kernel/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 void arch_spin_unlock(arch_spinlock_t * lock)
  20 {
  21         mb();
  22         lock->lock = 0;
  23 }
  24
  25 static inline void arch_spin_lock(arch_spinlock_t * lock)
  26 {
  27         long tmp;
  28
  29         __asm__ __volatile__(
  30         "1:     ldl_l   %0,%1\n"
  31         "       bne     %0,2f\n"
  32         "       lda     %0,1\n"
  33         "       stl_c   %0,%1\n"
  34         "       beq     %0,2f\n"
  35         "       mb\n"
  36         ".subsection 2\n"
  37         "2:     ldl     %0,%1\n"
  38         "       bne     %0,2b\n"
  39         "       br      1b\n"
  40         ".previous"
  41         : "=&r" (tmp), "=m" (lock->lock)
  42         : "m"(lock->lock) : "memory");
  43 }
  44
  45 static inline int arch_spin_trylock(arch_spinlock_t *lock)
  46 {
  47         return !test_and_set_bit(0, &lock->lock);
  48 }
  49
  50 /***********************************************************/
  51
  52 static inline int arch_read_can_lock(arch_rwlock_t *lock)
  53 {
  54         return (lock->lock & 1) == 0;
  55 }
  56
  57 static inline int arch_write_can_lock(arch_rwlock_t *lock)
  58 {
  59         return lock->lock == 0;
  60 }
  61
  62 static inline void arch_read_lock(arch_rwlock_t *lock)
  63 {
  64         long regx;
  65
  66         __asm__ __volatile__(
  67         "1:     ldl_l   %1,%0\n"
  68         "       blbs    %1,6f\n"
  69         "       subl    %1,2,%1\n"
  70         "       stl_c   %1,%0\n"
  71         "       beq     %1,6f\n"
  72         "       mb\n"
  73         ".subsection 2\n"
  74         "6:     ldl     %1,%0\n"
  75         "       blbs    %1,6b\n"
  76         "       br      1b\n"
  77         ".previous"
  78         : "=m" (*lock), "=&r" (regx)
  79         : "m" (*lock) : "memory");
  80 }
  81
  82 static inline void arch_write_lock(arch_rwlock_t *lock)
  83 {
  84         long regx;
  85
  86         __asm__ __volatile__(
  87         "1:     ldl_l   %1,%0\n"
  88         "       bne     %1,6f\n"
  89         "       lda     %1,1\n"
  90         "       stl_c   %1,%0\n"
  91         "       beq     %1,6f\n"
  92         "       mb\n"
  93         ".subsection 2\n"
  94         "6:     ldl     %1,%0\n"
  95         "       bne     %1,6b\n"
  96         "       br      1b\n"
  97         ".previous"
  98         : "=m" (*lock), "=&r" (regx)
  99         : "m" (*lock) : "memory");
 100 }
 101
 102 static inline int arch_read_trylock(arch_rwlock_t * lock)
 103 {
 104         long regx;
 105         int success;
 106
 107         __asm__ __volatile__(
 108         "1:     ldl_l   %1,%0\n"
 109         "       lda     %2,0\n"
 110         "       blbs    %1,2f\n"
 111         "       subl    %1,2,%2\n"
 112         "       stl_c   %2,%0\n"
 113         "       beq     %2,6f\n"
 114         "2:     mb\n"
 115         ".subsection 2\n"
 116         "6:     br      1b\n"
 117         ".previous"
 118         : "=m" (*lock), "=&r" (regx), "=&r" (success)
 119         : "m" (*lock) : "memory");
 120
 121         return success;
 122 }
 123
 124 static inline int arch_write_trylock(arch_rwlock_t * lock)
 125 {
 126         long regx;
 127         int success;
 128
 129         __asm__ __volatile__(
 130         "1:     ldl_l   %1,%0\n"
 131         "       lda     %2,0\n"
 132         "       bne     %1,2f\n"
 133         "       lda     %2,1\n"
 134         "       stl_c   %2,%0\n"
 135         "       beq     %2,6f\n"
 136         "2:     mb\n"
 137         ".subsection 2\n"
 138         "6:     br      1b\n"
 139         ".previous"
 140         : "=m" (*lock), "=&r" (regx), "=&r" (success)
 141         : "m" (*lock) : "memory");
 142
 143         return success;
 144 }
 145
 146 static inline void arch_read_unlock(arch_rwlock_t * lock)
 147 {
 148         long regx;
 149         __asm__ __volatile__(
 150         "       mb\n"
 151         "1:     ldl_l   %1,%0\n"
 152         "       addl    %1,2,%1\n"
 153         "       stl_c   %1,%0\n"
 154         "       beq     %1,6f\n"
 155         ".subsection 2\n"
 156         "6:     br      1b\n"
 157         ".previous"
 158         : "=m" (*lock), "=&r" (regx)
 159         : "m" (*lock) : "memory");
 160 }
 161
 162 static inline void arch_write_unlock(arch_rwlock_t * lock)
 163 {
 164         mb();
 165         lock->lock = 0;
 166 }
 167
 168 #define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
 169 #define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
 170
 171 #endif /* _ALPHA_SPINLOCK_H */