1 #ifdef __KERNEL__
2 #ifndef _PPC_SEMAPHORE_HELPER_H
3 #define _PPC_SEMAPHORE_HELPER_H
4
5 /*
6 * SMP- and interrupt-safe semaphores..
7 *
8 * (C) Copyright 1996 Linus Torvalds
9 * Adapted for PowerPC by Gary Thomas and Paul Mackerras
10 */
11
12 #include <asm/atomic.h>
13
14 /*
15 * These two (wake_one_more and waking_non_zero) _must_ execute
16 * atomically wrt each other.
17 *
18 * This is trivially done with load with reservation and
19 * store conditional on the ppc.
20 */
21
22 static inline void wake_one_more(struct semaphore * sem)
23 {
24 atomic_inc(&sem->waking);
25 }
26
27 static inline int waking_non_zero(struct semaphore *sem)
28 {
29 int ret, tmp;
30
31 /* Atomic decrement sem->waking iff it is > 0 */
32 __asm__ __volatile__(
33 "1: lwarx %1,0,%2\n" /* tmp = sem->waking */
34 " cmpwi 0,%1,0\n" /* test tmp */
35 " addic %1,%1,-1\n" /* --tmp */
36 " ble- 2f\n" /* exit if tmp was <= 0 */
37 " stwcx. %1,0,%2\n" /* update sem->waking */
38 " bne- 1b\n" /* try again if update failed*/
39 " li %0,1\n" /* ret = 1 */
40 "2:"
41 : "=r" (ret), "=&r" (tmp)
42 : "r" (&sem->waking), "" (0)
43 : "cr0", "memory");
44
45 return ret;
46 }
47 /*
48 * waking_non_zero_interruptible:
49 * 1 got the lock
50 * 0 go to sleep
51 * -EINTR interrupted
52 */
53 static inline int waking_non_zero_interruptible(struct semaphore *sem,
54 struct task_struct *tsk)
55 {
56 int ret, tmp;
57
58 /* Atomic decrement sem->waking iff it is > 0 */
59 __asm__ __volatile__(
60 "1: lwarx %1,0,%2\n" /* tmp = sem->waking */
61 " cmpwi 0,%1,0\n" /* test tmp */
62 " addic %1,%1,-1\n" /* --tmp */
63 " ble- 2f\n" /* exit if tmp was <= 0 */
64 " stwcx. %1,0,%2\n" /* update sem->waking */
65 " bne- 1b\n" /* try again if update failed*/
66 " li %0,1\n" /* ret = 1 */
67 "2:"
68 : "=r" (ret), "=&r" (tmp)
69 : "r" (&sem->waking), "" (0)
70 : "cr0", "memory");
71
72 if (ret == 0 && signal_pending(tsk)) {
73 atomic_inc(&sem->count);
74 ret = -EINTR;
75 }
76 return ret;
77 }
78
79 /*
80 * waking_non_zero_trylock:
81 * 1 failed to lock
82 * 0 got the lock
83 */
84 static inline int waking_non_zero_trylock(struct semaphore *sem)
85 {
86 int ret, tmp;
87
88 /* Atomic decrement sem->waking iff it is > 0 */
89 __asm__ __volatile__(
90 "1: lwarx %1,0,%2\n" /* tmp = sem->waking */
91 " cmpwi 0,%1,0\n" /* test tmp */
92 " addic %1,%1,-1\n" /* --tmp */
93 " ble- 2f\n" /* exit if tmp was <= 0 */
94 " stwcx. %1,0,%2\n" /* update sem->waking */
95 " bne- 1b\n" /* try again if update failed*/
96 " li %0,0\n" /* ret = 0 */
97 "2:"
98 : "=r" (ret), "=&r" (tmp)
99 : "r" (&sem->waking), "" (1)
100 : "cr0", "memory");
101
102 if (ret)
103 atomic_inc(&sem->count);
104
105 return ret;
106 }
107
108 #endif /* _PPC_SEMAPHORE_HELPER_H */
109 #endif /* __KERNEL__ */
110
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