Callback Functions for USBX Interrupt

[MauricioConceptu]

Hello, I have doubts about the operation of USBX interrupts in relation to USB Device High Speed.
Taking a deeper look at the
UINT (*ux_system_slave_change_function)(ULONG) parameter of the function ux_device_stack_initialize.
I found that there are a number of callback functions that tie the operating system to the HAL in ux_dcd_stm32_callback.c and of these functions only HAL_PCD_SuspendCallback is called when disconnecting or connecting the HOST through the chip USB3300 microchip.
In addition, the system only recognizes void OTG_HS_IRQHandler(void)
and never uses the VOID _ux_dcd_stm32_interrupt_handler(VOID) function. I'm curious when this interrupt_handle function is called in the operating system or if I need to implement a function.
And I'm still in doubt about how to communicate with the phy registers through the ULPI commands, I didn't find the function that makes this communication.
I'm trying to understand how the Operating System identifies that the HOST is connected or disconnected.