How to configure SP7021 board as an USB mass storage device

Owned by vincent.shih
Last updated: Aug 26, 2021

After getting source files (after kernel 4.19) from git server of SP7021, follow the steps shown below.

1. Configure “USB_CONFIGFS” in kernel menuconfig

Device Drivers → USB support → USB Gadget Support → USB Gadget functions configurable through

configfs <M> → Mass storage [ * ]

After compiling, it will procude libcomposite.ko at linux/kernel/drivers/usb/gadget and

usb_f_mass_storage.ko at linux/kernel/drivers/usb/gadget/function.

 

2. Configure “USB Gadget precomposed configurations” in kernel menuconfig

Device Drivers → USB support → USB Gadget Support → USB Gadget precomposed configurations

<M> → Mass Storage Gadget <M>

After compiling, it will procude g_mass_storage.ko at linux/kernel/drivers/usb/gadget/legacy.

3. Configure “USB_GADGET_SP7021” in kernel menuconfig

Device Drivers → USB support → USB Gadget Support → USB Peripheral Controllers → Sunplus SP7021

Gemini USB Device Controller [ * ]

4. Configure “CONFIGFS_FS” in kernel menuconfig

File systems → Pseudo filesystems → Userspace-driven configuration filesystem <Module>

After compiling, it will produce configfs.ko at linux/kernel/fs/configfs.

5. Run “make all” to build the Linux image, update it to SP7021 and boot (eMMC).

6. Configure attributes and set up in user space

echo 0xff > /sys/module/sunplus_udc/parameters/dmsg

insmod /lib/modules/`uname - r`/kernel/fs/configfs/configfs.ko

insmod /lib/modules/`uname - r`/kernel/drivers/usb/gadget/libcomposite.ko

insmod /lib/modules/`uname - r`/kernel/drivers/usb/gadget/function/usb_f_mass_storage.ko

insmod /lib/modules/`uname - r`/kernel/drivers/usb/gadget/legacy/g_mass_storage.ko file=/

dev/mmcblk08p removable=1 ro=0

mount -t configfs none /sys/kernel/config

mkdir /sys/kernel/config/usb_gadget/g1

cd /sys/kernel/config/usb_gadget/g1

echo “64” > bMaxPacketSize0

echo “0x200” > bcdUSB

mkdir configs/c.1

echo 120 > configs/c.1/MaxPower

mkdir functions/mass_storage.usb0

ln -s functions/mass_storage.usb0 configs/c.1

echo “9c102800.usb” > UDC (9c102800.usb is at /sys/class/udc)

echo d > /sys/devices/platform/soc@B/9c102800.usb/udc_ctrl

7. Connect SP7021 DEMO board (via micro USB0) to an Ubuntu PC

The mass storage device of 3.8GB Volumn will show up. It is the root directory of SP7021.