drivers/usb/host/ehci-timer.c

   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                 COUNT(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 }