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 <linux/spinlock.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 #define wake_up_interruptible(eq)       wakeup_one(eq)
  50 #define wake_up_interruptible_all(eq)   wakeup(eq)
  51
  52 /*
  53  * wait_event_interruptible_timeout:
  54  * - The process is put to sleep until the condition evaluates to true.
  55  * - The condition is checked each time the waitqueue wq is woken up.
  56  * - wake_up has to be called after changing any variable that could change
  57  * the result of the wait condition.
  58  *
  59  * returns:
  60  *   - 0 if the timeout elapsed
  61  *   - the remaining jiffies if the condition evaluated to true before
  62  *   the timeout elapsed.
  63  *   - remaining jiffies are always at least 1
  64  *   - -ERESTARTSYS if interrupted by a signal (when PCATCH is set in flags)
  65 */
  66 #define __wait_event_common(wq, condition, timeout_jiffies, flags)      \
  67 ({                                                                      \
  68         int start_jiffies, elapsed_jiffies, remaining_jiffies, ret;     \
  69         bool timeout_expired = false;                                   \
  70         bool interrupted = false;                                       \
  71         long retval;                                                    \
  72                                                                         \
  73         start_jiffies = ticks;                                          \
  74                                                                         \
  75         lockmgr(&wq.lock, LK_EXCLUSIVE);                                \
  76         while (1) {                                                     \
  77                 if (condition)                                          \
  78                         break;                                          \
  79                                                                         \
  80                 ret = lksleep(&wq, &wq.lock, flags,                     \
  81                                         "lwe", timeout_jiffies);        \
  82                 if (ret == EINTR || ret == ERESTART) {                  \
  83                         interrupted = true;                             \
  84                         break;                                          \
  85                 }                                                       \
  86                 if (ret == EWOULDBLOCK) {                               \
  87                         timeout_expired = true;                         \
  88                         break;                                          \
  89                 }                                                       \
  90         }                                                               \
  91         lockmgr(&wq.lock, LK_RELEASE);                                  \
  92                                                                         \
  93         elapsed_jiffies = ticks - start_jiffies;                        \
  94         remaining_jiffies = timeout_jiffies - elapsed_jiffies;          \
  95         if (remaining_jiffies <= 0)                                     \
  96                 remaining_jiffies = 1;                                  \
  97                                                                         \
  98         if (timeout_expired)                                            \
  99                 retval = 0;                                             \
 100         else if (interrupted)                                           \
 101                 retval = -ERESTARTSYS;                                  \
 102         else if (timeout_jiffies > 0)                                   \
 103                 retval = remaining_jiffies;                             \
 104         else                                                            \
 105                 retval = 1;                                             \
 106                                                                         \
 107         retval;                                                         \
 108 })
 109
 110 #define wait_event(wq, condition)                                       \
 111                 __wait_event_common(wq, condition, 0, 0)
 112
 113 #define wait_event_timeout(wq, condition, timeout)                      \
 114                 __wait_event_common(wq, condition, timeout, 0)
 115
 116 #define wait_event_interruptible(wq, condition)                         \
 117 ({                                                                      \
 118         long retval;                                                    \
 119                                                                         \
 120         retval = __wait_event_common(wq, condition, 0, PCATCH);         \
 121         if (retval != -ERESTARTSYS)                                     \
 122                 retval = 0;                                             \
 123         retval;                                                         \
 124 })
 125
 126 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 127                 __wait_event_common(wq, condition, timeout, PCATCH)
 128
 129 static inline int
 130 waitqueue_active(wait_queue_head_t *q)
 131 {
 132         return 0;       /* XXX: not really implemented */
 133 }
 134
 135 #define DEFINE_WAIT(name)       \
 136         wait_queue_t name = {}
 137
 138 static inline void
 139 prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
 140 {
 141 }
 142
 143 static inline void
 144 finish_wait(wait_queue_head_t *q, wait_queue_t *wait)
 145 {
 146 }
 147
 148 #endif  /* _LINUX_WAIT_H_ */