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ehci-q-iram.c

/*
 * Copyright (C) 2001-2004 by David Brownell
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * 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.
 */
#undef EHCI_NO_ERR_COUNT
static size_t g_iram_size = IRAM_TD_SIZE;

/* this file is part of ehci-hcd.c */

/*-------------------------------------------------------------------------*/

/*
 * EHCI hardware queue manipulation ... the core.  QH/QTD manipulation.
 *
 * Control, bulk, and interrupt traffic all use "qh" lists.  They list "qtd"
 * entries describing USB transactions, max 16-20kB/entry (with 4kB-aligned
 * buffers needed for the larger number).  We use one QH per endpoint, queue
 * multiple urbs (all three types) per endpoint.  URBs may need several qtds.
 *
 * ISO traffic uses "ISO TD" (itd, and sitd) records, and (along with
 * interrupts) needs careful scheduling.  Performance improvements can be
 * an ongoing challenge.  That's in "ehci-sched.c".
 *
 * USB 1.1 devices are handled (a) by "companion" OHCI or UHCI root hubs,
 * or otherwise through transaction translators (TTs) in USB 2.0 hubs using
 * (b) special fields in qh entries or (c) split iso entries.  TTs will
 * buffer low/full speed data so the host collects it at high speed.
 */

/*-------------------------------------------------------------------------*/
/* fill a qtd, returning how much of the buffer we were able to queue up */
static int qtd_fill(struct ehci_hcd *ehci, struct ehci_qtd *qtd, dma_addr_t buf,
                size_t len, int token, int maxpacket)
{
      int i, count;
      u64 addr = buf;
      struct urb *urb = qtd->urb;

      if (usb_pipebulk(urb->pipe) &&
          (address_to_buffer(ehci, usb_pipedevice(urb->pipe)) != 2)) {
            urb->use_iram = 1;
            qtd->buffer_offset = (size_t) (buf - urb->transfer_dma);
            token |= QTD_IOC;
            if (usb_pipeout(urb->pipe)) {
                  addr = ehci->iram_buffer[address_to_buffer(ehci,
                                    usb_pipedevice(urb->pipe))];
            } else if (usb_pipein(urb->pipe)) {
                  addr = ehci->iram_buffer[address_to_buffer(ehci,
                                    usb_pipedevice(urb->pipe))] +
                                    g_iram_size;
            }
      } else {
            urb->use_iram = 0;
            addr = buf;
      }
      len = min(g_iram_size, len);

      /* one buffer entry per 4K ... first might be short or unaligned */
      qtd->hw_buf[0] = cpu_to_hc32(ehci, (u32) addr);
      qtd->hw_buf_hi[0] = cpu_to_hc32(ehci, (u32) (addr >> 32));
      count = 0x1000 - (buf & 0x0fff);    /* rest of that page */
      if (likely(len < count))      /* ... iff needed */
            count = len;
      else {
            buf += 0x1000;
            buf &= ~0x0fff;

            /* per-qtd limit: from 16K to 20K (best alignment) */
            for (i = 1; count < len && i < 5; i++) {
                  addr = buf;
                  qtd->hw_buf[i] = cpu_to_hc32(ehci, (u32) addr);
                  qtd->hw_buf_hi[i] =
                      cpu_to_hc32(ehci, (u32) (addr >> 32));
                  buf += 0x1000;
                  if ((count + 0x1000) < len)
                        count += 0x1000;
                  else
                        count = len;
            }

            /* short packets may only terminate transfers */
            if (count != len)
                  count -= (count % maxpacket);
      }
      qtd->hw_token = cpu_to_hc32(ehci, (count << 16) | token);
      qtd->length = count;

      return count;
}

/*-------------------------------------------------------------------------*/

static inline void
qh_update(struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd)
{
      /* writes to an active overlay are unsafe */
      BUG_ON(qh->qh_state != QH_STATE_IDLE);

      qh->hw_qtd_next = QTD_NEXT(ehci, qtd->qtd_dma);
      qh->hw_alt_next = EHCI_LIST_END(ehci);

      /* Except for control endpoints, we make hardware maintain data
       * toggle (like OHCI) ... here (re)initialize the toggle in the QH,
       * and set the pseudo-toggle in udev. Only usb_clear_halt() will
       * ever clear it.
       */
      if (!(qh->hw_info1 & cpu_to_hc32(ehci, 1 << 14))) {
            unsigned is_out, epnum;

            is_out = !(qtd->hw_token & cpu_to_hc32(ehci, 1 << 8));
            epnum = (hc32_to_cpup(ehci, &qh->hw_info1) >> 8) & 0x0f;
            if (unlikely(!usb_gettoggle(qh->dev, epnum, is_out))) {
                  qh->hw_token &= ~cpu_to_hc32(ehci, QTD_TOGGLE);
                  usb_settoggle(qh->dev, epnum, is_out, 1);
            }
      }

      /* HC must see latest qtd and qh data before we clear ACTIVE+HALT */
      wmb();
      qh->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING);
}

/* if it weren't for a common silicon quirk (writing the dummy into the qh
 * overlay, so qh->hw_token wrongly becomes inactive/halted), only fault
 * recovery (including urb dequeue) would need software changes to a QH...
 */
static void qh_refresh(struct ehci_hcd *ehci, struct ehci_qh *qh)
{
      struct ehci_qtd *qtd;

      if (list_empty(&qh->qtd_list))
            qtd = qh->dummy;
      else {
            qtd = list_entry(qh->qtd_list.next, struct ehci_qtd, qtd_list);
            /* first qtd may already be partially processed */
            if (cpu_to_hc32(ehci, qtd->qtd_dma) == qh->hw_current)
                  qtd = NULL;
      }

      if (qtd)
            qh_update(ehci, qh, qtd);
}

/*-------------------------------------------------------------------------*/

static int qtd_copy_status(struct ehci_hcd *ehci,
                     struct urb *urb, size_t length, u32 token)
{
      int status = -EINPROGRESS;

      /* count IN/OUT bytes, not SETUP (even short packets) */
      if (likely(QTD_PID(token) != 2))
            urb->actual_length += length - QTD_LENGTH(token);

      /* don't modify error codes */
      if (unlikely(urb->unlinked))
            return status;

      /* force cleanup after short read; not always an error */
      if (unlikely(IS_SHORT_READ(token)))
            status = -EREMOTEIO;

      /* serious "can't proceed" faults reported by the hardware */
      if (token & QTD_STS_HALT) {
            if (token & QTD_STS_BABBLE) {
                  /* FIXME "must" disable babbling device's port too */
                  status = -EOVERFLOW;
            } else if (token & QTD_STS_MMF) {
                  /* fs/ls interrupt xfer missed the complete-split */
                  status = -EPROTO;
            } else if (token & QTD_STS_DBE) {
                  status = (QTD_PID(token) == 1)      /* IN ? */
                      ? -ENOSR      /* hc couldn't read data */
                      : -ECOMM;     /* hc couldn't write data */
            } else if (token & QTD_STS_XACT) {
                  /* timeout, bad crc, wrong PID, etc; retried */
                  if (QTD_CERR(token))
                        status = -EPIPE;
                  else {
                        ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
                               urb->dev->devpath,
                               usb_pipeendpoint(urb->pipe),
                               usb_pipein(urb->pipe) ? "in" : "out");
                        status = -EPROTO;
                  }
                  /* CERR nonzero + no errors + halt --> stall */
            } else if (QTD_CERR(token))
                  status = -EPIPE;
            else        /* unknown */
                  status = -EPROTO;

            ehci_vdbg(ehci,
                    "dev%d ep%d%s qtd token %08x --> status %d\n",
                    usb_pipedevice(urb->pipe),
                    usb_pipeendpoint(urb->pipe),
                    usb_pipein(urb->pipe) ? "in" : "out", token, status);

            /* if async CSPLIT failed, try cleaning out the TT buffer */
            if (status != -EPIPE && urb->dev->tt && !usb_pipeint(urb->pipe)
                && ((token & QTD_STS_MMF) != 0 || QTD_CERR(token) == 0)
                && (!ehci_is_TDI(ehci)
                  || urb->dev->tt->hub !=
                  ehci_to_hcd(ehci)->self.root_hub)) {
#ifdef DEBUG
                  struct usb_device *tt = urb->dev->tt->hub;
                  dev_dbg(&tt->dev,
                        "clear tt buffer port %d, a%d ep%d t%08x\n",
                        urb->dev->ttport, urb->dev->devnum,
                        usb_pipeendpoint(urb->pipe), token);
#endif /* DEBUG */
                  /* REVISIT ARC-derived cores don't clear the root
                   * hub TT buffer in this way...
                   */
                  usb_hub_tt_clear_buffer(urb->dev, urb->pipe);
            }
      }

      return status;
}

static void
ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
__releases(ehci->lock) __acquires(ehci->lock)
{
      if (likely(urb->hcpriv != NULL)) {
            struct ehci_qh *qh = (struct ehci_qh *)urb->hcpriv;

            /* S-mask in a QH means it's an interrupt urb */
            if ((qh->hw_info2 & cpu_to_hc32(ehci, QH_SMASK)) != 0) {

                  /* ... update hc-wide periodic stats (for usbfs) */
                  ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
            }
            qh_put(qh);
      }

      if (unlikely(urb->unlinked)) {
            COUNT(ehci->stats.unlink);
      } else {
            /* report non-error and short read status as zero */
            if (status == -EINPROGRESS || status == -EREMOTEIO)
                  status = 0;
            COUNT(ehci->stats.complete);
      }

#ifdef EHCI_URB_TRACE
      ehci_dbg(ehci,
             "%s %s urb %p ep%d%s status %d len %d/%d\n",
             __func__, urb->dev->devpath, urb,
             usb_pipeendpoint(urb->pipe),
             usb_pipein(urb->pipe) ? "in" : "out",
             status, urb->actual_length, urb->transfer_buffer_length);
#endif

      /* complete() can reenter this HCD */
      usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
      spin_unlock(&ehci->lock);
      usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status);
      spin_lock(&ehci->lock);
}

static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
static void unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh);

static void intr_deschedule(struct ehci_hcd *ehci, struct ehci_qh *qh);
static int qh_schedule(struct ehci_hcd *ehci, struct ehci_qh *qh);

/*
 * Process and free completed qtds for a qh, returning URBs to drivers.
 * Chases up to qh->hw_current.  Returns number of completions called,
 * indicating how much "real" work we did.
 */
static unsigned qh_completions(struct ehci_hcd *ehci, struct ehci_qh *qh)
{
      struct ehci_qtd *last = NULL, *end = qh->dummy;
      struct list_head *entry, *tmp;
      int last_status = -EINPROGRESS;
      int stopped;
      unsigned count = 0;
      u8 state;
      __le32 halt = HALT_BIT(ehci);
      __hc32 temp_hw_qtd_next = 0;

      if (unlikely(list_empty(&qh->qtd_list)))
            return count;

      /* completions (or tasks on other cpus) must never clobber HALT
       * till we've gone through and cleaned everything up, even when
       * they add urbs to this qh's queue or mark them for unlinking.
       *
       * NOTE:  unlinking expects to be done in queue order.
       */
      state = qh->qh_state;
      qh->qh_state = QH_STATE_COMPLETING;
      stopped = (state == QH_STATE_IDLE);

      /* remove de-activated QTDs from front of queue.
       * after faults (including short reads), cleanup this urb
       * then let the queue advance.
       * if queue is stopped, handles unlinks.
       */
      list_for_each_safe(entry, tmp, &qh->qtd_list) {
            struct ehci_qtd *qtd;
            struct urb *urb;
            struct ehci_qtd *qtd2;
            struct urb *urb2;

            u32 token = 0;

            qtd = list_entry(entry, struct ehci_qtd, qtd_list);
            urb = qtd->urb;

            /* clean up any state from previous QTD ... */
            if (last) {
                  if (likely(last->urb != urb)) {
                        ehci_urb_done(ehci, last->urb, last_status);
                        count++;
                        last_status = -EINPROGRESS;
                  }
                  ehci_qtd_free(ehci, last);
                  last = NULL;
            }

            /* ignore urbs submitted during completions we reported */
            if (qtd == end)
                  break;

            /* hardware copies qtd out of qh overlay */
            rmb();
            token = hc32_to_cpu(ehci, qtd->hw_token);

            /* always clean up qtds the hc de-activated */
            if ((token & QTD_STS_ACTIVE) == 0) {

                  /* on STALL, error, and short reads this urb must
                   * complete and all its qtds must be recycled.
                   */
                  if ((token & QTD_STS_HALT) != 0) {
                        stopped = 1;

                  /* magic dummy for some short reads; qh won't advance.
                   * that silicon quirk can kick in with this dummy too.
                   *
                   * other short reads won't stop the queue, including
                   * control transfers (status stage handles that) or
                   * most other single-qtd reads ... the queue stops if
                   * URB_SHORT_NOT_OK was set so the driver submitting
                   * the urbs could clean it up.
                   */
                  } else if (IS_SHORT_READ(token)
                        && !(qtd->hw_alt_next & EHCI_LIST_END(ehci))) {
                        if (urb->use_iram && usb_pipein(urb->pipe)) {
                              if (urb->transfer_buffer == NULL) {
                                    memcpy(phys_to_virt
                                           (urb->transfer_dma) +
                                           qtd->buffer_offset,
                                           ehci->
                                           iram_buffer_v
                                           [address_to_buffer
                                          (ehci,
                                           usb_pipedevice(urb->
                                                      pipe))]
                                           + g_iram_size,
                                           min(g_iram_size,
                                             qtd->length));
                              } else {
                                    memcpy(urb->transfer_buffer +
                                           qtd->buffer_offset,
                                           ehci->
                                           iram_buffer_v
                                           [address_to_buffer
                                          (ehci,
                                           usb_pipedevice(urb->
                                                      pipe))]
                                           + g_iram_size,
                                           min(g_iram_size,
                                             qtd->length));
                              }
                        }
                        stopped = 1;
                        goto halt;
                  } else if (urb->use_iram && (!qtd->last_one)
                           && usb_pipeout(urb->pipe)) {
                        ehci->
                            iram_in_use[address_to_buffer
                                    (ehci,
                                     usb_pipedevice(urb->pipe))] =
                            1;
                        qtd2 =
                            list_entry(tmp, struct ehci_qtd, qtd_list);
                        if (urb->transfer_buffer == NULL) {
                              memcpy(ehci->
                                     iram_buffer_v[address_to_buffer
                                               (ehci,
                                                usb_pipedevice
                                                (urb->pipe))],
                                     phys_to_virt(urb->transfer_dma) +
                                     qtd->buffer_offset + qtd->length,
                                     min(g_iram_size, qtd2->length));
                        } else {
                              memcpy(ehci->
                                     iram_buffer_v[address_to_buffer
                                               (ehci,
                                                usb_pipedevice
                                                (urb->pipe))],
                                     urb->transfer_buffer +
                                     qtd->buffer_offset + qtd->length,
                                     min(g_iram_size, qtd2->length));
                        }
                        temp_hw_qtd_next =
                            QTD_NEXT(ehci, qtd->hw_next) & 0xFFFFFFFE;
                  } else if (urb->use_iram && (qtd->last_one)
                           && usb_pipeout(urb->pipe)) {
                        urb->use_iram = 0;
                        qtd2 =
                            list_entry(tmp, struct ehci_qtd, qtd_list);
                        if (tmp != &qh->qtd_list) {
                              urb2 = qtd2->urb;
                              if (urb2 && urb2->use_iram == 1) {
                                    ehci->
                                        iram_in_use
                                        [address_to_buffer
                                         (ehci,
                                          usb_pipedevice(urb->
                                                     pipe))] =
                                        1;
                                    if (urb2->transfer_buffer ==
                                        NULL) {
                                          memcpy(ehci->
                                                 iram_buffer_v
                                          [address_to_buffer
                                                (ehci,
                                                 usb_pipedevice
                                                 (urb->pipe))],
                                                 phys_to_virt
                                                 (urb2->
                                                transfer_dma),
                                                 min(g_iram_size,
                                                   qtd2->
                                                   length));
                                    } else {
                                          memcpy(ehci->
                                                 iram_buffer_v
                                          [address_to_buffer
                                                (ehci,
                                                 usb_pipedevice
                                                 (urb->pipe))],
                                                 urb2->
                                                 transfer_buffer,
                                                 min(g_iram_size,
                                                   qtd2->
                                                   length));
                                    }
                              } else {
                                    ehci->
                                        iram_in_use
                                        [address_to_buffer
                                         (ehci,
                                          usb_pipedevice(urb->
                                                     pipe))] =
                                        0;
                              }
                        } else {
                              ehci->
                                  iram_in_use[address_to_buffer
                                          (ehci,
                                           usb_pipedevice(urb->
                                                      pipe))]
                                  = 0;
                        }
                        temp_hw_qtd_next =
                            QTD_NEXT(ehci, qtd->hw_next) & 0xFFFFFFFE;
                  } else if (urb->use_iram && usb_pipein(urb->pipe)) {
                        if (urb->transfer_buffer == NULL) {
                              memcpy(phys_to_virt(urb->transfer_dma) +
                                     qtd->buffer_offset,
                                     ehci->
                                     iram_buffer_v[address_to_buffer
                                               (ehci,
                                                usb_pipedevice
                                                (urb->pipe))] +
                                     g_iram_size, min(g_iram_size,
                                                qtd->length));
                        } else {
                              memcpy(urb->transfer_buffer +
                                     qtd->buffer_offset,
                                     ehci->
                                     iram_buffer_v[address_to_buffer
                                               (ehci,
                                                usb_pipedevice
                                                (urb->pipe))] +
                                     g_iram_size, min(g_iram_size,
                                                qtd->length));
                        }
                        temp_hw_qtd_next =
                            QTD_NEXT(ehci, qtd->hw_next) & 0xFFFFFFFE;
                  }
                  /* stop scanning when we reach qtds the hc is using */
            } else if (likely(!stopped
                          && HC_IS_RUNNING(ehci_to_hcd(ehci)->state))) {
                  break;

            /* scan the whole queue for unlinks whenever it stops */
            } else {
                  stopped = 1;

                  /* cancel everything if we halt, suspend, etc */
                  if (!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))
                        last_status = -ESHUTDOWN;

                  /* this qtd is active; skip it unless a previous qtd
                   * for its urb faulted, or its urb was canceled.
                   */
                  else if (last_status == -EINPROGRESS && !urb->unlinked)
                        continue;

                  /* qh unlinked; token in overlay may be most current */
                  if (state == QH_STATE_IDLE
                              && cpu_to_hc32(ehci, qtd->qtd_dma)
                                    == qh->hw_current)
                        token = hc32_to_cpu(ehci, qh->hw_token);

                  /* qh unlinked; token in overlay may be most current */
                  if (state == QH_STATE_IDLE
                      && cpu_to_hc32(ehci, qtd->qtd_dma)
                      == qh->hw_current)
                        token = hc32_to_cpu(ehci, qh->hw_token);

                  /* force halt for unlinked or blocked qh, so we'll
                   * patch the qh later and so that completions can't
                   * activate it while we "know" it's stopped.
                   */
                  if ((halt & qh->hw_token) == 0) {
halt:
                        qh->hw_token |= halt;
                        wmb();
                  }
            }

            /* unless we already know the urb's status, collect qtd status
             * and update count of bytes transferred.  in common short read
             * cases with only one data qtd (including control transfers),
             * queue processing won't halt.  but with two or more qtds (for
             * example, with a 32 KB transfer), when the first qtd gets a
             * short read the second must be removed by hand.
             */
            if (last_status == -EINPROGRESS) {
                  last_status = qtd_copy_status(ehci, urb,
                              qtd->length, token);
                  if (last_status == -EREMOTEIO
                              && (qtd->hw_alt_next
                                    & EHCI_LIST_END(ehci)))
                        last_status = -EINPROGRESS;
            }

            /* if we're removing something not at the queue head,
             * patch the hardware queue pointer.
             */

            if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
                  last = list_entry(qtd->qtd_list.prev,
                                struct ehci_qtd, qtd_list);
                  last->hw_next = qtd->hw_next;
            }

/* remove qtd; it's recycled after possible urb completion */
            list_del(&qtd->qtd_list);
            last = qtd;
      }

      /* last urb's completion might still need calling */
      if (likely(last != NULL)) {
            ehci_urb_done(ehci, last->urb, last_status);
            count++;
            ehci_qtd_free(ehci, last);
      }

      /* restore original state; caller must unlink or relink */
      qh->qh_state = state;

      /* be sure the hardware's done with the qh before refreshing
       * it after fault cleanup, or recovering from silicon wrongly
       * overlaying the dummy qtd (which reduces DMA chatter).
       */
      if ((stopped != 0) || (qh->hw_qtd_next == EHCI_LIST_END(ehci))
          && (temp_hw_qtd_next == 0)) {
            switch (state) {
            case QH_STATE_IDLE:
                  qh_refresh(ehci, qh);
                  break;
            case QH_STATE_LINKED:
                  /* We won't refresh a QH that's linked (after the HC
                   * stopped the queue).  That avoids a race:
                   *  - HC reads first part of QH;
                   *  - CPU updates that first part and the token;
                   *  - HC reads rest of that QH, including token
                   * Result:  HC gets an inconsistent image, and then
                   * DMAs to/from the wrong memory (corrupting it).
                   *
                   * That should be rare for interrupt transfers,
                   * except maybe high bandwidth ...
                   */
                  if ((cpu_to_hc32(ehci, QH_SMASK)
                       & qh->hw_info2) != 0) {
                        intr_deschedule(ehci, qh);
                        (void)qh_schedule(ehci, qh);
                  } else
                        unlink_async(ehci, qh);
                  break;
                  /* otherwise, unlink already started */
            }
      }
      if (temp_hw_qtd_next)
            qh->hw_qtd_next = temp_hw_qtd_next;

      return count;
}

/*-------------------------------------------------------------------------*/

/* high bandwidth multiplier, as encoded in highspeed endpoint descriptors */
#define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
/* ... and packet size, for any kind of endpoint descriptor */
#define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)

/*
 * reverse of qh_urb_transaction:  free a list of TDs.
 * used for cleanup after errors, before HC sees an URB's TDs.
 */
static void qtd_list_free(struct ehci_hcd *ehci,
                    struct urb *urb, struct list_head *qtd_list)
{
      struct list_head *entry, *temp;

      list_for_each_safe(entry, temp, qtd_list) {
            struct ehci_qtd *qtd;

            qtd = list_entry(entry, struct ehci_qtd, qtd_list);
            list_del(&qtd->qtd_list);
            ehci_qtd_free(ehci, qtd);
      }
}

/*
 * create a list of filled qtds for this URB; won't link into qh.
 */
static struct list_head *qh_urb_transaction(struct ehci_hcd *ehci,
                                  struct urb *urb,
                                  struct list_head *head, gfp_t flags)
{
      struct ehci_qtd *qtd, *qtd_prev;
      dma_addr_t buf;
      int len, maxpacket;
      int is_input;
      u32 token;

      /*
       * URBs map to sequences of QTDs:  one logical transaction
       */
      qtd = ehci_qtd_alloc(ehci, flags);
      if (unlikely(!qtd))
            return NULL;
      list_add_tail(&qtd->qtd_list, head);
      qtd->urb = urb;

      token = QTD_STS_ACTIVE;
      token |= (EHCI_TUNE_CERR << 10);
      /* for split transactions, SplitXState initialized to zero */

      len = urb->transfer_buffer_length;
      is_input = usb_pipein(urb->pipe);
      if (usb_pipecontrol(urb->pipe)) {
            /* SETUP pid */
            qtd_fill(ehci, qtd, urb->setup_dma,
                   sizeof(struct usb_ctrlrequest),
                   token | (2 /* "setup" */  << 8), 8);

            /* ... and always at least one more pid */
            token ^= QTD_TOGGLE;
            qtd_prev = qtd;
            qtd = ehci_qtd_alloc(ehci, flags);
            if (unlikely(!qtd))
                  goto cleanup;
            qtd->urb = urb;
            qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
            list_add_tail(&qtd->qtd_list, head);

            /* for zero length DATA stages, STATUS is always IN */
            if (len == 0)
                  token |= (1 /* "in" */  << 8);
      }

      /*
       * data transfer stage:  buffer setup
       */
      buf = urb->transfer_dma;

      if (is_input)
            token |= (1 /* "in" */  << 8);
      /* else it's already initted to "out" pid (0 << 8) */

      maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));

      /*
       * buffer gets wrapped in one or more qtds;
       * last one may be "short" (including zero len)
       * and may serve as a control status ack
       */
      for (;;) {
            int this_qtd_len;
            this_qtd_len = qtd_fill(ehci, qtd, buf, len, token, maxpacket);
            if (urb->use_iram && (!qtd->buffer_offset)
                && usb_pipeout(urb->pipe)
                && (ehci->
                  iram_in_use[address_to_buffer
                            (ehci, usb_pipedevice(urb->pipe))] == 0)) {
                  ehci->
                      iram_in_use[address_to_buffer
                              (ehci, usb_pipedevice(urb->pipe))] = 1;
                  if (urb->transfer_buffer == NULL) {
                        memcpy(ehci->
                               iram_buffer_v[address_to_buffer
                                         (ehci,
                                          usb_pipedevice(urb->
                                                     pipe))],
                               phys_to_virt(urb->transfer_dma),
                               min((int)g_iram_size, len));
                  } else {
                        memcpy(ehci->
                               iram_buffer_v[address_to_buffer
                                         (ehci,
                                          usb_pipedevice(urb->
                                                     pipe))],
                               urb->transfer_buffer,
                               min((int)g_iram_size, len));
                  }
            }
            len -= this_qtd_len;
            buf += this_qtd_len;

            /*
             * short reads advance to a "magic" dummy instead of the next
             * qtd ... that forces the queue to stop, for manual cleanup.
             * (this will usually be overridden later.)
             */
            if (is_input)
                  qtd->hw_alt_next = ehci->async->hw_alt_next;

            /* qh makes control packets use qtd toggle; maybe switch it */
            if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
                  token ^= QTD_TOGGLE;

            if (likely(len <= 0)) {
                  qtd->last_one = 1;
                  break;
            }
            qtd_prev = qtd;
            qtd = ehci_qtd_alloc(ehci, flags);
            if (unlikely(!qtd))
                  goto cleanup;
            qtd->urb = urb;
            if (urb->use_iram)
                  qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma) | 0x1;
            else
                  qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);

            list_add_tail(&qtd->qtd_list, head);
      }

      /*
       * unless the caller requires manual cleanup after short reads,
       * have the alt_next mechanism keep the queue running after the
       * last data qtd (the only one, for control and most other cases).
       */
      if (likely((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
               || usb_pipecontrol(urb->pipe)))
            qtd->hw_alt_next = EHCI_LIST_END(ehci);

      /*
       * control requests may need a terminating data "status" ack;
       * bulk ones may need a terminating short packet (zero length).
       */
      if (likely(urb->transfer_buffer_length != 0)) {
            int one_more = 0;

            if (usb_pipecontrol(urb->pipe)) {
                  one_more = 1;
                  token ^= 0x0100;  /* "in" <--> "out"  */
                  token |= QTD_TOGGLE;    /* force DATA1 */
            } else if (usb_pipebulk(urb->pipe)
                     && (urb->transfer_flags & URB_ZERO_PACKET)
                     && !(urb->transfer_buffer_length % maxpacket))
                  one_more = 1;
            if (one_more) {
                  qtd_prev = qtd;
                  qtd = ehci_qtd_alloc(ehci, flags);
                  if (unlikely(!qtd))
                        goto cleanup;
                  qtd->urb = urb;
                  qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
                  list_add_tail(&qtd->qtd_list, head);

                  /* never any data in such packets */
                  qtd_fill(ehci, qtd, 0, 0, token, 0);
            }
      }

      /* by default, enable interrupt on urb completion */
      if (likely(!(urb->transfer_flags & URB_NO_INTERRUPT)))
            qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
      return head;

cleanup:
      qtd_list_free(ehci, urb, head);
      return NULL;
}

/*-------------------------------------------------------------------------*/

/* Would be best to create all qh's from config descriptors,
 * when each interface/altsetting is established.  Unlink
 * any previous qh and cancel its urbs first; endpoints are
 * implicitly reset then (data toggle too).
 * That'd mean updating how usbcore talks to HCDs. (2.7?)
 */

/*
 * Each QH holds a qtd list; a QH is used for everything except iso.
 *
 * For interrupt urbs, the scheduler must set the microframe scheduling
 * mask(s) each time the QH gets scheduled.  For highspeed, that's
 * just one microframe in the s-mask.  For split interrupt transactions
 * there are additional complications: c-mask, maybe FSTNs.
 */
static struct ehci_qh *qh_make(struct ehci_hcd *ehci,
                         struct urb *urb, gfp_t flags)
{
      struct ehci_qh *qh = ehci_qh_alloc(ehci, flags);
      u32 info1 = 0, info2 = 0;
      int is_input, type;
      int maxp = 0;
      struct usb_tt           *tt = urb->dev->tt;

      if (!qh)
            return qh;

      /*
       * init endpoint/device data for this QH
       */
      info1 |= usb_pipeendpoint(urb->pipe) << 8;
      info1 |= usb_pipedevice(urb->pipe) << 0;

      is_input = usb_pipein(urb->pipe);
      type = usb_pipetype(urb->pipe);
      maxp = usb_maxpacket(urb->dev, urb->pipe, !is_input);

      /* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
       * acts like up to 3KB, but is built from smaller packets.
       */
      if (max_packet(maxp) > 1024) {
            ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
            goto done;
      }

      /* Compute interrupt scheduling parameters just once, and save.
       * - allowing for high bandwidth, how many nsec/uframe are used?
       * - split transactions need a second CSPLIT uframe; same question
       * - splits also need a schedule gap (for full/low speed I/O)
       * - qh has a polling interval
       *
       * For control/bulk requests, the HC or TT handles these.
       */
      if (type == PIPE_INTERRUPT) {
            qh->usecs =
                NS_TO_US(usb_calc_bus_time
                       (USB_SPEED_HIGH, is_input, 0,
                        hb_mult(maxp) * max_packet(maxp)));
            qh->start = NO_FRAME;

            if (urb->dev->speed == USB_SPEED_HIGH) {
                  qh->c_usecs = 0;
                  qh->gap_uf = 0;

                  qh->period = urb->interval >> 3;
                  if (qh->period == 0 && urb->interval != 1) {
                        /* NOTE interval 2 or 4 uframes could work.
                         * But interval 1 scheduling is simpler, and
                         * includes high bandwidth.
                         */
                        dbg("intr period %d uframes, NYET!",
                            urb->interval);
                        goto done;
                  }
            } else {
                  int think_time;

                  /* gap is f(FS/LS transfer times) */
                  qh->gap_uf = 1 + usb_calc_bus_time(urb->dev->speed,
                                             is_input, 0,
                                             maxp) / (125 * 1000);

                  /* FIXME this just approximates SPLIT/CSPLIT times */
                  if (is_input) {
                        qh->c_usecs = qh->usecs + HS_USECS(0);
                        qh->usecs = HS_USECS(1);
                  } else {
                        qh->usecs += HS_USECS(1);
                        qh->c_usecs = HS_USECS(0);
                  }

                  think_time = tt ? tt->think_time : 0;
                  qh->tt_usecs = NS_TO_US(think_time +
                                    usb_calc_bus_time(urb->dev->
                                                  speed,
                                                  is_input, 0,
                                                  max_packet
                                                  (maxp)));
                  qh->period = urb->interval;
            }
      }

      /* support for tt scheduling, and access to toggles */
      qh->dev = urb->dev;

      /* using TT? */
      switch (urb->dev->speed) {
      case USB_SPEED_LOW:
            info1 |= (1 << 12);     /* EPS "low" */
            /* FALL THROUGH */

      case USB_SPEED_FULL:
            /* EPS 0 means "full" */
            if (type != PIPE_INTERRUPT)
                  info1 |= (EHCI_TUNE_RL_TT << 28);
            if (type == PIPE_CONTROL) {
                  info1 |= (1 << 27);     /* for TT */
                  info1 |= 1 << 14; /* toggle from qtd */
            }
            info1 |= maxp << 16;

            info2 |= (EHCI_TUNE_MULT_TT << 30);

            /* Some Freescale processors have an erratum in which the
             * port number in the queue head was 0..N-1 instead of 1..N.
             */
            if (ehci_has_fsl_portno_bug(ehci))
                  info2 |= (urb->dev->ttport - 1) << 23;
            else
                  info2 |= urb->dev->ttport << 23;

            /* set the address of the TT; for TDI's integrated
             * root hub tt, leave it zeroed.
             */
            if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub)
                  info2 |= tt->hub->devnum << 16;

            /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets c-mask } */

            break;

      case USB_SPEED_HIGH:    /* no TT involved */
            info1 |= (2 << 12);     /* EPS "high" */
            if (type == PIPE_CONTROL) {
                  info1 |= (EHCI_TUNE_RL_HS << 28);
                  info1 |= 64 << 16;      /* usb2 fixed maxpacket */
                  info1 |= 1 << 14; /* toggle from qtd */
                  info2 |= (EHCI_TUNE_MULT_HS << 30);
            } else if (type == PIPE_BULK) {
                  info1 |= (EHCI_TUNE_RL_HS << 28);
                  /* The USB spec says that high speed bulk endpoints
                   * always use 512 byte maxpacket.  But some device
                   * vendors decided to ignore that, and MSFT is happy
                   * to help them do so.  So now people expect to use
                   * such nonconformant devices with Linux too; sigh.
                   */
                  info1 |= max_packet(maxp) << 16;
                  info2 |= (EHCI_TUNE_MULT_HS << 30);
                  use_buffer(ehci, usb_pipedevice(urb->pipe));
            } else {    /* PIPE_INTERRUPT */
                  info1 |= max_packet(maxp) << 16;
                  info2 |= hb_mult(maxp) << 30;
            }
            break;
      default:
            dbg("bogus dev %p speed %d", urb->dev, urb->dev->speed);
done:
            qh_put(qh);
            return NULL;
      }

      /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */

      /* init as live, toggle clear, advance to dummy */
      qh->qh_state = QH_STATE_IDLE;
      qh->hw_info1 = cpu_to_hc32(ehci, info1);
      qh->hw_info2 = cpu_to_hc32(ehci, info2);
      usb_settoggle(urb->dev, usb_pipeendpoint(urb->pipe), !is_input, 1);
      qh_refresh(ehci, qh);
      return qh;
}

/*-------------------------------------------------------------------------*/

/* move qh (and its qtds) onto async queue; maybe enable queue.  */

static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
{
      __hc32 dma = QH_NEXT(ehci, qh->qh_dma);
      struct ehci_qh *head;

      /* (re)start the async schedule? */
      head = ehci->async;
      timer_action_done(ehci, TIMER_ASYNC_OFF);
      if (!head->qh_next.qh) {
            u32 cmd = ehci_readl(ehci, &ehci->regs->command);

            if (!(cmd & CMD_ASE)) {
                  /* in case a clear of CMD_ASE didn't take yet */
                  (void)handshake(ehci, &ehci->regs->status,
                              STS_ASS, 0, 150);
                  cmd |= CMD_ASE | CMD_RUN;
                  ehci_writel(ehci, cmd, &ehci->regs->command);
                  ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
                  /* posted write need not be known to HC yet ... */
            }
      }

      /* clear halt and/or toggle; and maybe recover from silicon quirk */
      if (qh->qh_state == QH_STATE_IDLE)
            qh_refresh(ehci, qh);

      /* splice right after start */
      qh->qh_next = head->qh_next;
      qh->hw_next = head->hw_next;
      wmb();

      head->qh_next.qh = qh;
      head->hw_next = dma;

      qh->qh_state = QH_STATE_LINKED;
      /* qtd completions reported later by interrupt */
}

/*-------------------------------------------------------------------------*/

/*
 * For control/bulk/interrupt, return QH with these TDs appended.
 * Allocates and initializes the QH if necessary.
 * Returns null if it can't allocate a QH it needs to.
 * If the QH has TDs (urbs) already, that's great.
 */
static struct ehci_qh *qh_append_tds(struct ehci_hcd *ehci,
                             struct urb *urb,
                             struct list_head *qtd_list,
                             int epnum, void **ptr)
{
      struct ehci_qh *qh = NULL;
      __hc32 qh_addr_mask = cpu_to_hc32(ehci, 0x7f);

      qh = (struct ehci_qh *)*ptr;
      if (unlikely(qh == NULL)) {
            /* can't sleep here, we have ehci->lock... */
            qh = qh_make(ehci, urb, GFP_ATOMIC);
            *ptr = qh;
      }
      if (likely(qh != NULL)) {
            struct ehci_qtd *qtd;

            if (unlikely(list_empty(qtd_list)))
                  qtd = NULL;
            else
                  qtd = list_entry(qtd_list->next, struct ehci_qtd,
                               qtd_list);

            /* control qh may need patching ... */
            if (unlikely(epnum == 0)) {

                  /* usb_reset_device() briefly reverts to address 0 */
                  if (usb_pipedevice(urb->pipe) == 0)
                        qh->hw_info1 &= ~qh_addr_mask;
            }

            /* just one way to queue requests: swap with the dummy qtd.
             * only hc or qh_refresh() ever modify the overlay.
             */
            if (likely(qtd != NULL)) {
                  struct ehci_qtd *dummy;
                  dma_addr_t dma;
                  __hc32 token;

                  /* to avoid racing the HC, use the dummy td instead of
                   * the first td of our list (becomes new dummy).  both
                   * tds stay deactivated until we're done, when the
                   * HC is allowed to fetch the old dummy (4.10.2).
                   */
                  token = qtd->hw_token;
                  qtd->hw_token = HALT_BIT(ehci);
                  wmb();
                  dummy = qh->dummy;

                  dma = dummy->qtd_dma;
                  *dummy = *qtd;
                  dummy->qtd_dma = dma;

                  list_del(&qtd->qtd_list);
                  list_add(&dummy->qtd_list, qtd_list);
                  __list_splice(qtd_list, qh->qtd_list.prev);

                  ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
                  qh->dummy = qtd;

                  /* hc must see the new dummy at list end */
                  dma = qtd->qtd_dma;
                  qtd = list_entry(qh->qtd_list.prev,
                               struct ehci_qtd, qtd_list);
                  if (urb->use_iram)
                        qtd->hw_next = QTD_NEXT(ehci, dma) | 0x1;
                  else
                        qtd->hw_next = QTD_NEXT(ehci, dma);

                  /* let the hc process these next qtds */
                  wmb();
                  dummy->hw_token = token;

                  urb->hcpriv = qh_get(qh);
            }
      }
      return qh;
}

/*-------------------------------------------------------------------------*/

static int
submit_async(struct ehci_hcd *ehci,
           struct urb *urb, struct list_head *qtd_list, gfp_t mem_flags)
{
      struct ehci_qtd *qtd;
      int epnum;
      unsigned long flags;
      struct ehci_qh *qh = NULL;
      int rc;

      qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list);
      epnum = urb->ep->desc.bEndpointAddress;

#ifdef EHCI_URB_TRACE
      ehci_dbg(ehci,
             "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
             __func__, urb->dev->devpath, urb,
             epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
             urb->transfer_buffer_length, qtd, urb->ep->hcpriv);
#endif

      spin_lock_irqsave(&ehci->lock, flags);
      if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
                         &ehci_to_hcd(ehci)->flags))) {
            rc = -ESHUTDOWN;
            goto done;
      }
      rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
      if (unlikely(rc))
            goto done;

      qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
      if (unlikely(qh == NULL)) {
            usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
            rc = -ENOMEM;
            goto done;
      }

      /* Control/bulk operations through TTs don't need scheduling,
       * the HC and TT handle it when the TT has a buffer ready.
       */
      if (likely(qh->qh_state == QH_STATE_IDLE))
            qh_link_async(ehci, qh_get(qh));
done:
      spin_unlock_irqrestore(&ehci->lock, flags);
      if (unlikely(qh == NULL))
            qtd_list_free(ehci, urb, qtd_list);
      return rc;
}

/*-------------------------------------------------------------------------*/

/* the async qh for the qtds being reclaimed are now unlinked from the HC */

static void end_unlink_async(struct ehci_hcd *ehci)
{
      struct ehci_qh *qh = ehci->reclaim;
      struct ehci_qh *next;

      iaa_watchdog_done(ehci);

      qh->qh_state = QH_STATE_IDLE;
      qh->qh_next.qh = NULL;
      qh_put(qh);       /* refcount from reclaim */

      /* other unlink(s) may be pending (in QH_STATE_UNLINK_WAIT) */
      next = qh->reclaim;
      ehci->reclaim = next;
      qh->reclaim = NULL;

      qh_completions(ehci, qh);

      if (!list_empty(&qh->qtd_list)
          && HC_IS_RUNNING(ehci_to_hcd(ehci)->state))
            qh_link_async(ehci, qh);
      else {
            qh_put(qh); /* refcount from async list */

            /* it's not free to turn the async schedule on/off; leave it
             * active but idle for a while once it empties.
             */
            if (HC_IS_RUNNING(ehci_to_hcd(ehci)->state)
                && ehci->async->qh_next.qh == NULL)
                  timer_action(ehci, TIMER_ASYNC_OFF);
      }

      if (next) {
            ehci->reclaim = NULL;
            start_unlink_async(ehci, next);
      }
}

/* makes sure the async qh will become idle */
/* caller must own ehci->lock */

static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
{
      int cmd = ehci_readl(ehci, &ehci->regs->command);
      struct ehci_qh *prev;

#ifdef DEBUG
      assert_spin_locked(&ehci->lock);
      if (ehci->reclaim
          || (qh->qh_state != QH_STATE_LINKED
            && qh->qh_state != QH_STATE_UNLINK_WAIT)
          )
            BUG();
#endif

      /* stop async schedule right now? */
      if (unlikely(qh == ehci->async)) {
            /* can't get here without STS_ASS set */
            if (ehci_to_hcd(ehci)->state != HC_STATE_HALT &&
                  !ehci->reclaim) {
                  /* ... and CMD_IAAD clear */
                  ehci_writel(ehci, cmd & ~CMD_ASE, &ehci->regs->command);
                  wmb();
                  /* handshake later, if we need to */
                  timer_action_done(ehci, TIMER_ASYNC_OFF);
            }
            return;
      }

      qh->qh_state = QH_STATE_UNLINK;
      ehci->reclaim = qh = qh_get(qh);

      prev = ehci->async;
      while (prev->qh_next.qh != qh)
            prev = prev->qh_next.qh;

      prev->hw_next = qh->hw_next;
      prev->qh_next = qh->qh_next;
      wmb();

      if (unlikely(ehci_to_hcd(ehci)->state == HC_STATE_HALT)) {
            /* if (unlikely (qh->reclaim != 0))
             *  this will recurse, probably not much
             */
            end_unlink_async(ehci);
            return;
      }

      cmd |= CMD_IAAD;
      ehci_writel(ehci, cmd, &ehci->regs->command);
      (void)ehci_readl(ehci, &ehci->regs->command);
      iaa_watchdog_start(ehci);
}

/*-------------------------------------------------------------------------*/

static void scan_async(struct ehci_hcd *ehci)
{
      struct ehci_qh *qh;
      enum ehci_timer_action action = TIMER_IO_WATCHDOG;

      if (!++(ehci->stamp))
            ehci->stamp++;
      timer_action_done(ehci, TIMER_ASYNC_SHRINK);
rescan:
      qh = ehci->async->qh_next.qh;
      if (likely(qh != NULL)) {
            do {
                  /* clean any finished work for this qh */
                  if (!list_empty(&qh->qtd_list)
                      && qh->stamp != ehci->stamp) {
                        int temp;

                        /* unlinks could happen here; completion
                         * reporting drops the lock.  rescan using
                         * the latest schedule, but don't rescan
                         * qhs we already finished (no looping).
                         */
                        qh = qh_get(qh);
                        qh->stamp = ehci->stamp;
                        temp = qh_completions(ehci, qh);
                        qh_put(qh);
                        if (temp != 0)
                              goto rescan;
                  }

                  /* unlink idle entries, reducing HC PCI usage as well
                   * as HCD schedule-scanning costs.  delay for any qh
                   * we just scanned, there's a not-unusual case that it
                   * doesn't stay idle for long.
                   * (plus, avoids some kind of re-activation race.)
                   */
                  if (list_empty(&qh->qtd_list)) {
                        if (qh->stamp == ehci->stamp)
                              action = TIMER_ASYNC_SHRINK;
                        else if (!ehci->reclaim
                               && qh->qh_state == QH_STATE_LINKED)
                              start_unlink_async(ehci, qh);
                  }

                  qh = qh->qh_next.qh;
            } while (qh);
      }
      if (action == TIMER_ASYNC_SHRINK)
            timer_action(ehci, TIMER_ASYNC_SHRINK);
}

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