1/* Copyright (C) 2000 Philipp Rumpf <prumpf@tux.org>
2 * Copyright (C) 2006 Kyle McMartin <kyle@parisc-linux.org>
3 */
4
5#ifndef _ASM_PARISC_ATOMIC_H_
6#define _ASM_PARISC_ATOMIC_H_
7
8#include <linux/types.h>
9#include <asm/cmpxchg.h>
10#include <asm/barrier.h>
11
12/*
13 * Atomic operations that C can't guarantee us.  Useful for
14 * resource counting etc..
15 *
16 * And probably incredibly slow on parisc.  OTOH, we don't
17 * have to write any serious assembly.   prumpf
18 */
19
20#ifdef CONFIG_SMP
21#include <asm/spinlock.h>
22#include <asm/cache.h>		/* we use L1_CACHE_BYTES */
23
24/* Use an array of spinlocks for our atomic_ts.
25 * Hash function to index into a different SPINLOCK.
26 * Since "a" is usually an address, use one spinlock per cacheline.
27 */
28#  define ATOMIC_HASH_SIZE 4
29#  define ATOMIC_HASH(a) (&(__atomic_hash[ (((unsigned long) (a))/L1_CACHE_BYTES) & (ATOMIC_HASH_SIZE-1) ]))
30
31extern arch_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned;
32
33/* Can't use raw_spin_lock_irq because of #include problems, so
34 * this is the substitute */
35#define _atomic_spin_lock_irqsave(l,f) do {	\
36	arch_spinlock_t *s = ATOMIC_HASH(l);		\
37	local_irq_save(f);			\
38	arch_spin_lock(s);			\
39} while(0)
40
41#define _atomic_spin_unlock_irqrestore(l,f) do {	\
42	arch_spinlock_t *s = ATOMIC_HASH(l);			\
43	arch_spin_unlock(s);				\
44	local_irq_restore(f);				\
45} while(0)
46
47
48#else
49#  define _atomic_spin_lock_irqsave(l,f) do { local_irq_save(f); } while (0)
50#  define _atomic_spin_unlock_irqrestore(l,f) do { local_irq_restore(f); } while (0)
51#endif
52
53/*
54 * Note that we need not lock read accesses - aligned word writes/reads
55 * are atomic, so a reader never sees inconsistent values.
56 */
57
58static __inline__ void atomic_set(atomic_t *v, int i)
59{
60	unsigned long flags;
61	_atomic_spin_lock_irqsave(v, flags);
62
63	v->counter = i;
64
65	_atomic_spin_unlock_irqrestore(v, flags);
66}
67
68static __inline__ int atomic_read(const atomic_t *v)
69{
70	return ACCESS_ONCE((v)->counter);
71}
72
73/* exported interface */
74#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
75#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
76
77/**
78 * __atomic_add_unless - add unless the number is a given value
79 * @v: pointer of type atomic_t
80 * @a: the amount to add to v...
81 * @u: ...unless v is equal to u.
82 *
83 * Atomically adds @a to @v, so long as it was not @u.
84 * Returns the old value of @v.
85 */
86static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u)
87{
88	int c, old;
89	c = atomic_read(v);
90	for (;;) {
91		if (unlikely(c == (u)))
92			break;
93		old = atomic_cmpxchg((v), c, c + (a));
94		if (likely(old == c))
95			break;
96		c = old;
97	}
98	return c;
99}
100
101#define ATOMIC_OP(op, c_op)						\
102static __inline__ void atomic_##op(int i, atomic_t *v)			\
103{									\
104	unsigned long flags;						\
105									\
106	_atomic_spin_lock_irqsave(v, flags);				\
107	v->counter c_op i;						\
108	_atomic_spin_unlock_irqrestore(v, flags);			\
109}									\
110
111#define ATOMIC_OP_RETURN(op, c_op)					\
112static __inline__ int atomic_##op##_return(int i, atomic_t *v)		\
113{									\
114	unsigned long flags;						\
115	int ret;							\
116									\
117	_atomic_spin_lock_irqsave(v, flags);				\
118	ret = (v->counter c_op i);					\
119	_atomic_spin_unlock_irqrestore(v, flags);			\
120									\
121	return ret;							\
122}
123
124#define ATOMIC_OPS(op, c_op) ATOMIC_OP(op, c_op) ATOMIC_OP_RETURN(op, c_op)
125
126ATOMIC_OPS(add, +=)
127ATOMIC_OPS(sub, -=)
128
129#undef ATOMIC_OPS
130#undef ATOMIC_OP_RETURN
131#undef ATOMIC_OP
132
133#define atomic_inc(v)	(atomic_add(   1,(v)))
134#define atomic_dec(v)	(atomic_add(  -1,(v)))
135
136#define atomic_inc_return(v)	(atomic_add_return(   1,(v)))
137#define atomic_dec_return(v)	(atomic_add_return(  -1,(v)))
138
139#define atomic_add_negative(a, v)	(atomic_add_return((a), (v)) < 0)
140
141/*
142 * atomic_inc_and_test - increment and test
143 * @v: pointer of type atomic_t
144 *
145 * Atomically increments @v by 1
146 * and returns true if the result is zero, or false for all
147 * other cases.
148 */
149#define atomic_inc_and_test(v) (atomic_inc_return(v) == 0)
150
151#define atomic_dec_and_test(v)	(atomic_dec_return(v) == 0)
152
153#define atomic_sub_and_test(i,v)	(atomic_sub_return((i),(v)) == 0)
154
155#define ATOMIC_INIT(i)	{ (i) }
156
157#ifdef CONFIG_64BIT
158
159#define ATOMIC64_INIT(i) { (i) }
160
161#define ATOMIC64_OP(op, c_op)						\
162static __inline__ void atomic64_##op(s64 i, atomic64_t *v)		\
163{									\
164	unsigned long flags;						\
165									\
166	_atomic_spin_lock_irqsave(v, flags);				\
167	v->counter c_op i;						\
168	_atomic_spin_unlock_irqrestore(v, flags);			\
169}									\
170
171#define ATOMIC64_OP_RETURN(op, c_op)					\
172static __inline__ s64 atomic64_##op##_return(s64 i, atomic64_t *v)	\
173{									\
174	unsigned long flags;						\
175	s64 ret;							\
176									\
177	_atomic_spin_lock_irqsave(v, flags);				\
178	ret = (v->counter c_op i);					\
179	_atomic_spin_unlock_irqrestore(v, flags);			\
180									\
181	return ret;							\
182}
183
184#define ATOMIC64_OPS(op, c_op) ATOMIC64_OP(op, c_op) ATOMIC64_OP_RETURN(op, c_op)
185
186ATOMIC64_OPS(add, +=)
187ATOMIC64_OPS(sub, -=)
188
189#undef ATOMIC64_OPS
190#undef ATOMIC64_OP_RETURN
191#undef ATOMIC64_OP
192
193static __inline__ void
194atomic64_set(atomic64_t *v, s64 i)
195{
196	unsigned long flags;
197	_atomic_spin_lock_irqsave(v, flags);
198
199	v->counter = i;
200
201	_atomic_spin_unlock_irqrestore(v, flags);
202}
203
204static __inline__ s64
205atomic64_read(const atomic64_t *v)
206{
207	return ACCESS_ONCE((v)->counter);
208}
209
210#define atomic64_inc(v)		(atomic64_add(   1,(v)))
211#define atomic64_dec(v)		(atomic64_add(  -1,(v)))
212
213#define atomic64_inc_return(v)		(atomic64_add_return(   1,(v)))
214#define atomic64_dec_return(v)		(atomic64_add_return(  -1,(v)))
215
216#define atomic64_add_negative(a, v)	(atomic64_add_return((a), (v)) < 0)
217
218#define atomic64_inc_and_test(v) 	(atomic64_inc_return(v) == 0)
219#define atomic64_dec_and_test(v)	(atomic64_dec_return(v) == 0)
220#define atomic64_sub_and_test(i,v)	(atomic64_sub_return((i),(v)) == 0)
221
222/* exported interface */
223#define atomic64_cmpxchg(v, o, n) \
224	((__typeof__((v)->counter))cmpxchg(&((v)->counter), (o), (n)))
225#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
226
227/**
228 * atomic64_add_unless - add unless the number is a given value
229 * @v: pointer of type atomic64_t
230 * @a: the amount to add to v...
231 * @u: ...unless v is equal to u.
232 *
233 * Atomically adds @a to @v, so long as it was not @u.
234 * Returns the old value of @v.
235 */
236static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u)
237{
238	long c, old;
239	c = atomic64_read(v);
240	for (;;) {
241		if (unlikely(c == (u)))
242			break;
243		old = atomic64_cmpxchg((v), c, c + (a));
244		if (likely(old == c))
245			break;
246		c = old;
247	}
248	return c != (u);
249}
250
251#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
252
253/*
254 * atomic64_dec_if_positive - decrement by 1 if old value positive
255 * @v: pointer of type atomic_t
256 *
257 * The function returns the old value of *v minus 1, even if
258 * the atomic variable, v, was not decremented.
259 */
260static inline long atomic64_dec_if_positive(atomic64_t *v)
261{
262	long c, old, dec;
263	c = atomic64_read(v);
264	for (;;) {
265		dec = c - 1;
266		if (unlikely(dec < 0))
267			break;
268		old = atomic64_cmpxchg((v), c, dec);
269		if (likely(old == c))
270			break;
271		c = old;
272	}
273	return dec;
274}
275
276#endif /* !CONFIG_64BIT */
277
278
279#endif /* _ASM_PARISC_ATOMIC_H_ */
280