include/asm-cris/arch-v32/spinlock.h

   1 #ifndef __ASM_ARCH_SPINLOCK_H
   2 #define __ASM_ARCH_SPINLOCK_H
   3
   4 #include <asm/system.h>
   5
   6 #define RW_LOCK_BIAS 0x01000000
   7 #define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 }
   8 #define spin_lock_init(x)       do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
   9
  10 #define spin_is_locked(x)       (*(volatile signed char *)(&(x)->lock) <= 0)
  11 #define spin_unlock_wait(x)     do { barrier(); } while(spin_is_locked(x))
  12
  13 extern void cris_spin_unlock(void *l, int val);
  14 extern void cris_spin_lock(void *l);
  15 extern int cris_spin_trylock(void* l);
  16
  17 static inline void _raw_spin_unlock(spinlock_t *lock)
  18 {
  19         __asm__ volatile ("move.d %1,%0" \
  20                           : "=m" (lock->lock) \
  21                           : "r" (1) \
  22                           : "memory");
  23 }
  24
  25 static inline int _raw_spin_trylock(spinlock_t *lock)
  26 {
  27         return cris_spin_trylock((void*)&lock->lock);
  28 }
  29
  30 static inline void _raw_spin_lock(spinlock_t *lock)
  31 {
  32         cris_spin_lock((void*)&lock->lock);
  33 }
  34
  35 static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
  36 {
  37   _raw_spin_lock(lock);
  38 }
  39
  40 /*
  41  * Read-write spinlocks, allowing multiple readers
  42  * but only one writer.
  43  *
  44  * NOTE! it is quite common to have readers in interrupts
  45  * but no interrupt writers. For those circumstances we
  46  * can "mix" irq-safe locks - any writer needs to get a
  47  * irq-safe write-lock, but readers can get non-irqsafe
  48  * read-locks.
  49  */
  50 typedef struct {
  51         spinlock_t lock;
  52         volatile int counter;
  53 #ifdef CONFIG_PREEMPT
  54         unsigned int break_lock;
  55 #endif
  56 } rwlock_t;
  57
  58 #define RW_LOCK_UNLOCKED (rwlock_t) { {1}, 0 }
  59
  60 #define rwlock_init(lp) do { *(lp) = RW_LOCK_UNLOCKED; } while (0)
  61
  62 /**
  63  * read_can_lock - would read_trylock() succeed?
  64  * @lock: the rwlock in question.
  65  */
  66 #define read_can_lock(x) ((int)(x)->counter >= 0)
  67
  68 /**
  69  * write_can_lock - would write_trylock() succeed?
  70  * @lock: the rwlock in question.
  71  */
  72 #define write_can_lock(x) ((x)->counter == 0)
  73
  74 #define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
  75
  76 /* read_lock, read_unlock are pretty straightforward.  Of course it somehow
  77  * sucks we end up saving/restoring flags twice for read_lock_irqsave aso. */
  78
  79 static  __inline__ void _raw_read_lock(rwlock_t *rw)
  80 {
  81         unsigned long flags;
  82         local_irq_save(flags);
  83         _raw_spin_lock(&rw->lock);
  84
  85         rw->counter++;
  86
  87         _raw_spin_unlock(&rw->lock);
  88         local_irq_restore(flags);
  89 }
  90
  91 static  __inline__ void _raw_read_unlock(rwlock_t *rw)
  92 {
  93         unsigned long flags;
  94         local_irq_save(flags);
  95         _raw_spin_lock(&rw->lock);
  96
  97         rw->counter--;
  98
  99         _raw_spin_unlock(&rw->lock);
 100         local_irq_restore(flags);
 101 }
 102
 103 /* write_lock is less trivial.  We optimistically grab the lock and check
 104  * if we surprised any readers.  If so we release the lock and wait till
 105  * they're all gone before trying again
 106  *
 107  * Also note that we don't use the _irqsave / _irqrestore suffixes here.
 108  * If we're called with interrupts enabled and we've got readers (or other
 109  * writers) in interrupt handlers someone fucked up and we'd dead-lock
 110  * sooner or later anyway.   prumpf */
 111
 112 static  __inline__ void _raw_write_lock(rwlock_t *rw)
 113 {
 114 retry:
 115         _raw_spin_lock(&rw->lock);
 116
 117         if(rw->counter != 0) {
 118                 /* this basically never happens */
 119                 _raw_spin_unlock(&rw->lock);
 120
 121                 while(rw->counter != 0);
 122
 123                 goto retry;
 124         }
 125
 126         /* got it.  now leave without unlocking */
 127         rw->counter = -1; /* remember we are locked */
 128 }
 129
 130 /* write_unlock is absolutely trivial - we don't have to wait for anything */
 131
 132 static  __inline__ void _raw_write_unlock(rwlock_t *rw)
 133 {
 134         rw->counter = 0;
 135         _raw_spin_unlock(&rw->lock);
 136 }
 137
 138 static  __inline__ int _raw_write_trylock(rwlock_t *rw)
 139 {
 140         _raw_spin_lock(&rw->lock);
 141         if (rw->counter != 0) {
 142                 /* this basically never happens */
 143                 _raw_spin_unlock(&rw->lock);
 144
 145                 return 0;
 146         }
 147
 148         /* got it.  now leave without unlocking */
 149         rw->counter = -1; /* remember we are locked */
 150         return 1;
 151 }
 152
 153 static __inline__ int is_read_locked(rwlock_t *rw)
 154 {
 155         return rw->counter > 0;
 156 }
 157
 158 static __inline__ int is_write_locked(rwlock_t *rw)
 159 {
 160         return rw->counter < 0;
 161 }
 162
 163 #endif /* __ASM_ARCH_SPINLOCK_H */