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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(),
92 ktime_set(0, event_delays_ns[event]));
93 ehci->enabled_hrtimer_events |= (1 << event);
94
95 /* Track only the lowest-numbered pending event */
96 if (event < ehci->next_hrtimer_event) {
97 ehci->next_hrtimer_event = event;
98 hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
99 NSEC_PER_MSEC, HRTIMER_MODE_ABS);
100 }
101}
102
103
104/* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
105static void ehci_poll_ASS(struct ehci_hcd *ehci)
106{
107 unsigned actual, want;
108
109 /* Don't enable anything if the controller isn't running (e.g., died) */
110 if (ehci->rh_state != EHCI_RH_RUNNING)
111 return;
112
113 want = (ehci->command & CMD_ASE) ? STS_ASS : 0;
114 actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS;
115
116 if (want != actual) {
117
118 /* Poll again later, but give up after about 2-4 ms */
119 if (ehci->ASS_poll_count++ < 2) {
120 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
121 return;
122 }
123 ehci_dbg(ehci, "Waited too long for the async schedule status (%x/%x), giving up\n",
124 want, actual);
125 }
126 ehci->ASS_poll_count = 0;
127
128 /* The status is up-to-date; restart or stop the schedule as needed */
129 if (want == 0) { /* Stopped */
130 if (ehci->async_count > 0)
131 ehci_set_command_bit(ehci, CMD_ASE);
132
133 } else { /* Running */
134 if (ehci->async_count == 0) {
135
136 /* Turn off the schedule after a while */
137 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC,
138 true);
139 }
140 }
141}
142
143/* Turn off the async schedule after a brief delay */
144static void ehci_disable_ASE(struct ehci_hcd *ehci)
145{
146 ehci_clear_command_bit(ehci, CMD_ASE);
147}
148
149
150/* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
151static void ehci_poll_PSS(struct ehci_hcd *ehci)
152{
153 unsigned actual, want;
154
155 /* Don't do anything if the controller isn't running (e.g., died) */
156 if (ehci->rh_state != EHCI_RH_RUNNING)
157 return;
158
159 want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
160 actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;
161
162 if (want != actual) {
163
164 /* Poll again later, but give up after about 2-4 ms */
165 if (ehci->PSS_poll_count++ < 2) {
166 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
167 return;
168 }
169 ehci_dbg(ehci, "Waited too long for the periodic schedule status (%x/%x), giving up\n",
170 want, actual);
171 }
172 ehci->PSS_poll_count = 0;
173
174 /* The status is up-to-date; restart or stop the schedule as needed */
175 if (want == 0) { /* Stopped */
176 if (ehci->periodic_count > 0)
177 ehci_set_command_bit(ehci, CMD_PSE);
178
179 } else { /* Running */
180 if (ehci->periodic_count == 0) {
181
182 /* Turn off the schedule after a while */
183 ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
184 true);
185 }
186 }
187}
188
189/* Turn off the periodic schedule after a brief delay */
190static void ehci_disable_PSE(struct ehci_hcd *ehci)
191{
192 ehci_clear_command_bit(ehci, CMD_PSE);
193}
194
195
196/* Poll the STS_HALT status bit; see when a dead controller stops */
197static void ehci_handle_controller_death(struct ehci_hcd *ehci)
198{
199 if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) {
200
201 /* Give up after a few milliseconds */
202 if (ehci->died_poll_count++ < 5) {
203 /* Try again later */
204 ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true);
205 return;
206 }
207 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n");
208 }
209
210 /* Clean up the mess */
211 ehci->rh_state = EHCI_RH_HALTED;
212 ehci_writel(ehci, 0, &ehci->regs->configured_flag);
213 ehci_writel(ehci, 0, &ehci->regs->intr_enable);
214 ehci_work(ehci);
215 end_unlink_async(ehci);
216
217 /* Not in process context, so don't try to reset the controller */
218}
219
220/* start to unlink interrupt QHs */
221static void ehci_handle_start_intr_unlinks(struct ehci_hcd *ehci)
222{
223 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);
224
225 /*
226 * Process all the QHs on the intr_unlink list that were added
227 * before the current unlink cycle began. The list is in
228 * temporal order, so stop when we reach the first entry in the
229 * current cycle. But if the root hub isn't running then
230 * process all the QHs on the list.
231 */
232 while (!list_empty(&ehci->intr_unlink_wait)) {
233 struct ehci_qh *qh;
234
235 qh = list_first_entry(&ehci->intr_unlink_wait,
236 struct ehci_qh, unlink_node);
237 if (!stopped && (qh->unlink_cycle ==
238 ehci->intr_unlink_wait_cycle))
239 break;
240 list_del_init(&qh->unlink_node);
241 qh->unlink_reason |= QH_UNLINK_QUEUE_EMPTY;
242 start_unlink_intr(ehci, qh);
243 }
244
245 /* Handle remaining entries later */
246 if (!list_empty(&ehci->intr_unlink_wait)) {
247 ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
248 ++ehci->intr_unlink_wait_cycle;
249 }
250}
251
252/* Handle unlinked interrupt QHs once they are gone from the hardware */
253static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
254{
255 bool stopped = (ehci->rh_state < EHCI_RH_RUNNING);
256
257 /*
258 * Process all the QHs on the intr_unlink list that were added
259 * before the current unlink cycle began. The list is in
260 * temporal order, so stop when we reach the first entry in the
261 * current cycle. But if the root hub isn't running then
262 * process all the QHs on the list.
263 */
264 ehci->intr_unlinking = true;
265 while (!list_empty(&ehci->intr_unlink)) {
266 struct ehci_qh *qh;
267
268 qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh,
269 unlink_node);
270 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
271 break;
272 list_del_init(&qh->unlink_node);
273 end_unlink_intr(ehci, qh);
274 }
275
276 /* Handle remaining entries later */
277 if (!list_empty(&ehci->intr_unlink)) {
278 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
279 ++ehci->intr_unlink_cycle;
280 }
281 ehci->intr_unlinking = false;
282}
283
284
285/* Start another free-iTDs/siTDs cycle */
286static void start_free_itds(struct ehci_hcd *ehci)
287{
288 if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) {
289 ehci->last_itd_to_free = list_entry(
290 ehci->cached_itd_list.prev,
291 struct ehci_itd, itd_list);
292 ehci->last_sitd_to_free = list_entry(
293 ehci->cached_sitd_list.prev,
294 struct ehci_sitd, sitd_list);
295 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true);
296 }
297}
298
299/* Wait for controller to stop using old iTDs and siTDs */
300static void end_free_itds(struct ehci_hcd *ehci)
301{
302 struct ehci_itd *itd, *n;
303 struct ehci_sitd *sitd, *sn;
304
305 if (ehci->rh_state < EHCI_RH_RUNNING) {
306 ehci->last_itd_to_free = NULL;
307 ehci->last_sitd_to_free = NULL;
308 }
309
310 list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
311 list_del(&itd->itd_list);
312 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma);
313 if (itd == ehci->last_itd_to_free)
314 break;
315 }
316 list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
317 list_del(&sitd->sitd_list);
318 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma);
319 if (sitd == ehci->last_sitd_to_free)
320 break;
321 }
322
323 if (!list_empty(&ehci->cached_itd_list) ||
324 !list_empty(&ehci->cached_sitd_list))
325 start_free_itds(ehci);
326}
327
328
329/* Handle lost (or very late) IAA interrupts */
330static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
331{
332 u32 cmd, status;
333
334 /*
335 * Lost IAA irqs wedge things badly; seen first with a vt8235.
336 * So we need this watchdog, but must protect it against both
337 * (a) SMP races against real IAA firing and retriggering, and
338 * (b) clean HC shutdown, when IAA watchdog was pending.
339 */
340 if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING)
341 return;
342
343 /* If we get here, IAA is *REALLY* late. It's barely
344 * conceivable that the system is so busy that CMD_IAAD
345 * is still legitimately set, so let's be sure it's
346 * clear before we read STS_IAA. (The HC should clear
347 * CMD_IAAD when it sets STS_IAA.)
348 */
349 cmd = ehci_readl(ehci, &ehci->regs->command);
350
351 /*
352 * If IAA is set here it either legitimately triggered
353 * after the watchdog timer expired (_way_ late, so we'll
354 * still count it as lost) ... or a silicon erratum:
355 * - VIA seems to set IAA without triggering the IRQ;
356 * - IAAD potentially cleared without setting IAA.
357 */
358 status = ehci_readl(ehci, &ehci->regs->status);
359 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
360 COUNT(ehci->stats.lost_iaa);
361 ehci_writel(ehci, STS_IAA, &ehci->regs->status);
362 }
363
364 ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd);
365 end_iaa_cycle(ehci);
366}
367
368
369/* Enable the I/O watchdog, if appropriate */
370static void turn_on_io_watchdog(struct ehci_hcd *ehci)
371{
372 /* Not needed if the controller isn't running or it's already enabled */
373 if (ehci->rh_state != EHCI_RH_RUNNING ||
374 (ehci->enabled_hrtimer_events &
375 BIT(EHCI_HRTIMER_IO_WATCHDOG)))
376 return;
377
378 /*
379 * Isochronous transfers always need the watchdog.
380 * For other sorts we use it only if the flag is set.
381 */
382 if (ehci->isoc_count > 0 || (ehci->need_io_watchdog &&
383 ehci->async_count + ehci->intr_count > 0))
384 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
385}
386
387
388/*
389 * Handler functions for the hrtimer event types.
390 * Keep this array in the same order as the event types indexed by
391 * enum ehci_hrtimer_event in ehci.h.
392 */
393static void (*event_handlers[])(struct ehci_hcd *) = {
394 ehci_poll_ASS, /* EHCI_HRTIMER_POLL_ASS */
395 ehci_poll_PSS, /* EHCI_HRTIMER_POLL_PSS */
396 ehci_handle_controller_death, /* EHCI_HRTIMER_POLL_DEAD */
397 ehci_handle_intr_unlinks, /* EHCI_HRTIMER_UNLINK_INTR */
398 end_free_itds, /* EHCI_HRTIMER_FREE_ITDS */
399 end_unlink_async, /* EHCI_HRTIMER_ACTIVE_UNLINK */
400 ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */
401 unlink_empty_async, /* EHCI_HRTIMER_ASYNC_UNLINKS */
402 ehci_iaa_watchdog, /* EHCI_HRTIMER_IAA_WATCHDOG */
403 ehci_disable_PSE, /* EHCI_HRTIMER_DISABLE_PERIODIC */
404 ehci_disable_ASE, /* EHCI_HRTIMER_DISABLE_ASYNC */
405 ehci_work, /* EHCI_HRTIMER_IO_WATCHDOG */
406};
407
408static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
409{
410 struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
411 ktime_t now;
412 unsigned long events;
413 unsigned long flags;
414 unsigned e;
415
416 spin_lock_irqsave(&ehci->lock, flags);
417
418 events = ehci->enabled_hrtimer_events;
419 ehci->enabled_hrtimer_events = 0;
420 ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
421
422 /*
423 * Check each pending event. If its time has expired, handle
424 * the event; otherwise re-enable it.
425 */
426 now = ktime_get();
427 for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
428 if (now.tv64 >= ehci->hr_timeouts[e].tv64)
429 event_handlers[e](ehci);
430 else
431 ehci_enable_event(ehci, e, false);
432 }
433
434 spin_unlock_irqrestore(&ehci->lock, flags);
435 return HRTIMER_NORESTART;
436}