Mikael Starvik | 51533b6 | 2005-07-27 11:44:44 -0700 | [diff] [blame] | 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 */ |