Usb device detection in grub

[Arindam Khan]

Hi,

   I am working on a custom STM32 board and have configured the board's USB
OTG as a serial modem device. In Linux, it is getting detected as a
"/dev/ttyACM" and all read and write is working fine. However, when I load
the "usbtest" module of grub and run it with the "usb" command, it does not
show any USB devices. Is it possible to iterate over all usb devices
attached in a machine in GRUB?

kindly help.

-- 
with regards,
Arindam