1 /*
2 * Atomic operations that C can't guarantee us. Useful for
3 * resource counting etc.
4 *
5 * But use these as seldom as possible since they are slower than
6 * regular operations.
7 *
8 * Copyright (C) 2004-2006 Atmel Corporation
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14 #ifndef __ASM_AVR32_ATOMIC_H
15 #define __ASM_AVR32_ATOMIC_H
16
17 #include <linux/types.h>
18 #include <asm/cmpxchg.h>
19
20 #define ATOMIC_INIT(i) { (i) }
21
22 #define atomic_read(v) READ_ONCE((v)->counter)
23 #define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i))
24
25 #define ATOMIC_OP_RETURN(op, asm_op, asm_con) \
26 static inline int __atomic_##op##_return(int i, atomic_t *v) \
27 { \
28 int result; \
29 \
30 asm volatile( \
31 "/* atomic_" #op "_return */\n" \
32 "1: ssrf 5\n" \
33 " ld.w %0, %2\n" \
34 " " #asm_op " %0, %3\n" \
35 " stcond %1, %0\n" \
36 " brne 1b" \
37 : "=&r" (result), "=o" (v->counter) \
38 : "m" (v->counter), #asm_con (i) \
39 : "cc"); \
40 \
41 return result; \
42 }
43
44 #define ATOMIC_FETCH_OP(op, asm_op, asm_con) \
45 static inline int __atomic_fetch_##op(int i, atomic_t *v) \
46 { \
47 int result, val; \
48 \
49 asm volatile( \
50 "/* atomic_fetch_" #op " */\n" \
51 "1: ssrf 5\n" \
52 " ld.w %0, %3\n" \
53 " mov %1, %0\n" \
54 " " #asm_op " %1, %4\n" \
55 " stcond %2, %1\n" \
56 " brne 1b" \
57 : "=&r" (result), "=&r" (val), "=o" (v->counter) \
58 : "m" (v->counter), #asm_con (i) \
59 : "cc"); \
60 \
61 return result; \
62 }
63
ATOMIC_OP_RETURN(sub,sub,rKs21)64 ATOMIC_OP_RETURN(sub, sub, rKs21)
65 ATOMIC_OP_RETURN(add, add, r)
66 ATOMIC_FETCH_OP (sub, sub, rKs21)
67 ATOMIC_FETCH_OP (add, add, r)
68
69 #define ATOMIC_OPS(op, asm_op) \
70 ATOMIC_OP_RETURN(op, asm_op, r) \
71 static inline void atomic_##op(int i, atomic_t *v) \
72 { \
73 (void)__atomic_##op##_return(i, v); \
74 } \
75 ATOMIC_FETCH_OP(op, asm_op, r) \
76 static inline int atomic_fetch_##op(int i, atomic_t *v) \
77 { \
78 return __atomic_fetch_##op(i, v); \
79 }
80
81 ATOMIC_OPS(and, and)
82 ATOMIC_OPS(or, or)
83 ATOMIC_OPS(xor, eor)
84
85 #undef ATOMIC_OPS
86 #undef ATOMIC_FETCH_OP
87 #undef ATOMIC_OP_RETURN
88
89 /*
90 * Probably found the reason why we want to use sub with the signed 21-bit
91 * limit, it uses one less register than the add instruction that can add up to
92 * 32-bit values.
93 *
94 * Both instructions are 32-bit, to use a 16-bit instruction the immediate is
95 * very small; 4 bit.
96 *
97 * sub 32-bit, type IV, takes a register and subtracts a 21-bit immediate.
98 * add 32-bit, type II, adds two register values together.
99 */
100 #define IS_21BIT_CONST(i) \
101 (__builtin_constant_p(i) && ((i) >= -1048575) && ((i) <= 1048576))
102
103 /*
104 * atomic_add_return - add integer to atomic variable
105 * @i: integer value to add
106 * @v: pointer of type atomic_t
107 *
108 * Atomically adds @i to @v. Returns the resulting value.
109 */
110 static inline int atomic_add_return(int i, atomic_t *v)
111 {
112 if (IS_21BIT_CONST(i))
113 return __atomic_sub_return(-i, v);
114
115 return __atomic_add_return(i, v);
116 }
117
atomic_fetch_add(int i,atomic_t * v)118 static inline int atomic_fetch_add(int i, atomic_t *v)
119 {
120 if (IS_21BIT_CONST(i))
121 return __atomic_fetch_sub(-i, v);
122
123 return __atomic_fetch_add(i, v);
124 }
125
126 /*
127 * atomic_sub_return - subtract the atomic variable
128 * @i: integer value to subtract
129 * @v: pointer of type atomic_t
130 *
131 * Atomically subtracts @i from @v. Returns the resulting value.
132 */
atomic_sub_return(int i,atomic_t * v)133 static inline int atomic_sub_return(int i, atomic_t *v)
134 {
135 if (IS_21BIT_CONST(i))
136 return __atomic_sub_return(i, v);
137
138 return __atomic_add_return(-i, v);
139 }
140
atomic_fetch_sub(int i,atomic_t * v)141 static inline int atomic_fetch_sub(int i, atomic_t *v)
142 {
143 if (IS_21BIT_CONST(i))
144 return __atomic_fetch_sub(i, v);
145
146 return __atomic_fetch_add(-i, v);
147 }
148
149 /*
150 * __atomic_add_unless - add unless the number is a given value
151 * @v: pointer of type atomic_t
152 * @a: the amount to add to v...
153 * @u: ...unless v is equal to u.
154 *
155 * Atomically adds @a to @v, so long as it was not @u.
156 * Returns the old value of @v.
157 */
__atomic_add_unless(atomic_t * v,int a,int u)158 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
159 {
160 int tmp, old = atomic_read(v);
161
162 if (IS_21BIT_CONST(a)) {
163 asm volatile(
164 "/* __atomic_sub_unless */\n"
165 "1: ssrf 5\n"
166 " ld.w %0, %2\n"
167 " cp.w %0, %4\n"
168 " breq 1f\n"
169 " sub %0, %3\n"
170 " stcond %1, %0\n"
171 " brne 1b\n"
172 "1:"
173 : "=&r"(tmp), "=o"(v->counter)
174 : "m"(v->counter), "rKs21"(-a), "rKs21"(u)
175 : "cc", "memory");
176 } else {
177 asm volatile(
178 "/* __atomic_add_unless */\n"
179 "1: ssrf 5\n"
180 " ld.w %0, %2\n"
181 " cp.w %0, %4\n"
182 " breq 1f\n"
183 " add %0, %3\n"
184 " stcond %1, %0\n"
185 " brne 1b\n"
186 "1:"
187 : "=&r"(tmp), "=o"(v->counter)
188 : "m"(v->counter), "r"(a), "ir"(u)
189 : "cc", "memory");
190 }
191
192 return old;
193 }
194
195 #undef IS_21BIT_CONST
196
197 /*
198 * atomic_sub_if_positive - conditionally subtract integer from atomic variable
199 * @i: integer value to subtract
200 * @v: pointer of type atomic_t
201 *
202 * Atomically test @v and subtract @i if @v is greater or equal than @i.
203 * The function returns the old value of @v minus @i.
204 */
atomic_sub_if_positive(int i,atomic_t * v)205 static inline int atomic_sub_if_positive(int i, atomic_t *v)
206 {
207 int result;
208
209 asm volatile(
210 "/* atomic_sub_if_positive */\n"
211 "1: ssrf 5\n"
212 " ld.w %0, %2\n"
213 " sub %0, %3\n"
214 " brlt 1f\n"
215 " stcond %1, %0\n"
216 " brne 1b\n"
217 "1:"
218 : "=&r"(result), "=o"(v->counter)
219 : "m"(v->counter), "ir"(i)
220 : "cc", "memory");
221
222 return result;
223 }
224
225 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
226 #define atomic_cmpxchg(v, o, n) (cmpxchg(&((v)->counter), (o), (n)))
227
228 #define atomic_sub(i, v) (void)atomic_sub_return(i, v)
229 #define atomic_add(i, v) (void)atomic_add_return(i, v)
230 #define atomic_dec(v) atomic_sub(1, (v))
231 #define atomic_inc(v) atomic_add(1, (v))
232
233 #define atomic_dec_return(v) atomic_sub_return(1, v)
234 #define atomic_inc_return(v) atomic_add_return(1, v)
235
236 #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)
237 #define atomic_inc_and_test(v) (atomic_add_return(1, v) == 0)
238 #define atomic_dec_and_test(v) (atomic_sub_return(1, v) == 0)
239 #define atomic_add_negative(i, v) (atomic_add_return(i, v) < 0)
240
241 #define atomic_dec_if_positive(v) atomic_sub_if_positive(1, v)
242
243 #endif /* __ASM_AVR32_ATOMIC_H */
244