sys/dev/drm/include/linux/wait.h

   1 /*
   2  * Copyright (c) 2014-2015 François Tigeot
   3  * Copyright (c) 2014 Imre Vadász
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice unmodified, this list of conditions, and the following
  11  *    disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27
  28 #ifndef _LINUX_WAIT_H_
  29 #define _LINUX_WAIT_H_
  30
  31 #include <sys/spinlock2.h>
  32 #include <sys/param.h>
  33
  34 typedef struct {
  35 } wait_queue_t;
  36
  37 typedef struct {
  38         struct lock     lock;
  39 } wait_queue_head_t;
  40
  41 static inline void
  42 init_waitqueue_head(wait_queue_head_t *eq)
  43 {
  44         lockinit(&eq->lock, "lwq", 0, LK_CANRECURSE);
  45 }
  46
  47 #define wake_up(eq)             wakeup_one(eq)
  48 #define wake_up_all(eq)         wakeup(eq)
  49
  50 /*
  51  * wait_event_interruptible_timeout:
  52  * - The process is put to sleep until the condition evaluates to true.
  53  * - The condition is checked each time the waitqueue wq is woken up.
  54  * - wake_up has to be called after changing any variable that could change
  55  * the result of the wait condition.
  56  *
  57  * returns:
  58  *   - 0 if the timeout elapsed
  59  *   - the remaining jiffies if the condition evaluated to true before
  60  *   the timeout elapsed.
  61  *   - remaining jiffies are always at least 1
  62  *   - -ERESTARTSYS if interrupted by a signal (when PCATCH is set in flags)
  63 */
  64 #define __wait_event_common(wq, condition, timeout_jiffies, flags)      \
  65 ({                                                                      \
  66         int start_jiffies, elapsed_jiffies, remaining_jiffies, ret;     \
  67         bool timeout_expired = false;                                   \
  68         bool interrupted = false;                                       \
  69         long retval;                                                    \
  70                                                                         \
  71         start_jiffies = ticks;                                          \
  72                                                                         \
  73         lockmgr(&wq.lock, LK_EXCLUSIVE);                                \
  74         while (1) {                                                     \
  75                 if (condition)                                          \
  76                         break;                                          \
  77                                                                         \
  78                 ret = lksleep(&wq, &wq.lock, flags,                     \
  79                                         "lwe", timeout_jiffies);        \
  80                 if (ret == EINTR || ret == ERESTART) {                  \
  81                         interrupted = true;                             \
  82                         break;                                          \
  83                 }                                                       \
  84                 if (ret == EWOULDBLOCK) {                               \
  85                         timeout_expired = true;                         \
  86                         break;                                          \
  87                 }                                                       \
  88         }                                                               \
  89         lockmgr(&wq.lock, LK_RELEASE);                                  \
  90                                                                         \
  91         elapsed_jiffies = ticks - start_jiffies;                        \
  92         remaining_jiffies = timeout_jiffies - elapsed_jiffies;          \
  93         if (remaining_jiffies <= 0)                                     \
  94                 remaining_jiffies = 1;                                  \
  95                                                                         \
  96         if (timeout_expired)                                            \
  97                 retval = 0;                                             \
  98         else if (interrupted)                                           \
  99                 retval = -ERESTARTSYS;                                  \
 100         else if (timeout_jiffies > 0)                                   \
 101                 retval = remaining_jiffies;                             \
 102         else                                                            \
 103                 retval = 1;                                             \
 104                                                                         \
 105         retval;                                                         \
 106 })
 107
 108 #define wait_event(wq, condition)                                       \
 109                 __wait_event_common(wq, condition, 0, 0)
 110
 111 #define wait_event_timeout(wq, condition, timeout)                      \
 112                 __wait_event_common(wq, condition, timeout, 0)
 113
 114 #define wait_event_interruptible(wq, condition)                         \
 115 ({                                                                      \
 116         long retval;                                                    \
 117                                                                         \
 118         retval = __wait_event_common(wq, condition, 0, PCATCH);         \
 119         if (retval != -ERESTARTSYS)                                     \
 120                 retval = 0;                                             \
 121         retval;                                                         \
 122 })
 123
 124 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 125                 __wait_event_common(wq, condition, timeout, PCATCH)
 126
 127 static inline int
 128 waitqueue_active(wait_queue_head_t *q)
 129 {
 130         return 0;       /* XXX: not really implemented */
 131 }
 132
 133 #define DEFINE_WAIT(name)       \
 134         wait_queue_t name = {}
 135
 136 static inline void
 137 prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
 138 {
 139 }
 140
 141 static inline void
 142 finish_wait(wait_queue_head_t *q, wait_queue_t *wait)
 143 {
 144 }
 145
 146 #endif  /* _LINUX_WAIT_H_ */