xref: /linux/drivers/usb/host/ehci-sched.c (revision f2ee442115c9b6219083c019939a9cc0c9abb2f8)
1 /*
2  * Copyright (c) 2001-2004 by David Brownell
3  * Copyright (c) 2003 Michal Sojka, for high-speed iso transfers
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License as published by the
7  * Free Software Foundation; either version 2 of the License, or (at your
8  * option) any later version.
9  *
10  * This program is distributed in the hope that it will be useful, but
11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13  * for more details.
14  *
15  * You should have received a copy of the GNU General Public License
16  * along with this program; if not, write to the Free Software Foundation,
17  * Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18  */
19 
20 /* this file is part of ehci-hcd.c */
21 
22 /*-------------------------------------------------------------------------*/
23 
24 /*
25  * EHCI scheduled transaction support:  interrupt, iso, split iso
26  * These are called "periodic" transactions in the EHCI spec.
27  *
28  * Note that for interrupt transfers, the QH/QTD manipulation is shared
29  * with the "asynchronous" transaction support (control/bulk transfers).
30  * The only real difference is in how interrupt transfers are scheduled.
31  *
32  * For ISO, we make an "iso_stream" head to serve the same role as a QH.
33  * It keeps track of every ITD (or SITD) that's linked, and holds enough
34  * pre-calculated schedule data to make appending to the queue be quick.
35  */
36 
37 static int ehci_get_frame (struct usb_hcd *hcd);
38 
39 #ifdef CONFIG_PCI
40 
41 static unsigned ehci_read_frame_index(struct ehci_hcd *ehci)
42 {
43 	unsigned uf;
44 
45 	/*
46 	 * The MosChip MCS9990 controller updates its microframe counter
47 	 * a little before the frame counter, and occasionally we will read
48 	 * the invalid intermediate value.  Avoid problems by checking the
49 	 * microframe number (the low-order 3 bits); if they are 0 then
50 	 * re-read the register to get the correct value.
51 	 */
52 	uf = ehci_readl(ehci, &ehci->regs->frame_index);
53 	if (unlikely(ehci->frame_index_bug && ((uf & 7) == 0)))
54 		uf = ehci_readl(ehci, &ehci->regs->frame_index);
55 	return uf;
56 }
57 
58 #endif
59 
60 /*-------------------------------------------------------------------------*/
61 
62 /*
63  * periodic_next_shadow - return "next" pointer on shadow list
64  * @periodic: host pointer to qh/itd/sitd
65  * @tag: hardware tag for type of this record
66  */
67 static union ehci_shadow *
68 periodic_next_shadow(struct ehci_hcd *ehci, union ehci_shadow *periodic,
69 		__hc32 tag)
70 {
71 	switch (hc32_to_cpu(ehci, tag)) {
72 	case Q_TYPE_QH:
73 		return &periodic->qh->qh_next;
74 	case Q_TYPE_FSTN:
75 		return &periodic->fstn->fstn_next;
76 	case Q_TYPE_ITD:
77 		return &periodic->itd->itd_next;
78 	// case Q_TYPE_SITD:
79 	default:
80 		return &periodic->sitd->sitd_next;
81 	}
82 }
83 
84 static __hc32 *
85 shadow_next_periodic(struct ehci_hcd *ehci, union ehci_shadow *periodic,
86 		__hc32 tag)
87 {
88 	switch (hc32_to_cpu(ehci, tag)) {
89 	/* our ehci_shadow.qh is actually software part */
90 	case Q_TYPE_QH:
91 		return &periodic->qh->hw->hw_next;
92 	/* others are hw parts */
93 	default:
94 		return periodic->hw_next;
95 	}
96 }
97 
98 /* caller must hold ehci->lock */
99 static void periodic_unlink (struct ehci_hcd *ehci, unsigned frame, void *ptr)
100 {
101 	union ehci_shadow	*prev_p = &ehci->pshadow[frame];
102 	__hc32			*hw_p = &ehci->periodic[frame];
103 	union ehci_shadow	here = *prev_p;
104 
105 	/* find predecessor of "ptr"; hw and shadow lists are in sync */
106 	while (here.ptr && here.ptr != ptr) {
107 		prev_p = periodic_next_shadow(ehci, prev_p,
108 				Q_NEXT_TYPE(ehci, *hw_p));
109 		hw_p = shadow_next_periodic(ehci, &here,
110 				Q_NEXT_TYPE(ehci, *hw_p));
111 		here = *prev_p;
112 	}
113 	/* an interrupt entry (at list end) could have been shared */
114 	if (!here.ptr)
115 		return;
116 
117 	/* update shadow and hardware lists ... the old "next" pointers
118 	 * from ptr may still be in use, the caller updates them.
119 	 */
120 	*prev_p = *periodic_next_shadow(ehci, &here,
121 			Q_NEXT_TYPE(ehci, *hw_p));
122 
123 	if (!ehci->use_dummy_qh ||
124 	    *shadow_next_periodic(ehci, &here, Q_NEXT_TYPE(ehci, *hw_p))
125 			!= EHCI_LIST_END(ehci))
126 		*hw_p = *shadow_next_periodic(ehci, &here,
127 				Q_NEXT_TYPE(ehci, *hw_p));
128 	else
129 		*hw_p = ehci->dummy->qh_dma;
130 }
131 
132 /* how many of the uframe's 125 usecs are allocated? */
133 static unsigned short
134 periodic_usecs (struct ehci_hcd *ehci, unsigned frame, unsigned uframe)
135 {
136 	__hc32			*hw_p = &ehci->periodic [frame];
137 	union ehci_shadow	*q = &ehci->pshadow [frame];
138 	unsigned		usecs = 0;
139 	struct ehci_qh_hw	*hw;
140 
141 	while (q->ptr) {
142 		switch (hc32_to_cpu(ehci, Q_NEXT_TYPE(ehci, *hw_p))) {
143 		case Q_TYPE_QH:
144 			hw = q->qh->hw;
145 			/* is it in the S-mask? */
146 			if (hw->hw_info2 & cpu_to_hc32(ehci, 1 << uframe))
147 				usecs += q->qh->usecs;
148 			/* ... or C-mask? */
149 			if (hw->hw_info2 & cpu_to_hc32(ehci,
150 					1 << (8 + uframe)))
151 				usecs += q->qh->c_usecs;
152 			hw_p = &hw->hw_next;
153 			q = &q->qh->qh_next;
154 			break;
155 		// case Q_TYPE_FSTN:
156 		default:
157 			/* for "save place" FSTNs, count the relevant INTR
158 			 * bandwidth from the previous frame
159 			 */
160 			if (q->fstn->hw_prev != EHCI_LIST_END(ehci)) {
161 				ehci_dbg (ehci, "ignoring FSTN cost ...\n");
162 			}
163 			hw_p = &q->fstn->hw_next;
164 			q = &q->fstn->fstn_next;
165 			break;
166 		case Q_TYPE_ITD:
167 			if (q->itd->hw_transaction[uframe])
168 				usecs += q->itd->stream->usecs;
169 			hw_p = &q->itd->hw_next;
170 			q = &q->itd->itd_next;
171 			break;
172 		case Q_TYPE_SITD:
173 			/* is it in the S-mask?  (count SPLIT, DATA) */
174 			if (q->sitd->hw_uframe & cpu_to_hc32(ehci,
175 					1 << uframe)) {
176 				if (q->sitd->hw_fullspeed_ep &
177 						cpu_to_hc32(ehci, 1<<31))
178 					usecs += q->sitd->stream->usecs;
179 				else	/* worst case for OUT start-split */
180 					usecs += HS_USECS_ISO (188);
181 			}
182 
183 			/* ... C-mask?  (count CSPLIT, DATA) */
184 			if (q->sitd->hw_uframe &
185 					cpu_to_hc32(ehci, 1 << (8 + uframe))) {
186 				/* worst case for IN complete-split */
187 				usecs += q->sitd->stream->c_usecs;
188 			}
189 
190 			hw_p = &q->sitd->hw_next;
191 			q = &q->sitd->sitd_next;
192 			break;
193 		}
194 	}
195 #ifdef	DEBUG
196 	if (usecs > ehci->uframe_periodic_max)
197 		ehci_err (ehci, "uframe %d sched overrun: %d usecs\n",
198 			frame * 8 + uframe, usecs);
199 #endif
200 	return usecs;
201 }
202 
203 /*-------------------------------------------------------------------------*/
204 
205 static int same_tt (struct usb_device *dev1, struct usb_device *dev2)
206 {
207 	if (!dev1->tt || !dev2->tt)
208 		return 0;
209 	if (dev1->tt != dev2->tt)
210 		return 0;
211 	if (dev1->tt->multi)
212 		return dev1->ttport == dev2->ttport;
213 	else
214 		return 1;
215 }
216 
217 #ifdef CONFIG_USB_EHCI_TT_NEWSCHED
218 
219 /* Which uframe does the low/fullspeed transfer start in?
220  *
221  * The parameter is the mask of ssplits in "H-frame" terms
222  * and this returns the transfer start uframe in "B-frame" terms,
223  * which allows both to match, e.g. a ssplit in "H-frame" uframe 0
224  * will cause a transfer in "B-frame" uframe 0.  "B-frames" lag
225  * "H-frames" by 1 uframe.  See the EHCI spec sec 4.5 and figure 4.7.
226  */
227 static inline unsigned char tt_start_uframe(struct ehci_hcd *ehci, __hc32 mask)
228 {
229 	unsigned char smask = QH_SMASK & hc32_to_cpu(ehci, mask);
230 	if (!smask) {
231 		ehci_err(ehci, "invalid empty smask!\n");
232 		/* uframe 7 can't have bw so this will indicate failure */
233 		return 7;
234 	}
235 	return ffs(smask) - 1;
236 }
237 
238 static const unsigned char
239 max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 30, 0 };
240 
241 /* carryover low/fullspeed bandwidth that crosses uframe boundries */
242 static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8])
243 {
244 	int i;
245 	for (i=0; i<7; i++) {
246 		if (max_tt_usecs[i] < tt_usecs[i]) {
247 			tt_usecs[i+1] += tt_usecs[i] - max_tt_usecs[i];
248 			tt_usecs[i] = max_tt_usecs[i];
249 		}
250 	}
251 }
252 
253 /* How many of the tt's periodic downstream 1000 usecs are allocated?
254  *
255  * While this measures the bandwidth in terms of usecs/uframe,
256  * the low/fullspeed bus has no notion of uframes, so any particular
257  * low/fullspeed transfer can "carry over" from one uframe to the next,
258  * since the TT just performs downstream transfers in sequence.
259  *
260  * For example two separate 100 usec transfers can start in the same uframe,
261  * and the second one would "carry over" 75 usecs into the next uframe.
262  */
263 static void
264 periodic_tt_usecs (
265 	struct ehci_hcd *ehci,
266 	struct usb_device *dev,
267 	unsigned frame,
268 	unsigned short tt_usecs[8]
269 )
270 {
271 	__hc32			*hw_p = &ehci->periodic [frame];
272 	union ehci_shadow	*q = &ehci->pshadow [frame];
273 	unsigned char		uf;
274 
275 	memset(tt_usecs, 0, 16);
276 
277 	while (q->ptr) {
278 		switch (hc32_to_cpu(ehci, Q_NEXT_TYPE(ehci, *hw_p))) {
279 		case Q_TYPE_ITD:
280 			hw_p = &q->itd->hw_next;
281 			q = &q->itd->itd_next;
282 			continue;
283 		case Q_TYPE_QH:
284 			if (same_tt(dev, q->qh->dev)) {
285 				uf = tt_start_uframe(ehci, q->qh->hw->hw_info2);
286 				tt_usecs[uf] += q->qh->tt_usecs;
287 			}
288 			hw_p = &q->qh->hw->hw_next;
289 			q = &q->qh->qh_next;
290 			continue;
291 		case Q_TYPE_SITD:
292 			if (same_tt(dev, q->sitd->urb->dev)) {
293 				uf = tt_start_uframe(ehci, q->sitd->hw_uframe);
294 				tt_usecs[uf] += q->sitd->stream->tt_usecs;
295 			}
296 			hw_p = &q->sitd->hw_next;
297 			q = &q->sitd->sitd_next;
298 			continue;
299 		// case Q_TYPE_FSTN:
300 		default:
301 			ehci_dbg(ehci, "ignoring periodic frame %d FSTN\n",
302 					frame);
303 			hw_p = &q->fstn->hw_next;
304 			q = &q->fstn->fstn_next;
305 		}
306 	}
307 
308 	carryover_tt_bandwidth(tt_usecs);
309 
310 	if (max_tt_usecs[7] < tt_usecs[7])
311 		ehci_err(ehci, "frame %d tt sched overrun: %d usecs\n",
312 			frame, tt_usecs[7] - max_tt_usecs[7]);
313 }
314 
315 /*
316  * Return true if the device's tt's downstream bus is available for a
317  * periodic transfer of the specified length (usecs), starting at the
318  * specified frame/uframe.  Note that (as summarized in section 11.19
319  * of the usb 2.0 spec) TTs can buffer multiple transactions for each
320  * uframe.
321  *
322  * The uframe parameter is when the fullspeed/lowspeed transfer
323  * should be executed in "B-frame" terms, which is the same as the
324  * highspeed ssplit's uframe (which is in "H-frame" terms).  For example
325  * a ssplit in "H-frame" 0 causes a transfer in "B-frame" 0.
326  * See the EHCI spec sec 4.5 and fig 4.7.
327  *
328  * This checks if the full/lowspeed bus, at the specified starting uframe,
329  * has the specified bandwidth available, according to rules listed
330  * in USB 2.0 spec section 11.18.1 fig 11-60.
331  *
332  * This does not check if the transfer would exceed the max ssplit
333  * limit of 16, specified in USB 2.0 spec section 11.18.4 requirement #4,
334  * since proper scheduling limits ssplits to less than 16 per uframe.
335  */
336 static int tt_available (
337 	struct ehci_hcd		*ehci,
338 	unsigned		period,
339 	struct usb_device	*dev,
340 	unsigned		frame,
341 	unsigned		uframe,
342 	u16			usecs
343 )
344 {
345 	if ((period == 0) || (uframe >= 7))	/* error */
346 		return 0;
347 
348 	for (; frame < ehci->periodic_size; frame += period) {
349 		unsigned short tt_usecs[8];
350 
351 		periodic_tt_usecs (ehci, dev, frame, tt_usecs);
352 
353 		ehci_vdbg(ehci, "tt frame %d check %d usecs start uframe %d in"
354 			" schedule %d/%d/%d/%d/%d/%d/%d/%d\n",
355 			frame, usecs, uframe,
356 			tt_usecs[0], tt_usecs[1], tt_usecs[2], tt_usecs[3],
357 			tt_usecs[4], tt_usecs[5], tt_usecs[6], tt_usecs[7]);
358 
359 		if (max_tt_usecs[uframe] <= tt_usecs[uframe]) {
360 			ehci_vdbg(ehci, "frame %d uframe %d fully scheduled\n",
361 				frame, uframe);
362 			return 0;
363 		}
364 
365 		/* special case for isoc transfers larger than 125us:
366 		 * the first and each subsequent fully used uframe
367 		 * must be empty, so as to not illegally delay
368 		 * already scheduled transactions
369 		 */
370 		if (125 < usecs) {
371 			int ufs = (usecs / 125);
372 			int i;
373 			for (i = uframe; i < (uframe + ufs) && i < 8; i++)
374 				if (0 < tt_usecs[i]) {
375 					ehci_vdbg(ehci,
376 						"multi-uframe xfer can't fit "
377 						"in frame %d uframe %d\n",
378 						frame, i);
379 					return 0;
380 				}
381 		}
382 
383 		tt_usecs[uframe] += usecs;
384 
385 		carryover_tt_bandwidth(tt_usecs);
386 
387 		/* fail if the carryover pushed bw past the last uframe's limit */
388 		if (max_tt_usecs[7] < tt_usecs[7]) {
389 			ehci_vdbg(ehci,
390 				"tt unavailable usecs %d frame %d uframe %d\n",
391 				usecs, frame, uframe);
392 			return 0;
393 		}
394 	}
395 
396 	return 1;
397 }
398 
399 #else
400 
401 /* return true iff the device's transaction translator is available
402  * for a periodic transfer starting at the specified frame, using
403  * all the uframes in the mask.
404  */
405 static int tt_no_collision (
406 	struct ehci_hcd		*ehci,
407 	unsigned		period,
408 	struct usb_device	*dev,
409 	unsigned		frame,
410 	u32			uf_mask
411 )
412 {
413 	if (period == 0)	/* error */
414 		return 0;
415 
416 	/* note bandwidth wastage:  split never follows csplit
417 	 * (different dev or endpoint) until the next uframe.
418 	 * calling convention doesn't make that distinction.
419 	 */
420 	for (; frame < ehci->periodic_size; frame += period) {
421 		union ehci_shadow	here;
422 		__hc32			type;
423 		struct ehci_qh_hw	*hw;
424 
425 		here = ehci->pshadow [frame];
426 		type = Q_NEXT_TYPE(ehci, ehci->periodic [frame]);
427 		while (here.ptr) {
428 			switch (hc32_to_cpu(ehci, type)) {
429 			case Q_TYPE_ITD:
430 				type = Q_NEXT_TYPE(ehci, here.itd->hw_next);
431 				here = here.itd->itd_next;
432 				continue;
433 			case Q_TYPE_QH:
434 				hw = here.qh->hw;
435 				if (same_tt (dev, here.qh->dev)) {
436 					u32		mask;
437 
438 					mask = hc32_to_cpu(ehci,
439 							hw->hw_info2);
440 					/* "knows" no gap is needed */
441 					mask |= mask >> 8;
442 					if (mask & uf_mask)
443 						break;
444 				}
445 				type = Q_NEXT_TYPE(ehci, hw->hw_next);
446 				here = here.qh->qh_next;
447 				continue;
448 			case Q_TYPE_SITD:
449 				if (same_tt (dev, here.sitd->urb->dev)) {
450 					u16		mask;
451 
452 					mask = hc32_to_cpu(ehci, here.sitd
453 								->hw_uframe);
454 					/* FIXME assumes no gap for IN! */
455 					mask |= mask >> 8;
456 					if (mask & uf_mask)
457 						break;
458 				}
459 				type = Q_NEXT_TYPE(ehci, here.sitd->hw_next);
460 				here = here.sitd->sitd_next;
461 				continue;
462 			// case Q_TYPE_FSTN:
463 			default:
464 				ehci_dbg (ehci,
465 					"periodic frame %d bogus type %d\n",
466 					frame, type);
467 			}
468 
469 			/* collision or error */
470 			return 0;
471 		}
472 	}
473 
474 	/* no collision */
475 	return 1;
476 }
477 
478 #endif /* CONFIG_USB_EHCI_TT_NEWSCHED */
479 
480 /*-------------------------------------------------------------------------*/
481 
482 static int enable_periodic (struct ehci_hcd *ehci)
483 {
484 	u32	cmd;
485 	int	status;
486 
487 	if (ehci->periodic_sched++)
488 		return 0;
489 
490 	/* did clearing PSE did take effect yet?
491 	 * takes effect only at frame boundaries...
492 	 */
493 	status = handshake_on_error_set_halt(ehci, &ehci->regs->status,
494 					     STS_PSS, 0, 9 * 125);
495 	if (status) {
496 		usb_hc_died(ehci_to_hcd(ehci));
497 		return status;
498 	}
499 
500 	cmd = ehci_readl(ehci, &ehci->regs->command) | CMD_PSE;
501 	ehci_writel(ehci, cmd, &ehci->regs->command);
502 	/* posted write ... PSS happens later */
503 
504 	/* make sure ehci_work scans these */
505 	ehci->next_uframe = ehci_read_frame_index(ehci)
506 		% (ehci->periodic_size << 3);
507 	if (unlikely(ehci->broken_periodic))
508 		ehci->last_periodic_enable = ktime_get_real();
509 	return 0;
510 }
511 
512 static int disable_periodic (struct ehci_hcd *ehci)
513 {
514 	u32	cmd;
515 	int	status;
516 
517 	if (--ehci->periodic_sched)
518 		return 0;
519 
520 	if (unlikely(ehci->broken_periodic)) {
521 		/* delay experimentally determined */
522 		ktime_t safe = ktime_add_us(ehci->last_periodic_enable, 1000);
523 		ktime_t now = ktime_get_real();
524 		s64 delay = ktime_us_delta(safe, now);
525 
526 		if (unlikely(delay > 0))
527 			udelay(delay);
528 	}
529 
530 	/* did setting PSE not take effect yet?
531 	 * takes effect only at frame boundaries...
532 	 */
533 	status = handshake_on_error_set_halt(ehci, &ehci->regs->status,
534 					     STS_PSS, STS_PSS, 9 * 125);
535 	if (status) {
536 		usb_hc_died(ehci_to_hcd(ehci));
537 		return status;
538 	}
539 
540 	cmd = ehci_readl(ehci, &ehci->regs->command) & ~CMD_PSE;
541 	ehci_writel(ehci, cmd, &ehci->regs->command);
542 	/* posted write ... */
543 
544 	free_cached_lists(ehci);
545 
546 	ehci->next_uframe = -1;
547 	return 0;
548 }
549 
550 /*-------------------------------------------------------------------------*/
551 
552 /* periodic schedule slots have iso tds (normal or split) first, then a
553  * sparse tree for active interrupt transfers.
554  *
555  * this just links in a qh; caller guarantees uframe masks are set right.
556  * no FSTN support (yet; ehci 0.96+)
557  */
558 static int qh_link_periodic (struct ehci_hcd *ehci, struct ehci_qh *qh)
559 {
560 	unsigned	i;
561 	unsigned	period = qh->period;
562 
563 	dev_dbg (&qh->dev->dev,
564 		"link qh%d-%04x/%p start %d [%d/%d us]\n",
565 		period, hc32_to_cpup(ehci, &qh->hw->hw_info2)
566 			& (QH_CMASK | QH_SMASK),
567 		qh, qh->start, qh->usecs, qh->c_usecs);
568 
569 	/* high bandwidth, or otherwise every microframe */
570 	if (period == 0)
571 		period = 1;
572 
573 	for (i = qh->start; i < ehci->periodic_size; i += period) {
574 		union ehci_shadow	*prev = &ehci->pshadow[i];
575 		__hc32			*hw_p = &ehci->periodic[i];
576 		union ehci_shadow	here = *prev;
577 		__hc32			type = 0;
578 
579 		/* skip the iso nodes at list head */
580 		while (here.ptr) {
581 			type = Q_NEXT_TYPE(ehci, *hw_p);
582 			if (type == cpu_to_hc32(ehci, Q_TYPE_QH))
583 				break;
584 			prev = periodic_next_shadow(ehci, prev, type);
585 			hw_p = shadow_next_periodic(ehci, &here, type);
586 			here = *prev;
587 		}
588 
589 		/* sorting each branch by period (slow-->fast)
590 		 * enables sharing interior tree nodes
591 		 */
592 		while (here.ptr && qh != here.qh) {
593 			if (qh->period > here.qh->period)
594 				break;
595 			prev = &here.qh->qh_next;
596 			hw_p = &here.qh->hw->hw_next;
597 			here = *prev;
598 		}
599 		/* link in this qh, unless some earlier pass did that */
600 		if (qh != here.qh) {
601 			qh->qh_next = here;
602 			if (here.qh)
603 				qh->hw->hw_next = *hw_p;
604 			wmb ();
605 			prev->qh = qh;
606 			*hw_p = QH_NEXT (ehci, qh->qh_dma);
607 		}
608 	}
609 	qh->qh_state = QH_STATE_LINKED;
610 	qh->xacterrs = 0;
611 	qh_get (qh);
612 
613 	/* update per-qh bandwidth for usbfs */
614 	ehci_to_hcd(ehci)->self.bandwidth_allocated += qh->period
615 		? ((qh->usecs + qh->c_usecs) / qh->period)
616 		: (qh->usecs * 8);
617 
618 	/* maybe enable periodic schedule processing */
619 	return enable_periodic(ehci);
620 }
621 
622 static int qh_unlink_periodic(struct ehci_hcd *ehci, struct ehci_qh *qh)
623 {
624 	unsigned	i;
625 	unsigned	period;
626 
627 	// FIXME:
628 	// IF this isn't high speed
629 	//   and this qh is active in the current uframe
630 	//   (and overlay token SplitXstate is false?)
631 	// THEN
632 	//   qh->hw_info1 |= cpu_to_hc32(1 << 7 /* "ignore" */);
633 
634 	/* high bandwidth, or otherwise part of every microframe */
635 	if ((period = qh->period) == 0)
636 		period = 1;
637 
638 	for (i = qh->start; i < ehci->periodic_size; i += period)
639 		periodic_unlink (ehci, i, qh);
640 
641 	/* update per-qh bandwidth for usbfs */
642 	ehci_to_hcd(ehci)->self.bandwidth_allocated -= qh->period
643 		? ((qh->usecs + qh->c_usecs) / qh->period)
644 		: (qh->usecs * 8);
645 
646 	dev_dbg (&qh->dev->dev,
647 		"unlink qh%d-%04x/%p start %d [%d/%d us]\n",
648 		qh->period,
649 		hc32_to_cpup(ehci, &qh->hw->hw_info2) & (QH_CMASK | QH_SMASK),
650 		qh, qh->start, qh->usecs, qh->c_usecs);
651 
652 	/* qh->qh_next still "live" to HC */
653 	qh->qh_state = QH_STATE_UNLINK;
654 	qh->qh_next.ptr = NULL;
655 	qh_put (qh);
656 
657 	/* maybe turn off periodic schedule */
658 	return disable_periodic(ehci);
659 }
660 
661 static void intr_deschedule (struct ehci_hcd *ehci, struct ehci_qh *qh)
662 {
663 	unsigned		wait;
664 	struct ehci_qh_hw	*hw = qh->hw;
665 	int			rc;
666 
667 	/* If the QH isn't linked then there's nothing we can do
668 	 * unless we were called during a giveback, in which case
669 	 * qh_completions() has to deal with it.
670 	 */
671 	if (qh->qh_state != QH_STATE_LINKED) {
672 		if (qh->qh_state == QH_STATE_COMPLETING)
673 			qh->needs_rescan = 1;
674 		return;
675 	}
676 
677 	qh_unlink_periodic (ehci, qh);
678 
679 	/* simple/paranoid:  always delay, expecting the HC needs to read
680 	 * qh->hw_next or finish a writeback after SPLIT/CSPLIT ... and
681 	 * expect khubd to clean up after any CSPLITs we won't issue.
682 	 * active high speed queues may need bigger delays...
683 	 */
684 	if (list_empty (&qh->qtd_list)
685 			|| (cpu_to_hc32(ehci, QH_CMASK)
686 					& hw->hw_info2) != 0)
687 		wait = 2;
688 	else
689 		wait = 55;	/* worst case: 3 * 1024 */
690 
691 	udelay (wait);
692 	qh->qh_state = QH_STATE_IDLE;
693 	hw->hw_next = EHCI_LIST_END(ehci);
694 	wmb ();
695 
696 	qh_completions(ehci, qh);
697 
698 	/* reschedule QH iff another request is queued */
699 	if (!list_empty(&qh->qtd_list) &&
700 			ehci->rh_state == EHCI_RH_RUNNING) {
701 		rc = qh_schedule(ehci, qh);
702 
703 		/* An error here likely indicates handshake failure
704 		 * or no space left in the schedule.  Neither fault
705 		 * should happen often ...
706 		 *
707 		 * FIXME kill the now-dysfunctional queued urbs
708 		 */
709 		if (rc != 0)
710 			ehci_err(ehci, "can't reschedule qh %p, err %d\n",
711 					qh, rc);
712 	}
713 }
714 
715 /*-------------------------------------------------------------------------*/
716 
717 static int check_period (
718 	struct ehci_hcd *ehci,
719 	unsigned	frame,
720 	unsigned	uframe,
721 	unsigned	period,
722 	unsigned	usecs
723 ) {
724 	int		claimed;
725 
726 	/* complete split running into next frame?
727 	 * given FSTN support, we could sometimes check...
728 	 */
729 	if (uframe >= 8)
730 		return 0;
731 
732 	/* convert "usecs we need" to "max already claimed" */
733 	usecs = ehci->uframe_periodic_max - usecs;
734 
735 	/* we "know" 2 and 4 uframe intervals were rejected; so
736 	 * for period 0, check _every_ microframe in the schedule.
737 	 */
738 	if (unlikely (period == 0)) {
739 		do {
740 			for (uframe = 0; uframe < 7; uframe++) {
741 				claimed = periodic_usecs (ehci, frame, uframe);
742 				if (claimed > usecs)
743 					return 0;
744 			}
745 		} while ((frame += 1) < ehci->periodic_size);
746 
747 	/* just check the specified uframe, at that period */
748 	} else {
749 		do {
750 			claimed = periodic_usecs (ehci, frame, uframe);
751 			if (claimed > usecs)
752 				return 0;
753 		} while ((frame += period) < ehci->periodic_size);
754 	}
755 
756 	// success!
757 	return 1;
758 }
759 
760 static int check_intr_schedule (
761 	struct ehci_hcd		*ehci,
762 	unsigned		frame,
763 	unsigned		uframe,
764 	const struct ehci_qh	*qh,
765 	__hc32			*c_maskp
766 )
767 {
768 	int		retval = -ENOSPC;
769 	u8		mask = 0;
770 
771 	if (qh->c_usecs && uframe >= 6)		/* FSTN territory? */
772 		goto done;
773 
774 	if (!check_period (ehci, frame, uframe, qh->period, qh->usecs))
775 		goto done;
776 	if (!qh->c_usecs) {
777 		retval = 0;
778 		*c_maskp = 0;
779 		goto done;
780 	}
781 
782 #ifdef CONFIG_USB_EHCI_TT_NEWSCHED
783 	if (tt_available (ehci, qh->period, qh->dev, frame, uframe,
784 				qh->tt_usecs)) {
785 		unsigned i;
786 
787 		/* TODO : this may need FSTN for SSPLIT in uframe 5. */
788 		for (i=uframe+1; i<8 && i<uframe+4; i++)
789 			if (!check_period (ehci, frame, i,
790 						qh->period, qh->c_usecs))
791 				goto done;
792 			else
793 				mask |= 1 << i;
794 
795 		retval = 0;
796 
797 		*c_maskp = cpu_to_hc32(ehci, mask << 8);
798 	}
799 #else
800 	/* Make sure this tt's buffer is also available for CSPLITs.
801 	 * We pessimize a bit; probably the typical full speed case
802 	 * doesn't need the second CSPLIT.
803 	 *
804 	 * NOTE:  both SPLIT and CSPLIT could be checked in just
805 	 * one smart pass...
806 	 */
807 	mask = 0x03 << (uframe + qh->gap_uf);
808 	*c_maskp = cpu_to_hc32(ehci, mask << 8);
809 
810 	mask |= 1 << uframe;
811 	if (tt_no_collision (ehci, qh->period, qh->dev, frame, mask)) {
812 		if (!check_period (ehci, frame, uframe + qh->gap_uf + 1,
813 					qh->period, qh->c_usecs))
814 			goto done;
815 		if (!check_period (ehci, frame, uframe + qh->gap_uf,
816 					qh->period, qh->c_usecs))
817 			goto done;
818 		retval = 0;
819 	}
820 #endif
821 done:
822 	return retval;
823 }
824 
825 /* "first fit" scheduling policy used the first time through,
826  * or when the previous schedule slot can't be re-used.
827  */
828 static int qh_schedule(struct ehci_hcd *ehci, struct ehci_qh *qh)
829 {
830 	int		status;
831 	unsigned	uframe;
832 	__hc32		c_mask;
833 	unsigned	frame;		/* 0..(qh->period - 1), or NO_FRAME */
834 	struct ehci_qh_hw	*hw = qh->hw;
835 
836 	qh_refresh(ehci, qh);
837 	hw->hw_next = EHCI_LIST_END(ehci);
838 	frame = qh->start;
839 
840 	/* reuse the previous schedule slots, if we can */
841 	if (frame < qh->period) {
842 		uframe = ffs(hc32_to_cpup(ehci, &hw->hw_info2) & QH_SMASK);
843 		status = check_intr_schedule (ehci, frame, --uframe,
844 				qh, &c_mask);
845 	} else {
846 		uframe = 0;
847 		c_mask = 0;
848 		status = -ENOSPC;
849 	}
850 
851 	/* else scan the schedule to find a group of slots such that all
852 	 * uframes have enough periodic bandwidth available.
853 	 */
854 	if (status) {
855 		/* "normal" case, uframing flexible except with splits */
856 		if (qh->period) {
857 			int		i;
858 
859 			for (i = qh->period; status && i > 0; --i) {
860 				frame = ++ehci->random_frame % qh->period;
861 				for (uframe = 0; uframe < 8; uframe++) {
862 					status = check_intr_schedule (ehci,
863 							frame, uframe, qh,
864 							&c_mask);
865 					if (status == 0)
866 						break;
867 				}
868 			}
869 
870 		/* qh->period == 0 means every uframe */
871 		} else {
872 			frame = 0;
873 			status = check_intr_schedule (ehci, 0, 0, qh, &c_mask);
874 		}
875 		if (status)
876 			goto done;
877 		qh->start = frame;
878 
879 		/* reset S-frame and (maybe) C-frame masks */
880 		hw->hw_info2 &= cpu_to_hc32(ehci, ~(QH_CMASK | QH_SMASK));
881 		hw->hw_info2 |= qh->period
882 			? cpu_to_hc32(ehci, 1 << uframe)
883 			: cpu_to_hc32(ehci, QH_SMASK);
884 		hw->hw_info2 |= c_mask;
885 	} else
886 		ehci_dbg (ehci, "reused qh %p schedule\n", qh);
887 
888 	/* stuff into the periodic schedule */
889 	status = qh_link_periodic (ehci, qh);
890 done:
891 	return status;
892 }
893 
894 static int intr_submit (
895 	struct ehci_hcd		*ehci,
896 	struct urb		*urb,
897 	struct list_head	*qtd_list,
898 	gfp_t			mem_flags
899 ) {
900 	unsigned		epnum;
901 	unsigned long		flags;
902 	struct ehci_qh		*qh;
903 	int			status;
904 	struct list_head	empty;
905 
906 	/* get endpoint and transfer/schedule data */
907 	epnum = urb->ep->desc.bEndpointAddress;
908 
909 	spin_lock_irqsave (&ehci->lock, flags);
910 
911 	if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
912 		status = -ESHUTDOWN;
913 		goto done_not_linked;
914 	}
915 	status = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
916 	if (unlikely(status))
917 		goto done_not_linked;
918 
919 	/* get qh and force any scheduling errors */
920 	INIT_LIST_HEAD (&empty);
921 	qh = qh_append_tds(ehci, urb, &empty, epnum, &urb->ep->hcpriv);
922 	if (qh == NULL) {
923 		status = -ENOMEM;
924 		goto done;
925 	}
926 	if (qh->qh_state == QH_STATE_IDLE) {
927 		if ((status = qh_schedule (ehci, qh)) != 0)
928 			goto done;
929 	}
930 
931 	/* then queue the urb's tds to the qh */
932 	qh = qh_append_tds(ehci, urb, qtd_list, epnum, &urb->ep->hcpriv);
933 	BUG_ON (qh == NULL);
934 
935 	/* ... update usbfs periodic stats */
936 	ehci_to_hcd(ehci)->self.bandwidth_int_reqs++;
937 
938 done:
939 	if (unlikely(status))
940 		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
941 done_not_linked:
942 	spin_unlock_irqrestore (&ehci->lock, flags);
943 	if (status)
944 		qtd_list_free (ehci, urb, qtd_list);
945 
946 	return status;
947 }
948 
949 /*-------------------------------------------------------------------------*/
950 
951 /* ehci_iso_stream ops work with both ITD and SITD */
952 
953 static struct ehci_iso_stream *
954 iso_stream_alloc (gfp_t mem_flags)
955 {
956 	struct ehci_iso_stream *stream;
957 
958 	stream = kzalloc(sizeof *stream, mem_flags);
959 	if (likely (stream != NULL)) {
960 		INIT_LIST_HEAD(&stream->td_list);
961 		INIT_LIST_HEAD(&stream->free_list);
962 		stream->next_uframe = -1;
963 		stream->refcount = 1;
964 	}
965 	return stream;
966 }
967 
968 static void
969 iso_stream_init (
970 	struct ehci_hcd		*ehci,
971 	struct ehci_iso_stream	*stream,
972 	struct usb_device	*dev,
973 	int			pipe,
974 	unsigned		interval
975 )
976 {
977 	static const u8 smask_out [] = { 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f };
978 
979 	u32			buf1;
980 	unsigned		epnum, maxp;
981 	int			is_input;
982 	long			bandwidth;
983 
984 	/*
985 	 * this might be a "high bandwidth" highspeed endpoint,
986 	 * as encoded in the ep descriptor's wMaxPacket field
987 	 */
988 	epnum = usb_pipeendpoint (pipe);
989 	is_input = usb_pipein (pipe) ? USB_DIR_IN : 0;
990 	maxp = usb_maxpacket(dev, pipe, !is_input);
991 	if (is_input) {
992 		buf1 = (1 << 11);
993 	} else {
994 		buf1 = 0;
995 	}
996 
997 	/* knows about ITD vs SITD */
998 	if (dev->speed == USB_SPEED_HIGH) {
999 		unsigned multi = hb_mult(maxp);
1000 
1001 		stream->highspeed = 1;
1002 
1003 		maxp = max_packet(maxp);
1004 		buf1 |= maxp;
1005 		maxp *= multi;
1006 
1007 		stream->buf0 = cpu_to_hc32(ehci, (epnum << 8) | dev->devnum);
1008 		stream->buf1 = cpu_to_hc32(ehci, buf1);
1009 		stream->buf2 = cpu_to_hc32(ehci, multi);
1010 
1011 		/* usbfs wants to report the average usecs per frame tied up
1012 		 * when transfers on this endpoint are scheduled ...
1013 		 */
1014 		stream->usecs = HS_USECS_ISO (maxp);
1015 		bandwidth = stream->usecs * 8;
1016 		bandwidth /= interval;
1017 
1018 	} else {
1019 		u32		addr;
1020 		int		think_time;
1021 		int		hs_transfers;
1022 
1023 		addr = dev->ttport << 24;
1024 		if (!ehci_is_TDI(ehci)
1025 				|| (dev->tt->hub !=
1026 					ehci_to_hcd(ehci)->self.root_hub))
1027 			addr |= dev->tt->hub->devnum << 16;
1028 		addr |= epnum << 8;
1029 		addr |= dev->devnum;
1030 		stream->usecs = HS_USECS_ISO (maxp);
1031 		think_time = dev->tt ? dev->tt->think_time : 0;
1032 		stream->tt_usecs = NS_TO_US (think_time + usb_calc_bus_time (
1033 				dev->speed, is_input, 1, maxp));
1034 		hs_transfers = max (1u, (maxp + 187) / 188);
1035 		if (is_input) {
1036 			u32	tmp;
1037 
1038 			addr |= 1 << 31;
1039 			stream->c_usecs = stream->usecs;
1040 			stream->usecs = HS_USECS_ISO (1);
1041 			stream->raw_mask = 1;
1042 
1043 			/* c-mask as specified in USB 2.0 11.18.4 3.c */
1044 			tmp = (1 << (hs_transfers + 2)) - 1;
1045 			stream->raw_mask |= tmp << (8 + 2);
1046 		} else
1047 			stream->raw_mask = smask_out [hs_transfers - 1];
1048 		bandwidth = stream->usecs + stream->c_usecs;
1049 		bandwidth /= interval << 3;
1050 
1051 		/* stream->splits gets created from raw_mask later */
1052 		stream->address = cpu_to_hc32(ehci, addr);
1053 	}
1054 	stream->bandwidth = bandwidth;
1055 
1056 	stream->udev = dev;
1057 
1058 	stream->bEndpointAddress = is_input | epnum;
1059 	stream->interval = interval;
1060 	stream->maxp = maxp;
1061 }
1062 
1063 static void
1064 iso_stream_put(struct ehci_hcd *ehci, struct ehci_iso_stream *stream)
1065 {
1066 	stream->refcount--;
1067 
1068 	/* free whenever just a dev->ep reference remains.
1069 	 * not like a QH -- no persistent state (toggle, halt)
1070 	 */
1071 	if (stream->refcount == 1) {
1072 		// BUG_ON (!list_empty(&stream->td_list));
1073 
1074 		while (!list_empty (&stream->free_list)) {
1075 			struct list_head	*entry;
1076 
1077 			entry = stream->free_list.next;
1078 			list_del (entry);
1079 
1080 			/* knows about ITD vs SITD */
1081 			if (stream->highspeed) {
1082 				struct ehci_itd		*itd;
1083 
1084 				itd = list_entry (entry, struct ehci_itd,
1085 						itd_list);
1086 				dma_pool_free (ehci->itd_pool, itd,
1087 						itd->itd_dma);
1088 			} else {
1089 				struct ehci_sitd	*sitd;
1090 
1091 				sitd = list_entry (entry, struct ehci_sitd,
1092 						sitd_list);
1093 				dma_pool_free (ehci->sitd_pool, sitd,
1094 						sitd->sitd_dma);
1095 			}
1096 		}
1097 
1098 		stream->bEndpointAddress &= 0x0f;
1099 		if (stream->ep)
1100 			stream->ep->hcpriv = NULL;
1101 
1102 		kfree(stream);
1103 	}
1104 }
1105 
1106 static inline struct ehci_iso_stream *
1107 iso_stream_get (struct ehci_iso_stream *stream)
1108 {
1109 	if (likely (stream != NULL))
1110 		stream->refcount++;
1111 	return stream;
1112 }
1113 
1114 static struct ehci_iso_stream *
1115 iso_stream_find (struct ehci_hcd *ehci, struct urb *urb)
1116 {
1117 	unsigned		epnum;
1118 	struct ehci_iso_stream	*stream;
1119 	struct usb_host_endpoint *ep;
1120 	unsigned long		flags;
1121 
1122 	epnum = usb_pipeendpoint (urb->pipe);
1123 	if (usb_pipein(urb->pipe))
1124 		ep = urb->dev->ep_in[epnum];
1125 	else
1126 		ep = urb->dev->ep_out[epnum];
1127 
1128 	spin_lock_irqsave (&ehci->lock, flags);
1129 	stream = ep->hcpriv;
1130 
1131 	if (unlikely (stream == NULL)) {
1132 		stream = iso_stream_alloc(GFP_ATOMIC);
1133 		if (likely (stream != NULL)) {
1134 			/* dev->ep owns the initial refcount */
1135 			ep->hcpriv = stream;
1136 			stream->ep = ep;
1137 			iso_stream_init(ehci, stream, urb->dev, urb->pipe,
1138 					urb->interval);
1139 		}
1140 
1141 	/* if dev->ep [epnum] is a QH, hw is set */
1142 	} else if (unlikely (stream->hw != NULL)) {
1143 		ehci_dbg (ehci, "dev %s ep%d%s, not iso??\n",
1144 			urb->dev->devpath, epnum,
1145 			usb_pipein(urb->pipe) ? "in" : "out");
1146 		stream = NULL;
1147 	}
1148 
1149 	/* caller guarantees an eventual matching iso_stream_put */
1150 	stream = iso_stream_get (stream);
1151 
1152 	spin_unlock_irqrestore (&ehci->lock, flags);
1153 	return stream;
1154 }
1155 
1156 /*-------------------------------------------------------------------------*/
1157 
1158 /* ehci_iso_sched ops can be ITD-only or SITD-only */
1159 
1160 static struct ehci_iso_sched *
1161 iso_sched_alloc (unsigned packets, gfp_t mem_flags)
1162 {
1163 	struct ehci_iso_sched	*iso_sched;
1164 	int			size = sizeof *iso_sched;
1165 
1166 	size += packets * sizeof (struct ehci_iso_packet);
1167 	iso_sched = kzalloc(size, mem_flags);
1168 	if (likely (iso_sched != NULL)) {
1169 		INIT_LIST_HEAD (&iso_sched->td_list);
1170 	}
1171 	return iso_sched;
1172 }
1173 
1174 static inline void
1175 itd_sched_init(
1176 	struct ehci_hcd		*ehci,
1177 	struct ehci_iso_sched	*iso_sched,
1178 	struct ehci_iso_stream	*stream,
1179 	struct urb		*urb
1180 )
1181 {
1182 	unsigned	i;
1183 	dma_addr_t	dma = urb->transfer_dma;
1184 
1185 	/* how many uframes are needed for these transfers */
1186 	iso_sched->span = urb->number_of_packets * stream->interval;
1187 
1188 	/* figure out per-uframe itd fields that we'll need later
1189 	 * when we fit new itds into the schedule.
1190 	 */
1191 	for (i = 0; i < urb->number_of_packets; i++) {
1192 		struct ehci_iso_packet	*uframe = &iso_sched->packet [i];
1193 		unsigned		length;
1194 		dma_addr_t		buf;
1195 		u32			trans;
1196 
1197 		length = urb->iso_frame_desc [i].length;
1198 		buf = dma + urb->iso_frame_desc [i].offset;
1199 
1200 		trans = EHCI_ISOC_ACTIVE;
1201 		trans |= buf & 0x0fff;
1202 		if (unlikely (((i + 1) == urb->number_of_packets))
1203 				&& !(urb->transfer_flags & URB_NO_INTERRUPT))
1204 			trans |= EHCI_ITD_IOC;
1205 		trans |= length << 16;
1206 		uframe->transaction = cpu_to_hc32(ehci, trans);
1207 
1208 		/* might need to cross a buffer page within a uframe */
1209 		uframe->bufp = (buf & ~(u64)0x0fff);
1210 		buf += length;
1211 		if (unlikely ((uframe->bufp != (buf & ~(u64)0x0fff))))
1212 			uframe->cross = 1;
1213 	}
1214 }
1215 
1216 static void
1217 iso_sched_free (
1218 	struct ehci_iso_stream	*stream,
1219 	struct ehci_iso_sched	*iso_sched
1220 )
1221 {
1222 	if (!iso_sched)
1223 		return;
1224 	// caller must hold ehci->lock!
1225 	list_splice (&iso_sched->td_list, &stream->free_list);
1226 	kfree (iso_sched);
1227 }
1228 
1229 static int
1230 itd_urb_transaction (
1231 	struct ehci_iso_stream	*stream,
1232 	struct ehci_hcd		*ehci,
1233 	struct urb		*urb,
1234 	gfp_t			mem_flags
1235 )
1236 {
1237 	struct ehci_itd		*itd;
1238 	dma_addr_t		itd_dma;
1239 	int			i;
1240 	unsigned		num_itds;
1241 	struct ehci_iso_sched	*sched;
1242 	unsigned long		flags;
1243 
1244 	sched = iso_sched_alloc (urb->number_of_packets, mem_flags);
1245 	if (unlikely (sched == NULL))
1246 		return -ENOMEM;
1247 
1248 	itd_sched_init(ehci, sched, stream, urb);
1249 
1250 	if (urb->interval < 8)
1251 		num_itds = 1 + (sched->span + 7) / 8;
1252 	else
1253 		num_itds = urb->number_of_packets;
1254 
1255 	/* allocate/init ITDs */
1256 	spin_lock_irqsave (&ehci->lock, flags);
1257 	for (i = 0; i < num_itds; i++) {
1258 
1259 		/* free_list.next might be cache-hot ... but maybe
1260 		 * the HC caches it too. avoid that issue for now.
1261 		 */
1262 
1263 		/* prefer previously-allocated itds */
1264 		if (likely (!list_empty(&stream->free_list))) {
1265 			itd = list_entry (stream->free_list.prev,
1266 					struct ehci_itd, itd_list);
1267 			list_del (&itd->itd_list);
1268 			itd_dma = itd->itd_dma;
1269 		} else {
1270 			spin_unlock_irqrestore (&ehci->lock, flags);
1271 			itd = dma_pool_alloc (ehci->itd_pool, mem_flags,
1272 					&itd_dma);
1273 			spin_lock_irqsave (&ehci->lock, flags);
1274 			if (!itd) {
1275 				iso_sched_free(stream, sched);
1276 				spin_unlock_irqrestore(&ehci->lock, flags);
1277 				return -ENOMEM;
1278 			}
1279 		}
1280 
1281 		memset (itd, 0, sizeof *itd);
1282 		itd->itd_dma = itd_dma;
1283 		list_add (&itd->itd_list, &sched->td_list);
1284 	}
1285 	spin_unlock_irqrestore (&ehci->lock, flags);
1286 
1287 	/* temporarily store schedule info in hcpriv */
1288 	urb->hcpriv = sched;
1289 	urb->error_count = 0;
1290 	return 0;
1291 }
1292 
1293 /*-------------------------------------------------------------------------*/
1294 
1295 static inline int
1296 itd_slot_ok (
1297 	struct ehci_hcd		*ehci,
1298 	u32			mod,
1299 	u32			uframe,
1300 	u8			usecs,
1301 	u32			period
1302 )
1303 {
1304 	uframe %= period;
1305 	do {
1306 		/* can't commit more than uframe_periodic_max usec */
1307 		if (periodic_usecs (ehci, uframe >> 3, uframe & 0x7)
1308 				> (ehci->uframe_periodic_max - usecs))
1309 			return 0;
1310 
1311 		/* we know urb->interval is 2^N uframes */
1312 		uframe += period;
1313 	} while (uframe < mod);
1314 	return 1;
1315 }
1316 
1317 static inline int
1318 sitd_slot_ok (
1319 	struct ehci_hcd		*ehci,
1320 	u32			mod,
1321 	struct ehci_iso_stream	*stream,
1322 	u32			uframe,
1323 	struct ehci_iso_sched	*sched,
1324 	u32			period_uframes
1325 )
1326 {
1327 	u32			mask, tmp;
1328 	u32			frame, uf;
1329 
1330 	mask = stream->raw_mask << (uframe & 7);
1331 
1332 	/* for IN, don't wrap CSPLIT into the next frame */
1333 	if (mask & ~0xffff)
1334 		return 0;
1335 
1336 	/* this multi-pass logic is simple, but performance may
1337 	 * suffer when the schedule data isn't cached.
1338 	 */
1339 
1340 	/* check bandwidth */
1341 	uframe %= period_uframes;
1342 	do {
1343 		u32		max_used;
1344 
1345 		frame = uframe >> 3;
1346 		uf = uframe & 7;
1347 
1348 #ifdef CONFIG_USB_EHCI_TT_NEWSCHED
1349 		/* The tt's fullspeed bus bandwidth must be available.
1350 		 * tt_available scheduling guarantees 10+% for control/bulk.
1351 		 */
1352 		if (!tt_available (ehci, period_uframes << 3,
1353 				stream->udev, frame, uf, stream->tt_usecs))
1354 			return 0;
1355 #else
1356 		/* tt must be idle for start(s), any gap, and csplit.
1357 		 * assume scheduling slop leaves 10+% for control/bulk.
1358 		 */
1359 		if (!tt_no_collision (ehci, period_uframes << 3,
1360 				stream->udev, frame, mask))
1361 			return 0;
1362 #endif
1363 
1364 		/* check starts (OUT uses more than one) */
1365 		max_used = ehci->uframe_periodic_max - stream->usecs;
1366 		for (tmp = stream->raw_mask & 0xff; tmp; tmp >>= 1, uf++) {
1367 			if (periodic_usecs (ehci, frame, uf) > max_used)
1368 				return 0;
1369 		}
1370 
1371 		/* for IN, check CSPLIT */
1372 		if (stream->c_usecs) {
1373 			uf = uframe & 7;
1374 			max_used = ehci->uframe_periodic_max - stream->c_usecs;
1375 			do {
1376 				tmp = 1 << uf;
1377 				tmp <<= 8;
1378 				if ((stream->raw_mask & tmp) == 0)
1379 					continue;
1380 				if (periodic_usecs (ehci, frame, uf)
1381 						> max_used)
1382 					return 0;
1383 			} while (++uf < 8);
1384 		}
1385 
1386 		/* we know urb->interval is 2^N uframes */
1387 		uframe += period_uframes;
1388 	} while (uframe < mod);
1389 
1390 	stream->splits = cpu_to_hc32(ehci, stream->raw_mask << (uframe & 7));
1391 	return 1;
1392 }
1393 
1394 /*
1395  * This scheduler plans almost as far into the future as it has actual
1396  * periodic schedule slots.  (Affected by TUNE_FLS, which defaults to
1397  * "as small as possible" to be cache-friendlier.)  That limits the size
1398  * transfers you can stream reliably; avoid more than 64 msec per urb.
1399  * Also avoid queue depths of less than ehci's worst irq latency (affected
1400  * by the per-urb URB_NO_INTERRUPT hint, the log2_irq_thresh module parameter,
1401  * and other factors); or more than about 230 msec total (for portability,
1402  * given EHCI_TUNE_FLS and the slop).  Or, write a smarter scheduler!
1403  */
1404 
1405 #define SCHEDULE_SLOP	80	/* microframes */
1406 
1407 static int
1408 iso_stream_schedule (
1409 	struct ehci_hcd		*ehci,
1410 	struct urb		*urb,
1411 	struct ehci_iso_stream	*stream
1412 )
1413 {
1414 	u32			now, next, start, period, span;
1415 	int			status;
1416 	unsigned		mod = ehci->periodic_size << 3;
1417 	struct ehci_iso_sched	*sched = urb->hcpriv;
1418 
1419 	period = urb->interval;
1420 	span = sched->span;
1421 	if (!stream->highspeed) {
1422 		period <<= 3;
1423 		span <<= 3;
1424 	}
1425 
1426 	if (span > mod - SCHEDULE_SLOP) {
1427 		ehci_dbg (ehci, "iso request %p too long\n", urb);
1428 		status = -EFBIG;
1429 		goto fail;
1430 	}
1431 
1432 	now = ehci_read_frame_index(ehci) & (mod - 1);
1433 
1434 	/* Typical case: reuse current schedule, stream is still active.
1435 	 * Hopefully there are no gaps from the host falling behind
1436 	 * (irq delays etc), but if there are we'll take the next
1437 	 * slot in the schedule, implicitly assuming URB_ISO_ASAP.
1438 	 */
1439 	if (likely (!list_empty (&stream->td_list))) {
1440 		u32	excess;
1441 
1442 		/* For high speed devices, allow scheduling within the
1443 		 * isochronous scheduling threshold.  For full speed devices
1444 		 * and Intel PCI-based controllers, don't (work around for
1445 		 * Intel ICH9 bug).
1446 		 */
1447 		if (!stream->highspeed && ehci->fs_i_thresh)
1448 			next = now + ehci->i_thresh;
1449 		else
1450 			next = now;
1451 
1452 		/* Fell behind (by up to twice the slop amount)?
1453 		 * We decide based on the time of the last currently-scheduled
1454 		 * slot, not the time of the next available slot.
1455 		 */
1456 		excess = (stream->next_uframe - period - next) & (mod - 1);
1457 		if (excess >= mod - 2 * SCHEDULE_SLOP)
1458 			start = next + excess - mod + period *
1459 					DIV_ROUND_UP(mod - excess, period);
1460 		else
1461 			start = next + excess + period;
1462 		if (start - now >= mod) {
1463 			ehci_dbg(ehci, "request %p would overflow (%d+%d >= %d)\n",
1464 					urb, start - now - period, period,
1465 					mod);
1466 			status = -EFBIG;
1467 			goto fail;
1468 		}
1469 	}
1470 
1471 	/* need to schedule; when's the next (u)frame we could start?
1472 	 * this is bigger than ehci->i_thresh allows; scheduling itself
1473 	 * isn't free, the slop should handle reasonably slow cpus.  it
1474 	 * can also help high bandwidth if the dma and irq loads don't
1475 	 * jump until after the queue is primed.
1476 	 */
1477 	else {
1478 		start = SCHEDULE_SLOP + (now & ~0x07);
1479 
1480 		/* NOTE:  assumes URB_ISO_ASAP, to limit complexity/bugs */
1481 
1482 		/* find a uframe slot with enough bandwidth */
1483 		next = start + period;
1484 		for (; start < next; start++) {
1485 
1486 			/* check schedule: enough space? */
1487 			if (stream->highspeed) {
1488 				if (itd_slot_ok(ehci, mod, start,
1489 						stream->usecs, period))
1490 					break;
1491 			} else {
1492 				if ((start % 8) >= 6)
1493 					continue;
1494 				if (sitd_slot_ok(ehci, mod, stream,
1495 						start, sched, period))
1496 					break;
1497 			}
1498 		}
1499 
1500 		/* no room in the schedule */
1501 		if (start == next) {
1502 			ehci_dbg(ehci, "iso resched full %p (now %d max %d)\n",
1503 				urb, now, now + mod);
1504 			status = -ENOSPC;
1505 			goto fail;
1506 		}
1507 	}
1508 
1509 	/* Tried to schedule too far into the future? */
1510 	if (unlikely(start - now + span - period
1511 				>= mod - 2 * SCHEDULE_SLOP)) {
1512 		ehci_dbg(ehci, "request %p would overflow (%d+%d >= %d)\n",
1513 				urb, start - now, span - period,
1514 				mod - 2 * SCHEDULE_SLOP);
1515 		status = -EFBIG;
1516 		goto fail;
1517 	}
1518 
1519 	stream->next_uframe = start & (mod - 1);
1520 
1521 	/* report high speed start in uframes; full speed, in frames */
1522 	urb->start_frame = stream->next_uframe;
1523 	if (!stream->highspeed)
1524 		urb->start_frame >>= 3;
1525 	return 0;
1526 
1527  fail:
1528 	iso_sched_free(stream, sched);
1529 	urb->hcpriv = NULL;
1530 	return status;
1531 }
1532 
1533 /*-------------------------------------------------------------------------*/
1534 
1535 static inline void
1536 itd_init(struct ehci_hcd *ehci, struct ehci_iso_stream *stream,
1537 		struct ehci_itd *itd)
1538 {
1539 	int i;
1540 
1541 	/* it's been recently zeroed */
1542 	itd->hw_next = EHCI_LIST_END(ehci);
1543 	itd->hw_bufp [0] = stream->buf0;
1544 	itd->hw_bufp [1] = stream->buf1;
1545 	itd->hw_bufp [2] = stream->buf2;
1546 
1547 	for (i = 0; i < 8; i++)
1548 		itd->index[i] = -1;
1549 
1550 	/* All other fields are filled when scheduling */
1551 }
1552 
1553 static inline void
1554 itd_patch(
1555 	struct ehci_hcd		*ehci,
1556 	struct ehci_itd		*itd,
1557 	struct ehci_iso_sched	*iso_sched,
1558 	unsigned		index,
1559 	u16			uframe
1560 )
1561 {
1562 	struct ehci_iso_packet	*uf = &iso_sched->packet [index];
1563 	unsigned		pg = itd->pg;
1564 
1565 	// BUG_ON (pg == 6 && uf->cross);
1566 
1567 	uframe &= 0x07;
1568 	itd->index [uframe] = index;
1569 
1570 	itd->hw_transaction[uframe] = uf->transaction;
1571 	itd->hw_transaction[uframe] |= cpu_to_hc32(ehci, pg << 12);
1572 	itd->hw_bufp[pg] |= cpu_to_hc32(ehci, uf->bufp & ~(u32)0);
1573 	itd->hw_bufp_hi[pg] |= cpu_to_hc32(ehci, (u32)(uf->bufp >> 32));
1574 
1575 	/* iso_frame_desc[].offset must be strictly increasing */
1576 	if (unlikely (uf->cross)) {
1577 		u64	bufp = uf->bufp + 4096;
1578 
1579 		itd->pg = ++pg;
1580 		itd->hw_bufp[pg] |= cpu_to_hc32(ehci, bufp & ~(u32)0);
1581 		itd->hw_bufp_hi[pg] |= cpu_to_hc32(ehci, (u32)(bufp >> 32));
1582 	}
1583 }
1584 
1585 static inline void
1586 itd_link (struct ehci_hcd *ehci, unsigned frame, struct ehci_itd *itd)
1587 {
1588 	union ehci_shadow	*prev = &ehci->pshadow[frame];
1589 	__hc32			*hw_p = &ehci->periodic[frame];
1590 	union ehci_shadow	here = *prev;
1591 	__hc32			type = 0;
1592 
1593 	/* skip any iso nodes which might belong to previous microframes */
1594 	while (here.ptr) {
1595 		type = Q_NEXT_TYPE(ehci, *hw_p);
1596 		if (type == cpu_to_hc32(ehci, Q_TYPE_QH))
1597 			break;
1598 		prev = periodic_next_shadow(ehci, prev, type);
1599 		hw_p = shadow_next_periodic(ehci, &here, type);
1600 		here = *prev;
1601 	}
1602 
1603 	itd->itd_next = here;
1604 	itd->hw_next = *hw_p;
1605 	prev->itd = itd;
1606 	itd->frame = frame;
1607 	wmb ();
1608 	*hw_p = cpu_to_hc32(ehci, itd->itd_dma | Q_TYPE_ITD);
1609 }
1610 
1611 /* fit urb's itds into the selected schedule slot; activate as needed */
1612 static int
1613 itd_link_urb (
1614 	struct ehci_hcd		*ehci,
1615 	struct urb		*urb,
1616 	unsigned		mod,
1617 	struct ehci_iso_stream	*stream
1618 )
1619 {
1620 	int			packet;
1621 	unsigned		next_uframe, uframe, frame;
1622 	struct ehci_iso_sched	*iso_sched = urb->hcpriv;
1623 	struct ehci_itd		*itd;
1624 
1625 	next_uframe = stream->next_uframe & (mod - 1);
1626 
1627 	if (unlikely (list_empty(&stream->td_list))) {
1628 		ehci_to_hcd(ehci)->self.bandwidth_allocated
1629 				+= stream->bandwidth;
1630 		ehci_vdbg (ehci,
1631 			"schedule devp %s ep%d%s-iso period %d start %d.%d\n",
1632 			urb->dev->devpath, stream->bEndpointAddress & 0x0f,
1633 			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out",
1634 			urb->interval,
1635 			next_uframe >> 3, next_uframe & 0x7);
1636 	}
1637 
1638 	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
1639 		if (ehci->amd_pll_fix == 1)
1640 			usb_amd_quirk_pll_disable();
1641 	}
1642 
1643 	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs++;
1644 
1645 	/* fill iTDs uframe by uframe */
1646 	for (packet = 0, itd = NULL; packet < urb->number_of_packets; ) {
1647 		if (itd == NULL) {
1648 			/* ASSERT:  we have all necessary itds */
1649 			// BUG_ON (list_empty (&iso_sched->td_list));
1650 
1651 			/* ASSERT:  no itds for this endpoint in this uframe */
1652 
1653 			itd = list_entry (iso_sched->td_list.next,
1654 					struct ehci_itd, itd_list);
1655 			list_move_tail (&itd->itd_list, &stream->td_list);
1656 			itd->stream = iso_stream_get (stream);
1657 			itd->urb = urb;
1658 			itd_init (ehci, stream, itd);
1659 		}
1660 
1661 		uframe = next_uframe & 0x07;
1662 		frame = next_uframe >> 3;
1663 
1664 		itd_patch(ehci, itd, iso_sched, packet, uframe);
1665 
1666 		next_uframe += stream->interval;
1667 		next_uframe &= mod - 1;
1668 		packet++;
1669 
1670 		/* link completed itds into the schedule */
1671 		if (((next_uframe >> 3) != frame)
1672 				|| packet == urb->number_of_packets) {
1673 			itd_link(ehci, frame & (ehci->periodic_size - 1), itd);
1674 			itd = NULL;
1675 		}
1676 	}
1677 	stream->next_uframe = next_uframe;
1678 
1679 	/* don't need that schedule data any more */
1680 	iso_sched_free (stream, iso_sched);
1681 	urb->hcpriv = NULL;
1682 
1683 	timer_action (ehci, TIMER_IO_WATCHDOG);
1684 	return enable_periodic(ehci);
1685 }
1686 
1687 #define	ISO_ERRS (EHCI_ISOC_BUF_ERR | EHCI_ISOC_BABBLE | EHCI_ISOC_XACTERR)
1688 
1689 /* Process and recycle a completed ITD.  Return true iff its urb completed,
1690  * and hence its completion callback probably added things to the hardware
1691  * schedule.
1692  *
1693  * Note that we carefully avoid recycling this descriptor until after any
1694  * completion callback runs, so that it won't be reused quickly.  That is,
1695  * assuming (a) no more than two urbs per frame on this endpoint, and also
1696  * (b) only this endpoint's completions submit URBs.  It seems some silicon
1697  * corrupts things if you reuse completed descriptors very quickly...
1698  */
1699 static unsigned
1700 itd_complete (
1701 	struct ehci_hcd	*ehci,
1702 	struct ehci_itd	*itd
1703 ) {
1704 	struct urb				*urb = itd->urb;
1705 	struct usb_iso_packet_descriptor	*desc;
1706 	u32					t;
1707 	unsigned				uframe;
1708 	int					urb_index = -1;
1709 	struct ehci_iso_stream			*stream = itd->stream;
1710 	struct usb_device			*dev;
1711 	unsigned				retval = false;
1712 
1713 	/* for each uframe with a packet */
1714 	for (uframe = 0; uframe < 8; uframe++) {
1715 		if (likely (itd->index[uframe] == -1))
1716 			continue;
1717 		urb_index = itd->index[uframe];
1718 		desc = &urb->iso_frame_desc [urb_index];
1719 
1720 		t = hc32_to_cpup(ehci, &itd->hw_transaction [uframe]);
1721 		itd->hw_transaction [uframe] = 0;
1722 
1723 		/* report transfer status */
1724 		if (unlikely (t & ISO_ERRS)) {
1725 			urb->error_count++;
1726 			if (t & EHCI_ISOC_BUF_ERR)
1727 				desc->status = usb_pipein (urb->pipe)
1728 					? -ENOSR  /* hc couldn't read */
1729 					: -ECOMM; /* hc couldn't write */
1730 			else if (t & EHCI_ISOC_BABBLE)
1731 				desc->status = -EOVERFLOW;
1732 			else /* (t & EHCI_ISOC_XACTERR) */
1733 				desc->status = -EPROTO;
1734 
1735 			/* HC need not update length with this error */
1736 			if (!(t & EHCI_ISOC_BABBLE)) {
1737 				desc->actual_length = EHCI_ITD_LENGTH(t);
1738 				urb->actual_length += desc->actual_length;
1739 			}
1740 		} else if (likely ((t & EHCI_ISOC_ACTIVE) == 0)) {
1741 			desc->status = 0;
1742 			desc->actual_length = EHCI_ITD_LENGTH(t);
1743 			urb->actual_length += desc->actual_length;
1744 		} else {
1745 			/* URB was too late */
1746 			desc->status = -EXDEV;
1747 		}
1748 	}
1749 
1750 	/* handle completion now? */
1751 	if (likely ((urb_index + 1) != urb->number_of_packets))
1752 		goto done;
1753 
1754 	/* ASSERT: it's really the last itd for this urb
1755 	list_for_each_entry (itd, &stream->td_list, itd_list)
1756 		BUG_ON (itd->urb == urb);
1757 	 */
1758 
1759 	/* give urb back to the driver; completion often (re)submits */
1760 	dev = urb->dev;
1761 	ehci_urb_done(ehci, urb, 0);
1762 	retval = true;
1763 	urb = NULL;
1764 	(void) disable_periodic(ehci);
1765 	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
1766 
1767 	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
1768 		if (ehci->amd_pll_fix == 1)
1769 			usb_amd_quirk_pll_enable();
1770 	}
1771 
1772 	if (unlikely(list_is_singular(&stream->td_list))) {
1773 		ehci_to_hcd(ehci)->self.bandwidth_allocated
1774 				-= stream->bandwidth;
1775 		ehci_vdbg (ehci,
1776 			"deschedule devp %s ep%d%s-iso\n",
1777 			dev->devpath, stream->bEndpointAddress & 0x0f,
1778 			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
1779 	}
1780 	iso_stream_put (ehci, stream);
1781 
1782 done:
1783 	itd->urb = NULL;
1784 	if (ehci->clock_frame != itd->frame || itd->index[7] != -1) {
1785 		/* OK to recycle this ITD now. */
1786 		itd->stream = NULL;
1787 		list_move(&itd->itd_list, &stream->free_list);
1788 		iso_stream_put(ehci, stream);
1789 	} else {
1790 		/* HW might remember this ITD, so we can't recycle it yet.
1791 		 * Move it to a safe place until a new frame starts.
1792 		 */
1793 		list_move(&itd->itd_list, &ehci->cached_itd_list);
1794 		if (stream->refcount == 2) {
1795 			/* If iso_stream_put() were called here, stream
1796 			 * would be freed.  Instead, just prevent reuse.
1797 			 */
1798 			stream->ep->hcpriv = NULL;
1799 			stream->ep = NULL;
1800 		}
1801 	}
1802 	return retval;
1803 }
1804 
1805 /*-------------------------------------------------------------------------*/
1806 
1807 static int itd_submit (struct ehci_hcd *ehci, struct urb *urb,
1808 	gfp_t mem_flags)
1809 {
1810 	int			status = -EINVAL;
1811 	unsigned long		flags;
1812 	struct ehci_iso_stream	*stream;
1813 
1814 	/* Get iso_stream head */
1815 	stream = iso_stream_find (ehci, urb);
1816 	if (unlikely (stream == NULL)) {
1817 		ehci_dbg (ehci, "can't get iso stream\n");
1818 		return -ENOMEM;
1819 	}
1820 	if (unlikely (urb->interval != stream->interval)) {
1821 		ehci_dbg (ehci, "can't change iso interval %d --> %d\n",
1822 			stream->interval, urb->interval);
1823 		goto done;
1824 	}
1825 
1826 #ifdef EHCI_URB_TRACE
1827 	ehci_dbg (ehci,
1828 		"%s %s urb %p ep%d%s len %d, %d pkts %d uframes [%p]\n",
1829 		__func__, urb->dev->devpath, urb,
1830 		usb_pipeendpoint (urb->pipe),
1831 		usb_pipein (urb->pipe) ? "in" : "out",
1832 		urb->transfer_buffer_length,
1833 		urb->number_of_packets, urb->interval,
1834 		stream);
1835 #endif
1836 
1837 	/* allocate ITDs w/o locking anything */
1838 	status = itd_urb_transaction (stream, ehci, urb, mem_flags);
1839 	if (unlikely (status < 0)) {
1840 		ehci_dbg (ehci, "can't init itds\n");
1841 		goto done;
1842 	}
1843 
1844 	/* schedule ... need to lock */
1845 	spin_lock_irqsave (&ehci->lock, flags);
1846 	if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
1847 		status = -ESHUTDOWN;
1848 		goto done_not_linked;
1849 	}
1850 	status = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
1851 	if (unlikely(status))
1852 		goto done_not_linked;
1853 	status = iso_stream_schedule(ehci, urb, stream);
1854 	if (likely (status == 0))
1855 		itd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
1856 	else
1857 		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
1858 done_not_linked:
1859 	spin_unlock_irqrestore (&ehci->lock, flags);
1860 
1861 done:
1862 	if (unlikely (status < 0))
1863 		iso_stream_put (ehci, stream);
1864 	return status;
1865 }
1866 
1867 /*-------------------------------------------------------------------------*/
1868 
1869 /*
1870  * "Split ISO TDs" ... used for USB 1.1 devices going through the
1871  * TTs in USB 2.0 hubs.  These need microframe scheduling.
1872  */
1873 
1874 static inline void
1875 sitd_sched_init(
1876 	struct ehci_hcd		*ehci,
1877 	struct ehci_iso_sched	*iso_sched,
1878 	struct ehci_iso_stream	*stream,
1879 	struct urb		*urb
1880 )
1881 {
1882 	unsigned	i;
1883 	dma_addr_t	dma = urb->transfer_dma;
1884 
1885 	/* how many frames are needed for these transfers */
1886 	iso_sched->span = urb->number_of_packets * stream->interval;
1887 
1888 	/* figure out per-frame sitd fields that we'll need later
1889 	 * when we fit new sitds into the schedule.
1890 	 */
1891 	for (i = 0; i < urb->number_of_packets; i++) {
1892 		struct ehci_iso_packet	*packet = &iso_sched->packet [i];
1893 		unsigned		length;
1894 		dma_addr_t		buf;
1895 		u32			trans;
1896 
1897 		length = urb->iso_frame_desc [i].length & 0x03ff;
1898 		buf = dma + urb->iso_frame_desc [i].offset;
1899 
1900 		trans = SITD_STS_ACTIVE;
1901 		if (((i + 1) == urb->number_of_packets)
1902 				&& !(urb->transfer_flags & URB_NO_INTERRUPT))
1903 			trans |= SITD_IOC;
1904 		trans |= length << 16;
1905 		packet->transaction = cpu_to_hc32(ehci, trans);
1906 
1907 		/* might need to cross a buffer page within a td */
1908 		packet->bufp = buf;
1909 		packet->buf1 = (buf + length) & ~0x0fff;
1910 		if (packet->buf1 != (buf & ~(u64)0x0fff))
1911 			packet->cross = 1;
1912 
1913 		/* OUT uses multiple start-splits */
1914 		if (stream->bEndpointAddress & USB_DIR_IN)
1915 			continue;
1916 		length = (length + 187) / 188;
1917 		if (length > 1) /* BEGIN vs ALL */
1918 			length |= 1 << 3;
1919 		packet->buf1 |= length;
1920 	}
1921 }
1922 
1923 static int
1924 sitd_urb_transaction (
1925 	struct ehci_iso_stream	*stream,
1926 	struct ehci_hcd		*ehci,
1927 	struct urb		*urb,
1928 	gfp_t			mem_flags
1929 )
1930 {
1931 	struct ehci_sitd	*sitd;
1932 	dma_addr_t		sitd_dma;
1933 	int			i;
1934 	struct ehci_iso_sched	*iso_sched;
1935 	unsigned long		flags;
1936 
1937 	iso_sched = iso_sched_alloc (urb->number_of_packets, mem_flags);
1938 	if (iso_sched == NULL)
1939 		return -ENOMEM;
1940 
1941 	sitd_sched_init(ehci, iso_sched, stream, urb);
1942 
1943 	/* allocate/init sITDs */
1944 	spin_lock_irqsave (&ehci->lock, flags);
1945 	for (i = 0; i < urb->number_of_packets; i++) {
1946 
1947 		/* NOTE:  for now, we don't try to handle wraparound cases
1948 		 * for IN (using sitd->hw_backpointer, like a FSTN), which
1949 		 * means we never need two sitds for full speed packets.
1950 		 */
1951 
1952 		/* free_list.next might be cache-hot ... but maybe
1953 		 * the HC caches it too. avoid that issue for now.
1954 		 */
1955 
1956 		/* prefer previously-allocated sitds */
1957 		if (!list_empty(&stream->free_list)) {
1958 			sitd = list_entry (stream->free_list.prev,
1959 					 struct ehci_sitd, sitd_list);
1960 			list_del (&sitd->sitd_list);
1961 			sitd_dma = sitd->sitd_dma;
1962 		} else {
1963 			spin_unlock_irqrestore (&ehci->lock, flags);
1964 			sitd = dma_pool_alloc (ehci->sitd_pool, mem_flags,
1965 					&sitd_dma);
1966 			spin_lock_irqsave (&ehci->lock, flags);
1967 			if (!sitd) {
1968 				iso_sched_free(stream, iso_sched);
1969 				spin_unlock_irqrestore(&ehci->lock, flags);
1970 				return -ENOMEM;
1971 			}
1972 		}
1973 
1974 		memset (sitd, 0, sizeof *sitd);
1975 		sitd->sitd_dma = sitd_dma;
1976 		list_add (&sitd->sitd_list, &iso_sched->td_list);
1977 	}
1978 
1979 	/* temporarily store schedule info in hcpriv */
1980 	urb->hcpriv = iso_sched;
1981 	urb->error_count = 0;
1982 
1983 	spin_unlock_irqrestore (&ehci->lock, flags);
1984 	return 0;
1985 }
1986 
1987 /*-------------------------------------------------------------------------*/
1988 
1989 static inline void
1990 sitd_patch(
1991 	struct ehci_hcd		*ehci,
1992 	struct ehci_iso_stream	*stream,
1993 	struct ehci_sitd	*sitd,
1994 	struct ehci_iso_sched	*iso_sched,
1995 	unsigned		index
1996 )
1997 {
1998 	struct ehci_iso_packet	*uf = &iso_sched->packet [index];
1999 	u64			bufp = uf->bufp;
2000 
2001 	sitd->hw_next = EHCI_LIST_END(ehci);
2002 	sitd->hw_fullspeed_ep = stream->address;
2003 	sitd->hw_uframe = stream->splits;
2004 	sitd->hw_results = uf->transaction;
2005 	sitd->hw_backpointer = EHCI_LIST_END(ehci);
2006 
2007 	bufp = uf->bufp;
2008 	sitd->hw_buf[0] = cpu_to_hc32(ehci, bufp);
2009 	sitd->hw_buf_hi[0] = cpu_to_hc32(ehci, bufp >> 32);
2010 
2011 	sitd->hw_buf[1] = cpu_to_hc32(ehci, uf->buf1);
2012 	if (uf->cross)
2013 		bufp += 4096;
2014 	sitd->hw_buf_hi[1] = cpu_to_hc32(ehci, bufp >> 32);
2015 	sitd->index = index;
2016 }
2017 
2018 static inline void
2019 sitd_link (struct ehci_hcd *ehci, unsigned frame, struct ehci_sitd *sitd)
2020 {
2021 	/* note: sitd ordering could matter (CSPLIT then SSPLIT) */
2022 	sitd->sitd_next = ehci->pshadow [frame];
2023 	sitd->hw_next = ehci->periodic [frame];
2024 	ehci->pshadow [frame].sitd = sitd;
2025 	sitd->frame = frame;
2026 	wmb ();
2027 	ehci->periodic[frame] = cpu_to_hc32(ehci, sitd->sitd_dma | Q_TYPE_SITD);
2028 }
2029 
2030 /* fit urb's sitds into the selected schedule slot; activate as needed */
2031 static int
2032 sitd_link_urb (
2033 	struct ehci_hcd		*ehci,
2034 	struct urb		*urb,
2035 	unsigned		mod,
2036 	struct ehci_iso_stream	*stream
2037 )
2038 {
2039 	int			packet;
2040 	unsigned		next_uframe;
2041 	struct ehci_iso_sched	*sched = urb->hcpriv;
2042 	struct ehci_sitd	*sitd;
2043 
2044 	next_uframe = stream->next_uframe;
2045 
2046 	if (list_empty(&stream->td_list)) {
2047 		/* usbfs ignores TT bandwidth */
2048 		ehci_to_hcd(ehci)->self.bandwidth_allocated
2049 				+= stream->bandwidth;
2050 		ehci_vdbg (ehci,
2051 			"sched devp %s ep%d%s-iso [%d] %dms/%04x\n",
2052 			urb->dev->devpath, stream->bEndpointAddress & 0x0f,
2053 			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out",
2054 			(next_uframe >> 3) & (ehci->periodic_size - 1),
2055 			stream->interval, hc32_to_cpu(ehci, stream->splits));
2056 	}
2057 
2058 	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
2059 		if (ehci->amd_pll_fix == 1)
2060 			usb_amd_quirk_pll_disable();
2061 	}
2062 
2063 	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs++;
2064 
2065 	/* fill sITDs frame by frame */
2066 	for (packet = 0, sitd = NULL;
2067 			packet < urb->number_of_packets;
2068 			packet++) {
2069 
2070 		/* ASSERT:  we have all necessary sitds */
2071 		BUG_ON (list_empty (&sched->td_list));
2072 
2073 		/* ASSERT:  no itds for this endpoint in this frame */
2074 
2075 		sitd = list_entry (sched->td_list.next,
2076 				struct ehci_sitd, sitd_list);
2077 		list_move_tail (&sitd->sitd_list, &stream->td_list);
2078 		sitd->stream = iso_stream_get (stream);
2079 		sitd->urb = urb;
2080 
2081 		sitd_patch(ehci, stream, sitd, sched, packet);
2082 		sitd_link(ehci, (next_uframe >> 3) & (ehci->periodic_size - 1),
2083 				sitd);
2084 
2085 		next_uframe += stream->interval << 3;
2086 	}
2087 	stream->next_uframe = next_uframe & (mod - 1);
2088 
2089 	/* don't need that schedule data any more */
2090 	iso_sched_free (stream, sched);
2091 	urb->hcpriv = NULL;
2092 
2093 	timer_action (ehci, TIMER_IO_WATCHDOG);
2094 	return enable_periodic(ehci);
2095 }
2096 
2097 /*-------------------------------------------------------------------------*/
2098 
2099 #define	SITD_ERRS (SITD_STS_ERR | SITD_STS_DBE | SITD_STS_BABBLE \
2100 				| SITD_STS_XACT | SITD_STS_MMF)
2101 
2102 /* Process and recycle a completed SITD.  Return true iff its urb completed,
2103  * and hence its completion callback probably added things to the hardware
2104  * schedule.
2105  *
2106  * Note that we carefully avoid recycling this descriptor until after any
2107  * completion callback runs, so that it won't be reused quickly.  That is,
2108  * assuming (a) no more than two urbs per frame on this endpoint, and also
2109  * (b) only this endpoint's completions submit URBs.  It seems some silicon
2110  * corrupts things if you reuse completed descriptors very quickly...
2111  */
2112 static unsigned
2113 sitd_complete (
2114 	struct ehci_hcd		*ehci,
2115 	struct ehci_sitd	*sitd
2116 ) {
2117 	struct urb				*urb = sitd->urb;
2118 	struct usb_iso_packet_descriptor	*desc;
2119 	u32					t;
2120 	int					urb_index = -1;
2121 	struct ehci_iso_stream			*stream = sitd->stream;
2122 	struct usb_device			*dev;
2123 	unsigned				retval = false;
2124 
2125 	urb_index = sitd->index;
2126 	desc = &urb->iso_frame_desc [urb_index];
2127 	t = hc32_to_cpup(ehci, &sitd->hw_results);
2128 
2129 	/* report transfer status */
2130 	if (t & SITD_ERRS) {
2131 		urb->error_count++;
2132 		if (t & SITD_STS_DBE)
2133 			desc->status = usb_pipein (urb->pipe)
2134 				? -ENOSR  /* hc couldn't read */
2135 				: -ECOMM; /* hc couldn't write */
2136 		else if (t & SITD_STS_BABBLE)
2137 			desc->status = -EOVERFLOW;
2138 		else /* XACT, MMF, etc */
2139 			desc->status = -EPROTO;
2140 	} else {
2141 		desc->status = 0;
2142 		desc->actual_length = desc->length - SITD_LENGTH(t);
2143 		urb->actual_length += desc->actual_length;
2144 	}
2145 
2146 	/* handle completion now? */
2147 	if ((urb_index + 1) != urb->number_of_packets)
2148 		goto done;
2149 
2150 	/* ASSERT: it's really the last sitd for this urb
2151 	list_for_each_entry (sitd, &stream->td_list, sitd_list)
2152 		BUG_ON (sitd->urb == urb);
2153 	 */
2154 
2155 	/* give urb back to the driver; completion often (re)submits */
2156 	dev = urb->dev;
2157 	ehci_urb_done(ehci, urb, 0);
2158 	retval = true;
2159 	urb = NULL;
2160 	(void) disable_periodic(ehci);
2161 	ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs--;
2162 
2163 	if (ehci_to_hcd(ehci)->self.bandwidth_isoc_reqs == 0) {
2164 		if (ehci->amd_pll_fix == 1)
2165 			usb_amd_quirk_pll_enable();
2166 	}
2167 
2168 	if (list_is_singular(&stream->td_list)) {
2169 		ehci_to_hcd(ehci)->self.bandwidth_allocated
2170 				-= stream->bandwidth;
2171 		ehci_vdbg (ehci,
2172 			"deschedule devp %s ep%d%s-iso\n",
2173 			dev->devpath, stream->bEndpointAddress & 0x0f,
2174 			(stream->bEndpointAddress & USB_DIR_IN) ? "in" : "out");
2175 	}
2176 	iso_stream_put (ehci, stream);
2177 
2178 done:
2179 	sitd->urb = NULL;
2180 	if (ehci->clock_frame != sitd->frame) {
2181 		/* OK to recycle this SITD now. */
2182 		sitd->stream = NULL;
2183 		list_move(&sitd->sitd_list, &stream->free_list);
2184 		iso_stream_put(ehci, stream);
2185 	} else {
2186 		/* HW might remember this SITD, so we can't recycle it yet.
2187 		 * Move it to a safe place until a new frame starts.
2188 		 */
2189 		list_move(&sitd->sitd_list, &ehci->cached_sitd_list);
2190 		if (stream->refcount == 2) {
2191 			/* If iso_stream_put() were called here, stream
2192 			 * would be freed.  Instead, just prevent reuse.
2193 			 */
2194 			stream->ep->hcpriv = NULL;
2195 			stream->ep = NULL;
2196 		}
2197 	}
2198 	return retval;
2199 }
2200 
2201 
2202 static int sitd_submit (struct ehci_hcd *ehci, struct urb *urb,
2203 	gfp_t mem_flags)
2204 {
2205 	int			status = -EINVAL;
2206 	unsigned long		flags;
2207 	struct ehci_iso_stream	*stream;
2208 
2209 	/* Get iso_stream head */
2210 	stream = iso_stream_find (ehci, urb);
2211 	if (stream == NULL) {
2212 		ehci_dbg (ehci, "can't get iso stream\n");
2213 		return -ENOMEM;
2214 	}
2215 	if (urb->interval != stream->interval) {
2216 		ehci_dbg (ehci, "can't change iso interval %d --> %d\n",
2217 			stream->interval, urb->interval);
2218 		goto done;
2219 	}
2220 
2221 #ifdef EHCI_URB_TRACE
2222 	ehci_dbg (ehci,
2223 		"submit %p dev%s ep%d%s-iso len %d\n",
2224 		urb, urb->dev->devpath,
2225 		usb_pipeendpoint (urb->pipe),
2226 		usb_pipein (urb->pipe) ? "in" : "out",
2227 		urb->transfer_buffer_length);
2228 #endif
2229 
2230 	/* allocate SITDs */
2231 	status = sitd_urb_transaction (stream, ehci, urb, mem_flags);
2232 	if (status < 0) {
2233 		ehci_dbg (ehci, "can't init sitds\n");
2234 		goto done;
2235 	}
2236 
2237 	/* schedule ... need to lock */
2238 	spin_lock_irqsave (&ehci->lock, flags);
2239 	if (unlikely(!HCD_HW_ACCESSIBLE(ehci_to_hcd(ehci)))) {
2240 		status = -ESHUTDOWN;
2241 		goto done_not_linked;
2242 	}
2243 	status = usb_hcd_link_urb_to_ep(ehci_to_hcd(ehci), urb);
2244 	if (unlikely(status))
2245 		goto done_not_linked;
2246 	status = iso_stream_schedule(ehci, urb, stream);
2247 	if (status == 0)
2248 		sitd_link_urb (ehci, urb, ehci->periodic_size << 3, stream);
2249 	else
2250 		usb_hcd_unlink_urb_from_ep(ehci_to_hcd(ehci), urb);
2251 done_not_linked:
2252 	spin_unlock_irqrestore (&ehci->lock, flags);
2253 
2254 done:
2255 	if (status < 0)
2256 		iso_stream_put (ehci, stream);
2257 	return status;
2258 }
2259 
2260 /*-------------------------------------------------------------------------*/
2261 
2262 static void free_cached_lists(struct ehci_hcd *ehci)
2263 {
2264 	struct ehci_itd *itd, *n;
2265 	struct ehci_sitd *sitd, *sn;
2266 
2267 	list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
2268 		struct ehci_iso_stream	*stream = itd->stream;
2269 		itd->stream = NULL;
2270 		list_move(&itd->itd_list, &stream->free_list);
2271 		iso_stream_put(ehci, stream);
2272 	}
2273 
2274 	list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
2275 		struct ehci_iso_stream	*stream = sitd->stream;
2276 		sitd->stream = NULL;
2277 		list_move(&sitd->sitd_list, &stream->free_list);
2278 		iso_stream_put(ehci, stream);
2279 	}
2280 }
2281 
2282 /*-------------------------------------------------------------------------*/
2283 
2284 static void
2285 scan_periodic (struct ehci_hcd *ehci)
2286 {
2287 	unsigned	now_uframe, frame, clock, clock_frame, mod;
2288 	unsigned	modified;
2289 
2290 	mod = ehci->periodic_size << 3;
2291 
2292 	/*
2293 	 * When running, scan from last scan point up to "now"
2294 	 * else clean up by scanning everything that's left.
2295 	 * Touches as few pages as possible:  cache-friendly.
2296 	 */
2297 	now_uframe = ehci->next_uframe;
2298 	if (ehci->rh_state == EHCI_RH_RUNNING) {
2299 		clock = ehci_read_frame_index(ehci);
2300 		clock_frame = (clock >> 3) & (ehci->periodic_size - 1);
2301 	} else  {
2302 		clock = now_uframe + mod - 1;
2303 		clock_frame = -1;
2304 	}
2305 	if (ehci->clock_frame != clock_frame) {
2306 		free_cached_lists(ehci);
2307 		ehci->clock_frame = clock_frame;
2308 	}
2309 	clock &= mod - 1;
2310 	clock_frame = clock >> 3;
2311 	++ehci->periodic_stamp;
2312 
2313 	for (;;) {
2314 		union ehci_shadow	q, *q_p;
2315 		__hc32			type, *hw_p;
2316 		unsigned		incomplete = false;
2317 
2318 		frame = now_uframe >> 3;
2319 
2320 restart:
2321 		/* scan each element in frame's queue for completions */
2322 		q_p = &ehci->pshadow [frame];
2323 		hw_p = &ehci->periodic [frame];
2324 		q.ptr = q_p->ptr;
2325 		type = Q_NEXT_TYPE(ehci, *hw_p);
2326 		modified = 0;
2327 
2328 		while (q.ptr != NULL) {
2329 			unsigned		uf;
2330 			union ehci_shadow	temp;
2331 			int			live;
2332 
2333 			live = (ehci->rh_state == EHCI_RH_RUNNING);
2334 			switch (hc32_to_cpu(ehci, type)) {
2335 			case Q_TYPE_QH:
2336 				/* handle any completions */
2337 				temp.qh = qh_get (q.qh);
2338 				type = Q_NEXT_TYPE(ehci, q.qh->hw->hw_next);
2339 				q = q.qh->qh_next;
2340 				if (temp.qh->stamp != ehci->periodic_stamp) {
2341 					modified = qh_completions(ehci, temp.qh);
2342 					if (!modified)
2343 						temp.qh->stamp = ehci->periodic_stamp;
2344 					if (unlikely(list_empty(&temp.qh->qtd_list) ||
2345 							temp.qh->needs_rescan))
2346 						intr_deschedule(ehci, temp.qh);
2347 				}
2348 				qh_put (temp.qh);
2349 				break;
2350 			case Q_TYPE_FSTN:
2351 				/* for "save place" FSTNs, look at QH entries
2352 				 * in the previous frame for completions.
2353 				 */
2354 				if (q.fstn->hw_prev != EHCI_LIST_END(ehci)) {
2355 					dbg ("ignoring completions from FSTNs");
2356 				}
2357 				type = Q_NEXT_TYPE(ehci, q.fstn->hw_next);
2358 				q = q.fstn->fstn_next;
2359 				break;
2360 			case Q_TYPE_ITD:
2361 				/* If this ITD is still active, leave it for
2362 				 * later processing ... check the next entry.
2363 				 * No need to check for activity unless the
2364 				 * frame is current.
2365 				 */
2366 				if (frame == clock_frame && live) {
2367 					rmb();
2368 					for (uf = 0; uf < 8; uf++) {
2369 						if (q.itd->hw_transaction[uf] &
2370 							    ITD_ACTIVE(ehci))
2371 							break;
2372 					}
2373 					if (uf < 8) {
2374 						incomplete = true;
2375 						q_p = &q.itd->itd_next;
2376 						hw_p = &q.itd->hw_next;
2377 						type = Q_NEXT_TYPE(ehci,
2378 							q.itd->hw_next);
2379 						q = *q_p;
2380 						break;
2381 					}
2382 				}
2383 
2384 				/* Take finished ITDs out of the schedule
2385 				 * and process them:  recycle, maybe report
2386 				 * URB completion.  HC won't cache the
2387 				 * pointer for much longer, if at all.
2388 				 */
2389 				*q_p = q.itd->itd_next;
2390 				if (!ehci->use_dummy_qh ||
2391 				    q.itd->hw_next != EHCI_LIST_END(ehci))
2392 					*hw_p = q.itd->hw_next;
2393 				else
2394 					*hw_p = ehci->dummy->qh_dma;
2395 				type = Q_NEXT_TYPE(ehci, q.itd->hw_next);
2396 				wmb();
2397 				modified = itd_complete (ehci, q.itd);
2398 				q = *q_p;
2399 				break;
2400 			case Q_TYPE_SITD:
2401 				/* If this SITD is still active, leave it for
2402 				 * later processing ... check the next entry.
2403 				 * No need to check for activity unless the
2404 				 * frame is current.
2405 				 */
2406 				if (((frame == clock_frame) ||
2407 				     (((frame + 1) & (ehci->periodic_size - 1))
2408 				      == clock_frame))
2409 				    && live
2410 				    && (q.sitd->hw_results &
2411 					SITD_ACTIVE(ehci))) {
2412 
2413 					incomplete = true;
2414 					q_p = &q.sitd->sitd_next;
2415 					hw_p = &q.sitd->hw_next;
2416 					type = Q_NEXT_TYPE(ehci,
2417 							q.sitd->hw_next);
2418 					q = *q_p;
2419 					break;
2420 				}
2421 
2422 				/* Take finished SITDs out of the schedule
2423 				 * and process them:  recycle, maybe report
2424 				 * URB completion.
2425 				 */
2426 				*q_p = q.sitd->sitd_next;
2427 				if (!ehci->use_dummy_qh ||
2428 				    q.sitd->hw_next != EHCI_LIST_END(ehci))
2429 					*hw_p = q.sitd->hw_next;
2430 				else
2431 					*hw_p = ehci->dummy->qh_dma;
2432 				type = Q_NEXT_TYPE(ehci, q.sitd->hw_next);
2433 				wmb();
2434 				modified = sitd_complete (ehci, q.sitd);
2435 				q = *q_p;
2436 				break;
2437 			default:
2438 				dbg ("corrupt type %d frame %d shadow %p",
2439 					type, frame, q.ptr);
2440 				// BUG ();
2441 				q.ptr = NULL;
2442 			}
2443 
2444 			/* assume completion callbacks modify the queue */
2445 			if (unlikely (modified)) {
2446 				if (likely(ehci->periodic_sched > 0))
2447 					goto restart;
2448 				/* short-circuit this scan */
2449 				now_uframe = clock;
2450 				break;
2451 			}
2452 		}
2453 
2454 		/* If we can tell we caught up to the hardware, stop now.
2455 		 * We can't advance our scan without collecting the ISO
2456 		 * transfers that are still pending in this frame.
2457 		 */
2458 		if (incomplete && ehci->rh_state == EHCI_RH_RUNNING) {
2459 			ehci->next_uframe = now_uframe;
2460 			break;
2461 		}
2462 
2463 		// FIXME:  this assumes we won't get lapped when
2464 		// latencies climb; that should be rare, but...
2465 		// detect it, and just go all the way around.
2466 		// FLR might help detect this case, so long as latencies
2467 		// don't exceed periodic_size msec (default 1.024 sec).
2468 
2469 		// FIXME:  likewise assumes HC doesn't halt mid-scan
2470 
2471 		if (now_uframe == clock) {
2472 			unsigned	now;
2473 
2474 			if (ehci->rh_state != EHCI_RH_RUNNING
2475 					|| ehci->periodic_sched == 0)
2476 				break;
2477 			ehci->next_uframe = now_uframe;
2478 			now = ehci_read_frame_index(ehci) & (mod - 1);
2479 			if (now_uframe == now)
2480 				break;
2481 
2482 			/* rescan the rest of this frame, then ... */
2483 			clock = now;
2484 			clock_frame = clock >> 3;
2485 			if (ehci->clock_frame != clock_frame) {
2486 				free_cached_lists(ehci);
2487 				ehci->clock_frame = clock_frame;
2488 				++ehci->periodic_stamp;
2489 			}
2490 		} else {
2491 			now_uframe++;
2492 			now_uframe &= mod - 1;
2493 		}
2494 	}
2495 }
2496