This document demonstrates how to implement an USB 2.0 / USB 3.0 mass storage gadget on SP7350 platforms.
Table of Contents
Kernel Setup
Enter the kernel configuration by running the following command in the top directory of project.
# make kconfig
Select submenus for USB 2.0 controller : Device Drivers > USB support > USB Gadget Support > USB Peripheral Controller. Select <*> for “Sunplus USB 2.0 Device Controller“.
Select submenus for USB 3.0 controller : Device Drivers > USB support. Select <*> for “DesignWare USB3 DRD Core Support“ and select “Dual Role mode“ for “Deware USB3 DRD Core Support“.
Select submenus for USB OTG Transceive driver : Device Drivers > USB support > USB Physical Layer drivers. Select <*> for “Sunplus USB OTG Transceive driver“.
Select submenus for USB Gadget configfs : Device Drivers > USB support > USB Gadget Support. Select <M> for “USB Gadget functions configurable through configfs“ and [*] for “Mass storage“.
Execute the make command to build the Linux image.
Create a backing storage file
The backing storage file must be prepared before the gadget uses it.
Use the following command to create 32MB files (backing_file_u2 and backing_file_u3) filled with zeros.
# dd bs=1M count=32 if=/dev/zero of=/backing_file_u2 32+0 records in 32+0 records out 33554432 bytes (34 MB, 32 MiB) copied, 0.0850515 s, 395 MB/s # dd bs=1M count=32 if=/dev/zero of=/backing_file_u3 32+0 records in 32+0 records out 33554432 bytes (34 MB, 32 MiB) copied, 0.0836486 s, 401 MB/s
Use the following command to create the FAT file system in backing_file_u2 and backing_file_u3.
# mkfs.fat /backing_file_u2 mkfs.fat 4.1 (2017-01-24) # mkfs.fat /backing_file_u3 mkfs.fat 4.1 (2017-01-24)
ConfigFS
Configure mass storage gadget through configfs saved as a file named usb_mass_storage.
#!/bin/bash MODULES=/lib/modules/`uname -r`/kernel LIBCOMPOSITE=/$MODULES/drivers/usb/gadget/libcomposite.ko FUNCTION=/$MODULES/drivers/usb/gadget/function/usb_f_mass_storage.ko #install the drivers insmod $LIBCOMPOSITE insmod $FUNCTION #mount configfs mount -t configfs none /sys/kernel/config ############################## USB2.0 ############################## UDC_NAME="f8102800.usb" BACKING_FILE=/backing_file_u2 #create gadget mkdir /sys/kernel/config/usb_gadget/g1 cd /sys/kernel/config/usb_gadget/g1 echo "64" > bMaxPacketSize0 echo "0x200" > bcdUSB #create configuration mkdir configs/c.1 mkdir configs/c.1/strings/0x409 echo 120 > configs/c.1/MaxPower mkdir strings/0x0409 echo "1234" > strings/0x0409/serialnumber echo "Sunplus" > strings/0x0409/manufacturer echo "SP7350 USB2.0 Mass Storage Gadget" > strings/0x0409/product #create functions mkdir functions/mass_storage.usb0 echo "$BACKING_FILE" > functions/mass_storage.usb0/lun.0/file #link functions and configuration ln -s functions/mass_storage.usb0 configs/c.1 #activate echo $UDC_NAME > UDC ############################## USB3.0 ############################## UDC_NAME="f80a1000.dwc3" BACKING_FILE=/backing_file_u3 #create gadget mkdir /sys/kernel/config/usb_gadget/g2 cd /sys/kernel/config/usb_gadget/g2 echo "64" > bMaxPacketSize0 echo "0x300" > bcdUSB #create configuration mkdir configs/c.1 mkdir configs/c.1/strings/0x409 echo 120 > configs/c.1/MaxPower mkdir strings/0x0409 echo "5678" > strings/0x0409/serialnumber echo "Sunplus" > strings/0x0409/manufacturer echo "SP7350 USB3.0 Mass Storage Gadget" > strings/0x0409/product #create functions mkdir functions/mass_storage.usb0 echo "$BACKING_FILE" > functions/mass_storage.usb0/lun.0/file #link functions and configuration ln -s functions/mass_storage.usb0 configs/c.1 #activate echo $UDC_NAME > UDC
Implementation
After updating the image to the SP7350 platform, booting the system and copying backing_file_u2 and backing_file_u3 to it, use sh usb_mass_storage command to configure USB 2.0 and USB 3.0 as mass storage devices.
After connecting the mass storage gadget to a Windows PC through an USB cable, “E:\” and “F:\”will show up in “Portable Devices” of “Device Manager” and 2 “USB Mass Storage Device“ in “Universal Serial Bus controllers“.
