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, 1 << 14))) {
 104                 unsigned        is_out, epnum;
 105
 106                 is_out = !(qtd->hw_token & cpu_to_hc32(ehci, 1 << 8));
 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         /* HC must see latest qtd and qh data before we clear ACTIVE+HALT */
 115         wmb ();
 116         hw->hw_token &= cpu_to_hc32(ehci, QTD_TOGGLE | QTD_STS_PING);
 117 }
 118
 119 /* if it weren't for a common silicon quirk (writing the dummy into the qh
 120  * overlay, so qh->hw_token wrongly becomes inactive/halted), only fault
 121  * recovery (including urb dequeue) would need software changes to a QH...
 122  */
 123 static void
 124 qh_refresh (struct ehci_hcd *ehci, struct ehci_qh *qh)
 125 {
 126         struct ehci_qtd *qtd;
 127
 128         if (list_empty (&qh->qtd_list))
 129                 qtd = qh->dummy;
 130         else {
 131                 qtd = list_entry (qh->qtd_list.next,
 132                                 struct ehci_qtd, qtd_list);
 133                 /* first qtd may already be partially processed */
 134                 if (cpu_to_hc32(ehci, qtd->qtd_dma) == qh->hw->hw_current)
 135                         qtd = NULL;
 136         }
 137
 138         if (qtd)
 139                 qh_update (ehci, qh, qtd);
 140 }
 141
 142 /*-------------------------------------------------------------------------*/
 143
 144 static void qh_link_async(struct ehci_hcd *ehci, struct ehci_qh *qh);
 145
 146 static void ehci_clear_tt_buffer_complete(struct usb_hcd *hcd,
 147                 struct usb_host_endpoint *ep)
 148 {
 149         struct ehci_hcd         *ehci = hcd_to_ehci(hcd);
 150         struct ehci_qh          *qh = ep->hcpriv;
 151         unsigned long           flags;
 152
 153         spin_lock_irqsave(&ehci->lock, flags);
 154         qh->clearing_tt = 0;
 155         if (qh->qh_state == QH_STATE_IDLE && !list_empty(&qh->qtd_list)
 156                         && HC_IS_RUNNING(hcd->state))
 157                 qh_link_async(ehci, qh);
 158         spin_unlock_irqrestore(&ehci->lock, flags);
 159 }
 160
 161 static void ehci_clear_tt_buffer(struct ehci_hcd *ehci, struct ehci_qh *qh,
 162                 struct urb *urb, u32 token)
 163 {
 164
 165         /* If an async split transaction gets an error or is unlinked,
 166          * the TT buffer may be left in an indeterminate state.  We
 167          * have to clear the TT buffer.
 168          *
 169          * Note: this routine is never called for Isochronous transfers.
 170          */
 171         if (urb->dev->tt && !usb_pipeint(urb->pipe) && !qh->clearing_tt) {
 172 #ifdef DEBUG
 173                 struct usb_device *tt = urb->dev->tt->hub;
 174                 dev_dbg(&tt->dev,
 175                         "clear tt buffer port %d, a%d ep%d t%08x\n",
 176                         urb->dev->ttport, urb->dev->devnum,
 177                         usb_pipeendpoint(urb->pipe), token);
 178 #endif /* DEBUG */
 179                 if (!ehci_is_TDI(ehci)
 180                                 || urb->dev->tt->hub !=
 181                                    ehci_to_hcd(ehci)->self.root_hub) {
 182                         if (usb_hub_clear_tt_buffer(urb) == 0)
 183                                 qh->clearing_tt = 1;
 184                 } else {
 185
 186                         /* REVISIT ARC-derived cores don't clear the root
 187                          * hub TT buffer in this way...
 188                          */
 189                 }
 190         }
 191 }
 192
 193 static int qtd_copy_status (
 194         struct ehci_hcd *ehci,
 195         struct urb *urb,
 196         size_t length,
 197         u32 token
 198 )
 199 {
 200         int     status = -EINPROGRESS;
 201
 202         /* count IN/OUT bytes, not SETUP (even short packets) */
 203         if (likely (QTD_PID (token) != 2))
 204                 urb->actual_length += length - QTD_LENGTH (token);
 205
 206         /* don't modify error codes */
 207         if (unlikely(urb->unlinked))
 208                 return status;
 209
 210         /* force cleanup after short read; not always an error */
 211         if (unlikely (IS_SHORT_READ (token)))
 212                 status = -EREMOTEIO;
 213
 214         /* serious "can't proceed" faults reported by the hardware */
 215         if (token & QTD_STS_HALT) {
 216                 if (token & QTD_STS_BABBLE) {
 217                         /* FIXME "must" disable babbling device's port too */
 218                         status = -EOVERFLOW;
 219                 /* CERR nonzero + halt --> stall */
 220                 } else if (QTD_CERR(token)) {
 221                         status = -EPIPE;
 222
 223                 /* In theory, more than one of the following bits can be set
 224                  * since they are sticky and the transaction is retried.
 225                  * Which to test first is rather arbitrary.
 226                  */
 227                 } else if (token & QTD_STS_MMF) {
 228                         /* fs/ls interrupt xfer missed the complete-split */
 229                         status = -EPROTO;
 230                 } else if (token & QTD_STS_DBE) {
 231                         status = (QTD_PID (token) == 1) /* IN ? */
 232                                 ? -ENOSR  /* hc couldn't read data */
 233                                 : -ECOMM; /* hc couldn't write data */
 234                 } else if (token & QTD_STS_XACT) {
 235                         /* timeout, bad CRC, wrong PID, etc */
 236                         ehci_dbg(ehci, "devpath %s ep%d%s 3strikes\n",
 237                                 urb->dev->devpath,
 238                                 usb_pipeendpoint(urb->pipe),
 239                                 usb_pipein(urb->pipe) ? "in" : "out");
 240                         status = -EPROTO;
 241                 } else {        /* unknown */
 242                         status = -EPROTO;
 243                 }
 244
 245                 ehci_vdbg (ehci,
 246                         "dev%d ep%d%s qtd token %08x --> status %d\n",
 247                         usb_pipedevice (urb->pipe),
 248                         usb_pipeendpoint (urb->pipe),
 249                         usb_pipein (urb->pipe) ? "in" : "out",
 250                         token, status);
 251         }
 252
 253         return status;
 254 }
 255
 256 static void
 257 ehci_urb_done(struct ehci_hcd *ehci, struct urb *urb, int status)
 258 __releases(ehci->lock)
 259 __acquires(ehci->lock)
 260 {
 261         if (likely (urb->hcpriv != NULL)) {
 262                 struct ehci_qh  *qh = (struct ehci_qh *) urb->hcpriv;
 263
 264                 /* S-mask in a QH means it's an interrupt urb */
 265                 if ((qh->hw->hw_info2 & cpu_to_hc32(ehci, QH_SMASK)) != 0) {
 266
 267                         /* ... update hc-wide periodic stats (for usbfs) */
 268                         ehci_to_hcd(ehci)->self.bandwidth_int_reqs--;
 269                 }
 270                 qh_put (qh);
 271         }
 272
 273         if (unlikely(urb->unlinked)) {
 274                 COUNT(ehci->stats.unlink);
 275         } else {
 276                 /* report non-error and short read status as zero */
 277                 if (status == -EINPROGRESS || status == -EREMOTEIO)
 278                         status = 0;
 279                 COUNT(ehci->stats.complete);
 280         }
 281
 282 #ifdef EHCI_URB_TRACE
 283         ehci_dbg (ehci,
 284                 "%s %s urb %p ep%d%s status %d len %d/%d\n",
 285                 __func__, urb->dev->devpath, urb,
 286                 usb_pipeendpoint (urb->pipe),
 287                 usb_pipein (urb->pipe) ? "in" : "out",
 288                 status,
 289                 urb->actual_length, urb->transfer_buffer_length);
 290 #endif
 291
 292         /* complete() can reenter this HCD */
 293         usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
 294         spin_unlock (&ehci->lock);
 295         usb_hcd_giveback_urb(ehci_to_hcd(ehci), urb, status);
 296         spin_lock (&ehci->lock);
 297 }
 298
 299 static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 300 static void unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh);
 301
 302 static int qh_schedule (struct ehci_hcd *ehci, struct ehci_qh *qh);
 303
 304 /*
 305  * Process and free completed qtds for a qh, returning URBs to drivers.
 306  * Chases up to qh->hw_current.  Returns number of completions called,
 307  * indicating how much "real" work we did.
 308  */
 309 static unsigned
 310 qh_completions (struct ehci_hcd *ehci, struct ehci_qh *qh)
 311 {
 312         struct ehci_qtd         *last, *end = qh->dummy;
 313         struct list_head        *entry, *tmp;
 314         int                     last_status;
 315         int                     stopped;
 316         unsigned                count = 0;
 317         u8                      state;
 318         const __le32            halt = HALT_BIT(ehci);
 319         struct ehci_qh_hw       *hw = qh->hw;
 320
 321         if (unlikely (list_empty (&qh->qtd_list)))
 322                 return count;
 323
 324         /* completions (or tasks on other cpus) must never clobber HALT
 325          * till we've gone through and cleaned everything up, even when
 326          * they add urbs to this qh's queue or mark them for unlinking.
 327          *
 328          * NOTE:  unlinking expects to be done in queue order.
 329          *
 330          * It's a bug for qh->qh_state to be anything other than
 331          * QH_STATE_IDLE, unless our caller is scan_async() or
 332          * scan_periodic().
 333          */
 334         state = qh->qh_state;
 335         qh->qh_state = QH_STATE_COMPLETING;
 336         stopped = (state == QH_STATE_IDLE);
 337
 338  rescan:
 339         last = NULL;
 340         last_status = -EINPROGRESS;
 341         qh->needs_rescan = 0;
 342
 343         /* remove de-activated QTDs from front of queue.
 344          * after faults (including short reads), cleanup this urb
 345          * then let the queue advance.
 346          * if queue is stopped, handles unlinks.
 347          */
 348         list_for_each_safe (entry, tmp, &qh->qtd_list) {
 349                 struct ehci_qtd *qtd;
 350                 struct urb      *urb;
 351                 u32             token = 0;
 352
 353                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 354                 urb = qtd->urb;
 355
 356                 /* clean up any state from previous QTD ...*/
 357                 if (last) {
 358                         if (likely (last->urb != urb)) {
 359                                 ehci_urb_done(ehci, last->urb, last_status);
 360                                 count++;
 361                                 last_status = -EINPROGRESS;
 362                         }
 363                         ehci_qtd_free (ehci, last);
 364                         last = NULL;
 365                 }
 366
 367                 /* ignore urbs submitted during completions we reported */
 368                 if (qtd == end)
 369                         break;
 370
 371                 /* hardware copies qtd out of qh overlay */
 372                 rmb ();
 373                 token = hc32_to_cpu(ehci, qtd->hw_token);
 374
 375                 /* always clean up qtds the hc de-activated */
 376  retry_xacterr:
 377                 if ((token & QTD_STS_ACTIVE) == 0) {
 378
 379                         /* on STALL, error, and short reads this urb must
 380                          * complete and all its qtds must be recycled.
 381                          */
 382                         if ((token & QTD_STS_HALT) != 0) {
 383
 384                                 /* retry transaction errors until we
 385                                  * reach the software xacterr limit
 386                                  */
 387                                 if ((token & QTD_STS_XACT) &&
 388                                                 QTD_CERR(token) == 0 &&
 389                                                 ++qh->xacterrs < QH_XACTERR_MAX &&
 390                                                 !urb->unlinked) {
 391                                         ehci_dbg(ehci,
 392         "detected XactErr len %zu/%zu retry %d\n",
 393         qtd->length - QTD_LENGTH(token), qtd->length, qh->xacterrs);
 394
 395                                         /* reset the token in the qtd and the
 396                                          * qh overlay (which still contains
 397                                          * the qtd) so that we pick up from
 398                                          * where we left off
 399                                          */
 400                                         token &= ~QTD_STS_HALT;
 401                                         token |= QTD_STS_ACTIVE |
 402                                                         (EHCI_TUNE_CERR << 10);
 403                                         qtd->hw_token = cpu_to_hc32(ehci,
 404                                                         token);
 405                                         wmb();
 406                                         hw->hw_token = cpu_to_hc32(ehci,
 407                                                         token);
 408                                         goto retry_xacterr;
 409                                 }
 410                                 stopped = 1;
 411
 412                         /* magic dummy for some short reads; qh won't advance.
 413                          * that silicon quirk can kick in with this dummy too.
 414                          *
 415                          * other short reads won't stop the queue, including
 416                          * control transfers (status stage handles that) or
 417                          * most other single-qtd reads ... the queue stops if
 418                          * URB_SHORT_NOT_OK was set so the driver submitting
 419                          * the urbs could clean it up.
 420                          */
 421                         } else if (IS_SHORT_READ (token)
 422                                         && !(qtd->hw_alt_next
 423                                                 & EHCI_LIST_END(ehci))) {
 424                                 stopped = 1;
 425                                 goto halt;
 426                         }
 427
 428                 /* stop scanning when we reach qtds the hc is using */
 429                 } else if (likely (!stopped
 430                                 && HC_IS_RUNNING (ehci_to_hcd(ehci)->state))) {
 431                         break;
 432
 433                 /* scan the whole queue for unlinks whenever it stops */
 434                 } else {
 435                         stopped = 1;
 436
 437                         /* cancel everything if we halt, suspend, etc */
 438                         if (!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))
 439                                 last_status = -ESHUTDOWN;
 440
 441                         /* this qtd is active; skip it unless a previous qtd
 442                          * for its urb faulted, or its urb was canceled.
 443                          */
 444                         else if (last_status == -EINPROGRESS && !urb->unlinked)
 445                                 continue;
 446
 447                         /* qh unlinked; token in overlay may be most current */
 448                         if (state == QH_STATE_IDLE
 449                                         && cpu_to_hc32(ehci, qtd->qtd_dma)
 450                                                 == hw->hw_current) {
 451                                 token = hc32_to_cpu(ehci, hw->hw_token);
 452
 453                                 /* An unlink may leave an incomplete
 454                                  * async transaction in the TT buffer.
 455                                  * We have to clear it.
 456                                  */
 457                                 ehci_clear_tt_buffer(ehci, qh, urb, token);
 458                         }
 459
 460                         /* force halt for unlinked or blocked qh, so we'll
 461                          * patch the qh later and so that completions can't
 462                          * activate it while we "know" it's stopped.
 463                          */
 464                         if ((halt & hw->hw_token) == 0) {
 465 halt:
 466                                 hw->hw_token |= halt;
 467                                 wmb ();
 468                         }
 469                 }
 470
 471                 /* unless we already know the urb's status, collect qtd status
 472                  * and update count of bytes transferred.  in common short read
 473                  * cases with only one data qtd (including control transfers),
 474                  * queue processing won't halt.  but with two or more qtds (for
 475                  * example, with a 32 KB transfer), when the first qtd gets a
 476                  * short read the second must be removed by hand.
 477                  */
 478                 if (last_status == -EINPROGRESS) {
 479                         last_status = qtd_copy_status(ehci, urb,
 480                                         qtd->length, token);
 481                         if (last_status == -EREMOTEIO
 482                                         && (qtd->hw_alt_next
 483                                                 & EHCI_LIST_END(ehci)))
 484                                 last_status = -EINPROGRESS;
 485
 486                         /* As part of low/full-speed endpoint-halt processing
 487                          * we must clear the TT buffer (11.17.5).
 488                          */
 489                         if (unlikely(last_status != -EINPROGRESS &&
 490                                         last_status != -EREMOTEIO)) {
 491                                 /* The TT's in some hubs malfunction when they
 492                                  * receive this request following a STALL (they
 493                                  * stop sending isochronous packets).  Since a
 494                                  * STALL can't leave the TT buffer in a busy
 495                                  * state (if you believe Figures 11-48 - 11-51
 496                                  * in the USB 2.0 spec), we won't clear the TT
 497                                  * buffer in this case.  Strictly speaking this
 498                                  * is a violation of the spec.
 499                                  */
 500                                 if (last_status != -EPIPE)
 501                                         ehci_clear_tt_buffer(ehci, qh, urb,
 502                                                         token);
 503                         }
 504                 }
 505
 506                 /* if we're removing something not at the queue head,
 507                  * patch the hardware queue pointer.
 508                  */
 509                 if (stopped && qtd->qtd_list.prev != &qh->qtd_list) {
 510                         last = list_entry (qtd->qtd_list.prev,
 511                                         struct ehci_qtd, qtd_list);
 512                         last->hw_next = qtd->hw_next;
 513                 }
 514
 515                 /* remove qtd; it's recycled after possible urb completion */
 516                 list_del (&qtd->qtd_list);
 517                 last = qtd;
 518
 519                 /* reinit the xacterr counter for the next qtd */
 520                 qh->xacterrs = 0;
 521         }
 522
 523         /* last urb's completion might still need calling */
 524         if (likely (last != NULL)) {
 525                 ehci_urb_done(ehci, last->urb, last_status);
 526                 count++;
 527                 ehci_qtd_free (ehci, last);
 528         }
 529
 530         /* Do we need to rescan for URBs dequeued during a giveback? */
 531         if (unlikely(qh->needs_rescan)) {
 532                 /* If the QH is already unlinked, do the rescan now. */
 533                 if (state == QH_STATE_IDLE)
 534                         goto rescan;
 535
 536                 /* Otherwise we have to wait until the QH is fully unlinked.
 537                  * Our caller will start an unlink if qh->needs_rescan is
 538                  * set.  But if an unlink has already started, nothing needs
 539                  * to be done.
 540                  */
 541                 if (state != QH_STATE_LINKED)
 542                         qh->needs_rescan = 0;
 543         }
 544
 545         /* restore original state; caller must unlink or relink */
 546         qh->qh_state = state;
 547
 548         /* be sure the hardware's done with the qh before refreshing
 549          * it after fault cleanup, or recovering from silicon wrongly
 550          * overlaying the dummy qtd (which reduces DMA chatter).
 551          */
 552         if (stopped != 0 || hw->hw_qtd_next == EHCI_LIST_END(ehci)) {
 553                 switch (state) {
 554                 case QH_STATE_IDLE:
 555                         qh_refresh(ehci, qh);
 556                         break;
 557                 case QH_STATE_LINKED:
 558                         /* We won't refresh a QH that's linked (after the HC
 559                          * stopped the queue).  That avoids a race:
 560                          *  - HC reads first part of QH;
 561                          *  - CPU updates that first part and the token;
 562                          *  - HC reads rest of that QH, including token
 563                          * Result:  HC gets an inconsistent image, and then
 564                          * DMAs to/from the wrong memory (corrupting it).
 565                          *
 566                          * That should be rare for interrupt transfers,
 567                          * except maybe high bandwidth ...
 568                          */
 569
 570                         /* Tell the caller to start an unlink */
 571                         qh->needs_rescan = 1;
 572                         break;
 573                 /* otherwise, unlink already started */
 574                 }
 575         }
 576
 577         return count;
 578 }
 579
 580 /*-------------------------------------------------------------------------*/
 581
 582 // high bandwidth multiplier, as encoded in highspeed endpoint descriptors
 583 #define hb_mult(wMaxPacketSize) (1 + (((wMaxPacketSize) >> 11) & 0x03))
 584 // ... and packet size, for any kind of endpoint descriptor
 585 #define max_packet(wMaxPacketSize) ((wMaxPacketSize) & 0x07ff)
 586
 587 /*
 588  * reverse of qh_urb_transaction:  free a list of TDs.
 589  * used for cleanup after errors, before HC sees an URB's TDs.
 590  */
 591 static void qtd_list_free (
 592         struct ehci_hcd         *ehci,
 593         struct urb              *urb,
 594         struct list_head        *qtd_list
 595 ) {
 596         struct list_head        *entry, *temp;
 597
 598         list_for_each_safe (entry, temp, qtd_list) {
 599                 struct ehci_qtd *qtd;
 600
 601                 qtd = list_entry (entry, struct ehci_qtd, qtd_list);
 602                 list_del (&qtd->qtd_list);
 603                 ehci_qtd_free (ehci, qtd);
 604         }
 605 }
 606
 607 /*
 608  * create a list of filled qtds for this URB; won't link into qh.
 609  */
 610 static struct list_head *
 611 qh_urb_transaction (
 612         struct ehci_hcd         *ehci,
 613         struct urb              *urb,
 614         struct list_head        *head,
 615         gfp_t                   flags
 616 ) {
 617         struct ehci_qtd         *qtd, *qtd_prev;
 618         dma_addr_t              buf;
 619         int                     len, this_sg_len, maxpacket;
 620         int                     is_input;
 621         u32                     token;
 622         int                     i;
 623         struct scatterlist      *sg;
 624
 625         /*
 626          * URBs map to sequences of QTDs:  one logical transaction
 627          */
 628         qtd = ehci_qtd_alloc (ehci, flags);
 629         if (unlikely (!qtd))
 630                 return NULL;
 631         list_add_tail (&qtd->qtd_list, head);
 632         qtd->urb = urb;
 633
 634         token = QTD_STS_ACTIVE;
 635         token |= (EHCI_TUNE_CERR << 10);
 636         /* for split transactions, SplitXState initialized to zero */
 637
 638         len = urb->transfer_buffer_length;
 639         is_input = usb_pipein (urb->pipe);
 640         if (usb_pipecontrol (urb->pipe)) {
 641                 /* SETUP pid */
 642                 qtd_fill(ehci, qtd, urb->setup_dma,
 643                                 sizeof (struct usb_ctrlrequest),
 644                                 token | (2 /* "setup" */ << 8), 8);
 645
 646                 /* ... and always at least one more pid */
 647                 token ^= QTD_TOGGLE;
 648                 qtd_prev = qtd;
 649                 qtd = ehci_qtd_alloc (ehci, flags);
 650                 if (unlikely (!qtd))
 651                         goto cleanup;
 652                 qtd->urb = urb;
 653                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 654                 list_add_tail (&qtd->qtd_list, head);
 655
 656                 /* for zero length DATA stages, STATUS is always IN */
 657                 if (len == 0)
 658                         token |= (1 /* "in" */ << 8);
 659         }
 660
 661         /*
 662          * data transfer stage:  buffer setup
 663          */
 664         i = urb->num_sgs;
 665         if (len > 0 && i > 0) {
 666                 sg = urb->sg->sg;
 667                 buf = sg_dma_address(sg);
 668
 669                 /* urb->transfer_buffer_length may be smaller than the
 670                  * size of the scatterlist (or vice versa)
 671                  */
 672                 this_sg_len = min_t(int, sg_dma_len(sg), len);
 673         } else {
 674                 sg = NULL;
 675                 buf = urb->transfer_dma;
 676                 this_sg_len = len;
 677         }
 678
 679         if (is_input)
 680                 token |= (1 /* "in" */ << 8);
 681         /* else it's already initted to "out" pid (0 << 8) */
 682
 683         maxpacket = max_packet(usb_maxpacket(urb->dev, urb->pipe, !is_input));
 684
 685         /*
 686          * buffer gets wrapped in one or more qtds;
 687          * last one may be "short" (including zero len)
 688          * and may serve as a control status ack
 689          */
 690         for (;;) {
 691                 int this_qtd_len;
 692
 693                 this_qtd_len = qtd_fill(ehci, qtd, buf, this_sg_len, token,
 694                                 maxpacket);
 695                 this_sg_len -= this_qtd_len;
 696                 len -= this_qtd_len;
 697                 buf += this_qtd_len;
 698
 699                 /*
 700                  * short reads advance to a "magic" dummy instead of the next
 701                  * qtd ... that forces the queue to stop, for manual cleanup.
 702                  * (this will usually be overridden later.)
 703                  */
 704                 if (is_input)
 705                         qtd->hw_alt_next = ehci->async->hw->hw_alt_next;
 706
 707                 /* qh makes control packets use qtd toggle; maybe switch it */
 708                 if ((maxpacket & (this_qtd_len + (maxpacket - 1))) == 0)
 709                         token ^= QTD_TOGGLE;
 710
 711                 if (likely(this_sg_len <= 0)) {
 712                         if (--i <= 0 || len <= 0)
 713                                 break;
 714                         sg = sg_next(sg);
 715                         buf = sg_dma_address(sg);
 716                         this_sg_len = min_t(int, sg_dma_len(sg), len);
 717                 }
 718
 719                 qtd_prev = qtd;
 720                 qtd = ehci_qtd_alloc (ehci, flags);
 721                 if (unlikely (!qtd))
 722                         goto cleanup;
 723                 qtd->urb = urb;
 724                 qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 725                 list_add_tail (&qtd->qtd_list, head);
 726         }
 727
 728         /*
 729          * unless the caller requires manual cleanup after short reads,
 730          * have the alt_next mechanism keep the queue running after the
 731          * last data qtd (the only one, for control and most other cases).
 732          */
 733         if (likely ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0
 734                                 || usb_pipecontrol (urb->pipe)))
 735                 qtd->hw_alt_next = EHCI_LIST_END(ehci);
 736
 737         /*
 738          * control requests may need a terminating data "status" ack;
 739          * bulk ones may need a terminating short packet (zero length).
 740          */
 741         if (likely (urb->transfer_buffer_length != 0)) {
 742                 int     one_more = 0;
 743
 744                 if (usb_pipecontrol (urb->pipe)) {
 745                         one_more = 1;
 746                         token ^= 0x0100;        /* "in" <--> "out"  */
 747                         token |= QTD_TOGGLE;    /* force DATA1 */
 748                 } else if (usb_pipebulk (urb->pipe)
 749                                 && (urb->transfer_flags & URB_ZERO_PACKET)
 750                                 && !(urb->transfer_buffer_length % maxpacket)) {
 751                         one_more = 1;
 752                 }
 753                 if (one_more) {
 754                         qtd_prev = qtd;
 755                         qtd = ehci_qtd_alloc (ehci, flags);
 756                         if (unlikely (!qtd))
 757                                 goto cleanup;
 758                         qtd->urb = urb;
 759                         qtd_prev->hw_next = QTD_NEXT(ehci, qtd->qtd_dma);
 760                         list_add_tail (&qtd->qtd_list, head);
 761
 762                         /* never any data in such packets */
 763                         qtd_fill(ehci, qtd, 0, 0, token, 0);
 764                 }
 765         }
 766
 767         /* by default, enable interrupt on urb completion */
 768         if (likely (!(urb->transfer_flags & URB_NO_INTERRUPT)))
 769                 qtd->hw_token |= cpu_to_hc32(ehci, QTD_IOC);
 770         return head;
 771
 772 cleanup:
 773         qtd_list_free (ehci, urb, head);
 774         return NULL;
 775 }
 776
 777 /*-------------------------------------------------------------------------*/
 778
 779 // Would be best to create all qh's from config descriptors,
 780 // when each interface/altsetting is established.  Unlink
 781 // any previous qh and cancel its urbs first; endpoints are
 782 // implicitly reset then (data toggle too).
 783 // That'd mean updating how usbcore talks to HCDs. (2.7?)
 784
 785
 786 /*
 787  * Each QH holds a qtd list; a QH is used for everything except iso.
 788  *
 789  * For interrupt urbs, the scheduler must set the microframe scheduling
 790  * mask(s) each time the QH gets scheduled.  For highspeed, that's
 791  * just one microframe in the s-mask.  For split interrupt transactions
 792  * there are additional complications: c-mask, maybe FSTNs.
 793  */
 794 static struct ehci_qh *
 795 qh_make (
 796         struct ehci_hcd         *ehci,
 797         struct urb              *urb,
 798         gfp_t                   flags
 799 ) {
 800         struct ehci_qh          *qh = ehci_qh_alloc (ehci, flags);
 801         u32                     info1 = 0, info2 = 0;
 802         int                     is_input, type;
 803         int                     maxp = 0;
 804         struct usb_tt           *tt = urb->dev->tt;
 805         struct ehci_qh_hw       *hw;
 806
 807         if (!qh)
 808                 return qh;
 809
 810         /*
 811          * init endpoint/device data for this QH
 812          */
 813         info1 |= usb_pipeendpoint (urb->pipe) << 8;
 814         info1 |= usb_pipedevice (urb->pipe) << 0;
 815
 816         is_input = usb_pipein (urb->pipe);
 817         type = usb_pipetype (urb->pipe);
 818         maxp = usb_maxpacket (urb->dev, urb->pipe, !is_input);
 819
 820         /* 1024 byte maxpacket is a hardware ceiling.  High bandwidth
 821          * acts like up to 3KB, but is built from smaller packets.
 822          */
 823         if (max_packet(maxp) > 1024) {
 824                 ehci_dbg(ehci, "bogus qh maxpacket %d\n", max_packet(maxp));
 825                 goto done;
 826         }
 827
 828         /* Compute interrupt scheduling parameters just once, and save.
 829          * - allowing for high bandwidth, how many nsec/uframe are used?
 830          * - split transactions need a second CSPLIT uframe; same question
 831          * - splits also need a schedule gap (for full/low speed I/O)
 832          * - qh has a polling interval
 833          *
 834          * For control/bulk requests, the HC or TT handles these.
 835          */
 836         if (type == PIPE_INTERRUPT) {
 837                 qh->usecs = NS_TO_US(usb_calc_bus_time(USB_SPEED_HIGH,
 838                                 is_input, 0,
 839                                 hb_mult(maxp) * max_packet(maxp)));
 840                 qh->start = NO_FRAME;
 841
 842                 if (urb->dev->speed == USB_SPEED_HIGH) {
 843                         qh->c_usecs = 0;
 844                         qh->gap_uf = 0;
 845
 846                         qh->period = urb->interval >> 3;
 847                         if (qh->period == 0 && urb->interval != 1) {
 848                                 /* NOTE interval 2 or 4 uframes could work.
 849                                  * But interval 1 scheduling is simpler, and
 850                                  * includes high bandwidth.
 851                                  */
 852                                 urb->interval = 1;
 853                         } else if (qh->period > ehci->periodic_size) {
 854                                 qh->period = ehci->periodic_size;
 855                                 urb->interval = qh->period << 3;
 856                         }
 857                 } else {
 858                         int             think_time;
 859
 860                         /* gap is f(FS/LS transfer times) */
 861                         qh->gap_uf = 1 + usb_calc_bus_time (urb->dev->speed,
 862                                         is_input, 0, maxp) / (125 * 1000);
 863
 864                         /* FIXME this just approximates SPLIT/CSPLIT times */
 865                         if (is_input) {         // SPLIT, gap, CSPLIT+DATA
 866                                 qh->c_usecs = qh->usecs + HS_USECS (0);
 867                                 qh->usecs = HS_USECS (1);
 868                         } else {                // SPLIT+DATA, gap, CSPLIT
 869                                 qh->usecs += HS_USECS (1);
 870                                 qh->c_usecs = HS_USECS (0);
 871                         }
 872
 873                         think_time = tt ? tt->think_time : 0;
 874                         qh->tt_usecs = NS_TO_US (think_time +
 875                                         usb_calc_bus_time (urb->dev->speed,
 876                                         is_input, 0, max_packet (maxp)));
 877                         qh->period = urb->interval;
 878                         if (qh->period > ehci->periodic_size) {
 879                                 qh->period = ehci->periodic_size;
 880                                 urb->interval = qh->period;
 881                         }
 882                 }
 883         }
 884
 885         /* support for tt scheduling, and access to toggles */
 886         qh->dev = urb->dev;
 887
 888         /* using TT? */
 889         switch (urb->dev->speed) {
 890         case USB_SPEED_LOW:
 891                 info1 |= (1 << 12);     /* EPS "low" */
 892                 /* FALL THROUGH */
 893
 894         case USB_SPEED_FULL:
 895                 /* EPS 0 means "full" */
 896                 if (type != PIPE_INTERRUPT)
 897                         info1 |= (EHCI_TUNE_RL_TT << 28);
 898                 if (type == PIPE_CONTROL) {
 899                         info1 |= (1 << 27);     /* for TT */
 900                         info1 |= 1 << 14;       /* toggle from qtd */
 901                 }
 902                 info1 |= maxp << 16;
 903
 904                 info2 |= (EHCI_TUNE_MULT_TT << 30);
 905
 906                 /* Some Freescale processors have an erratum in which the
 907                  * port number in the queue head was 0..N-1 instead of 1..N.
 908                  */
 909                 if (ehci_has_fsl_portno_bug(ehci))
 910                         info2 |= (urb->dev->ttport-1) << 23;
 911                 else
 912                         info2 |= urb->dev->ttport << 23;
 913
 914                 /* set the address of the TT; for TDI's integrated
 915                  * root hub tt, leave it zeroed.
 916                  */
 917                 if (tt && tt->hub != ehci_to_hcd(ehci)->self.root_hub)
 918                         info2 |= tt->hub->devnum << 16;
 919
 920                 /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets c-mask } */
 921
 922                 break;
 923
 924         case USB_SPEED_HIGH:            /* no TT involved */
 925                 info1 |= (2 << 12);     /* EPS "high" */
 926                 if (type == PIPE_CONTROL) {
 927                         info1 |= (EHCI_TUNE_RL_HS << 28);
 928                         info1 |= 64 << 16;      /* usb2 fixed maxpacket */
 929                         info1 |= 1 << 14;       /* toggle from qtd */
 930                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 931                 } else if (type == PIPE_BULK) {
 932                         info1 |= (EHCI_TUNE_RL_HS << 28);
 933                         /* The USB spec says that high speed bulk endpoints
 934                          * always use 512 byte maxpacket.  But some device
 935                          * vendors decided to ignore that, and MSFT is happy
 936                          * to help them do so.  So now people expect to use
 937                          * such nonconformant devices with Linux too; sigh.
 938                          */
 939                         info1 |= max_packet(maxp) << 16;
 940                         info2 |= (EHCI_TUNE_MULT_HS << 30);
 941                 } else {                /* PIPE_INTERRUPT */
 942                         info1 |= max_packet (maxp) << 16;
 943                         info2 |= hb_mult (maxp) << 30;
 944                 }
 945                 break;
 946         default:
 947                 dbg ("bogus dev %p speed %d", urb->dev, urb->dev->speed);
 948 done:
 949                 qh_put (qh);
 950                 return NULL;
 951         }
 952
 953         /* NOTE:  if (PIPE_INTERRUPT) { scheduler sets s-mask } */
 954
 955         /* init as live, toggle clear, advance to dummy */
 956         qh->qh_state = QH_STATE_IDLE;
 957         hw = qh->hw;
 958         hw->hw_info1 = cpu_to_hc32(ehci, info1);
 959         hw->hw_info2 = cpu_to_hc32(ehci, info2);
 960         usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe), !is_input, 1);
 961         qh_refresh (ehci, qh);
 962         return qh;
 963 }
 964
 965 /*-------------------------------------------------------------------------*/
 966
 967 /* move qh (and its qtds) onto async queue; maybe enable queue.  */
 968
 969 static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 970 {
 971         __hc32          dma = QH_NEXT(ehci, qh->qh_dma);
 972         struct ehci_qh  *head;
 973
 974         /* Don't link a QH if there's a Clear-TT-Buffer pending */
 975         if (unlikely(qh->clearing_tt))
 976                 return;
 977
 978         WARN_ON(qh->qh_state != QH_STATE_IDLE);
 979
 980         /* (re)start the async schedule? */
 981         head = ehci->async;
 982         timer_action_done (ehci, TIMER_ASYNC_OFF);
 983         if (!head->qh_next.qh) {
 984                 u32     cmd = ehci_readl(ehci, &ehci->regs->command);
 985
 986                 if (!(cmd & CMD_ASE)) {
 987                         /* in case a clear of CMD_ASE didn't take yet */
 988                         (void)handshake(ehci, &ehci->regs->status,
 989                                         STS_ASS, 0, 150);
 990                         cmd |= CMD_ASE | CMD_RUN;
 991                         ehci_writel(ehci, cmd, &ehci->regs->command);
 992                         ehci_to_hcd(ehci)->state = HC_STATE_RUNNING;
 993                         /* posted write need not be known to HC yet ... */
 994                 }
 995         }
 996
 997         /* clear halt and/or toggle; and maybe recover from silicon quirk */
 998         qh_refresh(ehci, qh);
 999
1000         /* splice right after start */
1001         qh->qh_next = head->qh_next;
1002         qh->hw->hw_next = head->hw->hw_next;
1003         wmb ();
1004
1005         head->qh_next.qh = qh;
1006         head->hw->hw_next = dma;
1007
1008         qh_get(qh);
1009         qh->xacterrs = 0;
1010         qh->qh_state = QH_STATE_LINKED;
1011         /* qtd completions reported later by interrupt */
1012 }
1013
1014 /*-------------------------------------------------------------------------*/
1015
1016 /*
1017  * For control/bulk/interrupt, return QH with these TDs appended.
1018  * Allocates and initializes the QH if necessary.
1019  * Returns null if it can't allocate a QH it needs to.
1020  * If the QH has TDs (urbs) already, that's great.
1021  */
1022 static struct ehci_qh *qh_append_tds (
1023         struct ehci_hcd         *ehci,
1024         struct urb              *urb,
1025         struct list_head        *qtd_list,
1026         int                     epnum,
1027         void                    **ptr
1028 )
1029 {
1030         struct ehci_qh          *qh = NULL;
1031         __hc32                  qh_addr_mask = cpu_to_hc32(ehci, 0x7f);
1032
1033         qh = (struct ehci_qh *) *ptr;
1034         if (unlikely (qh == NULL)) {
1035                 /* can't sleep here, we have ehci->lock... */
1036                 qh = qh_make (ehci, urb, GFP_ATOMIC);
1037                 *ptr = qh;
1038         }
1039         if (likely (qh != NULL)) {
1040                 struct ehci_qtd *qtd;
1041
1042                 if (unlikely (list_empty (qtd_list)))
1043                         qtd = NULL;
1044                 else
1045                         qtd = list_entry (qtd_list->next, struct ehci_qtd,
1046                                         qtd_list);
1047
1048                 /* control qh may need patching ... */
1049                 if (unlikely (epnum == 0)) {
1050
1051                         /* usb_reset_device() briefly reverts to address 0 */
1052                         if (usb_pipedevice (urb->pipe) == 0)
1053                                 qh->hw->hw_info1 &= ~qh_addr_mask;
1054                 }
1055
1056                 /* just one way to queue requests: swap with the dummy qtd.
1057                  * only hc or qh_refresh() ever modify the overlay.
1058                  */
1059                 if (likely (qtd != NULL)) {
1060                         struct ehci_qtd         *dummy;
1061                         dma_addr_t              dma;
1062                         __hc32                  token;
1063
1064                         /* to avoid racing the HC, use the dummy td instead of
1065                          * the first td of our list (becomes new dummy).  both
1066                          * tds stay deactivated until we're done, when the
1067                          * HC is allowed to fetch the old dummy (4.10.2).
1068                          */
1069                         token = qtd->hw_token;
1070                         qtd->hw_token = HALT_BIT(ehci);
1071                         wmb ();
1072                         dummy = qh->dummy;
1073
1074                         dma = dummy->qtd_dma;
1075                         *dummy = *qtd;
1076                         dummy->qtd_dma = dma;
1077
1078                         list_del (&qtd->qtd_list);
1079                         list_add (&dummy->qtd_list, qtd_list);
1080                         list_splice_tail(qtd_list, &qh->qtd_list);
1081
1082                         ehci_qtd_init(ehci, qtd, qtd->qtd_dma);
1083                         qh->dummy = qtd;
1084
1085                         /* hc must see the new dummy at list end */
1086                         dma = qtd->qtd_dma;
1087                         qtd = list_entry (qh->qtd_list.prev,
1088                                         struct ehci_qtd, qtd_list);
1089                         qtd->hw_next = QTD_NEXT(ehci, dma);
1090
1091                         /* let the hc process these next qtds */
1092                         wmb ();
1093                         dummy->hw_token = token;
1094
1095                         urb->hcpriv = qh_get (qh);
1096                 }
1097         }
1098         return qh;
1099 }
1100
1101 /*-------------------------------------------------------------------------*/
1102
1103 static int
1104 submit_async (
1105         struct ehci_hcd         *ehci,
1106         struct urb              *urb,
1107         struct list_head        *qtd_list,
1108         gfp_t                   mem_flags
1109 ) {
1110         struct ehci_qtd         *qtd;
1111         int                     epnum;
1112         unsigned long           flags;
1113         struct ehci_qh          *qh = NULL;
1114         int                     rc;
1115
1116         qtd = list_entry (qtd_list->next, struct ehci_qtd, qtd_list);
1117         epnum = urb->ep->desc.bEndpointAddress;
1118
1119 #ifdef EHCI_URB_TRACE
1120         ehci_dbg (ehci,
1121                 "%s %s urb %p ep%d%s len %d, qtd %p [qh %p]\n",
1122                 __func__, urb->dev->devpath, urb,
1123                 epnum & 0x0f, (epnum & USB_DIR_IN) ? "in" : "out",
1124                 urb->transfer_buffer_length,
1125                 qtd, urb->ep->hcpriv);
1126 #endif
1127
1128         spin_lock_irqsave (&ehci->lock, flags);
1129         if (unlikely(!test_bit(HCD_FLAG_HW_ACCESSIBLE,
1130                                &ehci_to_hcd(ehci)->flags))) {
1131                 rc = -ESHUTDOWN;
1132                 goto done;
1133         }
1134         rc = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1135         if (unlikely(rc))
1136                 goto done;
1137
1138         qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
1139         if (unlikely(qh == NULL)) {
1140                 usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1141                 rc = -ENOMEM;
1142                 goto done;
1143         }
1144
1145         /* Control/bulk operations through TTs don't need scheduling,
1146          * the HC and TT handle it when the TT has a buffer ready.
1147          */
1148         if (likely (qh->qh_state == QH_STATE_IDLE))
1149                 qh_link_async(ehci, qh);
1150  done:
1151         spin_unlock_irqrestore (&ehci->lock, flags);
1152         if (unlikely (qh == NULL))
1153                 qtd_list_free (ehci, urb, qtd_list);
1154         return rc;
1155 }
1156
1157 /*-------------------------------------------------------------------------*/
1158
1159 /* the async qh for the qtds being reclaimed are now unlinked from the HC */
1160
1161 static void end_unlink_async (struct ehci_hcd *ehci)
1162 {
1163         struct ehci_qh          *qh = ehci->reclaim;
1164         struct ehci_qh          *next;
1165
1166         iaa_watchdog_done(ehci);
1167
1168         // qh->hw_next = cpu_to_hc32(qh->qh_dma);
1169         qh->qh_state = QH_STATE_IDLE;
1170         qh->qh_next.qh = NULL;
1171         qh_put (qh);                    // refcount from reclaim
1172
1173         /* other unlink(s) may be pending (in QH_STATE_UNLINK_WAIT) */
1174         next = qh->reclaim;
1175         ehci->reclaim = next;
1176         qh->reclaim = NULL;
1177
1178         qh_completions (ehci, qh);
1179
1180         if (!list_empty (&qh->qtd_list)
1181                         && HC_IS_RUNNING (ehci_to_hcd(ehci)->state))
1182                 qh_link_async (ehci, qh);
1183         else {
1184                 /* it's not free to turn the async schedule on/off; leave it
1185                  * active but idle for a while once it empties.
1186                  */
1187                 if (HC_IS_RUNNING (ehci_to_hcd(ehci)->state)
1188                                 && ehci->async->qh_next.qh == NULL)
1189                         timer_action (ehci, TIMER_ASYNC_OFF);
1190         }
1191         qh_put(qh);                     /* refcount from async list */
1192
1193         if (next) {
1194                 ehci->reclaim = NULL;
1195                 start_unlink_async (ehci, next);
1196         }
1197 }
1198
1199 /* makes sure the async qh will become idle */
1200 /* caller must own ehci->lock */
1201
1202 static void start_unlink_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
1203 {
1204         int             cmd = ehci_readl(ehci, &ehci->regs->command);
1205         struct ehci_qh  *prev;
1206
1207 #ifdef DEBUG
1208         assert_spin_locked(&ehci->lock);
1209         if (ehci->reclaim
1210                         || (qh->qh_state != QH_STATE_LINKED
1211                                 && qh->qh_state != QH_STATE_UNLINK_WAIT)
1212                         )
1213                 BUG ();
1214 #endif
1215
1216         /* stop async schedule right now? */
1217         if (unlikely (qh == ehci->async)) {
1218                 /* can't get here without STS_ASS set */
1219                 if (ehci_to_hcd(ehci)->state != HC_STATE_HALT
1220                                 && !ehci->reclaim) {
1221                         /* ... and CMD_IAAD clear */
1222                         ehci_writel(ehci, cmd & ~CMD_ASE,
1223                                     &ehci->regs->command);
1224                         wmb ();
1225                         // handshake later, if we need to
1226                         timer_action_done (ehci, TIMER_ASYNC_OFF);
1227                 }
1228                 return;
1229         }
1230
1231         qh->qh_state = QH_STATE_UNLINK;
1232         ehci->reclaim = qh = qh_get (qh);
1233
1234         prev = ehci->async;
1235         while (prev->qh_next.qh != qh)
1236                 prev = prev->qh_next.qh;
1237
1238         prev->hw->hw_next = qh->hw->hw_next;
1239         prev->qh_next = qh->qh_next;
1240         wmb ();
1241
1242         /* If the controller isn't running, we don't have to wait for it */
1243         if (unlikely(!HC_IS_RUNNING(ehci_to_hcd(ehci)->state))) {
1244                 /* if (unlikely (qh->reclaim != 0))
1245                  *      this will recurse, probably not much
1246                  */
1247                 end_unlink_async (ehci);
1248                 return;
1249         }
1250
1251         cmd |= CMD_IAAD;
1252         ehci_writel(ehci, cmd, &ehci->regs->command);
1253         (void)ehci_readl(ehci, &ehci->regs->command);
1254         iaa_watchdog_start(ehci);
1255 }
1256
1257 /*-------------------------------------------------------------------------*/
1258
1259 static void scan_async (struct ehci_hcd *ehci)
1260 {
1261         struct ehci_qh          *qh;
1262         enum ehci_timer_action  action = TIMER_IO_WATCHDOG;
1263
1264         ehci->stamp = ehci_readl(ehci, &ehci->regs->frame_index);
1265         timer_action_done (ehci, TIMER_ASYNC_SHRINK);
1266 rescan:
1267         qh = ehci->async->qh_next.qh;
1268         if (likely (qh != NULL)) {
1269                 do {
1270                         /* clean any finished work for this qh */
1271                         if (!list_empty (&qh->qtd_list)
1272                                         && qh->stamp != ehci->stamp) {
1273                                 int temp;
1274
1275                                 /* unlinks could happen here; completion
1276                                  * reporting drops the lock.  rescan using
1277                                  * the latest schedule, but don't rescan
1278                                  * qhs we already finished (no looping).
1279                                  */
1280                                 qh = qh_get (qh);
1281                                 qh->stamp = ehci->stamp;
1282                                 temp = qh_completions (ehci, qh);
1283                                 if (qh->needs_rescan)
1284                                         unlink_async(ehci, qh);
1285                                 qh_put (qh);
1286                                 if (temp != 0) {
1287                                         goto rescan;
1288                                 }
1289                         }
1290
1291                         /* unlink idle entries, reducing DMA usage as well
1292                          * as HCD schedule-scanning costs.  delay for any qh
1293                          * we just scanned, there's a not-unusual case that it
1294                          * doesn't stay idle for long.
1295                          * (plus, avoids some kind of re-activation race.)
1296                          */
1297                         if (list_empty(&qh->qtd_list)
1298                                         && qh->qh_state == QH_STATE_LINKED) {
1299                                 if (!ehci->reclaim
1300                                         && ((ehci->stamp - qh->stamp) & 0x1fff)
1301                                                 >= (EHCI_SHRINK_FRAMES * 8))
1302                                         start_unlink_async(ehci, qh);
1303                                 else
1304                                         action = TIMER_ASYNC_SHRINK;
1305                         }
1306
1307                         qh = qh->qh_next.qh;
1308                 } while (qh);
1309         }
1310         if (action == TIMER_ASYNC_SHRINK)
1311                 timer_action (ehci, TIMER_ASYNC_SHRINK);
1312 }