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(),
  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 */
 105 static 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 */
 144 static 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 */
 151 static 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 */
 190 static 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 */
 197 static 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  */
 221 static 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 */
 253 static 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 */
 286 static 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 */
 300 static 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 */
 330 static 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 */
 370 static 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  */
 393 static 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
 408 static 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 }