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         5 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_START_UNLINK_INTR */
  76         6 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_ASYNC_UNLINKS */
  77         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_IAA_WATCHDOG */
  78         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_PERIODIC */
  79         15 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_ASYNC */
  80         100 * NSEC_PER_MSEC,    /* EHCI_HRTIMER_IO_WATCHDOG */
  81 };
  82
  83 /* Enable a pending hrtimer event */
  84 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
  85                 bool resched)
  86 {
  87         ktime_t         *timeout = &ehci->hr_timeouts[event];
  88
  89         if (resched)
  90                 *timeout = ktime_add(ktime_get(),
  91                                 ktime_set(0, 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                 start_unlink_intr(ehci, qh);
 241         }
 242
 243         /* Handle remaining entries later */
 244         if (!list_empty(&ehci->intr_unlink_wait)) {
 245                 ehci_enable_event(ehci, EHCI_HRTIMER_START_UNLINK_INTR, true);
 246                 ++ehci->intr_unlink_wait_cycle;
 247         }
 248 }
 249
 250 /* Handle unlinked interrupt QHs once they are gone from the hardware */
 251 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
 252 {
 253         bool            stopped = (ehci->rh_state < EHCI_RH_RUNNING);
 254
 255         /*
 256          * Process all the QHs on the intr_unlink list that were added
 257          * before the current unlink cycle began.  The list is in
 258          * temporal order, so stop when we reach the first entry in the
 259          * current cycle.  But if the root hub isn't running then
 260          * process all the QHs on the list.
 261          */
 262         ehci->intr_unlinking = true;
 263         while (!list_empty(&ehci->intr_unlink)) {
 264                 struct ehci_qh  *qh;
 265
 266                 qh = list_first_entry(&ehci->intr_unlink, struct ehci_qh,
 267                                 unlink_node);
 268                 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
 269                         break;
 270                 list_del_init(&qh->unlink_node);
 271                 end_unlink_intr(ehci, qh);
 272         }
 273
 274         /* Handle remaining entries later */
 275         if (!list_empty(&ehci->intr_unlink)) {
 276                 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
 277                 ++ehci->intr_unlink_cycle;
 278         }
 279         ehci->intr_unlinking = false;
 280 }
 281
 282
 283 /* Start another free-iTDs/siTDs cycle */
 284 static void start_free_itds(struct ehci_hcd *ehci)
 285 {
 286         if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) {
 287                 ehci->last_itd_to_free = list_entry(
 288                                 ehci->cached_itd_list.prev,
 289                                 struct ehci_itd, itd_list);
 290                 ehci->last_sitd_to_free = list_entry(
 291                                 ehci->cached_sitd_list.prev,
 292                                 struct ehci_sitd, sitd_list);
 293                 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true);
 294         }
 295 }
 296
 297 /* Wait for controller to stop using old iTDs and siTDs */
 298 static void end_free_itds(struct ehci_hcd *ehci)
 299 {
 300         struct ehci_itd         *itd, *n;
 301         struct ehci_sitd        *sitd, *sn;
 302
 303         if (ehci->rh_state < EHCI_RH_RUNNING) {
 304                 ehci->last_itd_to_free = NULL;
 305                 ehci->last_sitd_to_free = NULL;
 306         }
 307
 308         list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
 309                 list_del(&itd->itd_list);
 310                 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma);
 311                 if (itd == ehci->last_itd_to_free)
 312                         break;
 313         }
 314         list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
 315                 list_del(&sitd->sitd_list);
 316                 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma);
 317                 if (sitd == ehci->last_sitd_to_free)
 318                         break;
 319         }
 320
 321         if (!list_empty(&ehci->cached_itd_list) ||
 322                         !list_empty(&ehci->cached_sitd_list))
 323                 start_free_itds(ehci);
 324 }
 325
 326
 327 /* Handle lost (or very late) IAA interrupts */
 328 static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
 329 {
 330         u32 cmd, status;
 331
 332         /*
 333          * Lost IAA irqs wedge things badly; seen first with a vt8235.
 334          * So we need this watchdog, but must protect it against both
 335          * (a) SMP races against real IAA firing and retriggering, and
 336          * (b) clean HC shutdown, when IAA watchdog was pending.
 337          */
 338         if (!ehci->iaa_in_progress || ehci->rh_state != EHCI_RH_RUNNING)
 339                 return;
 340
 341         /* If we get here, IAA is *REALLY* late.  It's barely
 342          * conceivable that the system is so busy that CMD_IAAD
 343          * is still legitimately set, so let's be sure it's
 344          * clear before we read STS_IAA.  (The HC should clear
 345          * CMD_IAAD when it sets STS_IAA.)
 346          */
 347         cmd = ehci_readl(ehci, &ehci->regs->command);
 348
 349         /*
 350          * If IAA is set here it either legitimately triggered
 351          * after the watchdog timer expired (_way_ late, so we'll
 352          * still count it as lost) ... or a silicon erratum:
 353          * - VIA seems to set IAA without triggering the IRQ;
 354          * - IAAD potentially cleared without setting IAA.
 355          */
 356         status = ehci_readl(ehci, &ehci->regs->status);
 357         if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
 358                 COUNT(ehci->stats.lost_iaa);
 359                 ehci_writel(ehci, STS_IAA, &ehci->regs->status);
 360         }
 361
 362         ehci_dbg(ehci, "IAA watchdog: status %x cmd %x\n", status, cmd);
 363         end_unlink_async(ehci);
 364 }
 365
 366
 367 /* Enable the I/O watchdog, if appropriate */
 368 static void turn_on_io_watchdog(struct ehci_hcd *ehci)
 369 {
 370         /* Not needed if the controller isn't running or it's already enabled */
 371         if (ehci->rh_state != EHCI_RH_RUNNING ||
 372                         (ehci->enabled_hrtimer_events &
 373                                 BIT(EHCI_HRTIMER_IO_WATCHDOG)))
 374                 return;
 375
 376         /*
 377          * Isochronous transfers always need the watchdog.
 378          * For other sorts we use it only if the flag is set.
 379          */
 380         if (ehci->isoc_count > 0 || (ehci->need_io_watchdog &&
 381                         ehci->async_count + ehci->intr_count > 0))
 382                 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
 383 }
 384
 385
 386 /*
 387  * Handler functions for the hrtimer event types.
 388  * Keep this array in the same order as the event types indexed by
 389  * enum ehci_hrtimer_event in ehci.h.
 390  */
 391 static void (*event_handlers[])(struct ehci_hcd *) = {
 392         ehci_poll_ASS,                  /* EHCI_HRTIMER_POLL_ASS */
 393         ehci_poll_PSS,                  /* EHCI_HRTIMER_POLL_PSS */
 394         ehci_handle_controller_death,   /* EHCI_HRTIMER_POLL_DEAD */
 395         ehci_handle_intr_unlinks,       /* EHCI_HRTIMER_UNLINK_INTR */
 396         end_free_itds,                  /* EHCI_HRTIMER_FREE_ITDS */
 397         ehci_handle_start_intr_unlinks, /* EHCI_HRTIMER_START_UNLINK_INTR */
 398         unlink_empty_async,             /* EHCI_HRTIMER_ASYNC_UNLINKS */
 399         ehci_iaa_watchdog,              /* EHCI_HRTIMER_IAA_WATCHDOG */
 400         ehci_disable_PSE,               /* EHCI_HRTIMER_DISABLE_PERIODIC */
 401         ehci_disable_ASE,               /* EHCI_HRTIMER_DISABLE_ASYNC */
 402         ehci_work,                      /* EHCI_HRTIMER_IO_WATCHDOG */
 403 };
 404
 405 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
 406 {
 407         struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
 408         ktime_t         now;
 409         unsigned long   events;
 410         unsigned long   flags;
 411         unsigned        e;
 412
 413         spin_lock_irqsave(&ehci->lock, flags);
 414
 415         events = ehci->enabled_hrtimer_events;
 416         ehci->enabled_hrtimer_events = 0;
 417         ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
 418
 419         /*
 420          * Check each pending event.  If its time has expired, handle
 421          * the event; otherwise re-enable it.
 422          */
 423         now = ktime_get();
 424         for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
 425                 if (now.tv64 >= ehci->hr_timeouts[e].tv64)
 426                         event_handlers[e](ehci);
 427                 else
 428                         ehci_enable_event(ehci, e, false);
 429         }
 430
 431         spin_unlock_irqrestore(&ehci->lock, flags);
 432         return HRTIMER_NORESTART;
 433 }