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         6 * NSEC_PER_MSEC,      /* EHCI_HRTIMER_ASYNC_UNLINKS */
  76         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_IAA_WATCHDOG */
  77         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_PERIODIC */
  78         15 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_ASYNC */
  79         100 * NSEC_PER_MSEC,    /* EHCI_HRTIMER_IO_WATCHDOG */
  80 };
  81
  82 /* Enable a pending hrtimer event */
  83 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
  84                 bool resched)
  85 {
  86         ktime_t         *timeout = &ehci->hr_timeouts[event];
  87
  88         if (resched)
  89                 *timeout = ktime_add(ktime_get(),
  90                                 ktime_set(0, event_delays_ns[event]));
  91         ehci->enabled_hrtimer_events |= (1 << event);
  92
  93         /* Track only the lowest-numbered pending event */
  94         if (event < ehci->next_hrtimer_event) {
  95                 ehci->next_hrtimer_event = event;
  96                 hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
  97                                 NSEC_PER_MSEC, HRTIMER_MODE_ABS);
  98         }
  99 }
 100
 101
 102 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
 103 static void ehci_poll_ASS(struct ehci_hcd *ehci)
 104 {
 105         unsigned        actual, want;
 106
 107         /* Don't enable anything if the controller isn't running (e.g., died) */
 108         if (ehci->rh_state != EHCI_RH_RUNNING)
 109                 return;
 110
 111         want = (ehci->command & CMD_ASE) ? STS_ASS : 0;
 112         actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS;
 113
 114         if (want != actual) {
 115
 116                 /* Poll again later, but give up after about 20 ms */
 117                 if (ehci->ASS_poll_count++ < 20) {
 118                         ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
 119                         return;
 120                 }
 121                 ehci_warn(ehci, "Waited too long for the async schedule status, giving up\n");
 122         }
 123         ehci->ASS_poll_count = 0;
 124
 125         /* The status is up-to-date; restart or stop the schedule as needed */
 126         if (want == 0) {        /* Stopped */
 127                 if (ehci->async_count > 0)
 128                         ehci_set_command_bit(ehci, CMD_ASE);
 129
 130         } else {                /* Running */
 131                 if (ehci->async_count == 0) {
 132
 133                         /* Turn off the schedule after a while */
 134                         ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC,
 135                                         true);
 136                 }
 137         }
 138 }
 139
 140 /* Turn off the async schedule after a brief delay */
 141 static void ehci_disable_ASE(struct ehci_hcd *ehci)
 142 {
 143         ehci_clear_command_bit(ehci, CMD_ASE);
 144 }
 145
 146
 147 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
 148 static void ehci_poll_PSS(struct ehci_hcd *ehci)
 149 {
 150         unsigned        actual, want;
 151
 152         /* Don't do anything if the controller isn't running (e.g., died) */
 153         if (ehci->rh_state != EHCI_RH_RUNNING)
 154                 return;
 155
 156         want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
 157         actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;
 158
 159         if (want != actual) {
 160
 161                 /* Poll again later, but give up after about 20 ms */
 162                 if (ehci->PSS_poll_count++ < 20) {
 163                         ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
 164                         return;
 165                 }
 166                 ehci_warn(ehci, "Waited too long for the periodic schedule status, giving up\n");
 167         }
 168         ehci->PSS_poll_count = 0;
 169
 170         /* The status is up-to-date; restart or stop the schedule as needed */
 171         if (want == 0) {        /* Stopped */
 172                 if (ehci->periodic_count > 0)
 173                         ehci_set_command_bit(ehci, CMD_PSE);
 174
 175         } else {                /* Running */
 176                 if (ehci->periodic_count == 0) {
 177
 178                         /* Turn off the schedule after a while */
 179                         ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
 180                                         true);
 181                 }
 182         }
 183 }
 184
 185 /* Turn off the periodic schedule after a brief delay */
 186 static void ehci_disable_PSE(struct ehci_hcd *ehci)
 187 {
 188         ehci_clear_command_bit(ehci, CMD_PSE);
 189 }
 190
 191
 192 /* Poll the STS_HALT status bit; see when a dead controller stops */
 193 static void ehci_handle_controller_death(struct ehci_hcd *ehci)
 194 {
 195         if (!(ehci_readl(ehci, &ehci->regs->status) & STS_HALT)) {
 196
 197                 /* Give up after a few milliseconds */
 198                 if (ehci->died_poll_count++ < 5) {
 199                         /* Try again later */
 200                         ehci_enable_event(ehci, EHCI_HRTIMER_POLL_DEAD, true);
 201                         return;
 202                 }
 203                 ehci_warn(ehci, "Waited too long for the controller to stop, giving up\n");
 204         }
 205
 206         /* Clean up the mess */
 207         ehci->rh_state = EHCI_RH_HALTED;
 208         ehci_writel(ehci, 0, &ehci->regs->configured_flag);
 209         ehci_writel(ehci, 0, &ehci->regs->intr_enable);
 210         ehci_work(ehci);
 211         end_unlink_async(ehci);
 212
 213         /* Not in process context, so don't try to reset the controller */
 214 }
 215
 216
 217 /* Handle unlinked interrupt QHs once they are gone from the hardware */
 218 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
 219 {
 220         bool            stopped = (ehci->rh_state < EHCI_RH_RUNNING);
 221
 222         /*
 223          * Process all the QHs on the intr_unlink list that were added
 224          * before the current unlink cycle began.  The list is in
 225          * temporal order, so stop when we reach the first entry in the
 226          * current cycle.  But if the root hub isn't running then
 227          * process all the QHs on the list.
 228          */
 229         ehci->intr_unlinking = true;
 230         while (ehci->intr_unlink) {
 231                 struct ehci_qh  *qh = ehci->intr_unlink;
 232
 233                 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
 234                         break;
 235                 ehci->intr_unlink = qh->unlink_next;
 236                 qh->unlink_next = NULL;
 237                 end_unlink_intr(ehci, qh);
 238         }
 239
 240         /* Handle remaining entries later */
 241         if (ehci->intr_unlink) {
 242                 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
 243                 ++ehci->intr_unlink_cycle;
 244         }
 245         ehci->intr_unlinking = false;
 246 }
 247
 248
 249 /* Start another free-iTDs/siTDs cycle */
 250 static void start_free_itds(struct ehci_hcd *ehci)
 251 {
 252         if (!(ehci->enabled_hrtimer_events & BIT(EHCI_HRTIMER_FREE_ITDS))) {
 253                 ehci->last_itd_to_free = list_entry(
 254                                 ehci->cached_itd_list.prev,
 255                                 struct ehci_itd, itd_list);
 256                 ehci->last_sitd_to_free = list_entry(
 257                                 ehci->cached_sitd_list.prev,
 258                                 struct ehci_sitd, sitd_list);
 259                 ehci_enable_event(ehci, EHCI_HRTIMER_FREE_ITDS, true);
 260         }
 261 }
 262
 263 /* Wait for controller to stop using old iTDs and siTDs */
 264 static void end_free_itds(struct ehci_hcd *ehci)
 265 {
 266         struct ehci_itd         *itd, *n;
 267         struct ehci_sitd        *sitd, *sn;
 268
 269         if (ehci->rh_state < EHCI_RH_RUNNING) {
 270                 ehci->last_itd_to_free = NULL;
 271                 ehci->last_sitd_to_free = NULL;
 272         }
 273
 274         list_for_each_entry_safe(itd, n, &ehci->cached_itd_list, itd_list) {
 275                 list_del(&itd->itd_list);
 276                 dma_pool_free(ehci->itd_pool, itd, itd->itd_dma);
 277                 if (itd == ehci->last_itd_to_free)
 278                         break;
 279         }
 280         list_for_each_entry_safe(sitd, sn, &ehci->cached_sitd_list, sitd_list) {
 281                 list_del(&sitd->sitd_list);
 282                 dma_pool_free(ehci->sitd_pool, sitd, sitd->sitd_dma);
 283                 if (sitd == ehci->last_sitd_to_free)
 284                         break;
 285         }
 286
 287         if (!list_empty(&ehci->cached_itd_list) ||
 288                         !list_empty(&ehci->cached_sitd_list))
 289                 start_free_itds(ehci);
 290 }
 291
 292
 293 /* Handle lost (or very late) IAA interrupts */
 294 static void ehci_iaa_watchdog(struct ehci_hcd *ehci)
 295 {
 296         if (ehci->rh_state != EHCI_RH_RUNNING)
 297                 return;
 298
 299         /*
 300          * Lost IAA irqs wedge things badly; seen first with a vt8235.
 301          * So we need this watchdog, but must protect it against both
 302          * (a) SMP races against real IAA firing and retriggering, and
 303          * (b) clean HC shutdown, when IAA watchdog was pending.
 304          */
 305         if (ehci->async_iaa) {
 306                 u32 cmd, status;
 307
 308                 /* If we get here, IAA is *REALLY* late.  It's barely
 309                  * conceivable that the system is so busy that CMD_IAAD
 310                  * is still legitimately set, so let's be sure it's
 311                  * clear before we read STS_IAA.  (The HC should clear
 312                  * CMD_IAAD when it sets STS_IAA.)
 313                  */
 314                 cmd = ehci_readl(ehci, &ehci->regs->command);
 315
 316                 /*
 317                  * If IAA is set here it either legitimately triggered
 318                  * after the watchdog timer expired (_way_ late, so we'll
 319                  * still count it as lost) ... or a silicon erratum:
 320                  * - VIA seems to set IAA without triggering the IRQ;
 321                  * - IAAD potentially cleared without setting IAA.
 322                  */
 323                 status = ehci_readl(ehci, &ehci->regs->status);
 324                 if ((status & STS_IAA) || !(cmd & CMD_IAAD)) {
 325                         COUNT(ehci->stats.lost_iaa);
 326                         ehci_writel(ehci, STS_IAA, &ehci->regs->status);
 327                 }
 328
 329                 ehci_vdbg(ehci, "IAA watchdog: status %x cmd %x\n",
 330                                 status, cmd);
 331                 end_unlink_async(ehci);
 332         }
 333 }
 334
 335
 336 /* Enable the I/O watchdog, if appropriate */
 337 static void turn_on_io_watchdog(struct ehci_hcd *ehci)
 338 {
 339         /* Not needed if the controller isn't running or it's already enabled */
 340         if (ehci->rh_state != EHCI_RH_RUNNING ||
 341                         (ehci->enabled_hrtimer_events &
 342                                 BIT(EHCI_HRTIMER_IO_WATCHDOG)))
 343                 return;
 344
 345         /*
 346          * Isochronous transfers always need the watchdog.
 347          * For other sorts we use it only if the flag is set.
 348          */
 349         if (ehci->isoc_count > 0 || (ehci->need_io_watchdog &&
 350                         ehci->async_count + ehci->intr_count > 0))
 351                 ehci_enable_event(ehci, EHCI_HRTIMER_IO_WATCHDOG, true);
 352 }
 353
 354
 355 /*
 356  * Handler functions for the hrtimer event types.
 357  * Keep this array in the same order as the event types indexed by
 358  * enum ehci_hrtimer_event in ehci.h.
 359  */
 360 static void (*event_handlers[])(struct ehci_hcd *) = {
 361         ehci_poll_ASS,                  /* EHCI_HRTIMER_POLL_ASS */
 362         ehci_poll_PSS,                  /* EHCI_HRTIMER_POLL_PSS */
 363         ehci_handle_controller_death,   /* EHCI_HRTIMER_POLL_DEAD */
 364         ehci_handle_intr_unlinks,       /* EHCI_HRTIMER_UNLINK_INTR */
 365         end_free_itds,                  /* EHCI_HRTIMER_FREE_ITDS */
 366         unlink_empty_async,             /* EHCI_HRTIMER_ASYNC_UNLINKS */
 367         ehci_iaa_watchdog,              /* EHCI_HRTIMER_IAA_WATCHDOG */
 368         ehci_disable_PSE,               /* EHCI_HRTIMER_DISABLE_PERIODIC */
 369         ehci_disable_ASE,               /* EHCI_HRTIMER_DISABLE_ASYNC */
 370         ehci_work,                      /* EHCI_HRTIMER_IO_WATCHDOG */
 371 };
 372
 373 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
 374 {
 375         struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
 376         ktime_t         now;
 377         unsigned long   events;
 378         unsigned long   flags;
 379         unsigned        e;
 380
 381         spin_lock_irqsave(&ehci->lock, flags);
 382
 383         events = ehci->enabled_hrtimer_events;
 384         ehci->enabled_hrtimer_events = 0;
 385         ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
 386
 387         /*
 388          * Check each pending event.  If its time has expired, handle
 389          * the event; otherwise re-enable it.
 390          */
 391         now = ktime_get();
 392         for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
 393                 if (now.tv64 >= ehci->hr_timeouts[e].tv64)
 394                         event_handlers[e](ehci);
 395                 else
 396                         ehci_enable_event(ehci, e, false);
 397         }
 398
 399         spin_unlock_irqrestore(&ehci->lock, flags);
 400         return HRTIMER_NORESTART;
 401 }