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         local_save_flags(flags);
  76         local_irq_disable();
  77         failed = --(sem->count.counter) < 0;
  78         local_irq_restore(flags);
  79         if(failed) {
  80                 __down(sem);
  81         }
  82 }
  83
  84 /*
  85  * This version waits in interruptible state so that the waiting
  86  * process can be killed.  The down_interruptible routine
  87  * returns negative for signalled and zero for semaphore acquired.
  88  */
  89
  90 extern inline int down_interruptible(struct semaphore * sem)
  91 {
  92         unsigned long flags;
  93         int failed;
  94
  95         might_sleep();
  96
  97         /* atomically decrement the semaphores count, and if its negative, we wait */
  98         local_save_flags(flags);
  99         local_irq_disable();
 100         failed = --(sem->count.counter) < 0;
 101         local_irq_restore(flags);
 102         if(failed)
 103                 failed = __down_interruptible(sem);
 104         return(failed);
 105 }
 106
 107 extern inline int down_trylock(struct semaphore * sem)
 108 {
 109         unsigned long flags;
 110         int failed;
 111
 112         local_save_flags(flags);
 113         local_irq_disable();
 114         failed = --(sem->count.counter) < 0;
 115         local_irq_restore(flags);
 116         if(failed)
 117                 failed = __down_trylock(sem);
 118         return(failed);
 119 }
 120
 121 /*
 122  * Note! This is subtle. We jump to wake people up only if
 123  * the semaphore was negative (== somebody was waiting on it).
 124  * The default case (no contention) will result in NO
 125  * jumps for both down() and up().
 126  */
 127 extern inline void up(struct semaphore * sem)
 128 {
 129         unsigned long flags;
 130         int wakeup;
 131
 132         /* atomically increment the semaphores count, and if it was negative, we wake people */
 133         local_save_flags(flags);
 134         local_irq_disable();
 135         wakeup = ++(sem->count.counter) <= 0;
 136         local_irq_restore(flags);
 137         if(wakeup) {
 138                 __up(sem);
 139         }
 140 }
 141
 142 #endif