Struct devices::usb::xhci::event_ring::EventRing

pub struct EventRing {
    mem: GuestMemory,
    segment_table_size: u16,
    segment_table_base_address: GuestAddress,
    current_segment_index: u16,
    trb_count: u16,
    enqueue_pointer: GuestAddress,
    dequeue_pointer: GuestAddress,
    producer_cycle_state: bool,
}

Event rings are segmented circular buffers used to pass event TRBs from the xHCI device back to the guest. Each event ring is associated with a single interrupter. See section 4.9.4 of the xHCI specification for more details. This implementation is only for primary interrupter. Please review xhci spec before using it for secondary.

Fields

mem: GuestMemory

segment_table_size: u16

segment_table_base_address: GuestAddress

current_segment_index: u16

trb_count: u16

enqueue_pointer: GuestAddress

dequeue_pointer: GuestAddress

producer_cycle_state: bool

Implementations

impl EventRing

pub fn new(mem: GuestMemory) -> Self

Create an empty, uninitialized event ring.

pub fn add_event(&mut self, trb: Trb) -> Result<(), Error>

This function implements left side of xHCI spec, Figure 4-12.

pub fn set_seg_table_size(&mut self, size: u16) -> Result<(), Error>

Set segment table size.

pub fn set_seg_table_base_addr( &mut self, addr: GuestAddress, ) -> Result<(), Error>

Set segment table base addr.

pub fn set_dequeue_pointer(&mut self, addr: GuestAddress)

Set dequeue pointer.

pub fn is_empty(&self) -> bool

Check if event ring is empty.

pub fn is_full(&self) -> Result<bool, Error>

Event ring is considered full when there is only space for one last TRB. In this case, xHC should write an error Trb and do a bunch of handlings. See spec, figure 4-12 for more details. For now, we just check event ring full and fail (as it’s unlikely to happen).

fn try_reconfigure_event_ring(&mut self) -> Result<(), Error>

Try to init event ring. Will fail if seg table size/address are invalid.

fn check_inited(&self) -> Result<(), Error>

fn load_current_seg_table_entry(&mut self) -> Result<(), Error>

fn read_seg_table_entry( &self, index: u16, ) -> Result<EventRingSegmentTableEntry, Error>

fn get_seg_table_addr(&self, index: u16) -> Result<GuestAddress, Error>