- Complete PCI enumeration (class 0x0C, subclass 0x03, prog-if 0x00)
- I/O port register access (inb/outb style via volatile ptr)
- BAR4: I/O port range for operational registers (USBCMD, USBSTS, etc.)
- MMIO-mapped FLBASEADD for frame list base address
- 1024-entry frame list with QH pointers
- Control QH chain for transfer scheduling
- Full controller reset and initialization sequence
- Port polling with connect/disconnect detection
- Device enumeration via control transfers (GET_DESCRIPTOR, SET_ADDRESS)
- Port reset with proper timing (50ms hold, 10ms settle)
- Transfer descriptor (TD) construction for setup/data/status phases
- Wait-for-completion loop with error detection
- All registers documented in registers.rs per UHCI spec
- Scheme interface for scheme:usb access
