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x86: spinlocks: define dummy __raw_spin_is_contended
[linux-2.6/mini2440.git] / arch / mips / include / asm / spinlock.h
blob0884947ebe270c404bb293b2acac0b067e7fd9d7
1 /*
2 * This file is subject to the terms and conditions of the GNU General Public
3 * License. See the file "COPYING" in the main directory of this archive
4 * for more details.
5 *
6 * Copyright (C) 1999, 2000, 06 Ralf Baechle (ralf@linux-mips.org)
7 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
8 */
9 #ifndef _ASM_SPINLOCK_H
10 #define _ASM_SPINLOCK_H
11
12 #include <linux/compiler.h>
13
14 #include <asm/barrier.h>
15 #include <asm/war.h>
16
17 /*
18 * Your basic SMP spinlocks, allowing only a single CPU anywhere
19 *
20 * Simple spin lock operations. There are two variants, one clears IRQ's
21 * on the local processor, one does not.
22 *
23 * These are fair FIFO ticket locks
24 *
25 * (the type definitions are in asm/spinlock_types.h)
26 */
27
28
29 /*
30 * Ticket locks are conceptually two parts, one indicating the current head of
31 * the queue, and the other indicating the current tail. The lock is acquired
32 * by atomically noting the tail and incrementing it by one (thus adding
33 * ourself to the queue and noting our position), then waiting until the head
34 * becomes equal to the the initial value of the tail.
35 */
36
37 static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
38 {
39 unsigned int counters = ACCESS_ONCE(lock->lock);
40
41 return ((counters >> 14) ^ counters) & 0x1fff;
42 }
43
44 #define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
45 #define __raw_spin_unlock_wait(x) \
46 while (__raw_spin_is_locked(x)) { cpu_relax(); }
47
48 static inline int __raw_spin_is_contended(raw_spinlock_t *lock)
49 {
50 unsigned int counters = ACCESS_ONCE(lock->lock);
51
52 return (((counters >> 14) - counters) & 0x1fff) > 1;
53 }
54 #define __raw_spin_is_contended __raw_spin_is_contended
55
56 static inline void __raw_spin_lock(raw_spinlock_t *lock)
57 {
58 int my_ticket;
59 int tmp;
60
61 if (R10000_LLSC_WAR) {
62 __asm__ __volatile__ (
63 " .set push # __raw_spin_lock \n"
64 " .set noreorder \n"
65 " \n"
66 "1: ll %[ticket], %[ticket_ptr] \n"
67 " addiu %[my_ticket], %[ticket], 0x4000 \n"
68 " sc %[my_ticket], %[ticket_ptr] \n"
69 " beqzl %[my_ticket], 1b \n"
70 " nop \n"
71 " srl %[my_ticket], %[ticket], 14 \n"
72 " andi %[my_ticket], %[my_ticket], 0x1fff \n"
73 " andi %[ticket], %[ticket], 0x1fff \n"
74 " bne %[ticket], %[my_ticket], 4f \n"
75 " subu %[ticket], %[my_ticket], %[ticket] \n"
76 "2: \n"
77 " .subsection 2 \n"
78 "4: andi %[ticket], %[ticket], 0x1fff \n"
79 "5: sll %[ticket], 5 \n"
80 " \n"
81 "6: bnez %[ticket], 6b \n"
82 " subu %[ticket], 1 \n"
83 " \n"
84 " lw %[ticket], %[ticket_ptr] \n"
85 " andi %[ticket], %[ticket], 0x1fff \n"
86 " beq %[ticket], %[my_ticket], 2b \n"
87 " subu %[ticket], %[my_ticket], %[ticket] \n"
88 " b 5b \n"
89 " subu %[ticket], %[ticket], 1 \n"
90 " .previous \n"
91 " .set pop \n"
92 : [ticket_ptr] "+m" (lock->lock),
93 [ticket] "=&r" (tmp),
94 [my_ticket] "=&r" (my_ticket));
95 } else {
96 __asm__ __volatile__ (
97 " .set push # __raw_spin_lock \n"
98 " .set noreorder \n"
99 " \n"
100 " ll %[ticket], %[ticket_ptr] \n"
101 "1: addiu %[my_ticket], %[ticket], 0x4000 \n"
102 " sc %[my_ticket], %[ticket_ptr] \n"
103 " beqz %[my_ticket], 3f \n"
104 " nop \n"
105 " srl %[my_ticket], %[ticket], 14 \n"
106 " andi %[my_ticket], %[my_ticket], 0x1fff \n"
107 " andi %[ticket], %[ticket], 0x1fff \n"
108 " bne %[ticket], %[my_ticket], 4f \n"
109 " subu %[ticket], %[my_ticket], %[ticket] \n"
110 "2: \n"
111 " .subsection 2 \n"
112 "3: b 1b \n"
113 " ll %[ticket], %[ticket_ptr] \n"
114 " \n"
115 "4: andi %[ticket], %[ticket], 0x1fff \n"
116 "5: sll %[ticket], 5 \n"
117 " \n"
118 "6: bnez %[ticket], 6b \n"
119 " subu %[ticket], 1 \n"
120 " \n"
121 " lw %[ticket], %[ticket_ptr] \n"
122 " andi %[ticket], %[ticket], 0x1fff \n"
123 " beq %[ticket], %[my_ticket], 2b \n"
124 " subu %[ticket], %[my_ticket], %[ticket] \n"
125 " b 5b \n"
126 " subu %[ticket], %[ticket], 1 \n"
127 " .previous \n"
128 " .set pop \n"
129 : [ticket_ptr] "+m" (lock->lock),
130 [ticket] "=&r" (tmp),
131 [my_ticket] "=&r" (my_ticket));
132 }
133
134 smp_llsc_mb();
135 }
136
137 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
138 {
139 int tmp;
140
141 smp_llsc_mb();
142
143 if (R10000_LLSC_WAR) {
144 __asm__ __volatile__ (
145 " # __raw_spin_unlock \n"
146 "1: ll %[ticket], %[ticket_ptr] \n"
147 " addiu %[ticket], %[ticket], 1 \n"
148 " ori %[ticket], %[ticket], 0x2000 \n"
149 " xori %[ticket], %[ticket], 0x2000 \n"
150 " sc %[ticket], %[ticket_ptr] \n"
151 " beqzl %[ticket], 1b \n"
152 : [ticket_ptr] "+m" (lock->lock),
153 [ticket] "=&r" (tmp));
154 } else {
155 __asm__ __volatile__ (
156 " .set push # __raw_spin_unlock \n"
157 " .set noreorder \n"
158 " \n"
159 " ll %[ticket], %[ticket_ptr] \n"
160 "1: addiu %[ticket], %[ticket], 1 \n"
161 " ori %[ticket], %[ticket], 0x2000 \n"
162 " xori %[ticket], %[ticket], 0x2000 \n"
163 " sc %[ticket], %[ticket_ptr] \n"
164 " beqz %[ticket], 2f \n"
165 " nop \n"
166 " \n"
167 " .subsection 2 \n"
168 "2: b 1b \n"
169 " ll %[ticket], %[ticket_ptr] \n"
170 " .previous \n"
171 " .set pop \n"
172 : [ticket_ptr] "+m" (lock->lock),
173 [ticket] "=&r" (tmp));
174 }
175 }
176
177 static inline unsigned int __raw_spin_trylock(raw_spinlock_t *lock)
178 {
179 int tmp, tmp2, tmp3;
180
181 if (R10000_LLSC_WAR) {
182 __asm__ __volatile__ (
183 " .set push # __raw_spin_trylock \n"
184 " .set noreorder \n"
185 " \n"
186 "1: ll %[ticket], %[ticket_ptr] \n"
187 " srl %[my_ticket], %[ticket], 14 \n"
188 " andi %[my_ticket], %[my_ticket], 0x1fff \n"
189 " andi %[now_serving], %[ticket], 0x1fff \n"
190 " bne %[my_ticket], %[now_serving], 3f \n"
191 " addiu %[ticket], %[ticket], 0x4000 \n"
192 " sc %[ticket], %[ticket_ptr] \n"
193 " beqzl %[ticket], 1b \n"
194 " li %[ticket], 1 \n"
195 "2: \n"
196 " .subsection 2 \n"
197 "3: b 2b \n"
198 " li %[ticket], 0 \n"
199 " .previous \n"
200 " .set pop \n"
201 : [ticket_ptr] "+m" (lock->lock),
202 [ticket] "=&r" (tmp),
203 [my_ticket] "=&r" (tmp2),
204 [now_serving] "=&r" (tmp3));
205 } else {
206 __asm__ __volatile__ (
207 " .set push # __raw_spin_trylock \n"
208 " .set noreorder \n"
209 " \n"
210 " ll %[ticket], %[ticket_ptr] \n"
211 "1: srl %[my_ticket], %[ticket], 14 \n"
212 " andi %[my_ticket], %[my_ticket], 0x1fff \n"
213 " andi %[now_serving], %[ticket], 0x1fff \n"
214 " bne %[my_ticket], %[now_serving], 3f \n"
215 " addiu %[ticket], %[ticket], 0x4000 \n"
216 " sc %[ticket], %[ticket_ptr] \n"
217 " beqz %[ticket], 4f \n"
218 " li %[ticket], 1 \n"
219 "2: \n"
220 " .subsection 2 \n"
221 "3: b 2b \n"
222 " li %[ticket], 0 \n"
223 "4: b 1b \n"
224 " ll %[ticket], %[ticket_ptr] \n"
225 " .previous \n"
226 " .set pop \n"
227 : [ticket_ptr] "+m" (lock->lock),
228 [ticket] "=&r" (tmp),
229 [my_ticket] "=&r" (tmp2),
230 [now_serving] "=&r" (tmp3));
231 }
232
233 smp_llsc_mb();
234
235 return tmp;
236 }
237
238 /*
239 * Read-write spinlocks, allowing multiple readers but only one writer.
240 *
241 * NOTE! it is quite common to have readers in interrupts but no interrupt
242 * writers. For those circumstances we can "mix" irq-safe locks - any writer
243 * needs to get a irq-safe write-lock, but readers can get non-irqsafe
244 * read-locks.
245 */
246
247 /*
248 * read_can_lock - would read_trylock() succeed?
249 * @lock: the rwlock in question.
250 */
251 #define __raw_read_can_lock(rw) ((rw)->lock >= 0)
252
253 /*
254 * write_can_lock - would write_trylock() succeed?
255 * @lock: the rwlock in question.
256 */
257 #define __raw_write_can_lock(rw) (!(rw)->lock)
258
259 static inline void __raw_read_lock(raw_rwlock_t *rw)
260 {
261 unsigned int tmp;
262
263 if (R10000_LLSC_WAR) {
264 __asm__ __volatile__(
265 " .set noreorder # __raw_read_lock \n"
266 "1: ll %1, %2 \n"
267 " bltz %1, 1b \n"
268 " addu %1, 1 \n"
269 " sc %1, %0 \n"
270 " beqzl %1, 1b \n"
271 " nop \n"
272 " .set reorder \n"
273 : "=m" (rw->lock), "=&r" (tmp)
274 : "m" (rw->lock)
275 : "memory");
276 } else {
277 __asm__ __volatile__(
278 " .set noreorder # __raw_read_lock \n"
279 "1: ll %1, %2 \n"
280 " bltz %1, 2f \n"
281 " addu %1, 1 \n"
282 " sc %1, %0 \n"
283 " beqz %1, 1b \n"
284 " nop \n"
285 " .subsection 2 \n"
286 "2: ll %1, %2 \n"
287 " bltz %1, 2b \n"
288 " addu %1, 1 \n"
289 " b 1b \n"
290 " nop \n"
291 " .previous \n"
292 " .set reorder \n"
293 : "=m" (rw->lock), "=&r" (tmp)
294 : "m" (rw->lock)
295 : "memory");
296 }
297
298 smp_llsc_mb();
299 }
300
301 /* Note the use of sub, not subu which will make the kernel die with an
302 overflow exception if we ever try to unlock an rwlock that is already
303 unlocked or is being held by a writer. */
304 static inline void __raw_read_unlock(raw_rwlock_t *rw)
305 {
306 unsigned int tmp;
307
308 smp_llsc_mb();
309
310 if (R10000_LLSC_WAR) {
311 __asm__ __volatile__(
312 "1: ll %1, %2 # __raw_read_unlock \n"
313 " sub %1, 1 \n"
314 " sc %1, %0 \n"
315 " beqzl %1, 1b \n"
316 : "=m" (rw->lock), "=&r" (tmp)
317 : "m" (rw->lock)
318 : "memory");
319 } else {
320 __asm__ __volatile__(
321 " .set noreorder # __raw_read_unlock \n"
322 "1: ll %1, %2 \n"
323 " sub %1, 1 \n"
324 " sc %1, %0 \n"
325 " beqz %1, 2f \n"
326 " nop \n"
327 " .subsection 2 \n"
328 "2: b 1b \n"
329 " nop \n"
330 " .previous \n"
331 " .set reorder \n"
332 : "=m" (rw->lock), "=&r" (tmp)
333 : "m" (rw->lock)
334 : "memory");
335 }
336 }
337
338 static inline void __raw_write_lock(raw_rwlock_t *rw)
339 {
340 unsigned int tmp;
341
342 if (R10000_LLSC_WAR) {
343 __asm__ __volatile__(
344 " .set noreorder # __raw_write_lock \n"
345 "1: ll %1, %2 \n"
346 " bnez %1, 1b \n"
347 " lui %1, 0x8000 \n"
348 " sc %1, %0 \n"
349 " beqzl %1, 1b \n"
350 " nop \n"
351 " .set reorder \n"
352 : "=m" (rw->lock), "=&r" (tmp)
353 : "m" (rw->lock)
354 : "memory");
355 } else {
356 __asm__ __volatile__(
357 " .set noreorder # __raw_write_lock \n"
358 "1: ll %1, %2 \n"
359 " bnez %1, 2f \n"
360 " lui %1, 0x8000 \n"
361 " sc %1, %0 \n"
362 " beqz %1, 2f \n"
363 " nop \n"
364 " .subsection 2 \n"
365 "2: ll %1, %2 \n"
366 " bnez %1, 2b \n"
367 " lui %1, 0x8000 \n"
368 " b 1b \n"
369 " nop \n"
370 " .previous \n"
371 " .set reorder \n"
372 : "=m" (rw->lock), "=&r" (tmp)
373 : "m" (rw->lock)
374 : "memory");
375 }
376
377 smp_llsc_mb();
378 }
379
380 static inline void __raw_write_unlock(raw_rwlock_t *rw)
381 {
382 smp_mb();
383
384 __asm__ __volatile__(
385 " # __raw_write_unlock \n"
386 " sw $0, %0 \n"
387 : "=m" (rw->lock)
388 : "m" (rw->lock)
389 : "memory");
390 }
391
392 static inline int __raw_read_trylock(raw_rwlock_t *rw)
393 {
394 unsigned int tmp;
395 int ret;
396
397 if (R10000_LLSC_WAR) {
398 __asm__ __volatile__(
399 " .set noreorder # __raw_read_trylock \n"
400 " li %2, 0 \n"
401 "1: ll %1, %3 \n"
402 " bltz %1, 2f \n"
403 " addu %1, 1 \n"
404 " sc %1, %0 \n"
405 " .set reorder \n"
406 " beqzl %1, 1b \n"
407 " nop \n"
408 __WEAK_LLSC_MB
409 " li %2, 1 \n"
410 "2: \n"
411 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
412 : "m" (rw->lock)
413 : "memory");
414 } else {
415 __asm__ __volatile__(
416 " .set noreorder # __raw_read_trylock \n"
417 " li %2, 0 \n"
418 "1: ll %1, %3 \n"
419 " bltz %1, 2f \n"
420 " addu %1, 1 \n"
421 " sc %1, %0 \n"
422 " beqz %1, 1b \n"
423 " nop \n"
424 " .set reorder \n"
425 __WEAK_LLSC_MB
426 " li %2, 1 \n"
427 "2: \n"
428 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
429 : "m" (rw->lock)
430 : "memory");
431 }
432
433 return ret;
434 }
435
436 static inline int __raw_write_trylock(raw_rwlock_t *rw)
437 {
438 unsigned int tmp;
439 int ret;
440
441 if (R10000_LLSC_WAR) {
442 __asm__ __volatile__(
443 " .set noreorder # __raw_write_trylock \n"
444 " li %2, 0 \n"
445 "1: ll %1, %3 \n"
446 " bnez %1, 2f \n"
447 " lui %1, 0x8000 \n"
448 " sc %1, %0 \n"
449 " beqzl %1, 1b \n"
450 " nop \n"
451 __WEAK_LLSC_MB
452 " li %2, 1 \n"
453 " .set reorder \n"
454 "2: \n"
455 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
456 : "m" (rw->lock)
457 : "memory");
458 } else {
459 __asm__ __volatile__(
460 " .set noreorder # __raw_write_trylock \n"
461 " li %2, 0 \n"
462 "1: ll %1, %3 \n"
463 " bnez %1, 2f \n"
464 " lui %1, 0x8000 \n"
465 " sc %1, %0 \n"
466 " beqz %1, 3f \n"
467 " li %2, 1 \n"
468 "2: \n"
469 __WEAK_LLSC_MB
470 " .subsection 2 \n"
471 "3: b 1b \n"
472 " li %2, 0 \n"
473 " .previous \n"
474 " .set reorder \n"
475 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
476 : "m" (rw->lock)
477 : "memory");
478 }
479
480 return ret;
481 }
482
483
484 #define _raw_spin_relax(lock) cpu_relax()
485 #define _raw_read_relax(lock) cpu_relax()
486 #define _raw_write_relax(lock) cpu_relax()
487
488 #endif /* _ASM_SPINLOCK_H */
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