1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
/*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc.
*
* But use these as seldom as possible since they are slower than
* regular operations.
*
* Copyright (C) 2004-2006 Atmel Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef __ASM_AVR32_ATOMIC_H
#define __ASM_AVR32_ATOMIC_H
#include <linux/types.h>
#include <asm/cmpxchg.h>
#define ATOMIC_INIT(i) { (i) }
#define atomic_read(v) READ_ONCE((v)->counter)
#define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
#define ATOMIC_OP_RETURN(op, asm_op, asm_con) \
static inline int __atomic_##op##_return(int i, atomic_t *v) \
{ \
int result; \
\
asm volatile( \
"/* atomic_" #op "_return */\n" \
"1: ssrf 5\n" \
" ld.w %0, %2\n" \
" " #asm_op " %0, %3\n" \
" stcond %1, %0\n" \
" brne 1b" \
: "=&r" (result), "=o" (v->counter) \
: "m" (v->counter), #asm_con (i) \
: "cc"); \
\
return result; \
}
ATOMIC_OP_RETURN(sub, sub, rKs21)
ATOMIC_OP_RETURN(add, add, r)
#define ATOMIC_OP(op, asm_op) \
ATOMIC_OP_RETURN(op, asm_op, r) \
static inline void atomic_##op(int i, atomic_t *v) \
{ \
(void)__atomic_##op##_return(i, v); \
}
ATOMIC_OP(and, and)
ATOMIC_OP(or, or)
ATOMIC_OP(xor, eor)
#undef ATOMIC_OP
#undef ATOMIC_OP_RETURN
/*
* Probably found the reason why we want to use sub with the signed 21-bit
* limit, it uses one less register than the add instruction that can add up to
* 32-bit values.
*
* Both instructions are 32-bit, to use a 16-bit instruction the immediate is
* very small; 4 bit.
*
* sub 32-bit, type IV, takes a register and subtracts a 21-bit immediate.
* add 32-bit, type II, adds two register values together.
*/
#define IS_21BIT_CONST(i) \
(__builtin_constant_p(i) && ((i) >= -1048575) && ((i) <= 1048576))
/*
* atomic_add_return - add integer to atomic variable
* @i: integer value to add
* @v: pointer of type atomic_t
*
* Atomically adds @i to @v. Returns the resulting value.
*/
static inline int atomic_add_return(int i, atomic_t *v)
{
if (IS_21BIT_CONST(i))
return __atomic_sub_return(-i, v);
return __atomic_add_return(i, v);
}
/*
* atomic_sub_return - subtract the atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v. Returns the resulting value.
*/
static inline int atomic_sub_return(int i, atomic_t *v)
{
if (IS_21BIT_CONST(i))
return __atomic_sub_return(i, v);
return __atomic_add_return(-i, v);
}
/*
* __atomic_add_unless - add unless the number is a given value
* @v: pointer of type atomic_t
* @a: the amount to add to v...
* @u: ...unless v is equal to u.
*
* Atomically adds @a to @v, so long as it was not @u.
* Returns the old value of @v.
*/
static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
int tmp, old = atomic_read(v);
if (IS_21BIT_CONST(a)) {
asm volatile(
"/* __atomic_sub_unless */\n"
"1: ssrf 5\n"
" ld.w %0, %2\n"
" cp.w %0, %4\n"
" breq 1f\n"
" sub %0, %3\n"
" stcond %1, %0\n"
" brne 1b\n"
"1:"
: "=&r"(tmp), "=o"(v->counter)
: "m"(v->counter), "rKs21"(-a), "rKs21"(u)
: "cc", "memory");
} else {
asm volatile(
"/* __atomic_add_unless */\n"
"1: ssrf 5\n"
" ld.w %0, %2\n"
" cp.w %0, %4\n"
" breq 1f\n"
" add %0, %3\n"
" stcond %1, %0\n"
" brne 1b\n"
"1:"
: "=&r"(tmp), "=o"(v->counter)
: "m"(v->counter), "r"(a), "ir"(u)
: "cc", "memory");
}
return old;
}
#undef IS_21BIT_CONST
/*
* atomic_sub_if_positive - conditionally subtract integer from atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically test @v and subtract @i if @v is greater or equal than @i.
* The function returns the old value of @v minus @i.
*/
static inline int atomic_sub_if_positive(int i, atomic_t *v)
{
int result;
asm volatile(
"/* atomic_sub_if_positive */\n"
"1: ssrf 5\n"
" ld.w %0, %2\n"
" sub %0, %3\n"
" brlt 1f\n"
" stcond %1, %0\n"
" brne 1b\n"
"1:"
: "=&r"(result), "=o"(v->counter)
: "m"(v->counter), "ir"(i)
: "cc", "memory");
return result;
}
#define atomic_xchg(v, new) (xchg(&((v)->counter), new))
#define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
#define atomic_sub(i, v) (void)atomic_sub_return(i, v)
#define atomic_add(i, v) (void)atomic_add_return(i, v)
#define atomic_dec(v) atomic_sub(1, (v))
#define atomic_inc(v) atomic_add(1, (v))
#define atomic_dec_return(v) atomic_sub_return(1, v)
#define atomic_inc_return(v) atomic_add_return(1, v)
#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
#define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
#define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
#define atomic_add_negative(i, v) (atomic_add_return(i, v) < 0)
#define atomic_dec_if_positive(v) atomic_sub_if_positive(1, v)
#endif /* __ASM_AVR32_ATOMIC_H */
|
