Merge branch 'drm-nouveau-next' of git://anongit.freedesktop.org/git/nouveau/linux-2.6
[firefly-linux-kernel-4.4.55.git] / include / linux / spinlock_up.h
1 #ifndef __LINUX_SPINLOCK_UP_H
2 #define __LINUX_SPINLOCK_UP_H
3
4 #ifndef __LINUX_SPINLOCK_H
5 # error "please don't include this file directly"
6 #endif
7
8 #include <asm/processor.h>      /* for cpu_relax() */
9
10 /*
11  * include/linux/spinlock_up.h - UP-debug version of spinlocks.
12  *
13  * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
14  * Released under the General Public License (GPL).
15  *
16  * In the debug case, 1 means unlocked, 0 means locked. (the values
17  * are inverted, to catch initialization bugs)
18  *
19  * No atomicity anywhere, we are on UP. However, we still need
20  * the compiler barriers, because we do not want the compiler to
21  * move potentially faulting instructions (notably user accesses)
22  * into the locked sequence, resulting in non-atomic execution.
23  */
24
25 #ifdef CONFIG_DEBUG_SPINLOCK
26 #define arch_spin_is_locked(x)          ((x)->slock == 0)
27
28 static inline void arch_spin_lock(arch_spinlock_t *lock)
29 {
30         lock->slock = 0;
31         barrier();
32 }
33
34 static inline void
35 arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
36 {
37         local_irq_save(flags);
38         lock->slock = 0;
39         barrier();
40 }
41
42 static inline int arch_spin_trylock(arch_spinlock_t *lock)
43 {
44         char oldval = lock->slock;
45
46         lock->slock = 0;
47         barrier();
48
49         return oldval > 0;
50 }
51
52 static inline void arch_spin_unlock(arch_spinlock_t *lock)
53 {
54         barrier();
55         lock->slock = 1;
56 }
57
58 /*
59  * Read-write spinlocks. No debug version.
60  */
61 #define arch_read_lock(lock)            do { barrier(); (void)(lock); } while (0)
62 #define arch_write_lock(lock)           do { barrier(); (void)(lock); } while (0)
63 #define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; })
64 #define arch_write_trylock(lock)        ({ barrier(); (void)(lock); 1; })
65 #define arch_read_unlock(lock)          do { barrier(); (void)(lock); } while (0)
66 #define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0)
67
68 #else /* DEBUG_SPINLOCK */
69 #define arch_spin_is_locked(lock)       ((void)(lock), 0)
70 /* for sched/core.c and kernel_lock.c: */
71 # define arch_spin_lock(lock)           do { barrier(); (void)(lock); } while (0)
72 # define arch_spin_lock_flags(lock, flags)      do { barrier(); (void)(lock); } while (0)
73 # define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0)
74 # define arch_spin_trylock(lock)        ({ barrier(); (void)(lock); 1; })
75 #endif /* DEBUG_SPINLOCK */
76
77 #define arch_spin_is_contended(lock)    (((void)(lock), 0))
78
79 #define arch_read_can_lock(lock)        (((void)(lock), 1))
80 #define arch_write_can_lock(lock)       (((void)(lock), 1))
81
82 #define arch_spin_unlock_wait(lock) \
83                 do { cpu_relax(); } while (arch_spin_is_locked(lock))
84
85 #endif /* __LINUX_SPINLOCK_UP_H */