include/asm-cris/semaphore.h

   1 /* $Id: semaphore.h,v 1.3 2001/05/08 13:54:09 bjornw Exp $ */
   2
   3 /* On the i386 these are coded in asm, perhaps we should as well. Later.. */
   4
   5 #ifndef _CRIS_SEMAPHORE_H
   6 #define _CRIS_SEMAPHORE_H
   7
   8 #define RW_LOCK_BIAS             0x01000000
   9
  10 #include <linux/wait.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/rwsem.h>
  13
  14 #include <asm/system.h>
  15 #include <asm/atomic.h>
  16
  17 /*
  18  * CRIS semaphores, implemented in C-only so far.
  19  */
  20
  21 int printk(const char *fmt, ...);
  22
  23 struct semaphore {
  24         atomic_t count;
  25         atomic_t waking;
  26         wait_queue_head_t wait;
  27 };
  28
  29 #define __SEMAPHORE_INITIALIZER(name, n)                                \
  30 {                                                                       \
  31         .count          = ATOMIC_INIT(n),                               \
  32         .waking         = ATOMIC_INIT(0),                               \
  33         .wait           = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)    \
  34 }
  35
  36 #define __MUTEX_INITIALIZER(name) \
  37         __SEMAPHORE_INITIALIZER(name,1)
  38
  39 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \
  40         struct semaphore name = __SEMAPHORE_INITIALIZER(name,count)
  41
  42 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1)
  43 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0)
  44
  45 extern inline void sema_init(struct semaphore *sem, int val)
  46 {
  47         *sem = (struct semaphore)__SEMAPHORE_INITIALIZER((*sem),val);
  48 }
  49
  50 extern inline void init_MUTEX (struct semaphore *sem)
  51 {
  52         sema_init(sem, 1);
  53 }
  54
  55 extern inline void init_MUTEX_LOCKED (struct semaphore *sem)
  56 {
  57         sema_init(sem, 0);
  58 }
  59
  60 extern void __down(struct semaphore * sem);
  61 extern int __down_interruptible(struct semaphore * sem);
  62 extern int __down_trylock(struct semaphore * sem);
  63 extern void __up(struct semaphore * sem);
  64
  65 /* notice - we probably can do cli/sti here instead of saving */
  66
  67 extern inline void down(struct semaphore * sem)
  68 {
  69         unsigned long flags;
  70         int failed;
  71
  72         might_sleep();
  73
  74         /* atomically decrement the semaphores count, and if its negative, we wait */
  75         cris_atomic_save(sem, flags);
  76         failed = --(sem->count.counter) < 0;
  77         cris_atomic_restore(sem, flags);
  78         if(failed) {
  79                 __down(sem);
  80         }
  81 }
  82
  83 /*
  84  * This version waits in interruptible state so that the waiting
  85  * process can be killed.  The down_interruptible routine
  86  * returns negative for signalled and zero for semaphore acquired.
  87  */
  88
  89 extern inline int down_interruptible(struct semaphore * sem)
  90 {
  91         unsigned long flags;
  92         int failed;
  93
  94         might_sleep();
  95
  96         /* atomically decrement the semaphores count, and if its negative, we wait */
  97         cris_atomic_save(sem, flags);
  98         failed = --(sem->count.counter) < 0;
  99         cris_atomic_restore(sem, flags);
 100         if(failed)
 101                 failed = __down_interruptible(sem);
 102         return(failed);
 103 }
 104
 105 extern inline int down_trylock(struct semaphore * sem)
 106 {
 107         unsigned long flags;
 108         int failed;
 109
 110         cris_atomic_save(sem, flags);
 111         failed = --(sem->count.counter) < 0;
 112         cris_atomic_restore(sem, flags);
 113         if(failed)
 114                 failed = __down_trylock(sem);
 115         return(failed);
 116
 117 }
 118
 119 /*
 120  * Note! This is subtle. We jump to wake people up only if
 121  * the semaphore was negative (== somebody was waiting on it).
 122  * The default case (no contention) will result in NO
 123  * jumps for both down() and up().
 124  */
 125 extern inline void up(struct semaphore * sem)
 126 {
 127         unsigned long flags;
 128         int wakeup;
 129
 130         /* atomically increment the semaphores count, and if it was negative, we wake people */
 131         cris_atomic_save(sem, flags);
 132         wakeup = ++(sem->count.counter) <= 0;
 133         cris_atomic_restore(sem, flags);
 134         if(wakeup) {
 135                 __up(sem);
 136         }
 137 }
 138
 139 #endif