sys/dev/drm/linux_hrtimer.c

   1 /*
   2  * Copyright (c) 2017 François Tigeot
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice unmodified, this list of conditions, and the following
  10  *    disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  *
  15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  25  */
  26
  27 #include <linux/hrtimer.h>
  28 #include <linux/bug.h>
  29
  30 static inline void
  31 __hrtimer_function(void *arg)
  32 {
  33         struct hrtimer *timer = arg;
  34         enum hrtimer_restart restart = HRTIMER_RESTART;
  35
  36         if (timer->function) {
  37                 restart = timer->function(timer);
  38         }
  39
  40         if (restart == HRTIMER_RESTART) {
  41                 /*
  42                  * XXX Not implemented yet, we would need to store the
  43                  *     expiration period, to do the callout_reset here.
  44                  */
  45         } else {
  46                 timer->active = false;
  47         }
  48 }
  49
  50 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
  51                            enum hrtimer_mode mode)
  52 {
  53         BUG_ON(clock_id != CLOCK_MONOTONIC);
  54
  55         memset(timer, 0, sizeof(struct hrtimer));
  56         timer->clock_id = clock_id;
  57         timer->ht_mode = mode;
  58
  59         lwkt_token_init(&timer->timer_token, "timer token");
  60         callout_init_mp(&(timer)->timer_callout);
  61 }
  62
  63 void
  64 hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
  65                        u64 range_ns, const enum hrtimer_mode mode)
  66 {
  67         int expire_ticks = tim.tv64 / (NSEC_PER_SEC / hz);
  68
  69         if (mode == HRTIMER_MODE_ABS)
  70                 expire_ticks -= ticks;
  71
  72         if (expire_ticks <= 0)
  73                 expire_ticks = 1;
  74
  75         lwkt_gettoken(&timer->timer_token);
  76
  77         timer->active = true;
  78         callout_reset(&timer->timer_callout,
  79                       expire_ticks, __hrtimer_function, timer);
  80
  81         lwkt_reltoken(&timer->timer_token);
  82 }
  83
  84 int
  85 hrtimer_cancel(struct hrtimer *timer)
  86 {
  87         return callout_drain(&timer->timer_callout) == 0;
  88 }
  89
  90 /* Returns non-zero if the timer is already on the queue */
  91 bool
  92 hrtimer_active(const struct hrtimer *timer)
  93 {
  94         return callout_pending(&timer->timer_callout);
  95 }