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1/*
2 * include/asm-sh/rwsem.h: R/W semaphores for SH using the stuff
3 * in lib/rwsem.c.
4 */
5
6#ifndef _ASM_SH_RWSEM_H
7#define _ASM_SH_RWSEM_H
8
9#ifndef _LINUX_RWSEM_H
10#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
11#endif
12
13#ifdef __KERNEL__
14
15#define RWSEM_UNLOCKED_VALUE 0x00000000
16#define RWSEM_ACTIVE_BIAS 0x00000001
17#define RWSEM_ACTIVE_MASK 0x0000ffff
18#define RWSEM_WAITING_BIAS (-0x00010000)
19#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
20#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
21
22/*
23 * lock for reading
24 */
25static inline void __down_read(struct rw_semaphore *sem)
26{
27 if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
28 smp_wmb();
29 else
30 rwsem_down_read_failed(sem);
31}
32
33static inline int __down_read_trylock(struct rw_semaphore *sem)
34{
35 int tmp;
36
37 while ((tmp = sem->count) >= 0) {
38 if (tmp == cmpxchg(&sem->count, tmp,
39 tmp + RWSEM_ACTIVE_READ_BIAS)) {
40 smp_wmb();
41 return 1;
42 }
43 }
44 return 0;
45}
46
47/*
48 * lock for writing
49 */
50static inline void __down_write(struct rw_semaphore *sem)
51{
52 int tmp;
53
54 tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
55 (atomic_t *)(&sem->count));
56 if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
57 smp_wmb();
58 else
59 rwsem_down_write_failed(sem);
60}
61
62static inline int __down_write_trylock(struct rw_semaphore *sem)
63{
64 int tmp;
65
66 tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
67 RWSEM_ACTIVE_WRITE_BIAS);
68 smp_wmb();
69 return tmp == RWSEM_UNLOCKED_VALUE;
70}
71
72/*
73 * unlock after reading
74 */
75static inline void __up_read(struct rw_semaphore *sem)
76{
77 int tmp;
78
79 smp_wmb();
80 tmp = atomic_dec_return((atomic_t *)(&sem->count));
81 if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
82 rwsem_wake(sem);
83}
84
85/*
86 * unlock after writing
87 */
88static inline void __up_write(struct rw_semaphore *sem)
89{
90 smp_wmb();
91 if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
92 (atomic_t *)(&sem->count)) < 0)
93 rwsem_wake(sem);
94}
95
96/*
97 * implement atomic add functionality
98 */
99static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
100{
101 atomic_add(delta, (atomic_t *)(&sem->count));
102}
103
104/*
105 * downgrade write lock to read lock
106 */
107static inline void __downgrade_write(struct rw_semaphore *sem)
108{
109 int tmp;
110
111 smp_wmb();
112 tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
113 if (tmp < 0)
114 rwsem_downgrade_wake(sem);
115}
116
117static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
118{
119 __down_write(sem);
120}
121
122/*
123 * implement exchange and add functionality
124 */
125static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
126{
127 smp_mb();
128 return atomic_add_return(delta, (atomic_t *)(&sem->count));
129}
130
131#endif /* __KERNEL__ */
132#endif /* _ASM_SH_RWSEM_H */
1/*
2 * include/asm-sh/rwsem.h: R/W semaphores for SH using the stuff
3 * in lib/rwsem.c.
4 */
5
6#ifndef _ASM_SH_RWSEM_H
7#define _ASM_SH_RWSEM_H
8
9#ifndef _LINUX_RWSEM_H
10#error "please don't include asm/rwsem.h directly, use linux/rwsem.h instead"
11#endif
12
13#ifdef __KERNEL__
14
15#define RWSEM_UNLOCKED_VALUE 0x00000000
16#define RWSEM_ACTIVE_BIAS 0x00000001
17#define RWSEM_ACTIVE_MASK 0x0000ffff
18#define RWSEM_WAITING_BIAS (-0x00010000)
19#define RWSEM_ACTIVE_READ_BIAS RWSEM_ACTIVE_BIAS
20#define RWSEM_ACTIVE_WRITE_BIAS (RWSEM_WAITING_BIAS + RWSEM_ACTIVE_BIAS)
21
22/*
23 * lock for reading
24 */
25static inline void __down_read(struct rw_semaphore *sem)
26{
27 if (atomic_inc_return((atomic_t *)(&sem->count)) > 0)
28 smp_wmb();
29 else
30 rwsem_down_read_failed(sem);
31}
32
33static inline int __down_read_trylock(struct rw_semaphore *sem)
34{
35 int tmp;
36
37 while ((tmp = sem->count) >= 0) {
38 if (tmp == cmpxchg(&sem->count, tmp,
39 tmp + RWSEM_ACTIVE_READ_BIAS)) {
40 smp_wmb();
41 return 1;
42 }
43 }
44 return 0;
45}
46
47/*
48 * lock for writing
49 */
50static inline void __down_write(struct rw_semaphore *sem)
51{
52 int tmp;
53
54 tmp = atomic_add_return(RWSEM_ACTIVE_WRITE_BIAS,
55 (atomic_t *)(&sem->count));
56 if (tmp == RWSEM_ACTIVE_WRITE_BIAS)
57 smp_wmb();
58 else
59 rwsem_down_write_failed(sem);
60}
61
62static inline int __down_write_trylock(struct rw_semaphore *sem)
63{
64 int tmp;
65
66 tmp = cmpxchg(&sem->count, RWSEM_UNLOCKED_VALUE,
67 RWSEM_ACTIVE_WRITE_BIAS);
68 smp_wmb();
69 return tmp == RWSEM_UNLOCKED_VALUE;
70}
71
72/*
73 * unlock after reading
74 */
75static inline void __up_read(struct rw_semaphore *sem)
76{
77 int tmp;
78
79 smp_wmb();
80 tmp = atomic_dec_return((atomic_t *)(&sem->count));
81 if (tmp < -1 && (tmp & RWSEM_ACTIVE_MASK) == 0)
82 rwsem_wake(sem);
83}
84
85/*
86 * unlock after writing
87 */
88static inline void __up_write(struct rw_semaphore *sem)
89{
90 smp_wmb();
91 if (atomic_sub_return(RWSEM_ACTIVE_WRITE_BIAS,
92 (atomic_t *)(&sem->count)) < 0)
93 rwsem_wake(sem);
94}
95
96/*
97 * implement atomic add functionality
98 */
99static inline void rwsem_atomic_add(int delta, struct rw_semaphore *sem)
100{
101 atomic_add(delta, (atomic_t *)(&sem->count));
102}
103
104/*
105 * downgrade write lock to read lock
106 */
107static inline void __downgrade_write(struct rw_semaphore *sem)
108{
109 int tmp;
110
111 smp_wmb();
112 tmp = atomic_add_return(-RWSEM_WAITING_BIAS, (atomic_t *)(&sem->count));
113 if (tmp < 0)
114 rwsem_downgrade_wake(sem);
115}
116
117static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
118{
119 __down_write(sem);
120}
121
122/*
123 * implement exchange and add functionality
124 */
125static inline int rwsem_atomic_update(int delta, struct rw_semaphore *sem)
126{
127 smp_mb();
128 return atomic_add_return(delta, (atomic_t *)(&sem->count));
129}
130
131#endif /* __KERNEL__ */
132#endif /* _ASM_SH_RWSEM_H */