ssb: remove the ssb DMA API
[linux-2.6.git] / include / linux / bit_spinlock.h
1 #ifndef __LINUX_BIT_SPINLOCK_H
2 #define __LINUX_BIT_SPINLOCK_H
3
4 /*
5  *  bit-based spin_lock()
6  *
7  * Don't use this unless you really need to: spin_lock() and spin_unlock()
8  * are significantly faster.
9  */
10 static inline void bit_spin_lock(int bitnum, unsigned long *addr)
11 {
12         /*
13          * Assuming the lock is uncontended, this never enters
14          * the body of the outer loop. If it is contended, then
15          * within the inner loop a non-atomic test is used to
16          * busywait with less bus contention for a good time to
17          * attempt to acquire the lock bit.
18          */
19         preempt_disable();
20 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
21         while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
22                 while (test_bit(bitnum, addr)) {
23                         preempt_enable();
24                         cpu_relax();
25                         preempt_disable();
26                 }
27         }
28 #endif
29         __acquire(bitlock);
30 }
31
32 /*
33  * Return true if it was acquired
34  */
35 static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
36 {
37         preempt_disable();
38 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
39         if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
40                 preempt_enable();
41                 return 0;
42         }
43 #endif
44         __acquire(bitlock);
45         return 1;
46 }
47
48 /*
49  *  bit-based spin_unlock()
50  */
51 static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
52 {
53 #ifdef CONFIG_DEBUG_SPINLOCK
54         BUG_ON(!test_bit(bitnum, addr));
55 #endif
56 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
57         clear_bit_unlock(bitnum, addr);
58 #endif
59         preempt_enable();
60         __release(bitlock);
61 }
62
63 /*
64  *  bit-based spin_unlock()
65  *  non-atomic version, which can be used eg. if the bit lock itself is
66  *  protecting the rest of the flags in the word.
67  */
68 static inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
69 {
70 #ifdef CONFIG_DEBUG_SPINLOCK
71         BUG_ON(!test_bit(bitnum, addr));
72 #endif
73 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
74         __clear_bit_unlock(bitnum, addr);
75 #endif
76         preempt_enable();
77         __release(bitlock);
78 }
79
80 /*
81  * Return true if the lock is held.
82  */
83 static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
84 {
85 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
86         return test_bit(bitnum, addr);
87 #elif defined CONFIG_PREEMPT
88         return preempt_count();
89 #else
90         return 1;
91 #endif
92 }
93
94 #endif /* __LINUX_BIT_SPINLOCK_H */
95