1#ifndef _ASM_GENERIC_BITOPS_ATOMIC_H_
2#define _ASM_GENERIC_BITOPS_ATOMIC_H_
3
4#include <asm/types.h>
5#include <asm/system.h>
6
7#ifdef CONFIG_SMP
8#include <asm/spinlock.h>
9#include <asm/cache.h>		/* we use L1_CACHE_BYTES */
10
11/* Use an array of spinlocks for our atomic_ts.
12 * Hash function to index into a different SPINLOCK.
13 * Since "a" is usually an address, use one spinlock per cacheline.
14 */
15#  define ATOMIC_HASH_SIZE 4
16#  define ATOMIC_HASH(a) (&(__atomic_hash[ (((unsigned long) a)/L1_CACHE_BYTES) & (ATOMIC_HASH_SIZE-1) ]))
17
18extern raw_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned;
19
20/* Can't use raw_spin_lock_irq because of #include problems, so
21 * this is the substitute */
22#define _atomic_spin_lock_irqsave(l,f) do {	\
23	raw_spinlock_t *s = ATOMIC_HASH(l);	\
24	local_irq_save(f);			\
25	__raw_spin_lock(s);			\
26} while(0)
27
28#define _atomic_spin_unlock_irqrestore(l,f) do {	\
29	raw_spinlock_t *s = ATOMIC_HASH(l);		\
30	__raw_spin_unlock(s);				\
31	local_irq_restore(f);				\
32} while(0)
33
34
35#else
36#  define _atomic_spin_lock_irqsave(l,f) do { local_irq_save(f); } while (0)
37#  define _atomic_spin_unlock_irqrestore(l,f) do { local_irq_restore(f); } while (0)
38#endif
39
40/*
41 * NMI events can occur at any time, including when interrupts have been
42 * disabled by *_irqsave().  So you can get NMI events occurring while a
43 * *_bit function is holding a spin lock.  If the NMI handler also wants
44 * to do bit manipulation (and they do) then you can get a deadlock
45 * between the original caller of *_bit() and the NMI handler.
46 *
47 * by Keith Owens
48 */
49
50/**
51 * set_bit - Atomically set a bit in memory
52 * @nr: the bit to set
53 * @addr: the address to start counting from
54 *
55 * This function is atomic and may not be reordered.  See __set_bit()
56 * if you do not require the atomic guarantees.
57 *
58 * Note: there are no guarantees that this function will not be reordered
59 * on non x86 architectures, so if you are writing portable code,
60 * make sure not to rely on its reordering guarantees.
61 *
62 * Note that @nr may be almost arbitrarily large; this function is not
63 * restricted to acting on a single-word quantity.
64 */
65static inline void set_bit(int nr, volatile unsigned long *addr)
66{
67	unsigned long mask = BIT_MASK(nr);
68	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
69	unsigned long flags;
70
71	_atomic_spin_lock_irqsave(p, flags);
72	*p  |= mask;
73	_atomic_spin_unlock_irqrestore(p, flags);
74}
75
76/**
77 * clear_bit - Clears a bit in memory
78 * @nr: Bit to clear
79 * @addr: Address to start counting from
80 *
81 * clear_bit() is atomic and may not be reordered.  However, it does
82 * not contain a memory barrier, so if it is used for locking purposes,
83 * you should call smp_mb__before_clear_bit() and/or smp_mb__after_clear_bit()
84 * in order to ensure changes are visible on other processors.
85 */
86static inline void clear_bit(int nr, volatile unsigned long *addr)
87{
88	unsigned long mask = BIT_MASK(nr);
89	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
90	unsigned long flags;
91
92	_atomic_spin_lock_irqsave(p, flags);
93	*p &= ~mask;
94	_atomic_spin_unlock_irqrestore(p, flags);
95}
96
97/**
98 * change_bit - Toggle a bit in memory
99 * @nr: Bit to change
100 * @addr: Address to start counting from
101 *
102 * change_bit() is atomic and may not be reordered. It may be
103 * reordered on other architectures than x86.
104 * Note that @nr may be almost arbitrarily large; this function is not
105 * restricted to acting on a single-word quantity.
106 */
107static inline void change_bit(int nr, volatile unsigned long *addr)
108{
109	unsigned long mask = BIT_MASK(nr);
110	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
111	unsigned long flags;
112
113	_atomic_spin_lock_irqsave(p, flags);
114	*p ^= mask;
115	_atomic_spin_unlock_irqrestore(p, flags);
116}
117
118/**
119 * test_and_set_bit - Set a bit and return its old value
120 * @nr: Bit to set
121 * @addr: Address to count from
122 *
123 * This operation is atomic and cannot be reordered.
124 * It may be reordered on other architectures than x86.
125 * It also implies a memory barrier.
126 */
127static inline int test_and_set_bit(int nr, volatile unsigned long *addr)
128{
129	unsigned long mask = BIT_MASK(nr);
130	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
131	unsigned long old;
132	unsigned long flags;
133
134	_atomic_spin_lock_irqsave(p, flags);
135	old = *p;
136	*p = old | mask;
137	_atomic_spin_unlock_irqrestore(p, flags);
138
139	return (old & mask) != 0;
140}
141
142/**
143 * test_and_clear_bit - Clear a bit and return its old value
144 * @nr: Bit to clear
145 * @addr: Address to count from
146 *
147 * This operation is atomic and cannot be reordered.
148 * It can be reorderdered on other architectures other than x86.
149 * It also implies a memory barrier.
150 */
151static inline int test_and_clear_bit(int nr, volatile unsigned long *addr)
152{
153	unsigned long mask = BIT_MASK(nr);
154	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
155	unsigned long old;
156	unsigned long flags;
157
158	_atomic_spin_lock_irqsave(p, flags);
159	old = *p;
160	*p = old & ~mask;
161	_atomic_spin_unlock_irqrestore(p, flags);
162
163	return (old & mask) != 0;
164}
165
166/**
167 * test_and_change_bit - Change a bit and return its old value
168 * @nr: Bit to change
169 * @addr: Address to count from
170 *
171 * This operation is atomic and cannot be reordered.
172 * It also implies a memory barrier.
173 */
174static inline int test_and_change_bit(int nr, volatile unsigned long *addr)
175{
176	unsigned long mask = BIT_MASK(nr);
177	unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
178	unsigned long old;
179	unsigned long flags;
180
181	_atomic_spin_lock_irqsave(p, flags);
182	old = *p;
183	*p = old ^ mask;
184	_atomic_spin_unlock_irqrestore(p, flags);
185
186	return (old & mask) != 0;
187}
188
189#endif /* _ASM_GENERIC_BITOPS_ATOMIC_H */
190