Jon Loeliger | 342e73b | 2005-09-22 14:55:30 -0500 | [diff] [blame] | 1 | #ifndef _ASM_POWERPC_RWSEM_H |
| 2 | #define _ASM_POWERPC_RWSEM_H |
| 3 | |
Robert P. J. Day | 20b31b5 | 2007-07-18 23:36:36 +1000 | [diff] [blame] | 4 | #ifndef _LINUX_RWSEM_H |
| 5 | #error "Please don't include <asm/rwsem.h> directly, use <linux/rwsem.h> instead." |
| 6 | #endif |
| 7 | |
Jon Loeliger | 342e73b | 2005-09-22 14:55:30 -0500 | [diff] [blame] | 8 | #ifdef __KERNEL__ |
| 9 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 10 | /* |
Stephen Rothwell | b8b572e | 2008-08-01 15:20:30 +1000 | [diff] [blame] | 11 | * R/W semaphores for PPC using the stuff in lib/rwsem.c. |
| 12 | * Adapted largely from include/asm-i386/rwsem.h |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 13 | * by Paul Mackerras <paulus@samba.org>. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | */ |
| 15 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | /* |
| 17 | * the semaphore definition |
| 18 | */ |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 19 | #ifdef CONFIG_PPC64 |
| 20 | # define RWSEM_ACTIVE_MASK 0xffffffffL |
| 21 | #else |
| 22 | # define RWSEM_ACTIVE_MASK 0x0000ffffL |
| 23 | #endif |
| 24 | |
| 25 | #define RWSEM_UNLOCKED_VALUE 0x00000000L |
| 26 | #define RWSEM_ACTIVE_BIAS 0x00000001L |
| 27 | #define RWSEM_WAITING_BIAS (-RWSEM_ACTIVE_MASK-1) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 28 | #define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS |
| 29 | #define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS) |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 30 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 31 | /* |
| 32 | * lock for reading |
| 33 | */ |
| 34 | static inline void __down_read(struct rw_semaphore *sem) |
| 35 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 36 | if (unlikely(atomic_long_inc_return((atomic_long_t *)&sem->count) <= 0)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | rwsem_down_read_failed(sem); |
| 38 | } |
| 39 | |
| 40 | static inline int __down_read_trylock(struct rw_semaphore *sem) |
| 41 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 42 | long tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 43 | |
| 44 | while ((tmp = sem->count) >= 0) { |
| 45 | if (tmp == cmpxchg(&sem->count, tmp, |
| 46 | tmp + RWSEM_ACTIVE_READ_BIAS)) { |
| 47 | return 1; |
| 48 | } |
| 49 | } |
| 50 | return 0; |
| 51 | } |
| 52 | |
| 53 | /* |
| 54 | * lock for writing |
| 55 | */ |
Benjamin Herrenschmidt | 945feb1 | 2008-04-17 14:35:01 +1000 | [diff] [blame] | 56 | static inline void __down_write_nested(struct rw_semaphore *sem, int subclass) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 58 | long tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 60 | tmp = atomic_long_add_return(RWSEM_ACTIVE_WRITE_BIAS, |
| 61 | (atomic_long_t *)&sem->count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 62 | if (unlikely(tmp != RWSEM_ACTIVE_WRITE_BIAS)) |
| 63 | rwsem_down_write_failed(sem); |
| 64 | } |
| 65 | |
Benjamin Herrenschmidt | 945feb1 | 2008-04-17 14:35:01 +1000 | [diff] [blame] | 66 | static inline void __down_write(struct rw_semaphore *sem) |
| 67 | { |
| 68 | __down_write_nested(sem, 0); |
| 69 | } |
| 70 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 71 | static inline int __down_write_trylock(struct rw_semaphore *sem) |
| 72 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 73 | long tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | |
| 75 | tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE, |
| 76 | RWSEM_ACTIVE_WRITE_BIAS); |
| 77 | return tmp == RWSEM_UNLOCKED_VALUE; |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * unlock after reading |
| 82 | */ |
| 83 | static inline void __up_read(struct rw_semaphore *sem) |
| 84 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 85 | long tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 87 | tmp = atomic_long_dec_return((atomic_long_t *)&sem->count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | if (unlikely(tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)) |
| 89 | rwsem_wake(sem); |
| 90 | } |
| 91 | |
| 92 | /* |
| 93 | * unlock after writing |
| 94 | */ |
| 95 | static inline void __up_write(struct rw_semaphore *sem) |
| 96 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 97 | if (unlikely(atomic_long_sub_return(RWSEM_ACTIVE_WRITE_BIAS, |
| 98 | (atomic_long_t *)&sem->count) < 0)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | rwsem_wake(sem); |
| 100 | } |
| 101 | |
| 102 | /* |
| 103 | * implement atomic add functionality |
| 104 | */ |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 105 | static inline void rwsem_atomic_add(long delta, struct rw_semaphore *sem) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 107 | atomic_long_add(delta, (atomic_long_t *)&sem->count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 108 | } |
| 109 | |
| 110 | /* |
| 111 | * downgrade write lock to read lock |
| 112 | */ |
| 113 | static inline void __downgrade_write(struct rw_semaphore *sem) |
| 114 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 115 | long tmp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 116 | |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 117 | tmp = atomic_long_add_return(-RWSEM_WAITING_BIAS, |
| 118 | (atomic_long_t *)&sem->count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 119 | if (tmp < 0) |
| 120 | rwsem_downgrade_wake(sem); |
| 121 | } |
| 122 | |
| 123 | /* |
| 124 | * implement exchange and add functionality |
| 125 | */ |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 126 | static inline long rwsem_atomic_update(long delta, struct rw_semaphore *sem) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 127 | { |
Benjamin Herrenschmidt | 529b730 | 2010-08-24 14:41:48 +1000 | [diff] [blame] | 128 | return atomic_long_add_return(delta, (atomic_long_t *)&sem->count); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | } |
| 130 | |
Jon Loeliger | 342e73b | 2005-09-22 14:55:30 -0500 | [diff] [blame] | 131 | #endif /* __KERNEL__ */ |
| 132 | #endif /* _ASM_POWERPC_RWSEM_H */ |