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