usb gadget configfs 验证

内核打开对应的宏

1、必须打开CONFIG_CONFIGFS_FS和CONFIG_USB_LIBCOMPOSITE的宏，前者为用户空间提供访问配置内核驱动的configfs文件系统，后者提供usb gadget composite框架；
2、必须打开UDC(USB Device Controller)的配置，这个是配置硬件控制器。我这里使用CONFIG_USB_CHIPIDEA和CONFIG_USB_CHIPIDEA_UDC；
3、如果使用mass storage功能，需要打开USB_CONFIGFS_MASS_STORAGE和USB_F_MASS_STORAGE，对应于usb_f_mass_storage.ko驱动。

配置步骤

挂载configfs：mount -t configfs none /config/，在这之后，/configfs/目录下就会生成usb_gadget/目录；
创建gadget：mkdir usb_gadget/g1，创建g1/目录之后，该目录下会生成很多配置目录，这里的g1表示gadget 1，一个UDC对应一个gadget，如果你的SOC上有多个gadget，可以创建多个gx目录。

# ll usb_gadget/g1/
total 0
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 UDC
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 bDeviceClass
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 bDeviceProtocol
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 bDeviceSubClass
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 bMaxPacketSize0
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 bcdDevice
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 bcdUSB
drwxr-xr-x 2 root root    0 1999-11-30 00:02 configs
drwxr-xr-x 2 root root    0 1999-11-30 00:02 functions
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 idProduct
-rw-r--r-- 1 root root 4096 1999-11-30 00:02 idVendor
drwxr-xr-x 2 root root    0 1999-11-30 00:02 os_desc
drwxr-xr-x 2 root root    0 1999-11-30 00:02 strings

配置PID和VID

# echo 0x18d1 > usb_gadget/g1/idVendor
# echo 0x4ee2 > usb_gadget/g1/idProduct

# mkdir usb_gadget/g1/strings/0x409
# echo "123456789" > usb_gadget/g1/strings/0x409/serialnumber
# echo "xxx" > usb_gadget/g1/strings/0x409/manufacturer
# echo "xxx_product" > usb_gadget/g1/strings/0x409/product

创建configuration和字符串

# mkdir usb_gadget/g1/configs/c.1
# mkdir usb_gadget/g1/configs/c.1/strings/0x409
# echo "mass_storage" > usb_gadget/g1/configs/c.1/strings/0x409/configuration

创建functions

# mkdir usb_gadget/g1/functions/mass_storage.0
[  108.582976]  [1:          mkdir: 1976] Mass Storage Function, version: 2009/09/11
[  108.592679]  [1:          mkdir: 1976] LUN: removable file: (no medium)

这里的mass_storage的名字不能随便起，需要根据insmod的function驱动usb_f_mass_storage.ko来决定。否则会出现如下错误：

1|@android:/config # mkdir usb_gadget/g1/functions/msg.0
mkdir: 'usb_gadget/g1/functions/msg.0': No such file or directory

将functions和configuration关联起来

# ln -s usb_gadget/g1/functions/mass_storage.0 usb_gadget/g1/configs/c.1

上述配置之后，得到的结果为：

127|@android:/config # find .
.
./usb_gadget
./usb_gadget/g1
./usb_gadget/g1/os_desc
./usb_gadget/g1/os_desc/qw_sign
./usb_gadget/g1/os_desc/b_vendor_code
./usb_gadget/g1/os_desc/use
./usb_gadget/g1/strings
./usb_gadget/g1/strings/0x409
./usb_gadget/g1/strings/0x409/serialnumber
./usb_gadget/g1/strings/0x409/product
./usb_gadget/g1/strings/0x409/manufacturer
./usb_gadget/g1/configs
./usb_gadget/g1/configs/c.1
./usb_gadget/g1/configs/c.1/mass_storage.0
./usb_gadget/g1/configs/c.1/strings
./usb_gadget/g1/configs/c.1/strings/0x409
./usb_gadget/g1/configs/c.1/strings/0x409/configuration
./usb_gadget/g1/configs/c.1/bmAttributes
./usb_gadget/g1/configs/c.1/MaxPower
./usb_gadget/g1/functions
./usb_gadget/g1/functions/mass_storage.0
./usb_gadget/g1/functions/mass_storage.0/lun.0
./usb_gadget/g1/functions/mass_storage.0/lun.0/inquiry_string
./usb_gadget/g1/functions/mass_storage.0/lun.0/nofua
./usb_gadget/g1/functions/mass_storage.0/lun.0/cdrom
./usb_gadget/g1/functions/mass_storage.0/lun.0/removable
./usb_gadget/g1/functions/mass_storage.0/lun.0/ro
./usb_gadget/g1/functions/mass_storage.0/lun.0/file
./usb_gadget/g1/functions/mass_storage.0/stall
./usb_gadget/g1/UDC
./usb_gadget/g1/bcdUSB
./usb_gadget/g1/bcdDevice
./usb_gadget/g1/idProduct
./usb_gadget/g1/idVendor
./usb_gadget/g1/bMaxPacketSize0
./usb_gadget/g1/bDeviceProtocol
./usb_gadget/g1/bDeviceSubClass
./usb_gadget/g1/bDeviceClass

查看当前的UDC
可见当前的板子上有两个UDC，ci_hdrc.0和gadget-cdns3。

130|@android:/config # ll /sys/class/udc/
total 0
lrwxrwxrwx 1 root root 0 1999-11-30 00:09 ci_hdrc.0 -> ../../devices/platform/5b0d0000.usb/ci_hdrc.0/udc/ci_hdrc.0
lrwxrwxrwx 1 root root 0 1999-11-30 00:09 gadget-cdns3 -> ../../devices/platform/5b110000.usb3/gadget-cdns3/udc/gadget-cdns3

绑定到UDC，使能gadget
将UDC切换至device模式，这里使用OTG ID pin来实现切换。

# echo ci_hdrc.0 > usb_gadget/g1/UDC
# echo 1 > /sys/class/gpio/gpio358/value

验证结果

将配置好的开发板与ubuntu连接，从ubuntu上的串口可以看到如下信息，表示已将开发板配置成一个mass storage的设备了。

[95705.390004] usb 1-11: USB disconnect, device number 28
[95708.606717] usb 1-11: new high-speed USB device number 29 using xhci_hcd
[95708.756934] usb 1-11: New USB device found, idVendor=18d1, idProduct=4ee2
[95708.756941] usb 1-11: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[95708.756946] usb 1-11: Product: xxx_product
[95708.756950] usb 1-11: Manufacturer: xxx
[95708.756953] usb 1-11: SerialNumber: 123456789
[95708.766595] usb-storage 1-11:1.0: USB Mass Storage device detected
[95708.766798] scsi host6: usb-storage 1-11:1.0

当然，上述的结果是ubuntu只识别到一个mass storage的设备，但是没有识别看分区表，所以没有看到相应的磁盘信息。想要看到磁盘信息，可以更进一步的设置mass_storage的backen file属性。

定制分区

在上面创建functions步骤之后，执行以下的命令，为mass storage创建2个分区，分区的backing file是开发板上的/dev/block/mmcblk0p1和/dev/block/mmcblk0p2，也就是开发板上的system分区和data分区。

mkdir usb_gadget/g1/functions/mass_storage.0/partition.2
mkdir usb_gadget/g1/functions/mass_storage.0/lun.1
echo /dev/block/mmcblk0p1 > usb_gadget/g1/functions/mass_storage.0/lun.0/file
echo /dev/block/mmcblk0p2 > usb_gadget/g1/functions/mass_storage.0/lun.1/file

所有配置完成之后，插入到ubuntu后，可以看到能识别去新的分区信息：

130 victor@victor-HP:/mnt⟫ sudo dmesg -c
[40873.009026] EXT4-fs (sdc): mounted filesystem with ordered data mode. Opts: (null)
[41094.127318] usb 1-11: USB disconnect, device number 23
[41094.128072] print_req_error: I/O error, dev sdc, sector 0
[41094.131049] sd 6:0:0:0: [sdc] Synchronizing SCSI cache
[41094.131118] sd 6:0:0:0: [sdc] Synchronize Cache(10) failed: Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
[41466.480635] usb 1-11: new high-speed USB device number 24 using xhci_hcd
[41466.630904] usb 1-11: New USB device found, idVendor=18d1, idProduct=4ee2
[41466.630911] usb 1-11: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[41466.630915] usb 1-11: Product: xxx_product
[41466.630919] usb 1-11: Manufacturer: xxx
[41466.630923] usb 1-11: SerialNumber: 123456789
[41466.640789] usb-storage 1-11:1.0: USB Mass Storage device detected
[41466.641062] scsi host7: usb-storage 1-11:1.0
[41467.645699] scsi 7:0:0:0: Direct-Access     Linux    File-Stor Gadget 0414 PQ: 0 ANSI: 2
[41467.646291] scsi 7:0:0:1: Direct-Access     Linux    File-Stor Gadget 0414 PQ: 0 ANSI: 2
[41467.646826] scsi 7:0:0:2: Direct-Access     Linux    File-Stor Gadget 0414 PQ: 0 ANSI: 2
[41467.647387] sd 7:0:0:0: Attached scsi generic sg2 type 0
[41467.647764] sd 7:0:0:1: Attached scsi generic sg3 type 0
[41467.648144] sd 7:0:0:0: Power-on or device reset occurred
[41467.648173] sd 7:0:0:2: Attached scsi generic sg4 type 0
[41467.649026] sd 7:0:0:1: Power-on or device reset occurred
[41467.649555] sd 7:0:0:2: Power-on or device reset occurred
[41467.650006] sd 7:0:0:0: [sdd] 1048576 512-byte logical blocks: (537 MB/512 MiB)
[41467.650766] sd 7:0:0:1: [sde] 524288 512-byte logical blocks: (268 MB/256 MiB)
[41467.651726] sd 7:0:0:0: [sdd] Write Protect is off
[41467.651731] sd 7:0:0:0: [sdd] Mode Sense: 0f 00 00 00
[41467.651929] sd 7:0:0:1: [sde] Write Protect is off
[41467.651933] sd 7:0:0:1: [sde] Mode Sense: 0f 00 00 00
[41467.652327] sd 7:0:0:2: [sdf] Attached SCSI removable disk
[41467.652581] sd 7:0:0:0: [sdd] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[41467.652837] sd 7:0:0:1: [sde] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[41467.673305] sd 7:0:0:1: [sde] Attached SCSI removable disk
[41467.674915] sd 7:0:0:0: [sdd] Attached SCSI removable disk

参考

上述的配置过程太繁琐了，在Android上，基于configfs有专门的init.rc在启动过程中去配置对应的configuration和function，比如说init.usb.rc，里面包含了一系列gadget的配置方法。在后面的文章中，将详细讲述每条命令背后的实现原理。

on bootwrite /config/usb_gadget/g1/strings/0x409/serialnumber ${ro.serialno}write /config/usb_gadget/g1/strings/0x409/manufacturer ${ro.product.manufacturer}write /config/usb_gadget/g1/strings/0x409/product ${ro.product.model}setprop sys.usb.configfs 1# OS DESCRIPTORS#===============# OS STRING#----------write /config/usb_gadget/g1/os_desc/b_vendor_code 1write /config/usb_gadget/g1/os_desc/qw_sign "MSFT100"# use os desc or not is up to each usb functions respectively# write /config/usb_gadget/g1/os_desc/use 1# MAKE b.1 THE ONE ASSOCIATED WITH OS DESCRIPTORS#------------------------------------------------symlink /config/usb_gadget/g1/configs/b.1 /config/usb_gadget/g1/os_desc/b1# ci_hdrc.0 is the fixed UDC namesetprop sys.usb.controller ci_hdrc.0on fsmkdir /dev/usb-ffs 0770 shell shellmkdir /dev/usb-ffs/adb 0770 shell shell# mount the configfs on /configmount configfs none /config mode=0755mkdir /config/usb_gadget/g1mkdir /config/usb_gadget/g1/configs/b.1# mkdir for functions needed# this will call each gadget's alloc_inst()mkdir /config/usb_gadget/g1/functions/ffs.adbmkdir /config/usb_gadget/g1/functions/mtp.gs0mkdir /config/usb_gadget/g1/functions/ptp.gs1mkdir /config/usb_gadget/g1/functions/accessory.gs2mkdir /config/usb_gadget/g1/functions/audio_source.gs3mkdir /config/usb_gadget/g1/functions/rndis.gs4mkdir /config/usb_gadget/g1/functions/midi.gs5mkdir /config/usb_gadget/g1/strings/0x409mkdir /config/usb_gadget/g1/configs/b.1/strings/0x409# The mount of functionfs for adb must be put AFTER the mkdir for functions in configfson property:sys.usb.config=none && property:sys.usb.configfs=1write /config/usb_gadget/g1/os_desc/use 0on property:sys.usb.ffs.ready=1 && property:sys.usb.config=adb && property:sys.usb.configfs=1write /config/usb_gadget/g1/idProduct 0x4ee7write /config/usb_gadget/g1/idVendor 0x18d1on property:sys.usb.config=mtp && property:sys.usb.configfs=1write /config/usb_gadget/g1/functions/mtp.gs0/os_desc/interface.MTP/compatible_id "MTP"write /config/usb_gadget/g1/os_desc/use 1write /config/usb_gadget/g1/idProduct 0x4ee1write /config/usb_gadget/g1/idVendor 0x18d1