/**
* Create a new ring with zero or more segments.
*
* Link each segment together into a ring.
* Set the end flag and the cycle toggle bit on the last segment.
* See section 4.9.1 and figures 15 and 16.
*/
static struct xhci_ring *xhci_ring_alloc(struct xhci_hcd *xhci,
unsigned int num_segs, bool link_trbs, gfp_t flags)
{
struct xhci_ring *ring;
struct xhci_segment *prev;
ring = kzalloc(sizeof *(ring), flags);
xhci_dbg(xhci, "Allocating ring at %p\n", ring);
if (!ring)
return 0;
INIT_LIST_HEAD(&ring->td_list);
if (num_segs == 0)
return ring;
ring->first_seg = xhci_segment_alloc(xhci, flags);
if (!ring->first_seg)
goto fail;
num_segs--;
prev = ring->first_seg;
while (num_segs > 0) {
struct xhci_segment *next;
next = xhci_segment_alloc(xhci, flags);
if (!next)
goto fail;
xhci_link_segments(xhci, prev, next, link_trbs);
prev = next;
num_segs--;
}
xhci_link_segments(xhci, prev, ring->first_seg, link_trbs);
if (link_trbs) {
/* See section 4.9.2.1 and 6.4.4.1 */
prev->trbs[TRBS_PER_SEGMENT-1].link.control |= (LINK_TOGGLE);
xhci_dbg(xhci, "Wrote link toggle flag to"
" segment %p (virtual), 0x%llx (DMA)\n",
prev, (unsigned long long)prev->dma);
}
xhci_initialize_ring_info(ring);
return ring;
fail:
xhci_ring_free(xhci, ring);
return 0;
}
/* Zero an endpoint ring (except for link TRBs) and move the enqueue and dequeue
* pointers to the beginning of the ring.
*/
static void xhci_reinit_cached_ring(struct xhci_hcd *xhci,
struct xhci_ring *ring)
{
struct xhci_segment *seg = ring->first_seg;
do {
memset(seg->trbs, 0,
sizeof(union xhci_trb)*TRBS_PER_SEGMENT);
/* All endpoint rings have link TRBs */
xhci_link_segments(xhci, seg, seg->next, 1);
seg = seg->next;
} while (seg != ring->first_seg);
xhci_initialize_ring_info(ring);
/* td list should be empty since all URBs have been cancelled,
* but just in case...
*/
INIT_LIST_HEAD(&ring->td_list);
}
/**
* Create a new ring with zero or more segments.
* TODO: current code only uses one-time-allocated single-segment rings
* of 1KB anyway, so we might as well get rid of all the segment and
* linking code (and maybe increase the size a bit, e.g. 4KB).
*
*
* Link each segment together into a ring.
* Set the end flag and the cycle toggle bit on the last segment.
* See section 4.9.2 and figures 15 and 16 of XHCI spec rev1.0.
*
* @param num_segs number of segments in the ring
* @param link_trbs flag to indicate whether to link the trbs or NOT
* @return pointer to the newly created RING
*/
struct xhci_ring *xhci_ring_alloc(unsigned int num_segs, bool link_trbs)
{
struct xhci_ring *ring;
struct xhci_segment *prev;
ring = (struct xhci_ring *)malloc(sizeof(struct xhci_ring));
BUG_ON(!ring);
if (num_segs == 0)
return ring;
ring->first_seg = xhci_segment_alloc();
BUG_ON(!ring->first_seg);
num_segs--;
prev = ring->first_seg;
while (num_segs > 0) {
struct xhci_segment *next;
next = xhci_segment_alloc();
BUG_ON(!next);
xhci_link_segments(prev, next, link_trbs);
prev = next;
num_segs--;
}
xhci_link_segments(prev, ring->first_seg, link_trbs);
if (link_trbs) {
/* See section 4.9.2.1 and 6.4.4.1 */
prev->trbs[TRBS_PER_SEGMENT-1].link.control |=
cpu_to_le32(LINK_TOGGLE);
}
xhci_initialize_ring_info(ring);
return ring;
}
