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Linux/arch/xtensa/include/asm/atomic.h

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  1 /*
  2  * include/asm-xtensa/atomic.h
  3  *
  4  * Atomic operations that C can't guarantee us.  Useful for resource counting..
  5  *
  6  * This file is subject to the terms and conditions of the GNU General Public
  7  * License.  See the file "COPYING" in the main directory of this archive
  8  * for more details.
  9  *
 10  * Copyright (C) 2001 - 2008 Tensilica Inc.
 11  */
 12 
 13 #ifndef _XTENSA_ATOMIC_H
 14 #define _XTENSA_ATOMIC_H
 15 
 16 #include <linux/stringify.h>
 17 #include <linux/types.h>
 18 
 19 #ifdef __KERNEL__
 20 #include <asm/processor.h>
 21 #include <asm/cmpxchg.h>
 22 #include <asm/barrier.h>
 23 
 24 #define ATOMIC_INIT(i)  { (i) }
 25 
 26 /*
 27  * This Xtensa implementation assumes that the right mechanism
 28  * for exclusion is for locking interrupts to level EXCM_LEVEL.
 29  *
 30  * Locking interrupts looks like this:
 31  *
 32  *    rsil a15, LOCKLEVEL
 33  *    <code>
 34  *    wsr  a15, PS
 35  *    rsync
 36  *
 37  * Note that a15 is used here because the register allocation
 38  * done by the compiler is not guaranteed and a window overflow
 39  * may not occur between the rsil and wsr instructions. By using
 40  * a15 in the rsil, the machine is guaranteed to be in a state
 41  * where no register reference will cause an overflow.
 42  */
 43 
 44 /**
 45  * atomic_read - read atomic variable
 46  * @v: pointer of type atomic_t
 47  *
 48  * Atomically reads the value of @v.
 49  */
 50 #define atomic_read(v)          ACCESS_ONCE((v)->counter)
 51 
 52 /**
 53  * atomic_set - set atomic variable
 54  * @v: pointer of type atomic_t
 55  * @i: required value
 56  *
 57  * Atomically sets the value of @v to @i.
 58  */
 59 #define atomic_set(v,i)         ((v)->counter = (i))
 60 
 61 #if XCHAL_HAVE_S32C1I
 62 #define ATOMIC_OP(op)                                                   \
 63 static inline void atomic_##op(int i, atomic_t * v)                     \
 64 {                                                                       \
 65         unsigned long tmp;                                              \
 66         int result;                                                     \
 67                                                                         \
 68         __asm__ __volatile__(                                           \
 69                         "1:     l32i    %1, %3, 0\n"                    \
 70                         "       wsr     %1, scompare1\n"                \
 71                         "       " #op " %0, %1, %2\n"                   \
 72                         "       s32c1i  %0, %3, 0\n"                    \
 73                         "       bne     %0, %1, 1b\n"                   \
 74                         : "=&a" (result), "=&a" (tmp)                   \
 75                         : "a" (i), "a" (v)                              \
 76                         : "memory"                                      \
 77                         );                                              \
 78 }                                                                       \
 79 
 80 #define ATOMIC_OP_RETURN(op)                                            \
 81 static inline int atomic_##op##_return(int i, atomic_t * v)             \
 82 {                                                                       \
 83         unsigned long tmp;                                              \
 84         int result;                                                     \
 85                                                                         \
 86         __asm__ __volatile__(                                           \
 87                         "1:     l32i    %1, %3, 0\n"                    \
 88                         "       wsr     %1, scompare1\n"                \
 89                         "       " #op " %0, %1, %2\n"                   \
 90                         "       s32c1i  %0, %3, 0\n"                    \
 91                         "       bne     %0, %1, 1b\n"                   \
 92                         "       " #op " %0, %0, %2\n"                   \
 93                         : "=&a" (result), "=&a" (tmp)                   \
 94                         : "a" (i), "a" (v)                              \
 95                         : "memory"                                      \
 96                         );                                              \
 97                                                                         \
 98         return result;                                                  \
 99 }
100 
101 #else /* XCHAL_HAVE_S32C1I */
102 
103 #define ATOMIC_OP(op)                                                   \
104 static inline void atomic_##op(int i, atomic_t * v)                     \
105 {                                                                       \
106         unsigned int vval;                                              \
107                                                                         \
108         __asm__ __volatile__(                                           \
109                         "       rsil    a15, "__stringify(LOCKLEVEL)"\n"\
110                         "       l32i    %0, %2, 0\n"                    \
111                         "       " #op " %0, %0, %1\n"                   \
112                         "       s32i    %0, %2, 0\n"                    \
113                         "       wsr     a15, ps\n"                      \
114                         "       rsync\n"                                \
115                         : "=&a" (vval)                                  \
116                         : "a" (i), "a" (v)                              \
117                         : "a15", "memory"                               \
118                         );                                              \
119 }                                                                       \
120 
121 #define ATOMIC_OP_RETURN(op)                                            \
122 static inline int atomic_##op##_return(int i, atomic_t * v)             \
123 {                                                                       \
124         unsigned int vval;                                              \
125                                                                         \
126         __asm__ __volatile__(                                           \
127                         "       rsil    a15,"__stringify(LOCKLEVEL)"\n" \
128                         "       l32i    %0, %2, 0\n"                    \
129                         "       " #op " %0, %0, %1\n"                   \
130                         "       s32i    %0, %2, 0\n"                    \
131                         "       wsr     a15, ps\n"                      \
132                         "       rsync\n"                                \
133                         : "=&a" (vval)                                  \
134                         : "a" (i), "a" (v)                              \
135                         : "a15", "memory"                               \
136                         );                                              \
137                                                                         \
138         return vval;                                                    \
139 }
140 
141 #endif /* XCHAL_HAVE_S32C1I */
142 
143 #define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
144 
145 ATOMIC_OPS(add)
146 ATOMIC_OPS(sub)
147 
148 #undef ATOMIC_OPS
149 #undef ATOMIC_OP_RETURN
150 #undef ATOMIC_OP
151 
152 /**
153  * atomic_sub_and_test - subtract value from variable and test result
154  * @i: integer value to subtract
155  * @v: pointer of type atomic_t
156  *
157  * Atomically subtracts @i from @v and returns
158  * true if the result is zero, or false for all
159  * other cases.
160  */
161 #define atomic_sub_and_test(i,v) (atomic_sub_return((i),(v)) == 0)
162 
163 /**
164  * atomic_inc - increment atomic variable
165  * @v: pointer of type atomic_t
166  *
167  * Atomically increments @v by 1.
168  */
169 #define atomic_inc(v) atomic_add(1,(v))
170 
171 /**
172  * atomic_inc - increment atomic variable
173  * @v: pointer of type atomic_t
174  *
175  * Atomically increments @v by 1.
176  */
177 #define atomic_inc_return(v) atomic_add_return(1,(v))
178 
179 /**
180  * atomic_dec - decrement atomic variable
181  * @v: pointer of type atomic_t
182  *
183  * Atomically decrements @v by 1.
184  */
185 #define atomic_dec(v) atomic_sub(1,(v))
186 
187 /**
188  * atomic_dec_return - decrement atomic variable
189  * @v: pointer of type atomic_t
190  *
191  * Atomically decrements @v by 1.
192  */
193 #define atomic_dec_return(v) atomic_sub_return(1,(v))
194 
195 /**
196  * atomic_dec_and_test - decrement and test
197  * @v: pointer of type atomic_t
198  *
199  * Atomically decrements @v by 1 and
200  * returns true if the result is 0, or false for all other
201  * cases.
202  */
203 #define atomic_dec_and_test(v) (atomic_sub_return(1,(v)) == 0)
204 
205 /**
206  * atomic_inc_and_test - increment and test
207  * @v: pointer of type atomic_t
208  *
209  * Atomically increments @v by 1
210  * and returns true if the result is zero, or false for all
211  * other cases.
212  */
213 #define atomic_inc_and_test(v) (atomic_add_return(1,(v)) == 0)
214 
215 /**
216  * atomic_add_negative - add and test if negative
217  * @v: pointer of type atomic_t
218  * @i: integer value to add
219  *
220  * Atomically adds @i to @v and returns true
221  * if the result is negative, or false when
222  * result is greater than or equal to zero.
223  */
224 #define atomic_add_negative(i,v) (atomic_add_return((i),(v)) < 0)
225 
226 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
227 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
228 
229 /**
230  * __atomic_add_unless - add unless the number is a given value
231  * @v: pointer of type atomic_t
232  * @a: the amount to add to v...
233  * @u: ...unless v is equal to u.
234  *
235  * Atomically adds @a to @v, so long as it was not @u.
236  * Returns the old value of @v.
237  */
238 static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u)
239 {
240         int c, old;
241         c = atomic_read(v);
242         for (;;) {
243                 if (unlikely(c == (u)))
244                         break;
245                 old = atomic_cmpxchg((v), c, c + (a));
246                 if (likely(old == c))
247                         break;
248                 c = old;
249         }
250         return c;
251 }
252 
253 
254 static inline void atomic_clear_mask(unsigned int mask, atomic_t *v)
255 {
256 #if XCHAL_HAVE_S32C1I
257         unsigned long tmp;
258         int result;
259 
260         __asm__ __volatile__(
261                         "1:     l32i    %1, %3, 0\n"
262                         "       wsr     %1, scompare1\n"
263                         "       and     %0, %1, %2\n"
264                         "       s32c1i  %0, %3, 0\n"
265                         "       bne     %0, %1, 1b\n"
266                         : "=&a" (result), "=&a" (tmp)
267                         : "a" (~mask), "a" (v)
268                         : "memory"
269                         );
270 #else
271         unsigned int all_f = -1;
272         unsigned int vval;
273 
274         __asm__ __volatile__(
275                         "       rsil    a15,"__stringify(LOCKLEVEL)"\n"
276                         "       l32i    %0, %2, 0\n"
277                         "       xor     %1, %4, %3\n"
278                         "       and     %0, %0, %4\n"
279                         "       s32i    %0, %2, 0\n"
280                         "       wsr     a15, ps\n"
281                         "       rsync\n"
282                         : "=&a" (vval), "=a" (mask)
283                         : "a" (v), "a" (all_f), "1" (mask)
284                         : "a15", "memory"
285                         );
286 #endif
287 }
288 
289 static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
290 {
291 #if XCHAL_HAVE_S32C1I
292         unsigned long tmp;
293         int result;
294 
295         __asm__ __volatile__(
296                         "1:     l32i    %1, %3, 0\n"
297                         "       wsr     %1, scompare1\n"
298                         "       or      %0, %1, %2\n"
299                         "       s32c1i  %0, %3, 0\n"
300                         "       bne     %0, %1, 1b\n"
301                         : "=&a" (result), "=&a" (tmp)
302                         : "a" (mask), "a" (v)
303                         : "memory"
304                         );
305 #else
306         unsigned int vval;
307 
308         __asm__ __volatile__(
309                         "       rsil    a15,"__stringify(LOCKLEVEL)"\n"
310                         "       l32i    %0, %2, 0\n"
311                         "       or      %0, %0, %1\n"
312                         "       s32i    %0, %2, 0\n"
313                         "       wsr     a15, ps\n"
314                         "       rsync\n"
315                         : "=&a" (vval)
316                         : "a" (mask), "a" (v)
317                         : "a15", "memory"
318                         );
319 #endif
320 }
321 
322 #endif /* __KERNEL__ */
323 
324 #endif /* _XTENSA_ATOMIC_H */
325 

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