6 1
                    &cppi41dma  7 1 &cppi41dma  8 1
                    &cppi41dma  9 1 &cppi41dma 10 1
                    &cppi41dma 11 1 &cppi41dma 12 1
                    &cppi41dma 13 1 &cppi41dma 14 1>;
                dma-names =
                    "rx1", "rx2", "rx3", "rx4", "rx5", "rx6", "rx7",
                    "rx8", "rx9", "rx10", "rx11", "rx12", "rx13",
                    "rx14", "rx15",
                    "tx1", "tx2", "tx3", "tx4", "tx5", "tx6", "tx7",
                    "tx8", "tx9", "tx10", "tx11", "tx12", "tx13",
                    "tx14", "tx15";
            };

            usb1_phy: usb-phy@47401b00 {
                compatible = "ti,am335x-usb-phy";
                reg = <0x47401b00 0x100>;
                reg-names = "phy";
                status = "disabled";
                ti,ctrl_mod = <&usb_ctrl_mod>;
            };

            usb1: usb@47401800 {
                compatible = "ti,musb-am33xx";
                status = "disabled";
                reg = <0x47401c00 0x400
                    0x47401800 0x200>;
                reg-names = "mc", "control";
                interrupts = <19>;
                interrupt-names = "mc";
                dr_mode = "otg";
                mentor,multipoint = <1>;
                mentor,num-eps = <16>;
                mentor,ram-bits = <12>;
                mentor,power = <500>;
                phys = <&usb1_phy>;

                dmas = <&cppi41dma 15 0 &cppi41dma 16 0
                    &cppi41dma 17 0 &cppi41dma 18 0
                    &cppi41dma 19 0 &cppi41dma 20 0
                    &cppi41dma 21 0 &cppi41dma 22 0
                    &cppi41dma 23 0 &cppi41dma 24 0
                    &cppi41dma 25 0 &cppi41dma 26 0
                    &cppi41dma 27 0 &cppi41dma 28 0
                    &cppi41dma 29 0 &cppi41dma 15 1
                    &cppi41dma 16 1 &cppi41dma 17 1
                    &cppi41dma 18 1 &cppi41dma 19 1
                    &cppi41dma 20 1 &cppi41dma 21 1
                    &cppi41dma 22 1 &cppi41dma 23 1
                    &cppi41dma 24 1 &cppi41dma 25 1
                    &cppi41dma 26 1 &cppi41dma 27 1
                    &cppi41dma 28 1 &cppi41dma 29 1>;
                dma-names =
                    "rx1", "rx2", "rx3", "rx4", "rx5", "rx6", "rx7",
                    "rx8", "rx9", "rx10", "rx11", "rx12", "rx13",
                    "rx14", "rx15",
                    "tx1", "tx2", "tx3", "tx4", "tx5", "tx6", "tx7",
                    "tx8", "tx9", "tx10", "tx11", "tx12", "tx13",
                    "tx14", "tx15";
            };

am335x-evm.dts

&usb {
    status = "okay";

    control@44e10000 {
        status = "okay";
    };

    usb-phy@47401300 {
        status = "okay";
    };

    usb-phy@47401b00 {
        status = "okay";
    };

    usb@47401000 {
        status = "okay";
        dr_mode = "host";
    };

    usb@47401800 {
        status = "okay";
    };

    dma-controller@07402000  {
        status = "okay";
    };
};

我們需要做的就是使能usb並且設置正確的模式，默認模式是otg。am33xx.dtsi中關於usb的設置不需要任何修改。當然，還需要驗證這些對應的驅動是否配置上，方法如之前所講。

熱插拔

配置內核

Device Drivers  --->
    [*] USB support  --->
        <*>   USB Gadget Support  --->
            <M>   USB Gadget Drivers 

文件系統

etc/mdev.conf增加usb熱插拔的支持

#hotplug usb disk
sd[a-z][0-9]      0:0 666        @(/etc/hotplug/insert.sh $MDEV $SUBSYSTEM)
sd[a-z]           0:0 666        $(/etc/hotplug/remove.sh $MDEV $SUBSYSTEM)
mmcblk[0-9]p[0-9] 0:0 666        @(/etc/hotplug/insert.sh $MDEV $SUBSYSTEM)
mmcblk[0-9]       0:0 666        $(/etc/hotplug/remove.sh $MDEV $SUBSYSTEM)

創建etc/hotplug目錄，並在該目錄下創建insert.sh和remove.sh腳本
insert.sh

#! /bin/sh
if [ -n "$1" ] ; then
    if [ -b /dev/$1 ]; then

        if [ ! -d /media ]; then
            mkdir -p /media
        fi

        if [ ! -d /media/$1 ]; then
            mkdir -p /media/$1
        fi
             mount /dev/$1 /media/$1
    fi
fi
echo "AAAA:insert:" > /dev/console
echo $1 > /dev/console

remove.sh

#! /bin/sh
MOUNTS=$(mount | grep $1 | cut -d' ' -f3)
umount $MOUNTS
rm -rf $MOUNTS
echo "AAAA:remove:$MOUNTS" > /dev/console
echo $1 > /dev/console

另外，還需在etc/init.d目錄下的初始化腳本中加入

/bin/echo /sbin/mdev > /proc/sys/kernel/hotplug
mdev -s

OTG模式

配置內核

Device Drivers  --->
    [*] USB support  --->
        <*>   USB Gadget Support  --->
            <M>     Mass Storage Gadget

製作鏡像

製作一個10M的鏡像

dd if=/dev/zero of=disk.img bs=1M count=10

格式化爲FAT32模式

mkdosfs disk.img

文件系統

把該disk.img拷貝到根文件系統的opt目錄下，在etc目錄下的初始化腳本中增加

mount -t vfat -o sync /opt/disk.img /mnt
/sbin/modprobe g_mass_storage file=/dev/loop0 removable=1

如此設置後，開機就可以把設備連接到電腦，當做u盤來使用，大小爲10M。