GPIO based peripheral-only VBUS sensing 'transceiver'

modulename: gpio_vbus.ko

and/or

phy-gpio-vbus-usb.ko

configname: CONFIG_USB_GPIO_VBUS

Linux Kernel Configuration
└─>Device Drivers
└─>USB support
└─>USB Gadget Support
└─>GPIO based peripheral-only VBUS sensing 'transceiver'
In linux kernel since version 2.6.29 (release Date: 2009-03-23)  
Provides simple GPIO VBUS sensing for controllers with an
internal transceiver via the usb_phy interface, and
optionally control of a D+ pullup GPIO as well as a VBUS
current limit regulator.

source code:
drivers/usb/otg/gpio_vbus.c