arch/alpha/include/asm/spinlock.h

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