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Arjan van de Ven2acbb8c2006-01-09 15:59:19 -08001/*
Nick Pigginae564c62008-11-11 17:54:15 +00002 * Optimised mutex implementation of include/asm-generic/mutex-dec.h algorithm
Arjan van de Ven2acbb8c2006-01-09 15:59:19 -08003 */
Nick Pigginae564c62008-11-11 17:54:15 +00004#ifndef _ASM_POWERPC_MUTEX_H
5#define _ASM_POWERPC_MUTEX_H
Arjan van de Ven2acbb8c2006-01-09 15:59:19 -08006
Nick Pigginae564c62008-11-11 17:54:15 +00007static inline int __mutex_cmpxchg_lock(atomic_t *v, int old, int new)
8{
9 int t;
10
11 __asm__ __volatile__ (
12"1: lwarx %0,0,%1 # mutex trylock\n\
13 cmpw 0,%0,%2\n\
14 bne- 2f\n"
15 PPC405_ERR77(0,%1)
16" stwcx. %3,0,%1\n\
17 bne- 1b"
Anton Blanchardf10e2e52010-02-10 01:04:06 +000018 PPC_ACQUIRE_BARRIER
Nick Pigginae564c62008-11-11 17:54:15 +000019 "\n\
202:"
21 : "=&r" (t)
22 : "r" (&v->counter), "r" (old), "r" (new)
23 : "cc", "memory");
24
25 return t;
26}
27
28static inline int __mutex_dec_return_lock(atomic_t *v)
29{
30 int t;
31
32 __asm__ __volatile__(
33"1: lwarx %0,0,%1 # mutex lock\n\
34 addic %0,%0,-1\n"
35 PPC405_ERR77(0,%1)
36" stwcx. %0,0,%1\n\
37 bne- 1b"
Anton Blanchardf10e2e52010-02-10 01:04:06 +000038 PPC_ACQUIRE_BARRIER
Nick Pigginae564c62008-11-11 17:54:15 +000039 : "=&r" (t)
40 : "r" (&v->counter)
41 : "cc", "memory");
42
43 return t;
44}
45
46static inline int __mutex_inc_return_unlock(atomic_t *v)
47{
48 int t;
49
50 __asm__ __volatile__(
Anton Blanchardf10e2e52010-02-10 01:04:06 +000051 PPC_RELEASE_BARRIER
Nick Pigginae564c62008-11-11 17:54:15 +000052"1: lwarx %0,0,%1 # mutex unlock\n\
53 addic %0,%0,1\n"
54 PPC405_ERR77(0,%1)
55" stwcx. %0,0,%1 \n\
56 bne- 1b"
57 : "=&r" (t)
58 : "r" (&v->counter)
59 : "cc", "memory");
60
61 return t;
62}
63
64/**
65 * __mutex_fastpath_lock - try to take the lock by moving the count
66 * from 1 to a 0 value
67 * @count: pointer of type atomic_t
68 * @fail_fn: function to call if the original value was not 1
69 *
70 * Change the count from 1 to a value lower than 1, and call <fail_fn> if
71 * it wasn't 1 originally. This function MUST leave the value lower than
72 * 1 even when the "1" assertion wasn't true.
73 */
74static inline void
75__mutex_fastpath_lock(atomic_t *count, void (*fail_fn)(atomic_t *))
76{
77 if (unlikely(__mutex_dec_return_lock(count) < 0))
78 fail_fn(count);
79}
80
81/**
82 * __mutex_fastpath_lock_retval - try to take the lock by moving the count
83 * from 1 to a 0 value
84 * @count: pointer of type atomic_t
85 * @fail_fn: function to call if the original value was not 1
86 *
87 * Change the count from 1 to a value lower than 1, and call <fail_fn> if
88 * it wasn't 1 originally. This function returns 0 if the fastpath succeeds,
89 * or anything the slow path function returns.
90 */
91static inline int
92__mutex_fastpath_lock_retval(atomic_t *count, int (*fail_fn)(atomic_t *))
93{
94 if (unlikely(__mutex_dec_return_lock(count) < 0))
95 return fail_fn(count);
96 return 0;
97}
98
99/**
100 * __mutex_fastpath_unlock - try to promote the count from 0 to 1
101 * @count: pointer of type atomic_t
102 * @fail_fn: function to call if the original value was not 0
103 *
104 * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>.
105 * In the failure case, this function is allowed to either set the value to
106 * 1, or to set it to a value lower than 1.
107 */
108static inline void
109__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
110{
111 if (unlikely(__mutex_inc_return_unlock(count) <= 0))
112 fail_fn(count);
113}
114
115#define __mutex_slowpath_needs_to_unlock() 1
116
117/**
118 * __mutex_fastpath_trylock - try to acquire the mutex, without waiting
119 *
120 * @count: pointer of type atomic_t
121 * @fail_fn: fallback function
122 *
123 * Change the count from 1 to 0, and return 1 (success), or if the count
124 * was not 1, then return 0 (failure).
125 */
126static inline int
127__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
128{
129 if (likely(__mutex_cmpxchg_lock(count, 1, 0) == 1))
130 return 1;
131 return 0;
132}
133
134#endif