xref: /openbmc/linux/arch/xtensa/include/asm/atomic.h (revision b6dcefde)
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 - 2005 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/system.h>
22 
23 #define ATOMIC_INIT(i)	{ (i) }
24 
25 /*
26  * This Xtensa implementation assumes that the right mechanism
27  * for exclusion is for locking interrupts to level 1.
28  *
29  * Locking interrupts looks like this:
30  *
31  *    rsil a15, 1
32  *    <code>
33  *    wsr  a15, PS
34  *    rsync
35  *
36  * Note that a15 is used here because the register allocation
37  * done by the compiler is not guaranteed and a window overflow
38  * may not occur between the rsil and wsr instructions. By using
39  * a15 in the rsil, the machine is guaranteed to be in a state
40  * where no register reference will cause an overflow.
41  */
42 
43 /**
44  * atomic_read - read atomic variable
45  * @v: pointer of type atomic_t
46  *
47  * Atomically reads the value of @v.
48  */
49 #define atomic_read(v)		((v)->counter)
50 
51 /**
52  * atomic_set - set atomic variable
53  * @v: pointer of type atomic_t
54  * @i: required value
55  *
56  * Atomically sets the value of @v to @i.
57  */
58 #define atomic_set(v,i)		((v)->counter = (i))
59 
60 /**
61  * atomic_add - add integer to atomic variable
62  * @i: integer value to add
63  * @v: pointer of type atomic_t
64  *
65  * Atomically adds @i to @v.
66  */
67 static inline void atomic_add(int i, atomic_t * v)
68 {
69     unsigned int vval;
70 
71     __asm__ __volatile__(
72 	"rsil    a15, "__stringify(LOCKLEVEL)"\n\t"
73 	"l32i    %0, %2, 0              \n\t"
74 	"add     %0, %0, %1             \n\t"
75 	"s32i    %0, %2, 0              \n\t"
76 	"wsr     a15, "__stringify(PS)"       \n\t"
77 	"rsync                          \n"
78 	: "=&a" (vval)
79 	: "a" (i), "a" (v)
80 	: "a15", "memory"
81 	);
82 }
83 
84 /**
85  * atomic_sub - subtract the atomic variable
86  * @i: integer value to subtract
87  * @v: pointer of type atomic_t
88  *
89  * Atomically subtracts @i from @v.
90  */
91 static inline void atomic_sub(int i, atomic_t *v)
92 {
93     unsigned int vval;
94 
95     __asm__ __volatile__(
96 	"rsil    a15, "__stringify(LOCKLEVEL)"\n\t"
97 	"l32i    %0, %2, 0              \n\t"
98 	"sub     %0, %0, %1             \n\t"
99 	"s32i    %0, %2, 0              \n\t"
100 	"wsr     a15, "__stringify(PS)"       \n\t"
101 	"rsync                          \n"
102 	: "=&a" (vval)
103 	: "a" (i), "a" (v)
104 	: "a15", "memory"
105 	);
106 }
107 
108 /*
109  * We use atomic_{add|sub}_return to define other functions.
110  */
111 
112 static inline int atomic_add_return(int i, atomic_t * v)
113 {
114      unsigned int vval;
115 
116     __asm__ __volatile__(
117 	"rsil    a15,"__stringify(LOCKLEVEL)"\n\t"
118 	"l32i    %0, %2, 0             \n\t"
119 	"add     %0, %0, %1            \n\t"
120 	"s32i    %0, %2, 0             \n\t"
121 	"wsr     a15, "__stringify(PS)"      \n\t"
122 	"rsync                         \n"
123 	: "=&a" (vval)
124 	: "a" (i), "a" (v)
125 	: "a15", "memory"
126 	);
127 
128     return vval;
129 }
130 
131 static inline int atomic_sub_return(int i, atomic_t * v)
132 {
133     unsigned int vval;
134 
135     __asm__ __volatile__(
136 	"rsil    a15,"__stringify(LOCKLEVEL)"\n\t"
137 	"l32i    %0, %2, 0             \n\t"
138 	"sub     %0, %0, %1            \n\t"
139 	"s32i    %0, %2, 0             \n\t"
140 	"wsr     a15, "__stringify(PS)"       \n\t"
141 	"rsync                         \n"
142 	: "=&a" (vval)
143 	: "a" (i), "a" (v)
144 	: "a15", "memory"
145 	);
146 
147     return vval;
148 }
149 
150 /**
151  * atomic_sub_and_test - subtract value from variable and test result
152  * @i: integer value to subtract
153  * @v: pointer of type atomic_t
154  *
155  * Atomically subtracts @i from @v and returns
156  * true if the result is zero, or false for all
157  * other cases.
158  */
159 #define atomic_sub_and_test(i,v) (atomic_sub_return((i),(v)) == 0)
160 
161 /**
162  * atomic_inc - increment atomic variable
163  * @v: pointer of type atomic_t
164  *
165  * Atomically increments @v by 1.
166  */
167 #define atomic_inc(v) atomic_add(1,(v))
168 
169 /**
170  * atomic_inc - increment atomic variable
171  * @v: pointer of type atomic_t
172  *
173  * Atomically increments @v by 1.
174  */
175 #define atomic_inc_return(v) atomic_add_return(1,(v))
176 
177 /**
178  * atomic_dec - decrement atomic variable
179  * @v: pointer of type atomic_t
180  *
181  * Atomically decrements @v by 1.
182  */
183 #define atomic_dec(v) atomic_sub(1,(v))
184 
185 /**
186  * atomic_dec_return - decrement atomic variable
187  * @v: pointer of type atomic_t
188  *
189  * Atomically decrements @v by 1.
190  */
191 #define atomic_dec_return(v) atomic_sub_return(1,(v))
192 
193 /**
194  * atomic_dec_and_test - decrement and test
195  * @v: pointer of type atomic_t
196  *
197  * Atomically decrements @v by 1 and
198  * returns true if the result is 0, or false for all other
199  * cases.
200  */
201 #define atomic_dec_and_test(v) (atomic_sub_return(1,(v)) == 0)
202 
203 /**
204  * atomic_inc_and_test - increment and test
205  * @v: pointer of type atomic_t
206  *
207  * Atomically increments @v by 1
208  * and returns true if the result is zero, or false for all
209  * other cases.
210  */
211 #define atomic_inc_and_test(v) (atomic_add_return(1,(v)) == 0)
212 
213 /**
214  * atomic_add_negative - add and test if negative
215  * @v: pointer of type atomic_t
216  * @i: integer value to add
217  *
218  * Atomically adds @i to @v and returns true
219  * if the result is negative, or false when
220  * result is greater than or equal to zero.
221  */
222 #define atomic_add_negative(i,v) (atomic_add_return((i),(v)) < 0)
223 
224 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n)))
225 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
226 
227 /**
228  * atomic_add_unless - add unless the number is a given value
229  * @v: pointer of type atomic_t
230  * @a: the amount to add to v...
231  * @u: ...unless v is equal to u.
232  *
233  * Atomically adds @a to @v, so long as it was not @u.
234  * Returns non-zero if @v was not @u, and zero otherwise.
235  */
236 static __inline__ int atomic_add_unless(atomic_t *v, int a, int u)
237 {
238 	int c, old;
239 	c = atomic_read(v);
240 	for (;;) {
241 		if (unlikely(c == (u)))
242 			break;
243 		old = atomic_cmpxchg((v), c, c + (a));
244 		if (likely(old == c))
245 			break;
246 		c = old;
247 	}
248 	return c != (u);
249 }
250 
251 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
252 
253 static inline void atomic_clear_mask(unsigned int mask, atomic_t *v)
254 {
255     unsigned int all_f = -1;
256     unsigned int vval;
257 
258     __asm__ __volatile__(
259 	"rsil    a15,"__stringify(LOCKLEVEL)"\n\t"
260 	"l32i    %0, %2, 0             \n\t"
261 	"xor     %1, %4, %3            \n\t"
262 	"and     %0, %0, %4            \n\t"
263 	"s32i    %0, %2, 0             \n\t"
264 	"wsr     a15, "__stringify(PS)"      \n\t"
265 	"rsync                         \n"
266 	: "=&a" (vval), "=a" (mask)
267 	: "a" (v), "a" (all_f), "1" (mask)
268 	: "a15", "memory"
269 	);
270 }
271 
272 static inline void atomic_set_mask(unsigned int mask, atomic_t *v)
273 {
274     unsigned int vval;
275 
276     __asm__ __volatile__(
277 	"rsil    a15,"__stringify(LOCKLEVEL)"\n\t"
278 	"l32i    %0, %2, 0             \n\t"
279 	"or      %0, %0, %1            \n\t"
280 	"s32i    %0, %2, 0             \n\t"
281 	"wsr     a15, "__stringify(PS)"       \n\t"
282 	"rsync                         \n"
283 	: "=&a" (vval)
284 	: "a" (mask), "a" (v)
285 	: "a15", "memory"
286 	);
287 }
288 
289 /* Atomic operations are already serializing */
290 #define smp_mb__before_atomic_dec()	barrier()
291 #define smp_mb__after_atomic_dec()	barrier()
292 #define smp_mb__before_atomic_inc()	barrier()
293 #define smp_mb__after_atomic_inc()	barrier()
294 
295 #include <asm-generic/atomic-long.h>
296 #endif /* __KERNEL__ */
297 
298 #endif /* _XTENSA_ATOMIC_H */
299 
300