1#ifndef _ALPHA_ATOMIC_H
2#define _ALPHA_ATOMIC_H
3
4/*
5 * Atomic operations that C can't guarantee us.  Useful for
6 * resource counting etc...
7 *
8 * But use these as seldom as possible since they are much slower
9 * than regular operations.
10 */
11
12
13/*
14 * Counter is volatile to make sure gcc doesn't try to be clever
15 * and move things around on us. We need to use _exactly_ the address
16 * the user gave us, not some alias that contains the same information.
17 */
18typedef struct { volatile int counter; } atomic_t;
19
20#define ATOMIC_INIT(i)	( (atomic_t) { (i) } )
21
22#define atomic_read(v)		((v)->counter)
23#define atomic_set(v,i)		((v)->counter = (i))
24
25/*
26 * To get proper branch prediction for the main line, we must branch
27 * forward to code at the end of this object's .text section, then
28 * branch back to restart the operation.
29 */
30
31static __inline__ void atomic_add(int i, atomic_t * v)
32{
33	unsigned long temp;
34	__asm__ __volatile__(
35	"1:	ldl_l %0,%1\n"
36	"	addl %0,%2,%0\n"
37	"	stl_c %0,%1\n"
38	"	beq %0,2f\n"
39	".subsection 2\n"
40	"2:	br 1b\n"
41	".previous"
42	:"=&r" (temp), "=m" (v->counter)
43	:"Ir" (i), "m" (v->counter));
44}
45
46static __inline__ void atomic_sub(int i, atomic_t * v)
47{
48	unsigned long temp;
49	__asm__ __volatile__(
50	"1:	ldl_l %0,%1\n"
51	"	subl %0,%2,%0\n"
52	"	stl_c %0,%1\n"
53	"	beq %0,2f\n"
54	".subsection 2\n"
55	"2:	br 1b\n"
56	".previous"
57	:"=&r" (temp), "=m" (v->counter)
58	:"Ir" (i), "m" (v->counter));
59}
60
61/*
62 * Same as above, but return the result value
63 */
64static __inline__ long atomic_add_return(int i, atomic_t * v)
65{
66	long temp, result;
67	__asm__ __volatile__(
68	"1:	ldl_l %0,%1\n"
69	"	addl %0,%3,%2\n"
70	"	addl %0,%3,%0\n"
71	"	stl_c %0,%1\n"
72	"	beq %0,2f\n"
73	"	mb\n"
74	".subsection 2\n"
75	"2:	br 1b\n"
76	".previous"
77	:"=&r" (temp), "=m" (v->counter), "=&r" (result)
78	:"Ir" (i), "m" (v->counter) : "memory");
79	return result;
80}
81
82static __inline__ long atomic_sub_return(int i, atomic_t * v)
83{
84	long temp, result;
85	__asm__ __volatile__(
86	"1:	ldl_l %0,%1\n"
87	"	subl %0,%3,%2\n"
88	"	subl %0,%3,%0\n"
89	"	stl_c %0,%1\n"
90	"	beq %0,2f\n"
91	"	mb\n"
92	".subsection 2\n"
93	"2:	br 1b\n"
94	".previous"
95	:"=&r" (temp), "=m" (v->counter), "=&r" (result)
96	:"Ir" (i), "m" (v->counter) : "memory");
97	return result;
98}
99
100#define atomic_dec_return(v) atomic_sub_return(1,(v))
101#define atomic_inc_return(v) atomic_add_return(1,(v))
102
103#define atomic_sub_and_test(i,v) (atomic_sub_return((i), (v)) == 0)
104#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)
105
106#define atomic_inc(v) atomic_add(1,(v))
107#define atomic_dec(v) atomic_sub(1,(v))
108
109#define smp_mb__before_atomic_dec()	smp_mb()
110#define smp_mb__after_atomic_dec()	smp_mb()
111#define smp_mb__before_atomic_inc()	smp_mb()
112#define smp_mb__after_atomic_inc()	smp_mb()
113
114#endif /* _ALPHA_ATOMIC_H */
115