1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2012 by Alan Stern
4 */
5
6 /* This file is part of ehci-hcd.c */
7
8 /*-------------------------------------------------------------------------*/
9
10 /* Set a bit in the USBCMD register */
11 static void ehci_set_command_bit(struct ehci_hcd *ehci, u32 bit)
12 {
13 ehci->command |= bit;
14 ehci_writel(ehci, ehci->command, &ehci->regs->command);
15
16 /* unblock posted write */
17 ehci_readl(ehci, &ehci->regs->command);
18 }
19
20 /* Clear a bit in the USBCMD register */
21 static void ehci_clear_command_bit(struct ehci_hcd *ehci, u32 bit)
22 {
23 ehci->command &= ~bit;
24 ehci_writel(ehci, ehci->command, &ehci->regs->command);
25
26 /* unblock posted write */
27 ehci_readl(ehci, &ehci->regs->command);
28 }
29
30 /*-------------------------------------------------------------------------*/
31
32 /*
33 * EHCI timer support... Now using hrtimers.
34 *
35 * Lots of different events are triggered from ehci->hrtimer. Whenever
36 * the timer routine runs, it checks each possible event; events that are
37 * currently enabled and whose expiration time has passed get handled.
38 * The set of enabled events is stored as a collection of bitflags in
39 * ehci->enabled_hrtimer_events, and they are numbered in order of
40 * increasing delay values (ranging between 1 ms and 100 ms).
41 *
42 * Rather than implementing a sorted list or tree of all pending events,
43 * we keep track only of the lowest-numbered pending event, in
44 * ehci->next_hrtimer_event. Whenever ehci->hrtimer gets restarted, its
45 * expiration time is set to the timeout value for this event.
46 *
47 * As a result, events might not get handled right away; the actual delay
48 * could be anywhere up to twice the requested delay. This doesn't
49 * matter, because none of the events are especially time-critical. The
50 * ones that matter most all have a delay of 1 ms, so they will be
51 * handled after 2 ms at most, which is okay. In addition to this, we
52 * allow for an expiration range of 1 ms.
53 */
54
55 /*
56 * Delay lengths for the hrtimer event types.
57 * Keep this list sorted by delay length, in the same order as
58 * the event types indexed by enum ehci_hrtimer_event in ehci.h.
59 */
60 static unsigned event_delays_ns[] = {
61 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_ASS */
62 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_PSS */
63 1 * NSEC_PER_MSEC, /* EHCI_HRTIMER_POLL_DEAD */
64 1125 * NSEC_PER_USEC, /* EHCI_HRTIMER_UNLINK_INTR */
65 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_FREE_ITDS */
66 2 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ACTIVE_UNLINK */
67 5 * NSEC_PER_MSEC, /* EHCI_HRTIMER_START_UNLINK_INTR */
68 6 * NSEC_PER_MSEC, /* EHCI_HRTIMER_ASYNC_UNLINKS */
69 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IAA_WATCHDOG */
70 10 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_PERIODIC */
71 15 * NSEC_PER_MSEC, /* EHCI_HRTIMER_DISABLE_ASYNC */
72 100 * NSEC_PER_MSEC, /* EHCI_HRTIMER_IO_WATCHDOG */
73 };
74
75 /* Enable a pending hrtimer event */
76 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
77 bool resched)
78 {
79 ktime_t *timeout = &ehci->hr_timeouts[event];
80
81 if (resched)
82 *timeout = ktime_add(ktime_get(), event_delays_ns[event]);
83 ehci->enabled_hrtimer_events |= (1 << event);
84
85 /* Track only the lowest-numbered pending event */
86 if (event < ehci->next_hrtimer_event) {
87 ehci->next_hrtimer_event = event;
88 hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
89 NSEC_PER_MSEC, HRTIMER_MODE_ABS);
90 }
91 }
92
93
94 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
95 static void ehci_poll_ASS(struct ehci_hcd *ehci)
96 {
97 unsigned actual, want;
98
99 /* Don't enable anything if the controller isn't running (e.g., died) */
100 if (ehci->rh_state != EHCI_RH_RUNNING)
101 return;
102
103 want = (ehci->command & CMD_ASE) ? STS_ASS : 0;
104 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS;
105
106 if (want != actual) {
107
108 /* Poll again later, but give up after about 2-4 ms */
109 if (ehci->ASS_poll_count++ < 2) {
110 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
111 return;
112 }
113 ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n",
114 want, actual);
115 }
116 ehci->ASS_poll_count = 0;
117
118 /* The status is up-to-date; restart or stop the schedule as needed */
119 if (want == 0) { /* Stopped */
120 if (ehci->async_count > 0)
121 ehci_set_command_bit(ehci, CMD_ASE);
122
123 } else { /* Running */
124 if (ehci->async_count == 0) {
125
126 /* Turn off the schedule after a while */
127 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC,
128 true);
129 }
130 }
131 }
132
133 /* Turn off the async schedule after a brief delay */
134 static void ehci_disable_ASE(struct ehci_hcd *ehci)
135 {
136 ehci_clear_command_bit(ehci, CMD_ASE);
137 }
138
139
140 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
141 static void ehci_poll_PSS(struct ehci_hcd *ehci)
142 {
143 unsigned actual, want;
144
145 /* Don't do anything if the controller isn't running (e.g., died) */
146 if (ehci->rh_state != EHCI_RH_RUNNING)
147 return;
148
149 want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
150 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;
151
152 if (want != actual) {
153
154 /* Poll again later, but give up after about 2-4 ms */
155 if (ehci->PSS_poll_count++ < 2) {
156 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
157 return;
158 }
159 ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n",
160 want, actual);
161 }
162 ehci->PSS_poll_count = 0;
163
164 /* The status is up-to-date; restart or stop the schedule as needed */
165 if (want == 0) { /* Stopped */
166 if (ehci->periodic_count > 0)
167 ehci_set_command_bit(ehci, CMD_PSE);
168
169 } else { /* Running */
170 if (ehci->periodic_count == 0) {
171
172 /* Turn off the schedule after a while */
173 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
174 true);
175 }
176 }
177 }
178
179 /* Turn off the periodic schedule after a brief delay */
180 static void ehci_disable_PSE(struct ehci_hcd *ehci)
181 {
182 ehci_clear_command_bit(ehci, CMD_PSE);
183 }
184
185
186 /* Poll the STS_HALT status bit; see when a dead controller stops */
187 static void ehci_handle_controller_death(struct ehci_hcd *ehci)
188 {
189 if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) {
190
191 /* Give up after a few milliseconds */
192 if (ehci->died_poll_count++ < 5) {
193 /* Try again later */
194 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true);
195 return;
196 }
197 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n");
198 }
199
200 /* Clean up the mess */
201 ehci->rh_state = EHCI_RH_HALTED;
202 ehci_writel(ehci, 0, &ehci->regs->configured_flag);
203 ehci_writel(ehci, 0, &ehci->regs->intr_enable);
204 ehci_work(ehci);
205 end_unlink_async(ehci);
206
207 /* Not in process context, so don't try to reset the controller */
208 }
209
210 /* start to unlink interrupt QHs */
211 static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci)
212 {
213 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);
214
215 /*
216 * Process all the QHs on the intr_unlink list that were added
217 * before the current unlink cycle began. The list is in
218 * temporal order, so stop when we reach the first entry in the
219 * current cycle. But if the root hub isn't running then
220 * process all the QHs on the list.
221 */
222 while (!list_empty(&ehci->intr_unlink_wait)) {
223 struct ehci_qh *qh;
224
225 qh = list_first_entry(&ehci->intr_unlink_wait,
226 struct ehci_qh, unlink_node);
227 if (!stopped && (qh->unlink_cycle ==
228 ehci->intr_unlink_wait_cycle))
229 break;
230 list_del_init(&qh->unlink_node);
231 qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY;
232 start_unlink_intr(ehci, qh);
233 }
234
235 /* Handle remaining entries later */
236 if (!list_empty(&ehci->intr_unlink_wait)) {
237 ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
238 ++ehci->intr_unlink_wait_cycle;
239 }
240 }
241
242 /* Handle unlinked interrupt QHs once they are gone from the hardware */
243 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
244 {
245 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);
246
247 /*
248 * Process all the QHs on the intr_unlink list that were added
249 * before the current unlink cycle began. The list is in
250 * temporal order, so stop when we reach the first entry in the
251 * current cycle. But if the root hub isn't running then
252 * process all the QHs on the list.
253 */
254 ehci->intr_unlinking = true;
255 while (!list_empty(&ehci->intr_unlink)) {
256 struct ehci_qh *qh;
257
258 qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh,
259 unlink_node);
260 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
261 break;
262 list_del_init(&qh->unlink_node);
263 end_unlink_intr(ehci, qh);
264 }
265
266 /* Handle remaining entries later */
267 if (!list_empty(&ehci->intr_unlink)) {
268 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
269 ++ehci->intr_unlink_cycle;
270 }
271 ehci->intr_unlinking = false;
272 }
273
274
275 /* Start another free-iTDs/siTDs cycle */
276 static void start_free_itds(struct ehci_hcd *ehci)
277 {
278 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) {
279 ehci->last_itd_to_free = list_entry(
280 ehci->cached_itd_list.prev,
281 struct ehci_itd, itd_list);
282 ehci->last_sitd_to_free = list_entry(
283 ehci->cached_sitd_list.prev,
284 struct ehci_sitd, sitd_list);
285 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true);
286 }
287 }
288
289 /* Wait for controller to stop using old iTDs and siTDs */
290 static void end_free_itds(struct ehci_hcd *ehci)
291 {
292 struct ehci_itd *itd, *n;
293 struct ehci_sitd *sitd, *sn;
294
295 if (ehci->rh_state < EHCI_RH_RUNNING) {
296 ehci->last_itd_to_free = NULL;
297 ehci->last_sitd_to_free = NULL;
298 }
299
300 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
301 list_del(&itd->itd_list);
302 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma);
303 if (itd == ehci->last_itd_to_free)
304 break;
305 }
306 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
307 list_del(&sitd->sitd_list);
308 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma);
309 if (sitd == ehci->last_sitd_to_free)
310 break;
311 }
312
313 if (!list_empty(&ehci->cached_itd_list) ||
314 !list_empty(&ehci->cached_sitd_list))
315 start_free_itds(ehci);
316 }
317
318
319 /* Handle lost (or very late) IAA interrupts */
320 static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
321 {
322 u32 cmd, status;
323
324 /*
325 * Lost IAA irqs wedge things badly; seen first with a vt8235.
326 * So we need this watchdog, but must protect it against both
327 * (a) SMP races against real IAA firing and retriggering, and
328 * (b) clean HC shutdown, when IAA watchdog was pending.
329 */
330 if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING)
331 return;
332
333 /* If we get here, IAA is *REALLY* late. It's barely
334 * conceivable that the system is so busy that CMD_IAAD
335 * is still legitimately set, so let's be sure it's
336 * clear before we read STS_IAA. (The HC should clear
337 * CMD_IAAD when it sets STS_IAA.)
338 */
339 cmd = ehci_readl(ehci, &ehci->regs->command);
340
341 /*
342 * If IAA is set here it either legitimately triggered
343 * after the watchdog timer expired (_way_ late, so we'll
344 * still count it as lost) ... or a silicon erratum:
345 * - VIA seems to set IAA without triggering the IRQ;
346 * - IAAD potentially cleared without setting IAA.
347 */
348 status = ehci_readl(ehci, &ehci->regs->status);
349 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
350 INCR(ehci->stats.lost_iaa);
351 ehci_writel(ehci, STS_IAA, &ehci->regs->status);
352 }
353
354 ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd);
355 end_iaa_cycle(ehci);
356 }
357
358
359 /* Enable the I/O watchdog, if appropriate */
360 static void turn_on_io_watchdog(struct ehci_hcd *ehci)
361 {
362 /* Not needed if the controller isn't running or it's already enabled */
363 if (ehci->rh_state != EHCI_RH_RUNNING ||
364 (ehci->enabled_hrtimer_events &
365 BIT(EHCI_HRTIMER_IO_WATCHDOG)))
366 return;
367
368 /*
369 * Isochronous transfers always need the watchdog.
370 * For other sorts we use it only if the flag is set.
371 */
372 if (ehci->isoc_count > 0 || (ehci->need_io_watchdog &&
373 ehci->async_count + ehci->intr_count > 0))
374 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
375 }
376
377
378 /*
379 * Handler functions for the hrtimer event types.
380 * Keep this array in the same order as the event types indexed by
381 * enum ehci_hrtimer_event in ehci.h.
382 */
383 static void (*event_handlers[])(struct ehci_hcd *) = {
384 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */
385 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */
386 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */
387 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */
388 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */
389 end_unlink_async, /* EHCI_HRTIMER_ACTIVE_UNLINK */
390 ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */
391 unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */
392 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */
393 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */
394 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */
395 ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */
396 };
397
398 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
399 {
400 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
401 ktime_t now;
402 unsigned long events;
403 unsigned long flags;
404 unsigned e;
405
406 spin_lock_irqsave(&ehci->lock, flags);
407
408 events = ehci->enabled_hrtimer_events;
409 ehci->enabled_hrtimer_events = 0;
410 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
411
412 /*
413 * Check each pending event. If its time has expired, handle
414 * the event; otherwise re-enable it.
415 */
416 now = ktime_get();
417 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
418 if (ktime_compare(now, ehci->hr_timeouts[e]) >= 0)
419 event_handlers[e](ehci);
420 else
421 ehci_enable_event(ehci, e, false);
422 }
423
424 spin_unlock_irqrestore(&ehci->lock, flags);
425 return HRTIMER_NORESTART;
426 }