1/*
2 * Optimised mutex implementation of include/asm-generic/mutex-dec.h algorithm
3 */
4#ifndef _ASM_POWERPC_MUTEX_H
5#define _ASM_POWERPC_MUTEX_H
6
7static 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"
18	PPC_ACQUIRE_BARRIER
19	"\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"
38	PPC_ACQUIRE_BARRIER
39	: "=&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__(
51	PPC_RELEASE_BARRIER
52"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 *
86 * Change the count from 1 to a value lower than 1. This function returns 0
87 * if the fastpath succeeds, or -1 otherwise.
88 */
89static inline int
90__mutex_fastpath_lock_retval(atomic_t *count)
91{
92	if (unlikely(__mutex_dec_return_lock(count) < 0))
93		return -1;
94	return 0;
95}
96
97/**
98 *  __mutex_fastpath_unlock - try to promote the count from 0 to 1
99 *  @count: pointer of type atomic_t
100 *  @fail_fn: function to call if the original value was not 0
101 *
102 * Try to promote the count from 0 to 1. If it wasn't 0, call <fail_fn>.
103 * In the failure case, this function is allowed to either set the value to
104 * 1, or to set it to a value lower than 1.
105 */
106static inline void
107__mutex_fastpath_unlock(atomic_t *count, void (*fail_fn)(atomic_t *))
108{
109	if (unlikely(__mutex_inc_return_unlock(count) <= 0))
110		fail_fn(count);
111}
112
113#define __mutex_slowpath_needs_to_unlock()		1
114
115/**
116 * __mutex_fastpath_trylock - try to acquire the mutex, without waiting
117 *
118 *  @count: pointer of type atomic_t
119 *  @fail_fn: fallback function
120 *
121 * Change the count from 1 to 0, and return 1 (success), or if the count
122 * was not 1, then return 0 (failure).
123 */
124static inline int
125__mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *))
126{
127	if (likely(__mutex_cmpxchg_lock(count, 1, 0) == 1))
128		return 1;
129	return 0;
130}
131
132#endif
133