drivers/usb/host/ehci-q.c

   1 /*
   2  * Copyright (C) 2001-2004 by David Brownell
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License as published by the
   6  * Free Software Foundation; either version 2 of the License, or (at your
   7  * option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  11  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software Foundation,
  16  * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 /* this file is part of ehci-hcd.c */
  20
  21 /*-------------------------------------------------------------------------*/
  22
  23 /*
  24  * EHCI hardware queue manipulation ... the core.  QH/QTD manipulation.
  25  *
  26  * Control, bulk, and interrupt traffic all use "qh" lists.  They list "qtd"
  27  * entries describing USB transactions, max 16-20kB/entry (with 4kB-aligned
  28  * buffers needed for the larger number).  We use one QH per endpoint, queue
  29  * multiple urbs (all three types) per endpoint.  URBs may need several qtds.
  30  *
  31  * ISO traffic uses "ISO TD" (itd, and sitd) records, and (along with
  32  * interrupts) needs careful scheduling.  Performance improvements can be
  33  * an ongoing challenge.  That's in "ehci-sched.c".
  34  *
  35  * USB 1.1 devices are handled (a) by "companion" OHCI or UHCI root hubs,
  36  * or otherwise through transaction translators (TTs) in USB 2.0 hubs using
  37  * (b) special fields in qh entries or (c) split iso entries.  TTs will
  38  * buffer low/full speed data so the host collects it at high speed.
  39  */
  40
  41 /*-------------------------------------------------------------------------*/
  42
  43 /* fill a qtd, returning how much of the buffer we were able to queue up */
  44
  45 static int
  46 qtd_fill(struct ehci_hcd *ehci, struct ehci_qtd *qtd, dma_addr_t buf,
  47                   size_t len, int token, int maxpacket)
  48 {
  49         int     i, count;
  50         u64     addr = buf;
  51
  52         /* one buffer entry per 4K ... first might be short or unaligned */
  53         qtd->hw_buf[0] = cpu_to_hc32(ehci, (u32)addr);
  54         qtd->hw_buf_hi[0] = cpu_to_hc32(ehci, (u32)(addr >> 32));
  55         count = 0x1000 - (buf & 0x0fff);        /* rest of that page */
  56         if (likely (len < count))               /* ... iff needed */
  57                 count = len;
  58         else {
  59                 buf +=  0x1000;
  60                 buf &= ~0x0fff;
  61
  62                 /* per-qtd limit: from 16K to 20K (best alignment) */
  63                 for (i = 1; count < len && i < 5; i++) {
  64                         addr = buf;
  65                         qtd->hw_buf[i] = cpu_to_hc32(ehci, (u32)addr);
  66                         qtd->hw_buf_hi[i] = cpu_to_hc32(ehci,
  67                                         (u32)(addr >> 32));
  68                         buf += 0x1000;
  69                         if ((count + 0x1000) < len)
  70                                 count += 0x1000;
  71                         else
  72                                 count = len;
  73                 }
  74
  75                 /* short packets may only terminate transfers */
  76                 if (count != len)
  77                         count -= (count % maxpacket);
  78         }
  79         qtd->hw_token = cpu_to_hc32(ehci, (count << 16) | token);
  80         qtd->length = count;
  81
  82         return count;
  83 }
  84
  85 /*-------------------------------------------------------------------------*/
  86
  87 static inline void
  88 qh_update (struct ehci_hcd *ehci, struct ehci_qh *qh, struct ehci_qtd *qtd)
  89 {
  90         struct ehci_qh_hw *hw = qh->hw;
  91
  92         /* writes to an active overlay are unsafe */
  93         BUG_ON(qh->qh_state != QH_STATE_IDLE);
  94
  95         hw->hw_qtd_next = QTD_NEXT(ehci, qtd->qtd_dma);
  96         hw->hw_alt_next = EHCI_LIST_END(ehci);
  97
  98         /* Except for control endpoints, we make hardware maintain data
  99          * toggle (like OHCI) ... here (re)initialize the toggle in the QH,
 100          * and set the pseudo-toggle in udev. Only usb_clear_halt() will
 101          * ever clear it.
 102          */
 103         if (!(hw->hw_info1 & cpu_to_hc32(ehci, QH_TOGGLE_CTL))) {
 104                 unsigned        is_out, epnum;
 105
 106                 is_out = qh->is_out;
 107                 epnum = (hc32_to_cpup(ehci, &hw->hw_info1) >> 8) & 0x0f;
 108                 if (unlikely (!usb_gettoggle (qh->dev, epnum, is_out))) {
 109                         hw->hw_token &= ~cpu_to_hc32(ehci, QTD_TOGGLE);
 110                         usb_settoggle (qh->dev, epnum, is_out, 1);
 111                 }
 112         }
 113
 114         hw->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING);
 115 }
 116
 117 /* if it weren't for a common silicon quirk (writing the dummy into the qh
 118  * overlay, so qh->hw_token wrongly becomes inactive/halted), only fault
 119  * recovery (including urb dequeue) would need software changes to a QH...
 120  */
 121 static void
 122 qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh)
 123 {
 124         struct ehci_qtd *qtd;
 125
 126         if (list_empty (&qh->qtd_list))
 127                 qtd = qh->dummy;
 128         else {
 129                 qtd = list_entry (qh->qtd_list.next,
 130                                 struct ehci_qtd, qtd_list);
 131                 /*
 132                  * first qtd may already be partially processed.
 133                  * If we come here during unlink, the QH overlay region
 134                  * might have reference to the just unlinked qtd. The
 135                  * qtd is updated in qh_completions(). Update the QH
 136                  * overlay here.
 137                  */
 138                 if (qh->hw->hw_token & ACTIVE_BIT(ehci)) {
 139                         qh->hw->hw_qtd_next = qtd->hw_next;
 140                         qtd = NULL;
 141                 }
 142         }
 143
 144         if (qtd)
 145                 qh_update (ehci, qh, qtd);
 146 }
 147
 148 /*-------------------------------------------------------------------------*/
 149
 150 static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
 151
 152 static void ehci_clear_tt_buffer_complete(struct usb_hcd *hcd,
 153                 struct usb_host_endpoint *ep)
 154 {
 155         struct ehci_hcd         *ehci = hcd_to_ehci(hcd);
 156         struct ehci_qh          *qh = ep->hcpriv;
 157         unsigned long           flags;
 158
 159         spin_lock_irqsave(&ehci->lock, flags);
 160         qh->clearing_tt = 0;
 161         if (qh->qh_state == QH_STATE_IDLE && !list_empty(&qh->qtd_list)
 162                         && ehci->rh_state == EHCI_RH_RUNNING)
 163                 qh_link_async(ehci, qh);
 164         spin_unlock_irqrestore(&ehci->lock, flags);
 165 }
 166
 167 static void ehci_clear_tt_buffer(struct ehci_hcd *ehci, struct ehci_qh *qh,
 168                 struct urb *urb, u32 token)
 169 {
 170
 171         /* If an async split transaction gets an error or is unlinked,
 172          * the TT buffer may be left in an indeterminate state.  We
 173          * have to clear the TT buffer.
 174          *
 175          * Note: this routine is never called for Isochronous transfers.
 176          */
 177         if (urb->dev->tt && !usb_pipeint(urb->pipe) && !qh->clearing_tt) {
 178 #ifdef DEBUG
 179                 struct usb_device *tt = urb->dev->tt->hub;
 180                 dev_dbg(&tt->dev,
 181                         "clear tt buffer port %d, a%d ep%d t%08x\n",
 182                         urb->dev->ttport, urb->dev->devnum,
 183                         usb_pipeendpoint(urb->pipe), token);
 184 #endif /* DEBUG */
 185                 if (!ehci_is_TDI(ehci)
 186                                 || urb->dev->tt->hub !=
 187                                    ehci_to_hcd(ehci)->self.root_hub) {
 188                         if (usb_hub_clear_tt_buffer(urb) == 0)
 189                                 qh->clearing_tt = 1;
 190                 } else {
 191
 192                         /* REVISIT ARC-derived cores don't clear the root
 193                          * hub TT buffer in this way...
 194                          */
 195                 }
 196         }
 197 }
 198
 199 static int qtd_copy_status (
 200         struct ehci_hcd *ehci,
 201         struct urb *urb,
 202         size_t length,
 203         u32 token
 204 )
 205 {
 206         int     status = -EINPROGRESS;
 207
 208         /* count IN/OUT bytes, not SETUP (even short packets) */
 209         if (likely (QTD_PID (token) != 2))
 210                 urb->actual_length += length - QTD_LENGTH (token);
 211
 212         /* don't modify error codes */
 213         if (unlikely(urb->unlinked))
 214                 return status;
 215
 216         /* force cleanup after short read; not always an error */
 217         if (unlikely (IS_SHORT_READ (token)))
 218                 status = -EREMOTEIO;
 219
 220         /* serious "can't proceed" faults reported by the hardware */
 221         if (token & QTD_STS_HALT) {
 222                 if (token & QTD_STS_BABBLE) {
 223                         /* FIXME "must" disable babbling device's port too */
 224                         status = -EOVERFLOW;
 225                 /* CERR nonzero + halt --> stall */
 226                 } else if (QTD_CERR(token)) {
 227                         status = -EPIPE;
 228
 229                 /* In theory, more than one of the following bits can be set
 230                  * since they are sticky and the transaction is retried.
 231                  * Which to test first is rather arbitrary.
 232                  */
 233                 } else if (token & QTD_STS_MMF) {
 234                         /* fs/ls interrupt xfer missed the complete-split */
 235                         status = -EPROTO;
 236                 } else if (token & QTD_STS_DBE) {
 237                         status = (QTD_PID (token) == 1) /* IN ? */
 238                                 ? -ENOSR  /* hc couldn't read data */
 239                                 : -ECOMM; /* hc couldn't write data */
 240                 } else if (token & QTD_STS_XACT) {
 241                         /* timeout, bad CRC, wrong PID, etc */
 242                         ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
 243                                 urb->dev->devpath,
 244                                 usb_pipeendpoint(urb->pipe),
 245                                 usb_pipein(urb->pipe) ? "in" : "out");
 246                         status = -EPROTO;
 247                 } else {        /* unknown */
 248                         status = -EPROTO;
 249                 }
 250
 251                 ehci_vdbg (ehci,
 252                         "dev%d ep%d%s qtd token %08x --> status %d\n",
 253                         usb_pipedevice (urb->pipe),
 254                         usb_pipeendpoint (urb->pipe),
 255                         usb_pipein (urb->pipe) ? "in" : "out",
 256                         token, status);
 257         }
 258
 259         return status;
 260 }
 261
 262 static void
 263 ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 264 __releases(ehci->lock)
 265 __acquires(ehci->lock)
 266 {
 267         if (usb_pipetype(urb->pipe) == PIPE_INTERRUPT) {
 268                 /* ... update hc-wide periodic stats */
 269                 ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
 270         }
 271
 272         if (unlikely(urb->unlinked)) {
 273                 COUNT(ehci->stats.unlink);
 274         } else {
 275                 /* report non-error and short read status as zero */
 276                 if (status == -EINPROGRESS || status == -EREMOTEIO)
 277                         status = 0;
 278                 COUNT(ehci->stats.complete);
 279         }
 280
 281 #ifdef EHCI_URB_TRACE
 282         ehci_dbg (ehci,
 283                 "%s %s urb %p ep%d%s status %d len %d/%d\n",
 284                 __func__, urb->dev->devpath, urb,
 285                 usb_pipeendpoint (urb->pipe),
 286                 usb_pipein (urb->pipe) ? "in" : "out",
 287                 status,
 288                 urb->actual_length, urb->transfer_buffer_length);
 289 #endif
 290
 291         /* complete() can reenter this HCD */
 292         usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 293         spin_unlock (&ehci->lock);
 294         usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status);
 295         spin_lock (&ehci->lock);
 296 }
 297
 298 static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);
 299
 300 /*
 301  * Process and free completed qtds for a qh, returning URBs to drivers.
 302  * Chases up to qh->hw_current.  Returns number of completions called,
 303  * indicating how much "real" work we did.
 304  */
 305 static unsigned
 306 qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 307 {
 308         struct ehci_qtd         *last, *end = qh->dummy;
 309         struct list_head        *entry, *tmp;
 310         int                     last_status;
 311         int                     stopped;
 312         unsigned                count = 0;
 313         u8                      state;
 314         struct ehci_qh_hw       *hw = qh->hw;
 315
 316         if (unlikely (list_empty (&qh->qtd_list)))
 317                 return count;
 318
 319         /* completions (or tasks on other cpus) must never clobber HALT
 320          * till we've gone through and cleaned everything up, even when
 321          * they add urbs to this qh's queue or mark them for unlinking.
 322          *
 323          * NOTE:  unlinking expects to be done in queue order.
 324          *
 325          * It's a bug for qh->qh_state to be anything other than
 326          * QH_STATE_IDLE, unless our caller is scan_async() or
 327          * scan_intr().
 328          */
 329         state = qh->qh_state;
 330         qh->qh_state = QH_STATE_COMPLETING;
 331         stopped = (state == QH_STATE_IDLE);
 332
 333  rescan:
 334         last = NULL;
 335         last_status = -EINPROGRESS;
 336         qh->needs_rescan = 0;
 337
 338         /* remove de-activated QTDs from front of queue.
 339          * after faults (including short reads), cleanup this urb
 340          * then let the queue advance.
 341          * if queue is stopped, handles unlinks.
 342          */
 343         list_for_each_safe (entry, tmp, &qh->qtd_list) {
 344                 struct ehci_qtd *qtd;
 345                 struct urb      *urb;
 346                 u32             token = 0;
 347
 348                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 349                 urb = qtd->urb;
 350
 351                 /* clean up any state from previous QTD ...*/
 352                 if (last) {
 353                         if (likely (last->urb != urb)) {
 354                                 ehci_urb_done(ehci, last->urb, last_status);
 355                                 count++;
 356                                 last_status = -EINPROGRESS;
 357                         }
 358                         ehci_qtd_free (ehci, last);
 359                         last = NULL;
 360                 }
 361
 362                 /* ignore urbs submitted during completions we reported */
 363                 if (qtd == end)
 364                         break;
 365
 366                 /* hardware copies qtd out of qh overlay */
 367                 rmb ();
 368                 token = hc32_to_cpu(ehci, qtd->hw_token);
 369
 370                 /* always clean up qtds the hc de-activated */
 371  retry_xacterr:
 372                 if ((token & QTD_STS_ACTIVE) == 0) {
 373
 374                         /* Report Data Buffer Error: non-fatal but useful */
 375                         if (token & QTD_STS_DBE)
 376                                 ehci_dbg(ehci,
 377                                         "detected DataBufferErr for urb %p ep%d%s len %d, qtd %p [qh %p]\n",
 378                                         urb,
 379                                         usb_endpoint_num(&urb->ep->desc),
 380                                         usb_endpoint_dir_in(&urb->ep->desc) ? "in" : "out",
 381                                         urb->transfer_buffer_length,
 382                                         qtd,
 383                                         qh);
 384
 385                         /* on STALL, error, and short reads this urb must
 386                          * complete and all its qtds must be recycled.
 387                          */
 388                         if ((token & QTD_STS_HALT) != 0) {
 389
 390                                 /* retry transaction errors until we
 391                                  * reach the software xacterr limit
 392                                  */
 393                                 if ((token & QTD_STS_XACT) &&
 394                                                 QTD_CERR(token) == 0 &&
 395                                                 ++qh->xacterrs < QH_XACTERR_MAX &&
 396                                                 !urb->unlinked) {
 397                                         ehci_dbg(ehci,
 398         "detected XactErr len %zu/%zu retry %d\n",
 399         qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs);
 400
 401                                         /* reset the token in the qtd and the
 402                                          * qh overlay (which still contains
 403                                          * the qtd) so that we pick up from
 404                                          * where we left off
 405                                          */
 406                                         token &= ~QTD_STS_HALT;
 407                                         token |= QTD_STS_ACTIVE |
 408                                                         (EHCI_TUNE_CERR << 10);
 409                                         qtd->hw_token = cpu_to_hc32(ehci,
 410                                                         token);
 411                                         wmb();
 412                                         hw->hw_token = cpu_to_hc32(ehci,
 413                                                         token);
 414                                         goto retry_xacterr;
 415                                 }
 416                                 stopped = 1;
 417
 418                         /* magic dummy for some short reads; qh won't advance.
 419                          * that silicon quirk can kick in with this dummy too.
 420                          *
 421                          * other short reads won't stop the queue, including
 422                          * control transfers (status stage handles that) or
 423                          * most other single-qtd reads ... the queue stops if
 424                          * URB_SHORT_NOT_OK was set so the driver submitting
 425                          * the urbs could clean it up.
 426                          */
 427                         } else if (IS_SHORT_READ (token)
 428                                         && !(qtd->hw_alt_next
 429                                                 & EHCI_LIST_END(ehci))) {
 430                                 stopped = 1;
 431                         }
 432
 433                 /* stop scanning when we reach qtds the hc is using */
 434                 } else if (likely (!stopped
 435                                 && ehci->rh_state >= EHCI_RH_RUNNING)) {
 436                         break;
 437
 438                 /* scan the whole queue for unlinks whenever it stops */
 439                 } else {
 440                         stopped = 1;
 441
 442                         /* cancel everything if we halt, suspend, etc */
 443                         if (ehci->rh_state < EHCI_RH_RUNNING)
 444                                 last_status = -ESHUTDOWN;
 445
 446                         /* this qtd is active; skip it unless a previous qtd
 447                          * for its urb faulted, or its urb was canceled.
 448                          */
 449                         else if (last_status == -EINPROGRESS && !urb->unlinked)
 450                                 continue;
 451
 452                         /*
 453                          * If this was the active qtd when the qh was unlinked
 454                          * and the overlay's token is active, then the overlay
 455                          * hasn't been written back to the qtd yet so use its
 456                          * token instead of the qtd's.  After the qtd is
 457                          * processed and removed, the overlay won't be valid
 458                          * any more.
 459                          */
 460                         if (state == QH_STATE_IDLE &&
 461                                         qh->qtd_list.next == &qtd->qtd_list &&
 462                                         (hw->hw_token & ACTIVE_BIT(ehci))) {
 463                                 token = hc32_to_cpu(ehci, hw->hw_token);
 464                                 hw->hw_token &= ~ACTIVE_BIT(ehci);
 465
 466                                 /* An unlink may leave an incomplete
 467                                  * async transaction in the TT buffer.
 468                                  * We have to clear it.
 469                                  */
 470                                 ehci_clear_tt_buffer(ehci, qh, urb, token);
 471                         }
 472                 }
 473
 474                 /* unless we already know the urb's status, collect qtd status
 475                  * and update count of bytes transferred.  in common short read
 476                  * cases with only one data qtd (including control transfers),
 477                  * queue processing won't halt.  but with two or more qtds (for
 478                  * example, with a 32 KB transfer), when the first qtd gets a
 479                  * short read the second must be removed by hand.
 480                  */
 481                 if (last_status == -EINPROGRESS) {
 482                         last_status = qtd_copy_status(ehci, urb,
 483                                         qtd->length, token);
 484                         if (last_status == -EREMOTEIO
 485                                         && (qtd->hw_alt_next
 486                                                 & EHCI_LIST_END(ehci)))
 487                                 last_status = -EINPROGRESS;
 488
 489                         /* As part of low/full-speed endpoint-halt processing
 490                          * we must clear the TT buffer (11.17.5).
 491                          */
 492                         if (unlikely(last_status != -EINPROGRESS &&
 493                                         last_status != -EREMOTEIO)) {
 494                                 /* The TT's in some hubs malfunction when they
 495                                  * receive this request following a STALL (they
 496                                  * stop sending isochronous packets).  Since a
 497                                  * STALL can't leave the TT buffer in a busy
 498                                  * state (if you believe Figures 11-48 - 11-51
 499                                  * in the USB 2.0 spec), we won't clear the TT
 500                                  * buffer in this case.  Strictly speaking this
 501                                  * is a violation of the spec.
 502                                  */
 503                                 if (last_status != -EPIPE)
 504                                         ehci_clear_tt_buffer(ehci, qh, urb,
 505                                                         token);
 506                         }
 507                 }
 508
 509                 /* if we're removing something not at the queue head,
 510                  * patch the hardware queue pointer.
 511                  */
 512                 if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
 513                         last = list_entry (qtd->qtd_list.prev,
 514                                         struct ehci_qtd, qtd_list);
 515                         last->hw_next = qtd->hw_next;
 516                 }
 517
 518                 /* remove qtd; it's recycled after possible urb completion */
 519                 list_del (&qtd->qtd_list);
 520                 last = qtd;
 521
 522                 /* reinit the xacterr counter for the next qtd */
 523                 qh->xacterrs = 0;
 524         }
 525
 526         /* last urb's completion might still need calling */
 527         if (likely (last != NULL)) {
 528                 ehci_urb_done(ehci, last->urb, last_status);
 529                 count++;
 530                 ehci_qtd_free (ehci, last);
 531         }
 532
 533         /* Do we need to rescan for URBs dequeued during a giveback? */
 534         if (unlikely(qh->needs_rescan)) {
 535                 /* If the QH is already unlinked, do the rescan now. */
 536                 if (state == QH_STATE_IDLE)
 537                         goto rescan;
 538
 539                 /* Otherwise we have to wait until the QH is fully unlinked.
 540                  * Our caller will start an unlink if qh->needs_rescan is
 541                  * set.  But if an unlink has already started, nothing needs
 542                  * to be done.
 543                  */
 544                 if (state != QH_STATE_LINKED)
 545                         qh->needs_rescan = 0;
 546         }
 547
 548         /* restore original state; caller must unlink or relink */
 549         qh->qh_state = state;
 550
 551         /* be sure the hardware's done with the qh before refreshing
 552          * it after fault cleanup, or recovering from silicon wrongly
 553          * overlaying the dummy qtd (which reduces DMA chatter).
 554          */
 555         if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {
 556                 switch (state) {
 557                 case QH_STATE_IDLE:
 558                         qh_refresh(ehci, qh);
 559                         break;
 560                 case QH_STATE_LINKED:
 561                         /* We won't refresh a QH that's linked (after the HC
 562                          * stopped the queue).  That avoids a race:
 563                          *  - HC reads first part of QH;
 564                          *  - CPU updates that first part and the token;
 565                          *  - HC reads rest of that QH, including token
 566                          * Result:  HC gets an inconsistent image, and then
 567                          * DMAs to/from the wrong memory (corrupting it).
 568                          *
 569                          * That should be rare for interrupt transfers,
 570                          * except maybe high bandwidth ...
 571                          */
 572
 573                         /* Tell the caller to start an unlink */
 574                         qh->needs_rescan = 1;
 575                         break;
 576                 /* otherwise, unlink already started */
 577                 }
 578         }
 579
 580         return count;
 581 }
 582
 583 /*-------------------------------------------------------------------------*/
 584
 585 // high bandwidth multiplier, as encoded in highspeed endpoint descriptors
 586 #define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
 587 // ... and packet size, for any kind of endpoint descriptor
 588 #define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)
 589
 590 /*
 591  * reverse of qh_urb_transaction:  free a list of TDs.
 592  * used for cleanup after errors, before HC sees an URB's TDs.
 593  */
 594 static void qtd_list_free (
 595         struct ehci_hcd         *ehci,
 596         struct urb              *urb,
 597         struct list_head        *qtd_list
 598 ) {
 599         struct list_head        *entry, *temp;
 600
 601         list_for_each_safe (entry, temp, qtd_list) {
 602                 struct ehci_qtd *qtd;
 603
 604                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 605                 list_del (&qtd->qtd_list);
 606                 ehci_qtd_free (ehci, qtd);
 607         }
 608 }
 609
 610 /*
 611  * create a list of filled qtds for this URB; won't link into qh.
 612  */
 613 static struct list_head *
 614 qh_urb_transaction (
 615         struct ehci_hcd         *ehci,
 616         struct urb              *urb,
 617         struct list_head        *head,
 618         gfp_t                   flags
 619 ) {
 620         struct ehci_qtd         *qtd, *qtd_prev;
 621         dma_addr_t              buf;
 622         int                     len, this_sg_len, maxpacket;
 623         int                     is_input;
 624         u32                     token;
 625         int                     i;
 626         struct scatterlist      *sg;
 627
 628         /*
 629          * URBs map to sequences of QTDs:  one logical transaction
 630          */
 631         qtd = ehci_qtd_alloc (ehci, flags);
 632         if (unlikely (!qtd))
 633                 return NULL;
 634         list_add_tail (&qtd->qtd_list, head);
 635         qtd->urb = urb;
 636
 637         token = QTD_STS_ACTIVE;
 638         token |= (EHCI_TUNE_CERR << 10);
 639         /* for split transactions, SplitXState initialized to zero */
 640
 641         len = urb->transfer_buffer_length;
 642         is_input = usb_pipein (urb->pipe);
 643         if (usb_pipecontrol (urb->pipe)) {
 644                 /* SETUP pid */
 645                 qtd_fill(ehci, qtd, urb->setup_dma,
 646                                 sizeof (struct usb_ctrlrequest),
 647                                 token | (2 /* "setup" */ << 8), 8);
 648
 649                 /* ... and always at least one more pid */
 650                 token ^= QTD_TOGGLE;
 651                 qtd_prev = qtd;
 652                 qtd = ehci_qtd_alloc (ehci, flags);
 653                 if (unlikely (!qtd))
 654                         goto cleanup;
 655                 qtd->urb = urb;
 656                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 657                 list_add_tail (&qtd->qtd_list, head);
 658
 659                 /* for zero length DATA stages, STATUS is always IN */
 660                 if (len == 0)
 661                         token |= (1 /* "in" */ << 8);
 662         }
 663
 664         /*
 665          * data transfer stage:  buffer setup
 666          */
 667         i = urb->num_mapped_sgs;
 668         if (len > 0 && i > 0) {
 669                 sg = urb->sg;
 670                 buf = sg_dma_address(sg);
 671
 672                 /* urb->transfer_buffer_length may be smaller than the
 673                  * size of the scatterlist (or vice versa)
 674                  */
 675                 this_sg_len = min_t(int, sg_dma_len(sg), len);
 676         } else {
 677                 sg = NULL;
 678                 buf = urb->transfer_dma;
 679                 this_sg_len = len;
 680         }
 681
 682         if (is_input)
 683                 token |= (1 /* "in" */ << 8);
 684         /* else it's already initted to "out" pid (0 << 8) */
 685
 686         maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));
 687
 688         /*
 689          * buffer gets wrapped in one or more qtds;
 690          * last one may be "short" (including zero len)
 691          * and may serve as a control status ack
 692          */
 693         for (;;) {
 694                 int this_qtd_len;
 695
 696                 this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
 697                                 maxpacket);
 698                 this_sg_len -= this_qtd_len;
 699                 len -= this_qtd_len;
 700                 buf += this_qtd_len;
 701
 702                 /*
 703                  * short reads advance to a "magic" dummy instead of the next
 704                  * qtd ... that forces the queue to stop, for manual cleanup.
 705                  * (this will usually be overridden later.)
 706                  */
 707                 if (is_input)
 708                         qtd->hw_alt_next = ehci->async->hw->hw_alt_next;
 709
 710                 /* qh makes control packets use qtd toggle; maybe switch it */
 711                 if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
 712                         token ^= QTD_TOGGLE;
 713
 714                 if (likely(this_sg_len <= 0)) {
 715                         if (--i <= 0 || len <= 0)
 716                                 break;
 717                         sg = sg_next(sg);
 718                         buf = sg_dma_address(sg);
 719                         this_sg_len = min_t(int, sg_dma_len(sg), len);
 720                 }
 721
 722                 qtd_prev = qtd;
 723                 qtd = ehci_qtd_alloc (ehci, flags);
 724                 if (unlikely (!qtd))
 725                         goto cleanup;
 726                 qtd->urb = urb;
 727                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 728                 list_add_tail (&qtd->qtd_list, head);
 729         }
 730
 731         /*
 732          * unless the caller requires manual cleanup after short reads,
 733          * have the alt_next mechanism keep the queue running after the
 734          * last data qtd (the only one, for control and most other cases).
 735          */
 736         if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
 737                                 || usb_pipecontrol (urb->pipe)))
 738                 qtd->hw_alt_next = EHCI_LIST_END(ehci);
 739
 740         /*
 741          * control requests may need a terminating data "status" ack;
 742          * other OUT ones may need a terminating short packet
 743          * (zero length).
 744          */
 745         if (likely (urb->transfer_buffer_length != 0)) {
 746                 int     one_more = 0;
 747
 748                 if (usb_pipecontrol (urb->pipe)) {
 749                         one_more = 1;
 750                         token ^= 0x0100;        /* "in" <--> "out"  */
 751                         token |= QTD_TOGGLE;    /* force DATA1 */
 752                 } else if (usb_pipeout(urb->pipe)
 753                                 && (urb->transfer_flags & URB_ZERO_PACKET)
 754                                 && !(urb->transfer_buffer_length % maxpacket)) {
 755                         one_more = 1;
 756                 }
 757                 if (one_more) {
 758                         qtd_prev = qtd;
 759                         qtd = ehci_qtd_alloc (ehci, flags);
 760                         if (unlikely (!qtd))
 761                                 goto cleanup;
 762                         qtd->urb = urb;
 763                         qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 764                         list_add_tail (&qtd->qtd_list, head);
 765
 766                         /* never any data in such packets */
 767                         qtd_fill(ehci, qtd, 0, 0, token, 0);
 768                 }
 769         }
 770
 771         /* by default, enable interrupt on urb completion */
 772         if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
 773                 qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
 774         return head;
 775
 776 cleanup:
 777         qtd_list_free (ehci, urb, head);
 778         return NULL;
 779 }
 780
 781 /*-------------------------------------------------------------------------*/
 782
 783 // Would be best to create all qh's from config descriptors,
 784 // when each interface/altsetting is established.  Unlink
 785 // any previous qh and cancel its urbs first; endpoints are
 786 // implicitly reset then (data toggle too).
 787 // That'd mean updating how usbcore talks to HCDs. (2.7?)
 788
 789
 790 /*
 791  * Each QH holds a qtd list; a QH is used for everything except iso.
 792  *
 793  * For interrupt urbs, the scheduler must set the microframe scheduling
 794  * mask(s) each time the QH gets scheduled.  For highspeed, that's
 795  * just one microframe in the s-mask.  For split interrupt transactions
 796  * there are additional complications: c-mask, maybe FSTNs.
 797  */
 798 static struct ehci_qh *
 799 qh_make (
 800         struct ehci_hcd         *ehci,
 801         struct urb              *urb,
 802         gfp_t                   flags
 803 ) {
 804         struct ehci_qh          *qh = ehci_qh_alloc (ehci, flags);
 805         u32                     info1 = 0, info2 = 0;
 806         int                     is_input, type;
 807         int                     maxp = 0;
 808         struct usb_tt           *tt = urb->dev->tt;
 809         struct ehci_qh_hw       *hw;
 810
 811         if (!qh)
 812                 return qh;
 813
 814         /*
 815          * init endpoint/device data for this QH
 816          */
 817         info1 |= usb_pipeendpoint (urb->pipe) << 8;
 818         info1 |= usb_pipedevice (urb->pipe) << 0;
 819
 820         is_input = usb_pipein (urb->pipe);
 821         type = usb_pipetype (urb->pipe);
 822         maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input);
 823
 824         /* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
 825          * acts like up to 3KB, but is built from smaller packets.
 826          */
 827         if (max_packet(maxp) > 1024) {
 828                 ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
 829                 goto done;
 830         }
 831
 832         /* Compute interrupt scheduling parameters just once, and save.
 833          * - allowing for high bandwidth, how many nsec/uframe are used?
 834          * - split transactions need a second CSPLIT uframe; same question
 835          * - splits also need a schedule gap (for full/low speed I/O)
 836          * - qh has a polling interval
 837          *
 838          * For control/bulk requests, the HC or TT handles these.
 839          */
 840         if (type == PIPE_INTERRUPT) {
 841                 qh->usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH,
 842                                 is_input, 0,
 843                                 hb_mult(maxp) * max_packet(maxp)));
 844                 qh->start = NO_FRAME;
 845
 846                 if (urb->dev->speed == USB_SPEED_HIGH) {
 847                         qh->c_usecs = 0;
 848                         qh->gap_uf = 0;
 849
 850                         qh->period = urb->interval >> 3;
 851                         if (qh->period == 0 && urb->interval != 1) {
 852                                 /* NOTE interval 2 or 4 uframes could work.
 853                                  * But interval 1 scheduling is simpler, and
 854                                  * includes high bandwidth.
 855                                  */
 856                                 urb->interval = 1;
 857                         } else if (qh->period > ehci->periodic_size) {
 858                                 qh->period = ehci->periodic_size;
 859                                 urb->interval = qh->period << 3;
 860                         }
 861                 } else {
 862                         int             think_time;
 863
 864                         /* gap is f(FS/LS transfer times) */
 865                         qh->gap_uf = 1 + usb_calc_bus_time (urb->dev->speed,
 866                                         is_input, 0, maxp) / (125 * 1000);
 867
 868                         /* FIXME this just approximates SPLIT/CSPLIT times */
 869                         if (is_input) {         // SPLIT, gap, CSPLIT+DATA
 870                                 qh->c_usecs = qh->usecs + HS_USECS (0);
 871                                 qh->usecs = HS_USECS (1);
 872                         } else {                // SPLIT+DATA, gap, CSPLIT
 873                                 qh->usecs += HS_USECS (1);
 874                                 qh->c_usecs = HS_USECS (0);
 875                         }
 876
 877                         think_time = tt ? tt->think_time : 0;
 878                         qh->tt_usecs = NS_TO_US (think_time +
 879                                         usb_calc_bus_time (urb->dev->speed,
 880                                         is_input, 0, max_packet (maxp)));
 881                         qh->period = urb->interval;
 882                         if (qh->period > ehci->periodic_size) {
 883                                 qh->period = ehci->periodic_size;
 884                                 urb->interval = qh->period;
 885                         }
 886                 }
 887         }
 888
 889         /* support for tt scheduling, and access to toggles */
 890         qh->dev = urb->dev;
 891
 892         /* using TT? */
 893         switch (urb->dev->speed) {
 894         case USB_SPEED_LOW:
 895                 info1 |= QH_LOW_SPEED;
 896                 /* FALL THROUGH */
 897
 898         case USB_SPEED_FULL:
 899                 /* EPS 0 means "full" */
 900                 if (type != PIPE_INTERRUPT)
 901                         info1 |= (EHCI_TUNE_RL_TT << 28);
 902                 if (type == PIPE_CONTROL) {
 903                         info1 |= QH_CONTROL_EP;         /* for TT */
 904                         info1 |= QH_TOGGLE_CTL;         /* toggle from qtd */
 905                 }
 906                 info1 |= maxp << 16;
 907
 908                 info2 |= (EHCI_TUNE_MULT_TT << 30);
 909
 910                 /* Some Freescale processors have an erratum in which the
 911                  * port number in the queue head was 0..N-1 instead of 1..N.
 912                  */
 913                 if (ehci_has_fsl_portno_bug(ehci))
 914                         info2 |= (urb->dev->ttport-1) << 23;
 915                 else
 916                         info2 |= urb->dev->ttport << 23;
 917
 918                 /* set the address of the TT; for TDI's integrated
 919                  * root hub tt, leave it zeroed.
 920                  */
 921                 if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub)
 922                         info2 |= tt->hub->devnum << 16;
 923
 924                 /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets c-mask } */
 925
 926                 break;
 927
 928         case USB_SPEED_HIGH:            /* no TT involved */
 929                 info1 |= QH_HIGH_SPEED;
 930                 if (type == PIPE_CONTROL) {
 931                         info1 |= (EHCI_TUNE_RL_HS << 28);
 932                         info1 |= 64 << 16;      /* usb2 fixed maxpacket */
 933                         info1 |= QH_TOGGLE_CTL; /* toggle from qtd */
 934                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 935                 } else if (type == PIPE_BULK) {
 936                         info1 |= (EHCI_TUNE_RL_HS << 28);
 937                         /* The USB spec says that high speed bulk endpoints
 938                          * always use 512 byte maxpacket.  But some device
 939                          * vendors decided to ignore that, and MSFT is happy
 940                          * to help them do so.  So now people expect to use
 941                          * such nonconformant devices with Linux too; sigh.
 942                          */
 943                         info1 |= max_packet(maxp) << 16;
 944                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 945                 } else {                /* PIPE_INTERRUPT */
 946                         info1 |= max_packet (maxp) << 16;
 947                         info2 |= hb_mult (maxp) << 30;
 948                 }
 949                 break;
 950         default:
 951                 ehci_dbg(ehci, "bogus dev %p speed %d\n", urb->dev,
 952                         urb->dev->speed);
 953 done:
 954                 qh_destroy(ehci, qh);
 955                 return NULL;
 956         }
 957
 958         /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */
 959
 960         /* init as live, toggle clear, advance to dummy */
 961         qh->qh_state = QH_STATE_IDLE;
 962         hw = qh->hw;
 963         hw->hw_info1 = cpu_to_hc32(ehci, info1);
 964         hw->hw_info2 = cpu_to_hc32(ehci, info2);
 965         qh->is_out = !is_input;
 966         usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);
 967         qh_refresh (ehci, qh);
 968         return qh;
 969 }
 970
 971 /*-------------------------------------------------------------------------*/
 972
 973 static void enable_async(struct ehci_hcd *ehci)
 974 {
 975         if (ehci->async_count++)
 976                 return;
 977
 978         /* Stop waiting to turn off the async schedule */
 979         ehci->enabled_hrtimer_events &= ~BIT(EHCI_HRTIMER_DISABLE_ASYNC);
 980
 981         /* Don't start the schedule until ASS is 0 */
 982         ehci_poll_ASS(ehci);
 983         turn_on_io_watchdog(ehci);
 984 }
 985
 986 static void disable_async(struct ehci_hcd *ehci)
 987 {
 988         if (--ehci->async_count)
 989                 return;
 990
 991         /* The async schedule and async_unlink list are supposed to be empty */
 992         WARN_ON(ehci->async->qh_next.qh || ehci->async_unlink);
 993
 994         /* Don't turn off the schedule until ASS is 1 */
 995         ehci_poll_ASS(ehci);
 996 }
 997
 998 /* move qh (and its qtds) onto async queue; maybe enable queue.  */
 999
1000 static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
1001 {
1002         __hc32          dma = QH_NEXT(ehci, qh->qh_dma);
1003         struct ehci_qh  *head;
1004
1005         /* Don't link a QH if there's a Clear-TT-Buffer pending */
1006         if (unlikely(qh->clearing_tt))
1007                 return;
1008
1009         WARN_ON(qh->qh_state != QH_STATE_IDLE);
1010
1011         /* clear halt and/or toggle; and maybe recover from silicon quirk */
1012         qh_refresh(ehci, qh);
1013
1014         /* splice right after start */
1015         head = ehci->async;
1016         qh->qh_next = head->qh_next;
1017         qh->hw->hw_next = head->hw->hw_next;
1018         wmb ();
1019
1020         head->qh_next.qh = qh;
1021         head->hw->hw_next = dma;
1022
1023         qh->xacterrs = 0;
1024         qh->qh_state = QH_STATE_LINKED;
1025         /* qtd completions reported later by interrupt */
1026
1027         enable_async(ehci);
1028 }
1029
1030 /*-------------------------------------------------------------------------*/
1031
1032 /*
1033  * For control/bulk/interrupt, return QH with these TDs appended.
1034  * Allocates and initializes the QH if necessary.
1035  * Returns null if it can't allocate a QH it needs to.
1036  * If the QH has TDs (urbs) already, that's great.
1037  */
1038 static struct ehci_qh *qh_append_tds (
1039         struct ehci_hcd         *ehci,
1040         struct urb              *urb,
1041         struct list_head        *qtd_list,
1042         int                     epnum,
1043         void                    **ptr
1044 )
1045 {
1046         struct ehci_qh          *qh = NULL;
1047         __hc32                  qh_addr_mask = cpu_to_hc32(ehci, 0x7f);
1048
1049         qh = (struct ehci_qh *) *ptr;
1050         if (unlikely (qh == NULL)) {
1051                 /* can't sleep here, we have ehci->lock... */
1052                 qh = qh_make (ehci, urb, GFP_ATOMIC);
1053                 *ptr = qh;
1054         }
1055         if (likely (qh != NULL)) {
1056                 struct ehci_qtd *qtd;
1057
1058                 if (unlikely (list_empty (qtd_list)))
1059                         qtd = NULL;
1060                 else
1061                         qtd = list_entry (qtd_list->next, struct ehci_qtd,
1062                                         qtd_list);
1063
1064                 /* control qh may need patching ... */
1065                 if (unlikely (epnum == 0)) {
1066
1067                         /* usb_reset_device() briefly reverts to address 0 */
1068                         if (usb_pipedevice (urb->pipe) == 0)
1069                                 qh->hw->hw_info1 &= ~qh_addr_mask;
1070                 }
1071
1072                 /* just one way to queue requests: swap with the dummy qtd.
1073                  * only hc or qh_refresh() ever modify the overlay.
1074                  */
1075                 if (likely (qtd != NULL)) {
1076                         struct ehci_qtd         *dummy;
1077                         dma_addr_t              dma;
1078                         __hc32                  token;
1079
1080                         /* to avoid racing the HC, use the dummy td instead of
1081                          * the first td of our list (becomes new dummy).  both
1082                          * tds stay deactivated until we're done, when the
1083                          * HC is allowed to fetch the old dummy (4.10.2).
1084                          */
1085                         token = qtd->hw_token;
1086                         qtd->hw_token = HALT_BIT(ehci);
1087
1088                         dummy = qh->dummy;
1089
1090                         dma = dummy->qtd_dma;
1091                         *dummy = *qtd;
1092                         dummy->qtd_dma = dma;
1093
1094                         list_del (&qtd->qtd_list);
1095                         list_add (&dummy->qtd_list, qtd_list);
1096                         list_splice_tail(qtd_list, &qh->qtd_list);
1097
1098                         ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
1099                         qh->dummy = qtd;
1100
1101                         /* hc must see the new dummy at list end */
1102                         dma = qtd->qtd_dma;
1103                         qtd = list_entry (qh->qtd_list.prev,
1104                                         struct ehci_qtd, qtd_list);
1105                         qtd->hw_next = QTD_NEXT(ehci, dma);
1106
1107                         /* let the hc process these next qtds */
1108                         wmb ();
1109                         dummy->hw_token = token;
1110
1111                         urb->hcpriv = qh;
1112                 }
1113         }
1114         return qh;
1115 }
1116
1117 /*-------------------------------------------------------------------------*/
1118
1119 static int
1120 submit_async (
1121         struct ehci_hcd         *ehci,
1122         struct urb              *urb,
1123         struct list_head        *qtd_list,
1124         gfp_t                   mem_flags
1125 ) {
1126         int                     epnum;
1127         unsigned long           flags;
1128         struct ehci_qh          *qh = NULL;
1129         int                     rc;
1130
1131         epnum = urb->ep->desc.bEndpointAddress;
1132
1133 #ifdef EHCI_URB_TRACE
1134         {
1135                 struct ehci_qtd *qtd;
1136                 qtd = list_entry(qtd_list->next, struct ehci_qtd, qtd_list);
1137                 ehci_dbg(ehci,
1138                          "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
1139                          __func__, urb->dev->devpath, urb,
1140                          epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
1141                          urb->transfer_buffer_length,
1142                          qtd, urb->ep->hcpriv);
1143         }
1144 #endif
1145
1146         spin_lock_irqsave (&ehci->lock, flags);
1147         if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
1148                 rc = -ESHUTDOWN;
1149                 goto done;
1150         }
1151         rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1152         if (unlikely(rc))
1153                 goto done;
1154
1155         qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
1156         if (unlikely(qh == NULL)) {
1157                 usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1158                 rc = -ENOMEM;
1159                 goto done;
1160         }
1161
1162         /* Control/bulk operations through TTs don't need scheduling,
1163          * the HC and TT handle it when the TT has a buffer ready.
1164          */
1165         if (likely (qh->qh_state == QH_STATE_IDLE))
1166                 qh_link_async(ehci, qh);
1167  done:
1168         spin_unlock_irqrestore (&ehci->lock, flags);
1169         if (unlikely (qh == NULL))
1170                 qtd_list_free (ehci, urb, qtd_list);
1171         return rc;
1172 }
1173
1174 /*-------------------------------------------------------------------------*/
1175
1176 static void single_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
1177 {
1178         struct ehci_qh          *prev;
1179
1180         /* Add to the end of the list of QHs waiting for the next IAAD */
1181         qh->qh_state = QH_STATE_UNLINK_WAIT;
1182         if (ehci->async_unlink)
1183                 ehci->async_unlink_last->unlink_next = qh;
1184         else
1185                 ehci->async_unlink = qh;
1186         ehci->async_unlink_last = qh;
1187
1188         /* Unlink it from the schedule */
1189         prev = ehci->async;
1190         while (prev->qh_next.qh != qh)
1191                 prev = prev->qh_next.qh;
1192
1193         prev->hw->hw_next = qh->hw->hw_next;
1194         prev->qh_next = qh->qh_next;
1195         if (ehci->qh_scan_next == qh)
1196                 ehci->qh_scan_next = qh->qh_next.qh;
1197 }
1198
1199 static void start_iaa_cycle(struct ehci_hcd *ehci, bool nested)
1200 {
1201         /*
1202          * Do nothing if an IAA cycle is already running or
1203          * if one will be started shortly.
1204          */
1205         if (ehci->async_iaa || ehci->async_unlinking)
1206                 return;
1207
1208         /* If the controller isn't running, we don't have to wait for it */
1209         if (unlikely(ehci->rh_state < EHCI_RH_RUNNING)) {
1210
1211                 /* Do all the waiting QHs */
1212                 ehci->async_iaa = ehci->async_unlink;
1213                 ehci->async_unlink = NULL;
1214
1215                 if (!nested)            /* Avoid recursion */
1216                         end_unlink_async(ehci);
1217
1218         /* Otherwise start a new IAA cycle */
1219         } else if (likely(ehci->rh_state == EHCI_RH_RUNNING)) {
1220                 struct ehci_qh          *qh;
1221
1222                 /* Do only the first waiting QH (nVidia bug?) */
1223                 qh = ehci->async_unlink;
1224
1225                 /*
1226                  * Intel (?) bug: The HC can write back the overlay region
1227                  * even after the IAA interrupt occurs.  In self-defense,
1228                  * always go through two IAA cycles for each QH.
1229                  */
1230                 if (qh->qh_state == QH_STATE_UNLINK_WAIT) {
1231                         qh->qh_state = QH_STATE_UNLINK;
1232                 } else {
1233                         ehci->async_iaa = qh;
1234                         ehci->async_unlink = qh->unlink_next;
1235                         qh->unlink_next = NULL;
1236                 }
1237
1238                 /* Make sure the unlinks are all visible to the hardware */
1239                 wmb();
1240
1241                 ehci_writel(ehci, ehci->command | CMD_IAAD,
1242                                 &ehci->regs->command);
1243                 ehci_readl(ehci, &ehci->regs->command);
1244                 ehci_enable_event(ehci, EHCI_HRTIMER_IAA_WATCHDOG, true);
1245         }
1246 }
1247
1248 /* the async qh for the qtds being unlinked are now gone from the HC */
1249
1250 static void end_unlink_async(struct ehci_hcd *ehci)
1251 {
1252         struct ehci_qh          *qh;
1253
1254         if (ehci->has_synopsys_hc_bug)
1255                 ehci_writel(ehci, (u32) ehci->async->qh_dma,
1256                             &ehci->regs->async_next);
1257
1258         /* Process the idle QHs */
1259  restart:
1260         ehci->async_unlinking = true;
1261         while (ehci->async_iaa) {
1262                 qh = ehci->async_iaa;
1263                 ehci->async_iaa = qh->unlink_next;
1264                 qh->unlink_next = NULL;
1265
1266                 qh->qh_state = QH_STATE_IDLE;
1267                 qh->qh_next.qh = NULL;
1268
1269                 qh_completions(ehci, qh);
1270                 if (!list_empty(&qh->qtd_list) &&
1271                                 ehci->rh_state == EHCI_RH_RUNNING)
1272                         qh_link_async(ehci, qh);
1273                 disable_async(ehci);
1274         }
1275         ehci->async_unlinking = false;
1276
1277         /* Start a new IAA cycle if any QHs are waiting for it */
1278         if (ehci->async_unlink) {
1279                 start_iaa_cycle(ehci, true);
1280                 if (unlikely(ehci->rh_state < EHCI_RH_RUNNING))
1281                         goto restart;
1282         }
1283 }
1284
1285 static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
1286
1287 static void unlink_empty_async(struct ehci_hcd *ehci)
1288 {
1289         struct ehci_qh          *qh;
1290         struct ehci_qh          *qh_to_unlink = NULL;
1291         bool                    check_unlinks_later = false;
1292         int                     count = 0;
1293
1294         /* Find the last async QH which has been empty for a timer cycle */
1295         for (qh = ehci->async->qh_next.qh; qh; qh = qh->qh_next.qh) {
1296                 if (list_empty(&qh->qtd_list) &&
1297                                 qh->qh_state == QH_STATE_LINKED) {
1298                         ++count;
1299                         if (qh->unlink_cycle == ehci->async_unlink_cycle)
1300                                 check_unlinks_later = true;
1301                         else
1302                                 qh_to_unlink = qh;
1303                 }
1304         }
1305
1306         /* If nothing else is being unlinked, unlink the last empty QH */
1307         if (!ehci->async_iaa && !ehci->async_unlink && qh_to_unlink) {
1308                 start_unlink_async(ehci, qh_to_unlink);
1309                 --count;
1310         }
1311
1312         /* Other QHs will be handled later */
1313         if (count > 0) {
1314                 ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true);
1315                 ++ehci->async_unlink_cycle;
1316         }
1317 }
1318
1319 /* The root hub is suspended; unlink all the async QHs */
1320 static void unlink_empty_async_suspended(struct ehci_hcd *ehci)
1321 {
1322         struct ehci_qh          *qh;
1323
1324         while (ehci->async->qh_next.qh) {
1325                 qh = ehci->async->qh_next.qh;
1326                 WARN_ON(!list_empty(&qh->qtd_list));
1327                 single_unlink_async(ehci, qh);
1328         }
1329         start_iaa_cycle(ehci, false);
1330 }
1331
1332 /* makes sure the async qh will become idle */
1333 /* caller must own ehci->lock */
1334
1335 static void start_unlink_async(struct ehci_hcd *ehci, struct ehci_qh *qh)
1336 {
1337         /*
1338          * If the QH isn't linked then there's nothing we can do
1339          * unless we were called during a giveback, in which case
1340          * qh_completions() has to deal with it.
1341          */
1342         if (qh->qh_state != QH_STATE_LINKED) {
1343                 if (qh->qh_state == QH_STATE_COMPLETING)
1344                         qh->needs_rescan = 1;
1345                 return;
1346         }
1347
1348         single_unlink_async(ehci, qh);
1349         start_iaa_cycle(ehci, false);
1350 }
1351
1352 /*-------------------------------------------------------------------------*/
1353
1354 static void scan_async (struct ehci_hcd *ehci)
1355 {
1356         struct ehci_qh          *qh;
1357         bool                    check_unlinks_later = false;
1358
1359         ehci->qh_scan_next = ehci->async->qh_next.qh;
1360         while (ehci->qh_scan_next) {
1361                 qh = ehci->qh_scan_next;
1362                 ehci->qh_scan_next = qh->qh_next.qh;
1363  rescan:
1364                 /* clean any finished work for this qh */
1365                 if (!list_empty(&qh->qtd_list)) {
1366                         int temp;
1367
1368                         /*
1369                          * Unlinks could happen here; completion reporting
1370                          * drops the lock.  That's why ehci->qh_scan_next
1371                          * always holds the next qh to scan; if the next qh
1372                          * gets unlinked then ehci->qh_scan_next is adjusted
1373                          * in single_unlink_async().
1374                          */
1375                         temp = qh_completions(ehci, qh);
1376                         if (qh->needs_rescan) {
1377                                 start_unlink_async(ehci, qh);
1378                         } else if (list_empty(&qh->qtd_list)
1379                                         && qh->qh_state == QH_STATE_LINKED) {
1380                                 qh->unlink_cycle = ehci->async_unlink_cycle;
1381                                 check_unlinks_later = true;
1382                         } else if (temp != 0)
1383                                 goto rescan;
1384                 }
1385         }
1386
1387         /*
1388          * Unlink empty entries, reducing DMA usage as well
1389          * as HCD schedule-scanning costs.  Delay for any qh
1390          * we just scanned, there's a not-unusual case that it
1391          * doesn't stay idle for long.
1392          */
1393         if (check_unlinks_later && ehci->rh_state == EHCI_RH_RUNNING &&
1394                         !(ehci->enabled_hrtimer_events &
1395                                 BIT(EHCI_HRTIMER_ASYNC_UNLINKS))) {
1396                 ehci_enable_event(ehci, EHCI_HRTIMER_ASYNC_UNLINKS, true);
1397                 ++ehci->async_unlink_cycle;
1398         }
1399 }