[deliverable/linux.git] / arch / powerpc / include / asm / rwsem.h

#ifndef _ASM_POWERPC_RWSEM_H
#define _ASM_POWERPC_RWSEM_H

#ifndef _LINUX_RWSEM_H
#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
#endif

#ifdef __KERNEL__

/*
 * R/W semaphores for PPC using the stuff in lib/rwsem.c.
 * Adapted largely from include/asm-i386/rwsem.h
 * by Paul Mackerras <paulus@samba.org>.
 */

#include <linux/list.h>
#include <linux/spinlock.h>
#include <asm/atomic.h>
#include <asm/system.h>

/*
 * the semaphore definition
 */
struct rw_semaphore {
	/* XXX this should be able to be an atomic_t  -- paulus */
	signed int		count;
#define RWSEM_UNLOCKED_VALUE		0x00000000
#define RWSEM_ACTIVE_BIAS		0x00000001
#define RWSEM_ACTIVE_MASK		0x0000ffff
#define RWSEM_WAITING_BIAS		(-0x00010000)
#define RWSEM_ACTIVE_READ_BIAS		RWSEM_ACTIVE_BIAS
#define RWSEM_ACTIVE_WRITE_BIAS		(RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
	spinlock_t		wait_lock;
	struct list_head	wait_list;
#ifdef CONFIG_DEBUG_LOCK_ALLOC
	struct lockdep_map	dep_map;
#endif
};

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
#else
# define __RWSEM_DEP_MAP_INIT(lockname)
#endif

#define __RWSEM_INITIALIZER(name) \
	{ RWSEM_UNLOCKED_VALUE, __SPIN_LOCK_UNLOCKED((name).wait_lock), \
	  LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) }

#define DECLARE_RWSEM(name)		\
	struct rw_semaphore name = __RWSEM_INITIALIZER(name)

extern struct rw_semaphore *rwsem_down_read_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_down_write_failed(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_wake(struct rw_semaphore *sem);
extern struct rw_semaphore *rwsem_downgrade_wake(struct rw_semaphore *sem);

extern void __init_rwsem(struct rw_semaphore *sem, const char *name,
			 struct lock_class_key *key);

#define init_rwsem(sem)					\
	do {						\
		static struct lock_class_key __key;	\
							\
		__init_rwsem((sem), #sem, &__key);	\
	} while (0)

/*
 * lock for reading
 */
static inline void __down_read(struct rw_semaphore *sem)
{
	if (unlikely(atomic_inc_return((atomic_t *)(&sem->count)) <= 0))
		rwsem_down_read_failed(sem);
}

static inline int __down_read_trylock(struct rw_semaphore *sem)
{
	int tmp;

	while ((tmp = sem->count) >= 0) {
		if (tmp == cmpxchg(&sem->count, tmp,
				   tmp + RWSEM_ACTIVE_READ_BIAS)) {
			return 1;
		}
	}
	return 0;
}

/*
 * lock for writing
 */
static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
{
	int tmp;

	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
				(atomic_t *)(&sem->count));
	if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
		rwsem_down_write_failed(sem);
}

static inline void __down_write(struct rw_semaphore *sem)
{
	__down_write_nested(sem, 0);
}

static inline int __down_write_trylock(struct rw_semaphore *sem)
{
	int tmp;

	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
		      RWSEM_ACTIVE_WRITE_BIAS);
	return tmp == RWSEM_UNLOCKED_VALUE;
}

/*
 * unlock after reading
 */
static inline void __up_read(struct rw_semaphore *sem)
{
	int tmp;

	tmp = atomic_dec_return((atomic_t *)(&sem->count));
	if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
		rwsem_wake(sem);
}

/*
 * unlock after writing
 */
static inline void __up_write(struct rw_semaphore *sem)
{
	if (unlikely(atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
			      (atomic_t *)(&sem->count)) < 0))
		rwsem_wake(sem);
}

/*
 * implement atomic add functionality
 */
static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
{
	atomic_add(delta, (atomic_t *)(&sem->count));
}

/*
 * downgrade write lock to read lock
 */
static inline void __downgrade_write(struct rw_semaphore *sem)
{
	int tmp;

	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
	if (tmp < 0)
		rwsem_downgrade_wake(sem);
}

/*
 * implement exchange and add functionality
 */
static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
{
	return atomic_add_return(delta, (atomic_t *)(&sem->count));
}

static inline int rwsem_is_locked(struct rw_semaphore *sem)
{
	return (sem->count != 0);
}

#endif	/* __KERNEL__ */
#endif	/* _ASM_POWERPC_RWSEM_H */
Commit	Line	Data
342e73b3 JL	1	#ifndef _ASM_POWERPC_RWSEM_H
	2	#define _ASM_POWERPC_RWSEM_H
	3
20b31b53 RD	4	#ifndef _LINUX_RWSEM_H
	5	#error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead."
	6	#endif
	7
342e73b3 JL	8	#ifdef __KERNEL__
342e73b3 JL	9
1da177e4	10	/*
b8b572e1 SR	11	* R/W semaphores for PPC using the stuff in lib/rwsem.c.
b8b572e1 SR	12	* Adapted largely from include/asm-i386/rwsem.h
1da177e4	13	* by Paul Mackerras <paulus@samba.org>.
1da177e4 LT	14	*/
1da177e4 LT	15
1da177e4 LT	16	#include <linux/list.h>
	17	#include <linux/spinlock.h>
	18	#include <asm/atomic.h>
	19	#include <asm/system.h>
	20
	21	/*
	22	* the semaphore definition
	23	*/
	24	struct rw_semaphore {
	25	/* XXX this should be able to be an atomic_t -- paulus */
	26	signed int count;
	27	#define RWSEM_UNLOCKED_VALUE 0x00000000
	28	#define RWSEM_ACTIVE_BIAS 0x00000001
	29	#define RWSEM_ACTIVE_MASK 0x0000ffff
	30	#define RWSEM_WAITING_BIAS (-0x00010000)
	31	#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
	32	#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
	33	spinlock_t wait_lock;
	34	struct list_head wait_list;
945feb17 BH	35	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	36	struct lockdep_map dep_map;
	37	#endif
1da177e4 LT	38	};
1da177e4 LT	39
945feb17 BH	40	#ifdef CONFIG_DEBUG_LOCK_ALLOC
	41	# define __RWSEM_DEP_MAP_INIT(lockname) , .dep_map = { .name = #lockname }
	42	#else
	43	# define __RWSEM_DEP_MAP_INIT(lockname)
	44	#endif
	45
1da177e4	46	#define __RWSEM_INITIALIZER(name) \
945feb17 BH	47	{ RWSEM_UNLOCKED_VALUE, __SPIN_LOCK_UNLOCKED((name).wait_lock), \
945feb17 BH	48	LIST_HEAD_INIT((name).wait_list) __RWSEM_DEP_MAP_INIT(name) }
1da177e4 LT	49
	50	#define DECLARE_RWSEM(name) \
	51	struct rw_semaphore name = __RWSEM_INITIALIZER(name)
	52
	53	extern struct rw_semaphore rwsem_down_read_failed(struct rw_semaphore sem);
	54	extern struct rw_semaphore rwsem_down_write_failed(struct rw_semaphore sem);
	55	extern struct rw_semaphore rwsem_wake(struct rw_semaphore sem);
	56	extern struct rw_semaphore rwsem_downgrade_wake(struct rw_semaphore sem);
	57
945feb17 BH	58	extern void __init_rwsem(struct rw_semaphore sem, const char name,
	59	struct lock_class_key *key);
	60
	61	#define init_rwsem(sem) \
	62	do { \
	63	static struct lock_class_key __key; \
	64	\
	65	__init_rwsem((sem), #sem, &__key); \
	66	} while (0)
1da177e4 LT	67
	68	/*
	69	* lock for reading
	70	*/
	71	static inline void __down_read(struct rw_semaphore *sem)
	72	{
	73	if (unlikely(atomic_inc_return((atomic_t *)(&sem->count)) <= 0))
	74	rwsem_down_read_failed(sem);
	75	}
	76
	77	static inline int __down_read_trylock(struct rw_semaphore *sem)
	78	{
	79	int tmp;
	80
	81	while ((tmp = sem->count) >= 0) {
	82	if (tmp == cmpxchg(&sem->count, tmp,
	83	tmp + RWSEM_ACTIVE_READ_BIAS)) {
	84	return 1;
	85	}
	86	}
	87	return 0;
	88	}
	89
	90	/*
	91	* lock for writing
	92	*/
945feb17	93	static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
1da177e4 LT	94	{
	95	int tmp;
	96
	97	tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
	98	(atomic_t *)(&sem->count));
	99	if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS))
	100	rwsem_down_write_failed(sem);
	101	}
	102
945feb17 BH	103	static inline void __down_write(struct rw_semaphore *sem)
	104	{
	105	__down_write_nested(sem, 0);
	106	}
	107
1da177e4 LT	108	static inline int __down_write_trylock(struct rw_semaphore *sem)
	109	{
	110	int tmp;
	111
	112	tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
	113	RWSEM_ACTIVE_WRITE_BIAS);
	114	return tmp == RWSEM_UNLOCKED_VALUE;
	115	}
	116
	117	/*
	118	* unlock after reading
	119	*/
	120	static inline void __up_read(struct rw_semaphore *sem)
	121	{
	122	int tmp;
	123
	124	tmp = atomic_dec_return((atomic_t *)(&sem->count));
	125	if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0))
	126	rwsem_wake(sem);
	127	}
	128
	129	/*
	130	* unlock after writing
	131	*/
	132	static inline void __up_write(struct rw_semaphore *sem)
	133	{
	134	if (unlikely(atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
	135	(atomic_t *)(&sem->count)) < 0))
	136	rwsem_wake(sem);
	137	}
	138
	139	/*
	140	* implement atomic add functionality
	141	*/
	142	static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
	143	{
	144	atomic_add(delta, (atomic_t *)(&sem->count));
	145	}
	146
	147	/*
	148	* downgrade write lock to read lock
	149	*/
	150	static inline void __downgrade_write(struct rw_semaphore *sem)
	151	{
	152	int tmp;
	153
	154	tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
	155	if (tmp < 0)
	156	rwsem_downgrade_wake(sem);
	157	}
	158
	159	/*
	160	* implement exchange and add functionality
	161	*/
	162	static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
	163	{
	164	return atomic_add_return(delta, (atomic_t *)(&sem->count));
	165	}
	166
eb92f4ef RVR	167	static inline int rwsem_is_locked(struct rw_semaphore *sem)
	168	{
	169	return (sem->count != 0);
	170	}
	171
342e73b3 JL	172	#endif /* __KERNEL__ */
342e73b3 JL	173	#endif /* _ASM_POWERPC_RWSEM_H */