usb的设置

背景

设置usb0为host模式，支持u盘的热插拔。设置usb1为otg模式，支持设备作为u盘连接到电脑。
我对usb没有研究，但是linux内核对usb的支持非常强大，不需要修改代码，只需配置就可以实现。

设备树

首先，查看并设置usb的设备树，其中具体设置在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";    };};

我们需要做的就是使能usb并且设置正确的模式，默认模式是otg。am33xx.dtsi中关于usb的设置不需要任何修改。当然，还需要验证这些对应的驱动是否配置上，方法如之前所讲。

热插拔

配置内核

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

文件系统

etc/mdev.conf增加usb热插拔的支持

#hotplug usb disksd[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)

创建etc/hotplug目录，并在该目录下创建insert.sh和remove.sh脚本
insert.sh

#! /bin/shif [ -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    fifiecho "AAAA:insert:" > /dev/consoleecho $1 > /dev/console

remove.sh

#! /bin/shMOUNTS=$(mount | grep $1 | cut -d' ' -f3)umount $MOUNTSrm -rf $MOUNTSecho "AAAA:remove:$MOUNTS" > /dev/consoleecho $1 > /dev/console

另外，还需在etc/init.d目录下的初始化脚本中加入

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

OTG模式

配置内核

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

制作镜像

制作一个10M的镜像

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

格式化为FAT32模式

mkdosfs disk.img

文件系统

把该disk.img拷贝到根文件系统的opt目录下，在etc目录下的初始化脚本中增加

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

如此设置后，开机就可以把设备连接到电脑，当做u盘来使用，大小为10M。