1 /* 2 * linux/include/asm-arm/semaphore.h 3 */ 4 #ifndef __ASM_ARM_SEMAPHORE_H 5 #define __ASM_ARM_SEMAPHORE_H 6 7 #include <linux/linkage.h> 8 #include <linux/spinlock.h> 9 #include <linux/wait.h> 10 #include <linux/rwsem.h> 11 12 #include <asm/atomic.h> 13 #include <asm/locks.h> 14 15 struct semaphore { 16 atomic_t count; 17 int sleepers; 18 wait_queue_head_t wait; 19 }; 20 21 #define __SEMAPHORE_INIT(name, cnt) \ 22 { \ 23 .count = ATOMIC_INIT(cnt), \ 24 .wait = __WAIT_QUEUE_HEAD_INITIALIZER((name).wait), \ 25 } 26 27 #define __DECLARE_SEMAPHORE_GENERIC(name,count) \ 28 struct semaphore name = __SEMAPHORE_INIT(name,count) 29 30 #define DECLARE_MUTEX(name) __DECLARE_SEMAPHORE_GENERIC(name,1) 31 #define DECLARE_MUTEX_LOCKED(name) __DECLARE_SEMAPHORE_GENERIC(name,0) 32 33 static inline void sema_init(struct semaphore *sem, int val) 34 { 35 atomic_set(&sem->count, val); 36 sem->sleepers = 0; 37 init_waitqueue_head(&sem->wait); 38 } 39 40 static inline void init_MUTEX(struct semaphore *sem) 41 { 42 sema_init(sem, 1); 43 } 44 45 static inline void init_MUTEX_LOCKED(struct semaphore *sem) 46 { 47 sema_init(sem, 0); 48 } 49 50 /* 51 * special register calling convention 52 */ 53 asmlinkage void __down_failed(void); 54 asmlinkage int __down_interruptible_failed(void); 55 asmlinkage int __down_trylock_failed(void); 56 asmlinkage void __up_wakeup(void); 57 58 extern void __down(struct semaphore * sem); 59 extern int __down_interruptible(struct semaphore * sem); 60 extern int __down_trylock(struct semaphore * sem); 61 extern void __up(struct semaphore * sem); 62 63 /* 64 * This is ugly, but we want the default case to fall through. 65 * "__down" is the actual routine that waits... 66 */ 67 static inline void down(struct semaphore * sem) 68 { 69 might_sleep(); 70 __down_op(sem, __down_failed); 71 } 72 73 /* 74 * This is ugly, but we want the default case to fall through. 75 * "__down_interruptible" is the actual routine that waits... 76 */ 77 static inline int down_interruptible (struct semaphore * sem) 78 { 79 might_sleep(); 80 return __down_op_ret(sem, __down_interruptible_failed); 81 } 82 83 static inline int down_trylock(struct semaphore *sem) 84 { 85 return __down_op_ret(sem, __down_trylock_failed); 86 } 87 88 /* 89 * Note! This is subtle. We jump to wake people up only if 90 * the semaphore was negative (== somebody was waiting on it). 91 * The default case (no contention) will result in NO 92 * jumps for both down() and up(). 93 */ 94 static inline void up(struct semaphore * sem) 95 { 96 __up_op(sem, __up_wakeup); 97 } 98 99 #endif 100