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

   1 /*
   2  * Copyright (c) 2014 Imre Vadász
   3  * Copyright (c) 2014-2018 François Tigeot <ftigeot@wolfpond.org>
   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/list.h>
  32 #include <linux/spinlock.h>
  33 #include <asm/current.h>
  34
  35 typedef struct {
  36 } wait_queue_t;
  37
  38 typedef struct {
  39         struct lock     lock;
  40 } wait_queue_head_t;
  41
  42 static inline void
  43 init_waitqueue_head(wait_queue_head_t *eq)
  44 {
  45         lockinit(&eq->lock, "lwq", 0, LK_CANRECURSE);
  46 }
  47
  48 #define wake_up(eq)                     wakeup_one(eq)
  49 #define wake_up_all(eq)                 wakeup(eq)
  50 #define wake_up_interruptible(eq)       wakeup_one(eq)
  51 #define wake_up_interruptible_all(eq)   wakeup(eq)
  52
  53 /*
  54  * wait_event_interruptible_timeout:
  55  * - The process is put to sleep until the condition evaluates to true.
  56  * - The condition is checked each time the waitqueue wq is woken up.
  57  * - wake_up has to be called after changing any variable that could change
  58  * the result of the wait condition.
  59  *
  60  * returns:
  61  *   - 0 if the timeout elapsed
  62  *   - the remaining jiffies if the condition evaluated to true before
  63  *   the timeout elapsed.
  64  *   - remaining jiffies are always at least 1
  65  *   - -ERESTARTSYS if interrupted by a signal (when PCATCH is set in flags)
  66 */
  67 #define __wait_event_common(wq, condition, timeout_jiffies, flags)      \
  68 ({                                                                      \
  69         int start_jiffies, elapsed_jiffies, remaining_jiffies, ret;     \
  70         bool timeout_expired = false;                                   \
  71         bool interrupted = false;                                       \
  72         long retval;                                                    \
  73                                                                         \
  74         start_jiffies = ticks;                                          \
  75                                                                         \
  76         lockmgr(&wq.lock, LK_EXCLUSIVE);                                \
  77         while (1) {                                                     \
  78                 if (condition)                                          \
  79                         break;                                          \
  80                                                                         \
  81                 ret = lksleep(&wq, &wq.lock, flags,                     \
  82                                         "lwe", timeout_jiffies);        \
  83                 if (ret == EINTR || ret == ERESTART) {                  \
  84                         interrupted = true;                             \
  85                         break;                                          \
  86                 }                                                       \
  87                 if (ret == EWOULDBLOCK) {                               \
  88                         timeout_expired = true;                         \
  89                         break;                                          \
  90                 }                                                       \
  91         }                                                               \
  92         lockmgr(&wq.lock, LK_RELEASE);                                  \
  93                                                                         \
  94         elapsed_jiffies = ticks - start_jiffies;                        \
  95         remaining_jiffies = timeout_jiffies - elapsed_jiffies;          \
  96         if (remaining_jiffies <= 0)                                     \
  97                 remaining_jiffies = 1;                                  \
  98                                                                         \
  99         if (timeout_expired)                                            \
 100                 retval = 0;                                             \
 101         else if (interrupted)                                           \
 102                 retval = -ERESTARTSYS;                                  \
 103         else if (timeout_jiffies > 0)                                   \
 104                 retval = remaining_jiffies;                             \
 105         else                                                            \
 106                 retval = 1;                                             \
 107                                                                         \
 108         retval;                                                         \
 109 })
 110
 111 #define wait_event(wq, condition)                                       \
 112                 __wait_event_common(wq, condition, 0, 0)
 113
 114 #define wait_event_timeout(wq, condition, timeout)                      \
 115                 __wait_event_common(wq, condition, timeout, 0)
 116
 117 #define wait_event_interruptible(wq, condition)                         \
 118 ({                                                                      \
 119         long retval;                                                    \
 120                                                                         \
 121         retval = __wait_event_common(wq, condition, 0, PCATCH);         \
 122         if (retval != -ERESTARTSYS)                                     \
 123                 retval = 0;                                             \
 124         retval;                                                         \
 125 })
 126
 127 #define wait_event_interruptible_timeout(wq, condition, timeout)        \
 128                 __wait_event_common(wq, condition, timeout, PCATCH)
 129
 130 static inline int
 131 waitqueue_active(wait_queue_head_t *q)
 132 {
 133         return 0;       /* XXX: not really implemented */
 134 }
 135
 136 #define DEFINE_WAIT(name)       \
 137         wait_queue_t name = {}
 138
 139 static inline void
 140 prepare_to_wait(wait_queue_head_t *q, wait_queue_t *wait, int state)
 141 {
 142 }
 143
 144 static inline void
 145 finish_wait(wait_queue_head_t *q, wait_queue_t *wait)
 146 {
 147 }
 148
 149 static inline void
 150 add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
 151 {
 152 }
 153
 154 #endif  /* _LINUX_WAIT_H_ */