This document demonstrates how to implement an USB 2.0 / USB 3.0 mass storage gadget on SP7350 platforms.
Table of Contents
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Kernel Setup
Enter the kernel configuration by running the following command in the top directory of project.
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# 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 OTG Transceive driver : Device Drivers > USB support > USB Physical Layer drivers. Select <*> for “Sunplus USB OTG Transceive driver“.
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 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.
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# 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.
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# 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.
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#!/bin/bash
USB2_UMS_EN=on
USB3_UMS_EN=on
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
mkdir -p /sys/kernel/config
mount -t configfs none /sys/kernel/config
if [ $USB2_UMS_EN = on ]
then
UDC_NAME="f8102800.usb"
BACKING_FILE=/backing_file_u2
#create gadget
cd /sys/kernel/config/usb_gadget
mkdir g1
cd g1
echo "64" > bMaxPacketSize0
echo "0x200" > bcdUSB
#create configuration
mkdir -p configs/c.1
mkdir -p configs/c.1/strings/0x409
echo 120 > configs/c.1/MaxPower
mkdir strings/0x0409
echo "1234" > strings/0x0409/serialnumber
echo "Sunplus" > strings/0x0409/manufacturer
echo "SP7350 USB2.0 Mass Storage Gadget" > strings/0x0409/product
#create functions
mkdir functions/mass_storage.usb0
echo "$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
fi
if [ $USB3_UMS_EN = on ]
then
UDC_NAME="f80a1000.dwc3"
BACKING_FILE=/backing_file_u3
#create gadget
cd /sys/kernel/config/usb_gadget
if [ $USB2_UMS_EN = on ]
then
mkdir g2
cd g2
else
mkdir g1
cd g1
fi
echo "64" > bMaxPacketSize0
echo "0x300" > bcdUSB
#create configuration
mkdir configs/c.1
mkdir configs/c.1/strings/0x409
echo 120 > configs/c.1/MaxPower
mkdir strings/0x0409
echo "5678" > strings/0x0409/serialnumber
echo "Sunplus" > strings/0x0409/manufacturer
echo "SP7350 USB3.0 Mass Storage Gadget" > strings/0x0409/product
#create functions
mkdir functions/mass_storage.usb0
echo "$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
fi |
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“.
