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1/*
2 * Copyright (C) 2012 by Alan Stern
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License as published by the
6 * Free Software Foundation; either version 2 of the License, or (at your
7 * option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * for more details.
13 */
14
15/* This file is part of ehci-hcd.c */
16
17/*-------------------------------------------------------------------------*/
18
19/* Set a bit in the USBCMD register */
20static void ehci_set_command_bit(struct ehci_hcd *ehci, u32 bit)
21{
22 ehci->command |= bit;
23 ehci_writel(ehci, ehci->command, &ehci->regs->command);
24
25 /* unblock posted write */
26 ehci_readl(ehci, &ehci->regs->command);
27}
28
29/* Clear a bit in the USBCMD register */
30static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit)
31{
32 ehci->command &= ~bit;
33 ehci_writel(ehci, ehci->command, &ehci->regs->command);
34
35 /* unblock posted write */
36 ehci_readl(ehci, &ehci->regs->command);
37}
38
39/*-------------------------------------------------------------------------*/
40
41/*
42 * EHCI timer support... Now using hrtimers.
43 *
44 * Lots of different events are triggered from ehci->hrtimer. Whenever
45 * the timer routine runs, it checks each possible event; events that are
46 * currently enabled and whose expiration time has passed get handled.
47 * The set of enabled events is stored as a collection of bitflags in
48 * ehci->enabled_hrtimer_events, and they are numbered in order of
49 * increasing delay values (ranging between 1 ms and 100 ms).
50 *
51 * Rather than implementing a sorted list or tree of all pending events,
52 * we keep track only of the lowest-numbered pending event, in
53 * ehci->next_hrtimer_event. Whenever ehci->hrtimer gets restarted, its
54 * expiration time is set to the timeout value for this event.
55 *
56 * As a result, events might not get handled right away; the actual delay
57 * could be anywhere up to twice the requested delay. This doesn't
58 * matter, because none of the events are especially time-critical. The
59 * ones that matter most all have a delay of 1 ms, so they will be
60 * handled after 2 ms at most, which is okay. In addition to this, we
61 * allow for an expiration range of 1 ms.
62 */
63
64/*
65 * Delay lengths for the hrtimer event types.
66 * Keep this list sorted by delay length, in the same order as
67 * the event types indexed by enum ehci_hrtimer_event in ehci.h.
68 */
69static unsigned event_delays_ns[] = {
70 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_ASS */
71 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_PSS */
72 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_DEAD */
73 1125 * NSEC_PER_USEC, /* EHCI_HRTIMER_UNLINK_INTR */
74 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_FREE_ITDS */
75 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ACTIVE_UNLINK */
76 5 * NSEC_PER_MSEC, /* EHCI_HRTIMER_START_UNLINK_INTR */
77 6 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ASYNC_UNLINKS */
78 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */
79 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */
80 15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */
81 100 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IO_WATCHDOG */
82};
83
84/* Enable a pending hrtimer event */
85static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
86 bool resched)
87{
88 ktime_t *timeout = &ehci->hr_timeouts[event];
89
90 if (resched)
91 *timeout = ktime_add(ktime_get(), event_delays_ns[event]);
92 ehci->enabled_hrtimer_events |= (1 << event);
93
94 /* Track only the lowest-numbered pending event */
95 if (event < ehci->next_hrtimer_event) {
96 ehci->next_hrtimer_event = event;
97 hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
98 NSEC_PER_MSEC, HRTIMER_MODE_ABS);
99 }
100}
101
102
103/* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
104static void ehci_poll_ASS(struct ehci_hcd *ehci)
105{
106 unsigned actual, want;
107
108 /* Don't enable anything if the controller isn't running (e.g., died) */
109 if (ehci->rh_state != EHCI_RH_RUNNING)
110 return;
111
112 want = (ehci->command & CMD_ASE) ? STS_ASS : 0;
113 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS;
114
115 if (want != actual) {
116
117 /* Poll again later, but give up after about 2-4 ms */
118 if (ehci->ASS_poll_count++ < 2) {
119 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
120 return;
121 }
122 ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n",
123 want, actual);
124 }
125 ehci->ASS_poll_count = 0;
126
127 /* The status is up-to-date; restart or stop the schedule as needed */
128 if (want == 0) { /* Stopped */
129 if (ehci->async_count > 0)
130 ehci_set_command_bit(ehci, CMD_ASE);
131
132 } else { /* Running */
133 if (ehci->async_count == 0) {
134
135 /* Turn off the schedule after a while */
136 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC,
137 true);
138 }
139 }
140}
141
142/* Turn off the async schedule after a brief delay */
143static void ehci_disable_ASE(struct ehci_hcd *ehci)
144{
145 ehci_clear_command_bit(ehci, CMD_ASE);
146}
147
148
149/* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
150static void ehci_poll_PSS(struct ehci_hcd *ehci)
151{
152 unsigned actual, want;
153
154 /* Don't do anything if the controller isn't running (e.g., died) */
155 if (ehci->rh_state != EHCI_RH_RUNNING)
156 return;
157
158 want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
159 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;
160
161 if (want != actual) {
162
163 /* Poll again later, but give up after about 2-4 ms */
164 if (ehci->PSS_poll_count++ < 2) {
165 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
166 return;
167 }
168 ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n",
169 want, actual);
170 }
171 ehci->PSS_poll_count = 0;
172
173 /* The status is up-to-date; restart or stop the schedule as needed */
174 if (want == 0) { /* Stopped */
175 if (ehci->periodic_count > 0)
176 ehci_set_command_bit(ehci, CMD_PSE);
177
178 } else { /* Running */
179 if (ehci->periodic_count == 0) {
180
181 /* Turn off the schedule after a while */
182 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
183 true);
184 }
185 }
186}
187
188/* Turn off the periodic schedule after a brief delay */
189static void ehci_disable_PSE(struct ehci_hcd *ehci)
190{
191 ehci_clear_command_bit(ehci, CMD_PSE);
192}
193
194
195/* Poll the STS_HALT status bit; see when a dead controller stops */
196static void ehci_handle_controller_death(struct ehci_hcd *ehci)
197{
198 if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) {
199
200 /* Give up after a few milliseconds */
201 if (ehci->died_poll_count++ < 5) {
202 /* Try again later */
203 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true);
204 return;
205 }
206 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n");
207 }
208
209 /* Clean up the mess */
210 ehci->rh_state = EHCI_RH_HALTED;
211 ehci_writel(ehci, 0, &ehci->regs->configured_flag);
212 ehci_writel(ehci, 0, &ehci->regs->intr_enable);
213 ehci_work(ehci);
214 end_unlink_async(ehci);
215
216 /* Not in process context, so don't try to reset the controller */
217}
218
219/* start to unlink interrupt QHs */
220static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci)
221{
222 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);
223
224 /*
225 * Process all the QHs on the intr_unlink list that were added
226 * before the current unlink cycle began. The list is in
227 * temporal order, so stop when we reach the first entry in the
228 * current cycle. But if the root hub isn't running then
229 * process all the QHs on the list.
230 */
231 while (!list_empty(&ehci->intr_unlink_wait)) {
232 struct ehci_qh *qh;
233
234 qh = list_first_entry(&ehci->intr_unlink_wait,
235 struct ehci_qh, unlink_node);
236 if (!stopped && (qh->unlink_cycle ==
237 ehci->intr_unlink_wait_cycle))
238 break;
239 list_del_init(&qh->unlink_node);
240 qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY;
241 start_unlink_intr(ehci, qh);
242 }
243
244 /* Handle remaining entries later */
245 if (!list_empty(&ehci->intr_unlink_wait)) {
246 ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
247 ++ehci->intr_unlink_wait_cycle;
248 }
249}
250
251/* Handle unlinked interrupt QHs once they are gone from the hardware */
252static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
253{
254 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);
255
256 /*
257 * Process all the QHs on the intr_unlink list that were added
258 * before the current unlink cycle began. The list is in
259 * temporal order, so stop when we reach the first entry in the
260 * current cycle. But if the root hub isn't running then
261 * process all the QHs on the list.
262 */
263 ehci->intr_unlinking = true;
264 while (!list_empty(&ehci->intr_unlink)) {
265 struct ehci_qh *qh;
266
267 qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh,
268 unlink_node);
269 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
270 break;
271 list_del_init(&qh->unlink_node);
272 end_unlink_intr(ehci, qh);
273 }
274
275 /* Handle remaining entries later */
276 if (!list_empty(&ehci->intr_unlink)) {
277 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
278 ++ehci->intr_unlink_cycle;
279 }
280 ehci->intr_unlinking = false;
281}
282
283
284/* Start another free-iTDs/siTDs cycle */
285static void start_free_itds(struct ehci_hcd *ehci)
286{
287 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) {
288 ehci->last_itd_to_free = list_entry(
289 ehci->cached_itd_list.prev,
290 struct ehci_itd, itd_list);
291 ehci->last_sitd_to_free = list_entry(
292 ehci->cached_sitd_list.prev,
293 struct ehci_sitd, sitd_list);
294 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true);
295 }
296}
297
298/* Wait for controller to stop using old iTDs and siTDs */
299static void end_free_itds(struct ehci_hcd *ehci)
300{
301 struct ehci_itd *itd, *n;
302 struct ehci_sitd *sitd, *sn;
303
304 if (ehci->rh_state < EHCI_RH_RUNNING) {
305 ehci->last_itd_to_free = NULL;
306 ehci->last_sitd_to_free = NULL;
307 }
308
309 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
310 list_del(&itd->itd_list);
311 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma);
312 if (itd == ehci->last_itd_to_free)
313 break;
314 }
315 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
316 list_del(&sitd->sitd_list);
317 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma);
318 if (sitd == ehci->last_sitd_to_free)
319 break;
320 }
321
322 if (!list_empty(&ehci->cached_itd_list) ||
323 !list_empty(&ehci->cached_sitd_list))
324 start_free_itds(ehci);
325}
326
327
328/* Handle lost (or very late) IAA interrupts */
329static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
330{
331 u32 cmd, status;
332
333 /*
334 * Lost IAA irqs wedge things badly; seen first with a vt8235.
335 * So we need this watchdog, but must protect it against both
336 * (a) SMP races against real IAA firing and retriggering, and
337 * (b) clean HC shutdown, when IAA watchdog was pending.
338 */
339 if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING)
340 return;
341
342 /* If we get here, IAA is *REALLY* late. It's barely
343 * conceivable that the system is so busy that CMD_IAAD
344 * is still legitimately set, so let's be sure it's
345 * clear before we read STS_IAA. (The HC should clear
346 * CMD_IAAD when it sets STS_IAA.)
347 */
348 cmd = ehci_readl(ehci, &ehci->regs->command);
349
350 /*
351 * If IAA is set here it either legitimately triggered
352 * after the watchdog timer expired (_way_ late, so we'll
353 * still count it as lost) ... or a silicon erratum:
354 * - VIA seems to set IAA without triggering the IRQ;
355 * - IAAD potentially cleared without setting IAA.
356 */
357 status = ehci_readl(ehci, &ehci->regs->status);
358 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
359 COUNT(ehci->stats.lost_iaa);
360 ehci_writel(ehci, STS_IAA, &ehci->regs->status);
361 }
362
363 ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd);
364 end_iaa_cycle(ehci);
365}
366
367
368/* Enable the I/O watchdog, if appropriate */
369static void turn_on_io_watchdog(struct ehci_hcd *ehci)
370{
371 /* Not needed if the controller isn't running or it's already enabled */
372 if (ehci->rh_state != EHCI_RH_RUNNING ||
373 (ehci->enabled_hrtimer_events &
374 BIT(EHCI_HRTIMER_IO_WATCHDOG)))
375 return;
376
377 /*
378 * Isochronous transfers always need the watchdog.
379 * For other sorts we use it only if the flag is set.
380 */
381 if (ehci->isoc_count > 0 || (ehci->need_io_watchdog &&
382 ehci->async_count + ehci->intr_count > 0))
383 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
384}
385
386
387/*
388 * Handler functions for the hrtimer event types.
389 * Keep this array in the same order as the event types indexed by
390 * enum ehci_hrtimer_event in ehci.h.
391 */
392static void (*event_handlers[])(struct ehci_hcd *) = {
393 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */
394 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */
395 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */
396 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */
397 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */
398 end_unlink_async, /* EHCI_HRTIMER_ACTIVE_UNLINK */
399 ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */
400 unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */
401 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */
402 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */
403 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */
404 ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */
405};
406
407static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
408{
409 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
410 ktime_t now;
411 unsigned long events;
412 unsigned long flags;
413 unsigned e;
414
415 spin_lock_irqsave(&ehci->lock, flags);
416
417 events = ehci->enabled_hrtimer_events;
418 ehci->enabled_hrtimer_events = 0;
419 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
420
421 /*
422 * Check each pending event. If its time has expired, handle
423 * the event; otherwise re-enable it.
424 */
425 now = ktime_get();
426 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
427 if (now >= ehci->hr_timeouts[e])
428 event_handlers[e](ehci);
429 else
430 ehci_enable_event(ehci, e, false);
431 }
432
433 spin_unlock_irqrestore(&ehci->lock, flags);
434 return HRTIMER_NORESTART;
435}