kernel/drivers/usb/host/ohci-q.c

   1 /*
   2  * OHCI HCD (Host Controller Driver) for USB.
   3  *
   4  * (C) Copyright 1999 Roman Weissgaerber <weissg@vienna.at>
   5  * (C) Copyright 2000-2002 David Brownell <dbrownell@users.sourceforge.net>
   6  *
   7  * This file is licenced under the GPL.
   8  */
   9
  10 #include <linux/irq.h>
  11 #include <linux/slab.h>
  12
  13 static void urb_free_priv (struct ohci_hcd *hc, urb_priv_t *urb_priv)
  14 {
  15         int             last = urb_priv->length - 1;
  16
  17         if (last >= 0) {
  18                 int             i;
  19                 struct td       *td;
  20
  21                 for (i = 0; i <= last; i++) {
  22                         td = urb_priv->td [i];
  23                         if (td)
  24                                 td_free (hc, td);
  25                 }
  26         }
  27
  28         list_del (&urb_priv->pending);
  29         kfree (urb_priv);
  30 }
  31
  32 /*-------------------------------------------------------------------------*/
  33
  34 /*
  35  * URB goes back to driver, and isn't reissued.
  36  * It's completely gone from HC data structures.
  37  * PRECONDITION:  ohci lock held, irqs blocked.
  38  */
  39 static void
  40 finish_urb(struct ohci_hcd *ohci, struct urb *urb, int status)
  41 __releases(ohci->lock)
  42 __acquires(ohci->lock)
  43 {
  44         struct device *dev = ohci_to_hcd(ohci)->self.controller;
  45         struct usb_host_endpoint *ep = urb->ep;
  46         struct urb_priv *urb_priv;
  47
  48         // ASSERT (urb->hcpriv != 0);
  49
  50  restart:
  51         urb_free_priv (ohci, urb->hcpriv);
  52         urb->hcpriv = NULL;
  53         if (likely(status == -EINPROGRESS))
  54                 status = 0;
  55
  56         switch (usb_pipetype (urb->pipe)) {
  57         case PIPE_ISOCHRONOUS:
  58                 ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs--;
  59                 if (ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0) {
  60                         if (quirk_amdiso(ohci))
  61                                 usb_amd_quirk_pll_enable();
  62                         if (quirk_amdprefetch(ohci))
  63                                 sb800_prefetch(dev, 0);
  64                 }
  65                 break;
  66         case PIPE_INTERRUPT:
  67                 ohci_to_hcd(ohci)->self.bandwidth_int_reqs--;
  68                 break;
  69         }
  70
  71         /* urb->complete() can reenter this HCD */
  72         usb_hcd_unlink_urb_from_ep(ohci_to_hcd(ohci), urb);
  73         spin_unlock (&ohci->lock);
  74         usb_hcd_giveback_urb(ohci_to_hcd(ohci), urb, status);
  75         spin_lock (&ohci->lock);
  76
  77         /* stop periodic dma if it's not needed */
  78         if (ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0
  79                         && ohci_to_hcd(ohci)->self.bandwidth_int_reqs == 0) {
  80                 ohci->hc_control &= ~(OHCI_CTRL_PLE|OHCI_CTRL_IE);
  81                 ohci_writel (ohci, ohci->hc_control, &ohci->regs->control);
  82         }
  83
  84         /*
  85          * An isochronous URB that is sumitted too late won't have any TDs
  86          * (marked by the fact that the td_cnt value is larger than the
  87          * actual number of TDs).  If the next URB on this endpoint is like
  88          * that, give it back now.
  89          */
  90         if (!list_empty(&ep->urb_list)) {
  91                 urb = list_first_entry(&ep->urb_list, struct urb, urb_list);
  92                 urb_priv = urb->hcpriv;
  93                 if (urb_priv->td_cnt > urb_priv->length) {
  94                         status = 0;
  95                         goto restart;
  96                 }
  97         }
  98 }
  99
 100
 101 /*-------------------------------------------------------------------------*
 102  * ED handling functions
 103  *-------------------------------------------------------------------------*/
 104
 105 /* search for the right schedule branch to use for a periodic ed.
 106  * does some load balancing; returns the branch, or negative errno.
 107  */
 108 static int balance (struct ohci_hcd *ohci, int interval, int load)
 109 {
 110         int     i, branch = -ENOSPC;
 111
 112         /* iso periods can be huge; iso tds specify frame numbers */
 113         if (interval > NUM_INTS)
 114                 interval = NUM_INTS;
 115
 116         /* search for the least loaded schedule branch of that period
 117          * that has enough bandwidth left unreserved.
 118          */
 119         for (i = 0; i < interval ; i++) {
 120                 if (branch < 0 || ohci->load [branch] > ohci->load [i]) {
 121                         int     j;
 122
 123                         /* usb 1.1 says 90% of one frame */
 124                         for (j = i; j < NUM_INTS; j += interval) {
 125                                 if ((ohci->load [j] + load) > 900)
 126                                         break;
 127                         }
 128                         if (j < NUM_INTS)
 129                                 continue;
 130                         branch = i;
 131                 }
 132         }
 133         return branch;
 134 }
 135
 136 /*-------------------------------------------------------------------------*/
 137
 138 /* both iso and interrupt requests have periods; this routine puts them
 139  * into the schedule tree in the apppropriate place.  most iso devices use
 140  * 1msec periods, but that's not required.
 141  */
 142 static void periodic_link (struct ohci_hcd *ohci, struct ed *ed)
 143 {
 144         unsigned        i;
 145
 146         ohci_dbg(ohci, "link %sed %p branch %d [%dus.], interval %d\n",
 147                 (ed->hwINFO & cpu_to_hc32 (ohci, ED_ISO)) ? "iso " : "",
 148                 ed, ed->branch, ed->load, ed->interval);
 149
 150         for (i = ed->branch; i < NUM_INTS; i += ed->interval) {
 151                 struct ed       **prev = &ohci->periodic [i];
 152                 __hc32          *prev_p = &ohci->hcca->int_table [i];
 153                 struct ed       *here = *prev;
 154
 155                 /* sorting each branch by period (slow before fast)
 156                  * lets us share the faster parts of the tree.
 157                  * (plus maybe: put interrupt eds before iso)
 158                  */
 159                 while (here && ed != here) {
 160                         if (ed->interval > here->interval)
 161                                 break;
 162                         prev = &here->ed_next;
 163                         prev_p = &here->hwNextED;
 164                         here = *prev;
 165                 }
 166                 if (ed != here) {
 167                         ed->ed_next = here;
 168                         if (here)
 169                                 ed->hwNextED = *prev_p;
 170                         wmb ();
 171                         *prev = ed;
 172                         *prev_p = cpu_to_hc32(ohci, ed->dma);
 173                         wmb();
 174                 }
 175                 ohci->load [i] += ed->load;
 176         }
 177         ohci_to_hcd(ohci)->self.bandwidth_allocated += ed->load / ed->interval;
 178 }
 179
 180 /* link an ed into one of the HC chains */
 181
 182 static int ed_schedule (struct ohci_hcd *ohci, struct ed *ed)
 183 {
 184         int     branch;
 185
 186         ed->ed_prev = NULL;
 187         ed->ed_next = NULL;
 188         ed->hwNextED = 0;
 189         wmb ();
 190
 191         /* we care about rm_list when setting CLE/BLE in case the HC was at
 192          * work on some TD when CLE/BLE was turned off, and isn't quiesced
 193          * yet.  finish_unlinks() restarts as needed, some upcoming INTR_SF.
 194          *
 195          * control and bulk EDs are doubly linked (ed_next, ed_prev), but
 196          * periodic ones are singly linked (ed_next). that's because the
 197          * periodic schedule encodes a tree like figure 3-5 in the ohci
 198          * spec:  each qh can have several "previous" nodes, and the tree
 199          * doesn't have unused/idle descriptors.
 200          */
 201         switch (ed->type) {
 202         case PIPE_CONTROL:
 203                 if (ohci->ed_controltail == NULL) {
 204                         WARN_ON (ohci->hc_control & OHCI_CTRL_CLE);
 205                         ohci_writel (ohci, ed->dma,
 206                                         &ohci->regs->ed_controlhead);
 207                 } else {
 208                         ohci->ed_controltail->ed_next = ed;
 209                         ohci->ed_controltail->hwNextED = cpu_to_hc32 (ohci,
 210                                                                 ed->dma);
 211                 }
 212                 ed->ed_prev = ohci->ed_controltail;
 213                 if (!ohci->ed_controltail && !ohci->ed_rm_list) {
 214                         wmb();
 215                         ohci->hc_control |= OHCI_CTRL_CLE;
 216                         ohci_writel (ohci, 0, &ohci->regs->ed_controlcurrent);
 217                         ohci_writel (ohci, ohci->hc_control,
 218                                         &ohci->regs->control);
 219                 }
 220                 ohci->ed_controltail = ed;
 221                 break;
 222
 223         case PIPE_BULK:
 224                 if (ohci->ed_bulktail == NULL) {
 225                         WARN_ON (ohci->hc_control & OHCI_CTRL_BLE);
 226                         ohci_writel (ohci, ed->dma, &ohci->regs->ed_bulkhead);
 227                 } else {
 228                         ohci->ed_bulktail->ed_next = ed;
 229                         ohci->ed_bulktail->hwNextED = cpu_to_hc32 (ohci,
 230                                                                 ed->dma);
 231                 }
 232                 ed->ed_prev = ohci->ed_bulktail;
 233                 if (!ohci->ed_bulktail && !ohci->ed_rm_list) {
 234                         wmb();
 235                         ohci->hc_control |= OHCI_CTRL_BLE;
 236                         ohci_writel (ohci, 0, &ohci->regs->ed_bulkcurrent);
 237                         ohci_writel (ohci, ohci->hc_control,
 238                                         &ohci->regs->control);
 239                 }
 240                 ohci->ed_bulktail = ed;
 241                 break;
 242
 243         // case PIPE_INTERRUPT:
 244         // case PIPE_ISOCHRONOUS:
 245         default:
 246                 branch = balance (ohci, ed->interval, ed->load);
 247                 if (branch < 0) {
 248                         ohci_dbg (ohci,
 249                                 "ERR %d, interval %d msecs, load %d\n",
 250                                 branch, ed->interval, ed->load);
 251                         // FIXME if there are TDs queued, fail them!
 252                         return branch;
 253                 }
 254                 ed->branch = branch;
 255                 periodic_link (ohci, ed);
 256         }
 257
 258         /* the HC may not see the schedule updates yet, but if it does
 259          * then they'll be properly ordered.
 260          */
 261
 262         ed->state = ED_OPER;
 263         return 0;
 264 }
 265
 266 /*-------------------------------------------------------------------------*/
 267
 268 /* scan the periodic table to find and unlink this ED */
 269 static void periodic_unlink (struct ohci_hcd *ohci, struct ed *ed)
 270 {
 271         int     i;
 272
 273         for (i = ed->branch; i < NUM_INTS; i += ed->interval) {
 274                 struct ed       *temp;
 275                 struct ed       **prev = &ohci->periodic [i];
 276                 __hc32          *prev_p = &ohci->hcca->int_table [i];
 277
 278                 while (*prev && (temp = *prev) != ed) {
 279                         prev_p = &temp->hwNextED;
 280                         prev = &temp->ed_next;
 281                 }
 282                 if (*prev) {
 283                         *prev_p = ed->hwNextED;
 284                         *prev = ed->ed_next;
 285                 }
 286                 ohci->load [i] -= ed->load;
 287         }
 288         ohci_to_hcd(ohci)->self.bandwidth_allocated -= ed->load / ed->interval;
 289
 290         ohci_dbg(ohci, "unlink %sed %p branch %d [%dus.], interval %d\n",
 291                 (ed->hwINFO & cpu_to_hc32 (ohci, ED_ISO)) ? "iso " : "",
 292                 ed, ed->branch, ed->load, ed->interval);
 293 }
 294
 295 /* unlink an ed from one of the HC chains.
 296  * just the link to the ed is unlinked.
 297  * the link from the ed still points to another operational ed or 0
 298  * so the HC can eventually finish the processing of the unlinked ed
 299  * (assuming it already started that, which needn't be true).
 300  *
 301  * ED_UNLINK is a transient state: the HC may still see this ED, but soon
 302  * it won't.  ED_SKIP means the HC will finish its current transaction,
 303  * but won't start anything new.  The TD queue may still grow; device
 304  * drivers don't know about this HCD-internal state.
 305  *
 306  * When the HC can't see the ED, something changes ED_UNLINK to one of:
 307  *
 308  *  - ED_OPER: when there's any request queued, the ED gets rescheduled
 309  *    immediately.  HC should be working on them.
 310  *
 311  *  - ED_IDLE: when there's no TD queue or the HC isn't running.
 312  *
 313  * When finish_unlinks() runs later, after SOF interrupt, it will often
 314  * complete one or more URB unlinks before making that state change.
 315  */
 316 static void ed_deschedule (struct ohci_hcd *ohci, struct ed *ed)
 317 {
 318         ed->hwINFO |= cpu_to_hc32 (ohci, ED_SKIP);
 319         wmb ();
 320         ed->state = ED_UNLINK;
 321
 322         /* To deschedule something from the control or bulk list, just
 323          * clear CLE/BLE and wait.  There's no safe way to scrub out list
 324          * head/current registers until later, and "later" isn't very
 325          * tightly specified.  Figure 6-5 and Section 6.4.2.2 show how
 326          * the HC is reading the ED queues (while we modify them).
 327          *
 328          * For now, ed_schedule() is "later".  It might be good paranoia
 329          * to scrub those registers in finish_unlinks(), in case of bugs
 330          * that make the HC try to use them.
 331          */
 332         switch (ed->type) {
 333         case PIPE_CONTROL:
 334                 /* remove ED from the HC's list: */
 335                 if (ed->ed_prev == NULL) {
 336                         if (!ed->hwNextED) {
 337                                 ohci->hc_control &= ~OHCI_CTRL_CLE;
 338                                 ohci_writel (ohci, ohci->hc_control,
 339                                                 &ohci->regs->control);
 340                                 // a ohci_readl() later syncs CLE with the HC
 341                         } else
 342                                 ohci_writel (ohci,
 343                                         hc32_to_cpup (ohci, &ed->hwNextED),
 344                                         &ohci->regs->ed_controlhead);
 345                 } else {
 346                         ed->ed_prev->ed_next = ed->ed_next;
 347                         ed->ed_prev->hwNextED = ed->hwNextED;
 348                 }
 349                 /* remove ED from the HCD's list: */
 350                 if (ohci->ed_controltail == ed) {
 351                         ohci->ed_controltail = ed->ed_prev;
 352                         if (ohci->ed_controltail)
 353                                 ohci->ed_controltail->ed_next = NULL;
 354                 } else if (ed->ed_next) {
 355                         ed->ed_next->ed_prev = ed->ed_prev;
 356                 }
 357                 break;
 358
 359         case PIPE_BULK:
 360                 /* remove ED from the HC's list: */
 361                 if (ed->ed_prev == NULL) {
 362                         if (!ed->hwNextED) {
 363                                 ohci->hc_control &= ~OHCI_CTRL_BLE;
 364                                 ohci_writel (ohci, ohci->hc_control,
 365                                                 &ohci->regs->control);
 366                                 // a ohci_readl() later syncs BLE with the HC
 367                         } else
 368                                 ohci_writel (ohci,
 369                                         hc32_to_cpup (ohci, &ed->hwNextED),
 370                                         &ohci->regs->ed_bulkhead);
 371                 } else {
 372                         ed->ed_prev->ed_next = ed->ed_next;
 373                         ed->ed_prev->hwNextED = ed->hwNextED;
 374                 }
 375                 /* remove ED from the HCD's list: */
 376                 if (ohci->ed_bulktail == ed) {
 377                         ohci->ed_bulktail = ed->ed_prev;
 378                         if (ohci->ed_bulktail)
 379                                 ohci->ed_bulktail->ed_next = NULL;
 380                 } else if (ed->ed_next) {
 381                         ed->ed_next->ed_prev = ed->ed_prev;
 382                 }
 383                 break;
 384
 385         // case PIPE_INTERRUPT:
 386         // case PIPE_ISOCHRONOUS:
 387         default:
 388                 periodic_unlink (ohci, ed);
 389                 break;
 390         }
 391 }
 392
 393
 394 /*-------------------------------------------------------------------------*/
 395
 396 /* get and maybe (re)init an endpoint. init _should_ be done only as part
 397  * of enumeration, usb_set_configuration() or usb_set_interface().
 398  */
 399 static struct ed *ed_get (
 400         struct ohci_hcd         *ohci,
 401         struct usb_host_endpoint *ep,
 402         struct usb_device       *udev,
 403         unsigned int            pipe,
 404         int                     interval
 405 ) {
 406         struct ed               *ed;
 407         unsigned long           flags;
 408
 409         spin_lock_irqsave (&ohci->lock, flags);
 410
 411         ed = ep->hcpriv;
 412         if (!ed) {
 413                 struct td       *td;
 414                 int             is_out;
 415                 u32             info;
 416
 417                 ed = ed_alloc (ohci, GFP_ATOMIC);
 418                 if (!ed) {
 419                         /* out of memory */
 420                         goto done;
 421                 }
 422
 423                 /* dummy td; end of td list for ed */
 424                 td = td_alloc (ohci, GFP_ATOMIC);
 425                 if (!td) {
 426                         /* out of memory */
 427                         ed_free (ohci, ed);
 428                         ed = NULL;
 429                         goto done;
 430                 }
 431                 ed->dummy = td;
 432                 ed->hwTailP = cpu_to_hc32 (ohci, td->td_dma);
 433                 ed->hwHeadP = ed->hwTailP;      /* ED_C, ED_H zeroed */
 434                 ed->state = ED_IDLE;
 435
 436                 is_out = !(ep->desc.bEndpointAddress & USB_DIR_IN);
 437
 438                 /* FIXME usbcore changes dev->devnum before SET_ADDRESS
 439                  * succeeds ... otherwise we wouldn't need "pipe".
 440                  */
 441                 info = usb_pipedevice (pipe);
 442                 ed->type = usb_pipetype(pipe);
 443
 444                 info |= (ep->desc.bEndpointAddress & ~USB_DIR_IN) << 7;
 445                 info |= usb_endpoint_maxp(&ep->desc) << 16;
 446                 if (udev->speed == USB_SPEED_LOW)
 447                         info |= ED_LOWSPEED;
 448                 /* only control transfers store pids in tds */
 449                 if (ed->type != PIPE_CONTROL) {
 450                         info |= is_out ? ED_OUT : ED_IN;
 451                         if (ed->type != PIPE_BULK) {
 452                                 /* periodic transfers... */
 453                                 if (ed->type == PIPE_ISOCHRONOUS)
 454                                         info |= ED_ISO;
 455                                 else if (interval > 32) /* iso can be bigger */
 456                                         interval = 32;
 457                                 ed->interval = interval;
 458                                 ed->load = usb_calc_bus_time (
 459                                         udev->speed, !is_out,
 460                                         ed->type == PIPE_ISOCHRONOUS,
 461                                         usb_endpoint_maxp(&ep->desc))
 462                                                 / 1000;
 463                         }
 464                 }
 465                 ed->hwINFO = cpu_to_hc32(ohci, info);
 466
 467                 ep->hcpriv = ed;
 468         }
 469
 470 done:
 471         spin_unlock_irqrestore (&ohci->lock, flags);
 472         return ed;
 473 }
 474
 475 /*-------------------------------------------------------------------------*/
 476
 477 /* request unlinking of an endpoint from an operational HC.
 478  * put the ep on the rm_list
 479  * real work is done at the next start frame (SF) hardware interrupt
 480  * caller guarantees HCD is running, so hardware access is safe,
 481  * and that ed->state is ED_OPER
 482  */
 483 static void start_ed_unlink (struct ohci_hcd *ohci, struct ed *ed)
 484 {
 485         ed->hwINFO |= cpu_to_hc32 (ohci, ED_DEQUEUE);
 486         ed_deschedule (ohci, ed);
 487
 488         /* rm_list is just singly linked, for simplicity */
 489         ed->ed_next = ohci->ed_rm_list;
 490         ed->ed_prev = NULL;
 491         ohci->ed_rm_list = ed;
 492
 493         /* enable SOF interrupt */
 494         ohci_writel (ohci, OHCI_INTR_SF, &ohci->regs->intrstatus);
 495         ohci_writel (ohci, OHCI_INTR_SF, &ohci->regs->intrenable);
 496         // flush those writes, and get latest HCCA contents
 497         (void) ohci_readl (ohci, &ohci->regs->control);
 498
 499         /* SF interrupt might get delayed; record the frame counter value that
 500          * indicates when the HC isn't looking at it, so concurrent unlinks
 501          * behave.  frame_no wraps every 2^16 msec, and changes right before
 502          * SF is triggered.
 503          */
 504         ed->tick = ohci_frame_no(ohci) + 1;
 505
 506 }
 507
 508 /*-------------------------------------------------------------------------*
 509  * TD handling functions
 510  *-------------------------------------------------------------------------*/
 511
 512 /* enqueue next TD for this URB (OHCI spec 5.2.8.2) */
 513
 514 static void
 515 td_fill (struct ohci_hcd *ohci, u32 info,
 516         dma_addr_t data, int len,
 517         struct urb *urb, int index)
 518 {
 519         struct td               *td, *td_pt;
 520         struct urb_priv         *urb_priv = urb->hcpriv;
 521         int                     is_iso = info & TD_ISO;
 522         int                     hash;
 523
 524         // ASSERT (index < urb_priv->length);
 525
 526         /* aim for only one interrupt per urb.  mostly applies to control
 527          * and iso; other urbs rarely need more than one TD per urb.
 528          * this way, only final tds (or ones with an error) cause IRQs.
 529          * at least immediately; use DI=6 in case any control request is
 530          * tempted to die part way through.  (and to force the hc to flush
 531          * its donelist soonish, even on unlink paths.)
 532          *
 533          * NOTE: could delay interrupts even for the last TD, and get fewer
 534          * interrupts ... increasing per-urb latency by sharing interrupts.
 535          * Drivers that queue bulk urbs may request that behavior.
 536          */
 537         if (index != (urb_priv->length - 1)
 538                         || (urb->transfer_flags & URB_NO_INTERRUPT))
 539                 info |= TD_DI_SET (6);
 540
 541         /* use this td as the next dummy */
 542         td_pt = urb_priv->td [index];
 543
 544         /* fill the old dummy TD */
 545         td = urb_priv->td [index] = urb_priv->ed->dummy;
 546         urb_priv->ed->dummy = td_pt;
 547
 548         td->ed = urb_priv->ed;
 549         td->next_dl_td = NULL;
 550         td->index = index;
 551         td->urb = urb;
 552         td->data_dma = data;
 553         if (!len)
 554                 data = 0;
 555
 556         td->hwINFO = cpu_to_hc32 (ohci, info);
 557         if (is_iso) {
 558                 td->hwCBP = cpu_to_hc32 (ohci, data & 0xFFFFF000);
 559                 *ohci_hwPSWp(ohci, td, 0) = cpu_to_hc16 (ohci,
 560                                                 (data & 0x0FFF) | 0xE000);
 561         } else {
 562                 td->hwCBP = cpu_to_hc32 (ohci, data);
 563         }
 564         if (data)
 565                 td->hwBE = cpu_to_hc32 (ohci, data + len - 1);
 566         else
 567                 td->hwBE = 0;
 568         td->hwNextTD = cpu_to_hc32 (ohci, td_pt->td_dma);
 569
 570         /* append to queue */
 571         list_add_tail (&td->td_list, &td->ed->td_list);
 572
 573         /* hash it for later reverse mapping */
 574         hash = TD_HASH_FUNC (td->td_dma);
 575         td->td_hash = ohci->td_hash [hash];
 576         ohci->td_hash [hash] = td;
 577
 578         /* HC might read the TD (or cachelines) right away ... */
 579         wmb ();
 580         td->ed->hwTailP = td->hwNextTD;
 581 }
 582
 583 /*-------------------------------------------------------------------------*/
 584
 585 /* Prepare all TDs of a transfer, and queue them onto the ED.
 586  * Caller guarantees HC is active.
 587  * Usually the ED is already on the schedule, so TDs might be
 588  * processed as soon as they're queued.
 589  */
 590 static void td_submit_urb (
 591         struct ohci_hcd *ohci,
 592         struct urb      *urb
 593 ) {
 594         struct urb_priv *urb_priv = urb->hcpriv;
 595         struct device *dev = ohci_to_hcd(ohci)->self.controller;
 596         dma_addr_t      data;
 597         int             data_len = urb->transfer_buffer_length;
 598         int             cnt = 0;
 599         u32             info = 0;
 600         int             is_out = usb_pipeout (urb->pipe);
 601         int             periodic = 0;
 602         int             i, this_sg_len, n;
 603         struct scatterlist      *sg;
 604
 605         /* OHCI handles the bulk/interrupt data toggles itself.  We just
 606          * use the device toggle bits for resetting, and rely on the fact
 607          * that resetting toggle is meaningless if the endpoint is active.
 608          */
 609         if (!usb_gettoggle (urb->dev, usb_pipeendpoint (urb->pipe), is_out)) {
 610                 usb_settoggle (urb->dev, usb_pipeendpoint (urb->pipe),
 611                         is_out, 1);
 612                 urb_priv->ed->hwHeadP &= ~cpu_to_hc32 (ohci, ED_C);
 613         }
 614
 615         list_add (&urb_priv->pending, &ohci->pending);
 616
 617         i = urb->num_mapped_sgs;
 618         if (data_len > 0 && i > 0) {
 619                 sg = urb->sg;
 620                 data = sg_dma_address(sg);
 621
 622                 /*
 623                  * urb->transfer_buffer_length may be smaller than the
 624                  * size of the scatterlist (or vice versa)
 625                  */
 626                 this_sg_len = min_t(int, sg_dma_len(sg), data_len);
 627         } else {
 628                 sg = NULL;
 629                 if (data_len)
 630                         data = urb->transfer_dma;
 631                 else
 632                         data = 0;
 633                 this_sg_len = data_len;
 634         }
 635
 636         /* NOTE:  TD_CC is set so we can tell which TDs the HC processed by
 637          * using TD_CC_GET, as well as by seeing them on the done list.
 638          * (CC = NotAccessed ... 0x0F, or 0x0E in PSWs for ISO.)
 639          */
 640         switch (urb_priv->ed->type) {
 641
 642         /* Bulk and interrupt are identical except for where in the schedule
 643          * their EDs live.
 644          */
 645         case PIPE_INTERRUPT:
 646                 /* ... and periodic urbs have extra accounting */
 647                 periodic = ohci_to_hcd(ohci)->self.bandwidth_int_reqs++ == 0
 648                         && ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0;
 649                 /* FALLTHROUGH */
 650         case PIPE_BULK:
 651                 info = is_out
 652                         ? TD_T_TOGGLE | TD_CC | TD_DP_OUT
 653                         : TD_T_TOGGLE | TD_CC | TD_DP_IN;
 654                 /* TDs _could_ transfer up to 8K each */
 655                 for (;;) {
 656                         n = min(this_sg_len, 4096);
 657
 658                         /* maybe avoid ED halt on final TD short read */
 659                         if (n >= data_len || (i == 1 && n >= this_sg_len)) {
 660                                 if (!(urb->transfer_flags & URB_SHORT_NOT_OK))
 661                                         info |= TD_R;
 662                         }
 663                         td_fill(ohci, info, data, n, urb, cnt);
 664                         this_sg_len -= n;
 665                         data_len -= n;
 666                         data += n;
 667                         cnt++;
 668
 669                         if (this_sg_len <= 0) {
 670                                 if (--i <= 0 || data_len <= 0)
 671                                         break;
 672                                 sg = sg_next(sg);
 673                                 data = sg_dma_address(sg);
 674                                 this_sg_len = min_t(int, sg_dma_len(sg),
 675                                                 data_len);
 676                         }
 677                 }
 678                 if ((urb->transfer_flags & URB_ZERO_PACKET)
 679                                 && cnt < urb_priv->length) {
 680                         td_fill (ohci, info, 0, 0, urb, cnt);
 681                         cnt++;
 682                 }
 683                 /* maybe kickstart bulk list */
 684                 if (urb_priv->ed->type == PIPE_BULK) {
 685                         wmb ();
 686                         ohci_writel (ohci, OHCI_BLF, &ohci->regs->cmdstatus);
 687                 }
 688                 break;
 689
 690         /* control manages DATA0/DATA1 toggle per-request; SETUP resets it,
 691          * any DATA phase works normally, and the STATUS ack is special.
 692          */
 693         case PIPE_CONTROL:
 694                 info = TD_CC | TD_DP_SETUP | TD_T_DATA0;
 695                 td_fill (ohci, info, urb->setup_dma, 8, urb, cnt++);
 696                 if (data_len > 0) {
 697                         info = TD_CC | TD_R | TD_T_DATA1;
 698                         info |= is_out ? TD_DP_OUT : TD_DP_IN;
 699                         /* NOTE:  mishandles transfers >8K, some >4K */
 700                         td_fill (ohci, info, data, data_len, urb, cnt++);
 701                 }
 702                 info = (is_out || data_len == 0)
 703                         ? TD_CC | TD_DP_IN | TD_T_DATA1
 704                         : TD_CC | TD_DP_OUT | TD_T_DATA1;
 705                 td_fill (ohci, info, data, 0, urb, cnt++);
 706                 /* maybe kickstart control list */
 707                 wmb ();
 708                 ohci_writel (ohci, OHCI_CLF, &ohci->regs->cmdstatus);
 709                 break;
 710
 711         /* ISO has no retransmit, so no toggle; and it uses special TDs.
 712          * Each TD could handle multiple consecutive frames (interval 1);
 713          * we could often reduce the number of TDs here.
 714          */
 715         case PIPE_ISOCHRONOUS:
 716                 for (cnt = urb_priv->td_cnt; cnt < urb->number_of_packets;
 717                                 cnt++) {
 718                         int     frame = urb->start_frame;
 719
 720                         // FIXME scheduling should handle frame counter
 721                         // roll-around ... exotic case (and OHCI has
 722                         // a 2^16 iso range, vs other HCs max of 2^10)
 723                         frame += cnt * urb->interval;
 724                         frame &= 0xffff;
 725                         td_fill (ohci, TD_CC | TD_ISO | frame,
 726                                 data + urb->iso_frame_desc [cnt].offset,
 727                                 urb->iso_frame_desc [cnt].length, urb, cnt);
 728                 }
 729                 if (ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs == 0) {
 730                         if (quirk_amdiso(ohci))
 731                                 usb_amd_quirk_pll_disable();
 732                         if (quirk_amdprefetch(ohci))
 733                                 sb800_prefetch(dev, 1);
 734                 }
 735                 periodic = ohci_to_hcd(ohci)->self.bandwidth_isoc_reqs++ == 0
 736                         && ohci_to_hcd(ohci)->self.bandwidth_int_reqs == 0;
 737                 break;
 738         }
 739
 740         /* start periodic dma if needed */
 741         if (periodic) {
 742                 wmb ();
 743                 ohci->hc_control |= OHCI_CTRL_PLE|OHCI_CTRL_IE;
 744                 ohci_writel (ohci, ohci->hc_control, &ohci->regs->control);
 745         }
 746
 747         // ASSERT (urb_priv->length == cnt);
 748 }
 749
 750 /*-------------------------------------------------------------------------*
 751  * Done List handling functions
 752  *-------------------------------------------------------------------------*/
 753
 754 /* calculate transfer length/status and update the urb */
 755 static int td_done(struct ohci_hcd *ohci, struct urb *urb, struct td *td)
 756 {
 757         u32     tdINFO = hc32_to_cpup (ohci, &td->hwINFO);
 758         int     cc = 0;
 759         int     status = -EINPROGRESS;
 760
 761         list_del (&td->td_list);
 762
 763         /* ISO ... drivers see per-TD length/status */
 764         if (tdINFO & TD_ISO) {
 765                 u16     tdPSW = ohci_hwPSW(ohci, td, 0);
 766                 int     dlen = 0;
 767
 768                 /* NOTE:  assumes FC in tdINFO == 0, and that
 769                  * only the first of 0..MAXPSW psws is used.
 770                  */
 771
 772                 cc = (tdPSW >> 12) & 0xF;
 773                 if (tdINFO & TD_CC)     /* hc didn't touch? */
 774                         return status;
 775
 776                 if (usb_pipeout (urb->pipe))
 777                         dlen = urb->iso_frame_desc [td->index].length;
 778                 else {
 779                         /* short reads are always OK for ISO */
 780                         if (cc == TD_DATAUNDERRUN)
 781                                 cc = TD_CC_NOERROR;
 782                         dlen = tdPSW & 0x3ff;
 783                 }
 784                 urb->actual_length += dlen;
 785                 urb->iso_frame_desc [td->index].actual_length = dlen;
 786                 urb->iso_frame_desc [td->index].status = cc_to_error [cc];
 787
 788                 if (cc != TD_CC_NOERROR)
 789                         ohci_dbg(ohci,
 790                                 "urb %p iso td %p (%d) len %d cc %d\n",
 791                                 urb, td, 1 + td->index, dlen, cc);
 792
 793         /* BULK, INT, CONTROL ... drivers see aggregate length/status,
 794          * except that "setup" bytes aren't counted and "short" transfers
 795          * might not be reported as errors.
 796          */
 797         } else {
 798                 int     type = usb_pipetype (urb->pipe);
 799                 u32     tdBE = hc32_to_cpup (ohci, &td->hwBE);
 800
 801                 cc = TD_CC_GET (tdINFO);
 802
 803                 /* update packet status if needed (short is normally ok) */
 804                 if (cc == TD_DATAUNDERRUN
 805                                 && !(urb->transfer_flags & URB_SHORT_NOT_OK))
 806                         cc = TD_CC_NOERROR;
 807                 if (cc != TD_CC_NOERROR && cc < 0x0E)
 808                         status = cc_to_error[cc];
 809
 810                 /* count all non-empty packets except control SETUP packet */
 811                 if ((type != PIPE_CONTROL || td->index != 0) && tdBE != 0) {
 812                         if (td->hwCBP == 0)
 813                                 urb->actual_length += tdBE - td->data_dma + 1;
 814                         else
 815                                 urb->actual_length +=
 816                                           hc32_to_cpup (ohci, &td->hwCBP)
 817                                         - td->data_dma;
 818                 }
 819
 820                 if (cc != TD_CC_NOERROR && cc < 0x0E)
 821                         ohci_dbg(ohci,
 822                                 "urb %p td %p (%d) cc %d, len=%d/%d\n",
 823                                 urb, td, 1 + td->index, cc,
 824                                 urb->actual_length,
 825                                 urb->transfer_buffer_length);
 826         }
 827         return status;
 828 }
 829
 830 /*-------------------------------------------------------------------------*/
 831
 832 static void ed_halted(struct ohci_hcd *ohci, struct td *td, int cc)
 833 {
 834         struct urb              *urb = td->urb;
 835         urb_priv_t              *urb_priv = urb->hcpriv;
 836         struct ed               *ed = td->ed;
 837         struct list_head        *tmp = td->td_list.next;
 838         __hc32                  toggle = ed->hwHeadP & cpu_to_hc32 (ohci, ED_C);
 839
 840         /* clear ed halt; this is the td that caused it, but keep it inactive
 841          * until its urb->complete() has a chance to clean up.
 842          */
 843         ed->hwINFO |= cpu_to_hc32 (ohci, ED_SKIP);
 844         wmb ();
 845         ed->hwHeadP &= ~cpu_to_hc32 (ohci, ED_H);
 846
 847         /* Get rid of all later tds from this urb.  We don't have
 848          * to be careful: no errors and nothing was transferred.
 849          * Also patch the ed so it looks as if those tds completed normally.
 850          */
 851         while (tmp != &ed->td_list) {
 852                 struct td       *next;
 853
 854                 next = list_entry (tmp, struct td, td_list);
 855                 tmp = next->td_list.next;
 856
 857                 if (next->urb != urb)
 858                         break;
 859
 860                 /* NOTE: if multi-td control DATA segments get supported,
 861                  * this urb had one of them, this td wasn't the last td
 862                  * in that segment (TD_R clear), this ed halted because
 863                  * of a short read, _and_ URB_SHORT_NOT_OK is clear ...
 864                  * then we need to leave the control STATUS packet queued
 865                  * and clear ED_SKIP.
 866                  */
 867
 868                 list_del(&next->td_list);
 869                 urb_priv->td_cnt++;
 870                 ed->hwHeadP = next->hwNextTD | toggle;
 871         }
 872
 873         /* help for troubleshooting:  report anything that
 874          * looks odd ... that doesn't include protocol stalls
 875          * (or maybe some other things)
 876          */
 877         switch (cc) {
 878         case TD_DATAUNDERRUN:
 879                 if ((urb->transfer_flags & URB_SHORT_NOT_OK) == 0)
 880                         break;
 881                 /* fallthrough */
 882         case TD_CC_STALL:
 883                 if (usb_pipecontrol (urb->pipe))
 884                         break;
 885                 /* fallthrough */
 886         default:
 887                 ohci_dbg (ohci,
 888                         "urb %p path %s ep%d%s %08x cc %d --> status %d\n",
 889                         urb, urb->dev->devpath,
 890                         usb_pipeendpoint (urb->pipe),
 891                         usb_pipein (urb->pipe) ? "in" : "out",
 892                         hc32_to_cpu (ohci, td->hwINFO),
 893                         cc, cc_to_error [cc]);
 894         }
 895 }
 896
 897 /* Add a TD to the done list */
 898 static void add_to_done_list(struct ohci_hcd *ohci, struct td *td)
 899 {
 900         struct td       *td2, *td_prev;
 901         struct ed       *ed;
 902
 903         if (td->next_dl_td)
 904                 return;         /* Already on the list */
 905
 906         /* Add all the TDs going back until we reach one that's on the list */
 907         ed = td->ed;
 908         td2 = td_prev = td;
 909         list_for_each_entry_continue_reverse(td2, &ed->td_list, td_list) {
 910                 if (td2->next_dl_td)
 911                         break;
 912                 td2->next_dl_td = td_prev;
 913                 td_prev = td2;
 914         }
 915
 916         if (ohci->dl_end)
 917                 ohci->dl_end->next_dl_td = td_prev;
 918         else
 919                 ohci->dl_start = td_prev;
 920
 921         /*
 922          * Make td->next_dl_td point to td itself, to mark the fact
 923          * that td is on the done list.
 924          */
 925         ohci->dl_end = td->next_dl_td = td;
 926
 927         /* Did we just add the latest pending TD? */
 928         td2 = ed->pending_td;
 929         if (td2 && td2->next_dl_td)
 930                 ed->pending_td = NULL;
 931 }
 932
 933 /* Get the entries on the hardware done queue and put them on our list */
 934 static void update_done_list(struct ohci_hcd *ohci)
 935 {
 936         u32             td_dma;
 937         struct td       *td = NULL;
 938
 939         td_dma = hc32_to_cpup (ohci, &ohci->hcca->done_head);
 940         ohci->hcca->done_head = 0;
 941         wmb();
 942
 943         /* get TD from hc's singly linked list, and
 944          * add to ours.  ed->td_list changes later.
 945          */
 946         while (td_dma) {
 947                 int             cc;
 948
 949                 td = dma_to_td (ohci, td_dma);
 950                 if (!td) {
 951                         ohci_err (ohci, "bad entry %8x\n", td_dma);
 952                         break;
 953                 }
 954
 955                 td->hwINFO |= cpu_to_hc32 (ohci, TD_DONE);
 956                 cc = TD_CC_GET (hc32_to_cpup (ohci, &td->hwINFO));
 957
 958                 /* Non-iso endpoints can halt on error; un-halt,
 959                  * and dequeue any other TDs from this urb.
 960                  * No other TD could have caused the halt.
 961                  */
 962                 if (cc != TD_CC_NOERROR
 963                                 && (td->ed->hwHeadP & cpu_to_hc32 (ohci, ED_H)))
 964                         ed_halted(ohci, td, cc);
 965
 966                 td_dma = hc32_to_cpup (ohci, &td->hwNextTD);
 967                 add_to_done_list(ohci, td);
 968         }
 969 }
 970
 971 /*-------------------------------------------------------------------------*/
 972
 973 /* there are some urbs/eds to unlink; called in_irq(), with HCD locked */
 974 static void finish_unlinks(struct ohci_hcd *ohci)
 975 {
 976         unsigned        tick = ohci_frame_no(ohci);
 977         struct ed       *ed, **last;
 978
 979 rescan_all:
 980         for (last = &ohci->ed_rm_list, ed = *last; ed != NULL; ed = *last) {
 981                 struct list_head        *entry, *tmp;
 982                 int                     completed, modified;
 983                 __hc32                  *prev;
 984
 985                 /* only take off EDs that the HC isn't using, accounting for
 986                  * frame counter wraps and EDs with partially retired TDs
 987                  */
 988                 if (likely(ohci->rh_state == OHCI_RH_RUNNING) &&
 989                                 tick_before(tick, ed->tick)) {
 990 skip_ed:
 991                         last = &ed->ed_next;
 992                         continue;
 993                 }
 994                 if (!list_empty(&ed->td_list)) {
 995                         struct td       *td;
 996                         u32             head;
 997
 998                         td = list_first_entry(&ed->td_list, struct td, td_list);
 999
1000                         /* INTR_WDH may need to clean up first */
1001                         head = hc32_to_cpu(ohci, ed->hwHeadP) & TD_MASK;
1002                         if (td->td_dma != head &&
1003                                         ohci->rh_state == OHCI_RH_RUNNING)
1004                                 goto skip_ed;
1005
1006                         /* Don't mess up anything already on the done list */
1007                         if (td->next_dl_td)
1008                                 goto skip_ed;
1009                 }
1010
1011                 /* ED's now officially unlinked, hc doesn't see */
1012                 ed->hwHeadP &= ~cpu_to_hc32(ohci, ED_H);
1013                 ed->hwNextED = 0;
1014                 wmb();
1015                 ed->hwINFO &= ~cpu_to_hc32(ohci, ED_SKIP | ED_DEQUEUE);
1016
1017                 /* reentrancy:  if we drop the schedule lock, someone might
1018                  * have modified this list.  normally it's just prepending
1019                  * entries (which we'd ignore), but paranoia won't hurt.
1020                  */
1021                 modified = 0;
1022
1023                 /* unlink urbs as requested, but rescan the list after
1024                  * we call a completion since it might have unlinked
1025                  * another (earlier) urb
1026                  *
1027                  * When we get here, the HC doesn't see this ed.  But it
1028                  * must not be rescheduled until all completed URBs have
1029                  * been given back to the driver.
1030                  */
1031 rescan_this:
1032                 completed = 0;
1033                 prev = &ed->hwHeadP;
1034                 list_for_each_safe (entry, tmp, &ed->td_list) {
1035                         struct td       *td;
1036                         struct urb      *urb;
1037                         urb_priv_t      *urb_priv;
1038                         __hc32          savebits;
1039                         u32             tdINFO;
1040
1041                         td = list_entry (entry, struct td, td_list);
1042                         urb = td->urb;
1043                         urb_priv = td->urb->hcpriv;
1044
1045                         if (!urb->unlinked) {
1046                                 prev = &td->hwNextTD;
1047                                 continue;
1048                         }
1049
1050                         /* patch pointer hc uses */
1051                         savebits = *prev & ~cpu_to_hc32 (ohci, TD_MASK);
1052                         *prev = td->hwNextTD | savebits;
1053
1054                         /* If this was unlinked, the TD may not have been
1055                          * retired ... so manually save the data toggle.
1056                          * The controller ignores the value we save for
1057                          * control and ISO endpoints.
1058                          */
1059                         tdINFO = hc32_to_cpup(ohci, &td->hwINFO);
1060                         if ((tdINFO & TD_T) == TD_T_DATA0)
1061                                 ed->hwHeadP &= ~cpu_to_hc32(ohci, ED_C);
1062                         else if ((tdINFO & TD_T) == TD_T_DATA1)
1063                                 ed->hwHeadP |= cpu_to_hc32(ohci, ED_C);
1064
1065                         /* HC may have partly processed this TD */
1066                         td_done (ohci, urb, td);
1067                         urb_priv->td_cnt++;
1068
1069                         /* if URB is done, clean up */
1070                         if (urb_priv->td_cnt >= urb_priv->length) {
1071                                 modified = completed = 1;
1072                                 finish_urb(ohci, urb, 0);
1073                         }
1074                 }
1075                 if (completed && !list_empty (&ed->td_list))
1076                         goto rescan_this;
1077
1078                 /*
1079                  * If no TDs are queued, take ED off the ed_rm_list.
1080                  * Otherwise, if the HC is running, reschedule.
1081                  * If not, leave it on the list for further dequeues.
1082                  */
1083                 if (list_empty(&ed->td_list)) {
1084                         *last = ed->ed_next;
1085                         ed->ed_next = NULL;
1086                         ed->state = ED_IDLE;
1087                         list_del(&ed->in_use_list);
1088                 } else if (ohci->rh_state == OHCI_RH_RUNNING) {
1089                         *last = ed->ed_next;
1090                         ed->ed_next = NULL;
1091                         ed_schedule(ohci, ed);
1092                 } else {
1093                         last = &ed->ed_next;
1094                 }
1095
1096                 if (modified)
1097                         goto rescan_all;
1098         }
1099
1100         /* maybe reenable control and bulk lists */
1101         if (ohci->rh_state == OHCI_RH_RUNNING && !ohci->ed_rm_list) {
1102                 u32     command = 0, control = 0;
1103
1104                 if (ohci->ed_controltail) {
1105                         command |= OHCI_CLF;
1106                         if (quirk_zfmicro(ohci))
1107                                 mdelay(1);
1108                         if (!(ohci->hc_control & OHCI_CTRL_CLE)) {
1109                                 control |= OHCI_CTRL_CLE;
1110                                 ohci_writel (ohci, 0,
1111                                         &ohci->regs->ed_controlcurrent);
1112                         }
1113                 }
1114                 if (ohci->ed_bulktail) {
1115                         command |= OHCI_BLF;
1116                         if (quirk_zfmicro(ohci))
1117                                 mdelay(1);
1118                         if (!(ohci->hc_control & OHCI_CTRL_BLE)) {
1119                                 control |= OHCI_CTRL_BLE;
1120                                 ohci_writel (ohci, 0,
1121                                         &ohci->regs->ed_bulkcurrent);
1122                         }
1123                 }
1124
1125                 /* CLE/BLE to enable, CLF/BLF to (maybe) kickstart */
1126                 if (control) {
1127                         ohci->hc_control |= control;
1128                         if (quirk_zfmicro(ohci))
1129                                 mdelay(1);
1130                         ohci_writel (ohci, ohci->hc_control,
1131                                         &ohci->regs->control);
1132                 }
1133                 if (command) {
1134                         if (quirk_zfmicro(ohci))
1135                                 mdelay(1);
1136                         ohci_writel (ohci, command, &ohci->regs->cmdstatus);
1137                 }
1138         }
1139 }
1140
1141
1142
1143 /*-------------------------------------------------------------------------*/
1144
1145 /* Take back a TD from the host controller */
1146 static void takeback_td(struct ohci_hcd *ohci, struct td *td)
1147 {
1148         struct urb      *urb = td->urb;
1149         urb_priv_t      *urb_priv = urb->hcpriv;
1150         struct ed       *ed = td->ed;
1151         int             status;
1152
1153         /* update URB's length and status from TD */
1154         status = td_done(ohci, urb, td);
1155         urb_priv->td_cnt++;
1156
1157         /* If all this urb's TDs are done, call complete() */
1158         if (urb_priv->td_cnt >= urb_priv->length)
1159                 finish_urb(ohci, urb, status);
1160
1161         /* clean schedule:  unlink EDs that are no longer busy */
1162         if (list_empty(&ed->td_list)) {
1163                 if (ed->state == ED_OPER)
1164                         start_ed_unlink(ohci, ed);
1165
1166         /* ... reenabling halted EDs only after fault cleanup */
1167         } else if ((ed->hwINFO & cpu_to_hc32(ohci, ED_SKIP | ED_DEQUEUE))
1168                         == cpu_to_hc32(ohci, ED_SKIP)) {
1169                 td = list_entry(ed->td_list.next, struct td, td_list);
1170                 if (!(td->hwINFO & cpu_to_hc32(ohci, TD_DONE))) {
1171                         ed->hwINFO &= ~cpu_to_hc32(ohci, ED_SKIP);
1172                         /* ... hc may need waking-up */
1173                         switch (ed->type) {
1174                         case PIPE_CONTROL:
1175                                 ohci_writel(ohci, OHCI_CLF,
1176                                                 &ohci->regs->cmdstatus);
1177                                 break;
1178                         case PIPE_BULK:
1179                                 ohci_writel(ohci, OHCI_BLF,
1180                                                 &ohci->regs->cmdstatus);
1181                                 break;
1182                         }
1183                 }
1184         }
1185 }
1186
1187 /*
1188  * Process normal completions (error or success) and clean the schedules.
1189  *
1190  * This is the main path for handing urbs back to drivers.  The only other
1191  * normal path is finish_unlinks(), which unlinks URBs using ed_rm_list,
1192  * instead of scanning the (re-reversed) donelist as this does.
1193  */
1194 static void process_done_list(struct ohci_hcd *ohci)
1195 {
1196         struct td       *td;
1197
1198         while (ohci->dl_start) {
1199                 td = ohci->dl_start;
1200                 if (td == ohci->dl_end)
1201                         ohci->dl_start = ohci->dl_end = NULL;
1202                 else
1203                         ohci->dl_start = td->next_dl_td;
1204
1205                 takeback_td(ohci, td);
1206         }
1207 }
1208
1209 /*
1210  * TD takeback and URB giveback must be single-threaded.
1211  * This routine takes care of it all.
1212  */
1213 static void ohci_work(struct ohci_hcd *ohci)
1214 {
1215         if (ohci->working) {
1216                 ohci->restart_work = 1;
1217                 return;
1218         }
1219         ohci->working = 1;
1220
1221  restart:
1222         process_done_list(ohci);
1223         if (ohci->ed_rm_list)
1224                 finish_unlinks(ohci);
1225
1226         if (ohci->restart_work) {
1227                 ohci->restart_work = 0;
1228                 goto restart;
1229         }
1230         ohci->working = 0;
1231 }