xhci-ring.rar_XHCI_ring_host_xhci_xhci driver

/* * xHCI host controller driver * * Copyright (C) 2008 Intel Corp. * * Author: Sarah Sharp * Some code borrowed from the Linux EHCI driver. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software Foundation, * Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* * Ring initialization rules: * 1. Each segment is initialized to zero, except for link TRBs. * 2. Ring cycle state = 0. This represents Producer Cycle State (PCS) or * Consumer Cycle State (CCS), depending on ring function. * 3. Enqueue pointer = dequeue pointer = address of first TRB in the segment. * * Ring behavior rules: * 1. A ring is empty if enqueue == dequeue. This means there will always be at * least one free TRB in the ring. This is useful if you want to turn that * into a link TRB and expand the ring. * 2. When incrementing an enqueue or dequeue pointer, if the next TRB is a * link TRB, then load the pointer with the address in the link TRB. If the * link TRB had its toggle bit set, you may need to update the ring cycle * state (see cycle bit rules). You may have to do this multiple times * until you reach a non-link TRB. * 3. A ring is full if enqueue++ (for the definition of increment above) * equals the dequeue pointer. * * Cycle bit rules: * 1. When a consumer increments a dequeue pointer and encounters a toggle bit * in a link TRB, it must toggle the ring cycle state. * 2. When a producer increments an enqueue pointer and encounters a toggle bit * in a link TRB, it must toggle the ring cycle state. * * Producer rules: * 1. Check if ring is full before you enqueue. * 2. Write the ring cycle state to the cycle bit in the TRB you're enqueuing. * Update enqueue pointer between each write (which may update the ring * cycle state). * 3. Notify consumer. If SW is producer, it rings the doorbell for command * and endpoint rings. If HC is the producer for the event ring, * and it generates an interrupt according to interrupt modulation rules. * * Consumer rules: * 1. Check if TRB belongs to you. If the cycle bit == your ring cycle state, * the TRB is owned by the consumer. * 2. Update dequeue pointer (which may update the ring cycle state) and * continue processing TRBs until you reach a TRB which is not owned by you. * 3. Notify the producer. SW is the consumer for the event ring, and it * updates event ring dequeue pointer. HC is the consumer for the command and * endpoint rings; it generates events on the event ring for these. */ #include <linux/scatterlist.h> #include <linux/slab.h> #include "xhci.h" #include "xhci-trace.h" /* * Returns zero if the TRB isn't in this segment, otherwise it returns the DMA * address of the TRB. */ dma_addr_t xhci_trb_virt_to_dma(struct xhci_segment *seg, union xhci_trb *trb) { unsigned long segment_offset; if (!seg || !trb || trb < seg->trbs) return 0; /* offset in TRBs */ segment_offset = trb - seg->trbs; if (segment_offset > TRBS_PER_SEGMENT) return 0; return seg->dma + (segment_offset * sizeof(*trb)); } /* Does this link TRB point to the first segment in a ring, * or was the previous TRB the last TRB on the last segment in the ERST? */ static bool last_trb_on_last_seg(struct xhci_hcd *xhci, struct xhci_ring *ring, struct xhci_segment *seg, union xhci_trb *trb) { if (ring == xhci->event_ring) return (trb == &seg->trbs[TRBS_PER_SEGMENT]) && (seg->next == xhci->event_ring->first_seg); else return le32_to_cpu(trb->link.control) & LINK_TOGGLE; } /* Is this TRB a link TRB or was the last TRB the last TRB in this event ring * segment? I.e. would the updated event TRB pointer step off the end of the * event seg? */ static int last_trb(struct xhci_hcd *xhci, struct xhci_ring *ring, struct xhci_segment *seg, union xhci_trb *trb) { if (ring == xhci->event_ring) return trb == &seg->trbs[TRBS_PER_SEGMENT]; else return TRB_TYPE_LINK_LE32(trb->link.control); } static int enqueue_is_link_trb(struct xhci_ring *ring) { struct xhci_link_trb *link = &ring->enqueue->link; return TRB_TYPE_LINK_LE32(link->control); } /* Updates trb to point to the next TRB in the ring, and updates seg if the next * TRB is in a new segment. This does not skip over link TRBs, and it does not * effect the ring dequeue or enqueue pointers. */ static void next_trb(struct xhci_hcd *xhci, struct xhci_ring *ring, struct xhci_segment **seg, union xhci_trb **trb) { if (last_trb(xhci, ring, *seg, *trb)) { *seg = (*seg)->next; *trb = ((*seg)->trbs); } else { (*trb)++; } } /* * See Cycle bit rules. SW is the consumer for the event ring only. * Don't make a ring full of link TRBs. That would be dumb and this would loop. */ static void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring) { ring->deq_updates++; /* * If this is not event ring, and the dequeue pointer * is not on a link TRB, there is one more usable TRB */ if (ring->type != TYPE_EVENT && !last_trb(xhci, ring, ring->deq_seg, ring->dequeue)) ring->num_trbs_free++; do { /* * Update the dequeue pointer further if that was a link TRB or * we're at the end of an event ring segment (which doesn't have * link TRBS) */ if (last_trb(xhci, ring, ring->deq_seg, ring->dequeue)) { if (ring->type == TYPE_EVENT && last_trb_on_last_seg(xhci, ring, ring->deq_seg, ring->dequeue)) { ring->cycle_state ^= 1; } ring->deq_seg = ring->deq_seg->next; ring->dequeue = ring->deq_seg->trbs; } else { ring->dequeue++; } } while (last_trb(xhci, ring, ring->deq_seg, ring->dequeue)); } /* * See Cycle bit rules. SW is the consumer for the event ring only. * Don't make a ring full of link TRBs. That would be dumb and this would loop. * * If we've just enqueued a TRB that is in the middle of a TD (meaning the * chain bit is set), then set the chain bit in all the following link TRBs. * If we've enqueued the last TRB in a TD, make sure the following link TRBs * have their chain bit cleared (so that each Link TRB is a separate TD). * * Section 6.4.4.1 of the 0.95 spec says link TRBs cannot have the chain bit * set, but other sections talk about dealing with the chain bit set. This was * fixed in the 0.96 specification errata, but we have to assume that all 0.95 * xHCI hardware can't handle the chain bit being cleared on a link TRB. * * @more_trbs_coming: Will you enqueue more TRBs before calling * prepare_transfer()? */ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring, bool more_trbs_coming) { u32 chain; union xhci_trb *next; chain = le32_to_cpu(ring->enqueue->generic.field[3]) & TRB_CHAIN; /* If this is not event ring, there is one less usable TRB */ if (ring->type != TYPE_EVENT && !last_trb(xhci, ring, ring->enq_seg, ring->enqueue)) ring->num_trbs_free--; next = ++(ring->enqueue); ring->enq_updates++; /* Update the dequeue pointer further if that was a link TRB or we're at * the end of an event ring segment (which doesn't have link TRBS) */ while (last_trb(xhci, ring, ring->enq_seg, next)) { if (ring->type != TYPE_EVENT) { /* * If the caller doesn't plan on enqueueing more * TDs before ringing the doorbell, then we * don't want to give the link TRB to the * hardware just yet. We'll give the link TRB * back in prepare_ring() just before we enqueue * the TD at the top of the ring. */ if (!chain && !more_trbs_coming)