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         1125 * NSEC_PER_USEC,   /* EHCI_HRTIMER_UNLINK_INTR */
  73         10 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_PERIODIC */
  74         15 * NSEC_PER_MSEC,     /* EHCI_HRTIMER_DISABLE_ASYNC */
  75 };
  76
  77 /* Enable a pending hrtimer event */
  78 static void ehci_enable_event(struct ehci_hcd *ehci, unsigned event,
  79                 bool resched)
  80 {
  81         ktime_t         *timeout = &ehci->hr_timeouts[event];
  82
  83         if (resched)
  84                 *timeout = ktime_add(ktime_get(),
  85                                 ktime_set(0, event_delays_ns[event]));
  86         ehci->enabled_hrtimer_events |= (1 << event);
  87
  88         /* Track only the lowest-numbered pending event */
  89         if (event < ehci->next_hrtimer_event) {
  90                 ehci->next_hrtimer_event = event;
  91                 hrtimer_start_range_ns(&ehci->hrtimer, *timeout,
  92                                 NSEC_PER_MSEC, HRTIMER_MODE_ABS);
  93         }
  94 }
  95
  96
  97 /* Poll the STS_ASS status bit; see when it agrees with CMD_ASE */
  98 static void ehci_poll_ASS(struct ehci_hcd *ehci)
  99 {
 100         unsigned        actual, want;
 101
 102         /* Don't enable anything if the controller isn't running (e.g., died) */
 103         if (ehci->rh_state != EHCI_RH_RUNNING)
 104                 return;
 105
 106         want = (ehci->command & CMD_ASE) ? STS_ASS : 0;
 107         actual = ehci_readl(ehci, &ehci->regs->status) & STS_ASS;
 108
 109         if (want != actual) {
 110
 111                 /* Poll again later, but give up after about 20 ms */
 112                 if (ehci->ASS_poll_count++ < 20) {
 113                         ehci_enable_event(ehci, EHCI_HRTIMER_POLL_ASS, true);
 114                         return;
 115                 }
 116                 ehci_warn(ehci, "Waited too long for the async schedule status, giving up\n");
 117         }
 118         ehci->ASS_poll_count = 0;
 119
 120         /* The status is up-to-date; restart or stop the schedule as needed */
 121         if (want == 0) {        /* Stopped */
 122                 if (ehci->async_count > 0)
 123                         ehci_set_command_bit(ehci, CMD_ASE);
 124
 125         } else {                /* Running */
 126                 if (ehci->async_count == 0) {
 127
 128                         /* Turn off the schedule after a while */
 129                         ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_ASYNC,
 130                                         true);
 131                 }
 132         }
 133 }
 134
 135 /* Turn off the async schedule after a brief delay */
 136 static void ehci_disable_ASE(struct ehci_hcd *ehci)
 137 {
 138         ehci_clear_command_bit(ehci, CMD_ASE);
 139 }
 140
 141
 142 /* Poll the STS_PSS status bit; see when it agrees with CMD_PSE */
 143 static void ehci_poll_PSS(struct ehci_hcd *ehci)
 144 {
 145         unsigned        actual, want;
 146
 147         /* Don't do anything if the controller isn't running (e.g., died) */
 148         if (ehci->rh_state != EHCI_RH_RUNNING)
 149                 return;
 150
 151         want = (ehci->command & CMD_PSE) ? STS_PSS : 0;
 152         actual = ehci_readl(ehci, &ehci->regs->status) & STS_PSS;
 153
 154         if (want != actual) {
 155
 156                 /* Poll again later, but give up after about 20 ms */
 157                 if (ehci->PSS_poll_count++ < 20) {
 158                         ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
 159                         return;
 160                 }
 161                 ehci_warn(ehci, "Waited too long for the periodic schedule status, giving up\n");
 162         }
 163         ehci->PSS_poll_count = 0;
 164
 165         /* The status is up-to-date; restart or stop the schedule as needed */
 166         if (want == 0) {        /* Stopped */
 167                 free_cached_lists(ehci);
 168                 if (ehci->periodic_count > 0) {
 169
 170                         /* make sure ehci_work scans these */
 171                         ehci->next_uframe = ehci_read_frame_index(ehci)
 172                                         & ((ehci->periodic_size << 3) - 1);
 173                         ehci_set_command_bit(ehci, CMD_PSE);
 174                 }
 175
 176         } else {                /* Running */
 177                 if (ehci->periodic_count == 0) {
 178
 179                         /* Turn off the schedule after a while */
 180                         ehci_enable_event(ehci, EHCI_HRTIMER_DISABLE_PERIODIC,
 181                                         true);
 182                 }
 183         }
 184 }
 185
 186 /* Turn off the periodic schedule after a brief delay */
 187 static void ehci_disable_PSE(struct ehci_hcd *ehci)
 188 {
 189         ehci_clear_command_bit(ehci, CMD_PSE);
 190
 191         /* Poll to see when it actually stops */
 192         ehci_enable_event(ehci, EHCI_HRTIMER_POLL_PSS, true);
 193 }
 194
 195
 196 /* Handle unlinked interrupt QHs once they are gone from the hardware */
 197 static void ehci_handle_intr_unlinks(struct ehci_hcd *ehci)
 198 {
 199         bool            stopped = (ehci->rh_state < EHCI_RH_RUNNING);
 200
 201         /*
 202          * Process all the QHs on the intr_unlink list that were added
 203          * before the current unlink cycle began.  The list is in
 204          * temporal order, so stop when we reach the first entry in the
 205          * current cycle.  But if the root hub isn't running then
 206          * process all the QHs on the list.
 207          */
 208         ehci->intr_unlinking = true;
 209         while (ehci->intr_unlink) {
 210                 struct ehci_qh  *qh = ehci->intr_unlink;
 211
 212                 if (!stopped && qh->unlink_cycle == ehci->intr_unlink_cycle)
 213                         break;
 214                 ehci->intr_unlink = qh->unlink_next;
 215                 qh->unlink_next = NULL;
 216                 end_unlink_intr(ehci, qh);
 217         }
 218
 219         /* Handle remaining entries later */
 220         if (ehci->intr_unlink) {
 221                 ehci_enable_event(ehci, EHCI_HRTIMER_UNLINK_INTR, true);
 222                 ++ehci->intr_unlink_cycle;
 223         }
 224         ehci->intr_unlinking = false;
 225 }
 226
 227
 228 /*
 229  * Handler functions for the hrtimer event types.
 230  * Keep this array in the same order as the event types indexed by
 231  * enum ehci_hrtimer_event in ehci.h.
 232  */
 233 static void (*event_handlers[])(struct ehci_hcd *) = {
 234         ehci_poll_ASS,                  /* EHCI_HRTIMER_POLL_ASS */
 235         ehci_poll_PSS,                  /* EHCI_HRTIMER_POLL_PSS */
 236         ehci_handle_intr_unlinks,       /* EHCI_HRTIMER_UNLINK_INTR */
 237         ehci_disable_PSE,               /* EHCI_HRTIMER_DISABLE_PERIODIC */
 238         ehci_disable_ASE,               /* EHCI_HRTIMER_DISABLE_ASYNC */
 239 };
 240
 241 static enum hrtimer_restart ehci_hrtimer_func(struct hrtimer *t)
 242 {
 243         struct ehci_hcd *ehci = container_of(t, struct ehci_hcd, hrtimer);
 244         ktime_t         now;
 245         unsigned long   events;
 246         unsigned long   flags;
 247         unsigned        e;
 248
 249         spin_lock_irqsave(&ehci->lock, flags);
 250
 251         events = ehci->enabled_hrtimer_events;
 252         ehci->enabled_hrtimer_events = 0;
 253         ehci->next_hrtimer_event = EHCI_HRTIMER_NO_EVENT;
 254
 255         /*
 256          * Check each pending event.  If its time has expired, handle
 257          * the event; otherwise re-enable it.
 258          */
 259         now = ktime_get();
 260         for_each_set_bit(e, &events, EHCI_HRTIMER_NUM_EVENTS) {
 261                 if (now.tv64 >= ehci->hr_timeouts[e].tv64)
 262                         event_handlers[e](ehci);
 263                 else
 264                         ehci_enable_event(ehci, e, false);
 265         }
 266
 267         spin_unlock_irqrestore(&ehci->lock, flags);
 268         return HRTIMER_NORESTART;
 269 }