drivers/usb/host/ehci-timer.c

   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 */
  20 static 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 */
  30 static 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  */
  69 static 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 */
  85 static 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 */
 104 static 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 */
 143 static 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 */
 150 static 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 */
 189 static 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 */
 196 static 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  */
 220 static 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 */
 252 static 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 */
 285 static 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 */
 299 static 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 */
 329 static 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 */
 369 static 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  */
 392 static 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
 407 static 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 }