arch/alpha/include/asm/spinlock.h

   1 #ifndef _ALPHA_SPINLOCK_H
   2 #define _ALPHA_SPINLOCK_H
   3
   4 #include <linux/kernel.h>
   5 #include <asm/current.h>
   6
   7 /*
   8  * Simple spin lock operations.  There are two variants, one clears IRQ's
   9  * on the local processor, one does not.
  10  *
  11  * We make no fairness assumptions. They have a cost.
  12  */
  13
  14 #define arch_spin_lock_flags(lock, flags) arch_spin_lock(lock)
  15 #define arch_spin_is_locked(x)  ((x)->lock != 0)
  16 #define arch_spin_unlock_wait(x) \
  17                 do { cpu_relax(); } while ((x)->lock)
  18
  19 static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
  20 {
  21         return lock.lock == 0;
  22 }
  23
  24 static inline void arch_spin_unlock(arch_spinlock_t * lock)
  25 {
  26         mb();
  27         lock->lock = 0;
  28 }
  29
  30 static inline void arch_spin_lock(arch_spinlock_t * lock)
  31 {
  32         long tmp;
  33
  34         __asm__ __volatile__(
  35         "1:     ldl_l   %0,%1\n"
  36         "       bne     %0,2f\n"
  37         "       lda     %0,1\n"
  38         "       stl_c   %0,%1\n"
  39         "       beq     %0,2f\n"
  40         "       mb\n"
  41         ".subsection 2\n"
  42         "2:     ldl     %0,%1\n"
  43         "       bne     %0,2b\n"
  44         "       br      1b\n"
  45         ".previous"
  46         : "=&r" (tmp), "=m" (lock->lock)
  47         : "m"(lock->lock) : "memory");
  48 }
  49
  50 static inline int arch_spin_trylock(arch_spinlock_t *lock)
  51 {
  52         return !test_and_set_bit(0, &lock->lock);
  53 }
  54
  55 /***********************************************************/
  56
  57 static inline int arch_read_can_lock(arch_rwlock_t *lock)
  58 {
  59         return (lock->lock & 1) == 0;
  60 }
  61
  62 static inline int arch_write_can_lock(arch_rwlock_t *lock)
  63 {
  64         return lock->lock == 0;
  65 }
  66
  67 static inline void arch_read_lock(arch_rwlock_t *lock)
  68 {
  69         long regx;
  70
  71         __asm__ __volatile__(
  72         "1:     ldl_l   %1,%0\n"
  73         "       blbs    %1,6f\n"
  74         "       subl    %1,2,%1\n"
  75         "       stl_c   %1,%0\n"
  76         "       beq     %1,6f\n"
  77         "       mb\n"
  78         ".subsection 2\n"
  79         "6:     ldl     %1,%0\n"
  80         "       blbs    %1,6b\n"
  81         "       br      1b\n"
  82         ".previous"
  83         : "=m" (*lock), "=&r" (regx)
  84         : "m" (*lock) : "memory");
  85 }
  86
  87 static inline void arch_write_lock(arch_rwlock_t *lock)
  88 {
  89         long regx;
  90
  91         __asm__ __volatile__(
  92         "1:     ldl_l   %1,%0\n"
  93         "       bne     %1,6f\n"
  94         "       lda     %1,1\n"
  95         "       stl_c   %1,%0\n"
  96         "       beq     %1,6f\n"
  97         "       mb\n"
  98         ".subsection 2\n"
  99         "6:     ldl     %1,%0\n"
 100         "       bne     %1,6b\n"
 101         "       br      1b\n"
 102         ".previous"
 103         : "=m" (*lock), "=&r" (regx)
 104         : "m" (*lock) : "memory");
 105 }
 106
 107 static inline int arch_read_trylock(arch_rwlock_t * lock)
 108 {
 109         long regx;
 110         int success;
 111
 112         __asm__ __volatile__(
 113         "1:     ldl_l   %1,%0\n"
 114         "       lda     %2,0\n"
 115         "       blbs    %1,2f\n"
 116         "       subl    %1,2,%2\n"
 117         "       stl_c   %2,%0\n"
 118         "       beq     %2,6f\n"
 119         "2:     mb\n"
 120         ".subsection 2\n"
 121         "6:     br      1b\n"
 122         ".previous"
 123         : "=m" (*lock), "=&r" (regx), "=&r" (success)
 124         : "m" (*lock) : "memory");
 125
 126         return success;
 127 }
 128
 129 static inline int arch_write_trylock(arch_rwlock_t * lock)
 130 {
 131         long regx;
 132         int success;
 133
 134         __asm__ __volatile__(
 135         "1:     ldl_l   %1,%0\n"
 136         "       lda     %2,0\n"
 137         "       bne     %1,2f\n"
 138         "       lda     %2,1\n"
 139         "       stl_c   %2,%0\n"
 140         "       beq     %2,6f\n"
 141         "2:     mb\n"
 142         ".subsection 2\n"
 143         "6:     br      1b\n"
 144         ".previous"
 145         : "=m" (*lock), "=&r" (regx), "=&r" (success)
 146         : "m" (*lock) : "memory");
 147
 148         return success;
 149 }
 150
 151 static inline void arch_read_unlock(arch_rwlock_t * lock)
 152 {
 153         long regx;
 154         __asm__ __volatile__(
 155         "       mb\n"
 156         "1:     ldl_l   %1,%0\n"
 157         "       addl    %1,2,%1\n"
 158         "       stl_c   %1,%0\n"
 159         "       beq     %1,6f\n"
 160         ".subsection 2\n"
 161         "6:     br      1b\n"
 162         ".previous"
 163         : "=m" (*lock), "=&r" (regx)
 164         : "m" (*lock) : "memory");
 165 }
 166
 167 static inline void arch_write_unlock(arch_rwlock_t * lock)
 168 {
 169         mb();
 170         lock->lock = 0;
 171 }
 172
 173 #define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
 174 #define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
 175
 176 #endif /* _ALPHA_SPINLOCK_H */