Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
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 by Ralf Baechle
7 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
8 */
9#ifndef _ASM_SPINLOCK_H
10#define _ASM_SPINLOCK_H
11
12#include <linux/config.h>
13#include <asm/war.h>
14
15/*
16 * Your basic SMP spinlocks, allowing only a single CPU anywhere
17 */
18
19typedef struct {
20 volatile unsigned int lock;
21#ifdef CONFIG_PREEMPT
22 unsigned int break_lock;
23#endif
24} spinlock_t;
25
26#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
27
28#define spin_lock_init(x) do { (x)->lock = 0; } while(0)
29
30#define spin_is_locked(x) ((x)->lock != 0)
31#define spin_unlock_wait(x) do { barrier(); } while ((x)->lock)
32#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
33
34/*
35 * Simple spin lock operations. There are two variants, one clears IRQ's
36 * on the local processor, one does not.
37 *
38 * We make no fairness assumptions. They have a cost.
39 */
40
41static inline void _raw_spin_lock(spinlock_t *lock)
42{
43 unsigned int tmp;
44
45 if (R10000_LLSC_WAR) {
46 __asm__ __volatile__(
47 " .set noreorder # _raw_spin_lock \n"
48 "1: ll %1, %2 \n"
49 " bnez %1, 1b \n"
50 " li %1, 1 \n"
51 " sc %1, %0 \n"
52 " beqzl %1, 1b \n"
53 " nop \n"
54 " sync \n"
55 " .set reorder \n"
56 : "=m" (lock->lock), "=&r" (tmp)
57 : "m" (lock->lock)
58 : "memory");
59 } else {
60 __asm__ __volatile__(
61 " .set noreorder # _raw_spin_lock \n"
62 "1: ll %1, %2 \n"
63 " bnez %1, 1b \n"
64 " li %1, 1 \n"
65 " sc %1, %0 \n"
66 " beqz %1, 1b \n"
67 " sync \n"
68 " .set reorder \n"
69 : "=m" (lock->lock), "=&r" (tmp)
70 : "m" (lock->lock)
71 : "memory");
72 }
73}
74
75static inline void _raw_spin_unlock(spinlock_t *lock)
76{
77 __asm__ __volatile__(
78 " .set noreorder # _raw_spin_unlock \n"
79 " sync \n"
80 " sw $0, %0 \n"
81 " .set\treorder \n"
82 : "=m" (lock->lock)
83 : "m" (lock->lock)
84 : "memory");
85}
86
87static inline unsigned int _raw_spin_trylock(spinlock_t *lock)
88{
89 unsigned int temp, res;
90
91 if (R10000_LLSC_WAR) {
92 __asm__ __volatile__(
93 " .set noreorder # _raw_spin_trylock \n"
94 "1: ll %0, %3 \n"
95 " ori %2, %0, 1 \n"
96 " sc %2, %1 \n"
97 " beqzl %2, 1b \n"
98 " nop \n"
99 " andi %2, %0, 1 \n"
100 " sync \n"
101 " .set reorder"
102 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
103 : "m" (lock->lock)
104 : "memory");
105 } else {
106 __asm__ __volatile__(
107 " .set noreorder # _raw_spin_trylock \n"
108 "1: ll %0, %3 \n"
109 " ori %2, %0, 1 \n"
110 " sc %2, %1 \n"
111 " beqz %2, 1b \n"
112 " andi %2, %0, 1 \n"
113 " sync \n"
114 " .set reorder"
115 : "=&r" (temp), "=m" (lock->lock), "=&r" (res)
116 : "m" (lock->lock)
117 : "memory");
118 }
119
120 return res == 0;
121}
122
123/*
124 * Read-write spinlocks, allowing multiple readers but only one writer.
125 *
126 * NOTE! it is quite common to have readers in interrupts but no interrupt
127 * writers. For those circumstances we can "mix" irq-safe locks - any writer
128 * needs to get a irq-safe write-lock, but readers can get non-irqsafe
129 * read-locks.
130 */
131
132typedef struct {
133 volatile unsigned int lock;
134#ifdef CONFIG_PREEMPT
135 unsigned int break_lock;
136#endif
137} rwlock_t;
138
139#define RW_LOCK_UNLOCKED (rwlock_t) { 0 }
140
141#define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0)
142
143static inline void _raw_read_lock(rwlock_t *rw)
144{
145 unsigned int tmp;
146
147 if (R10000_LLSC_WAR) {
148 __asm__ __volatile__(
149 " .set noreorder # _raw_read_lock \n"
150 "1: ll %1, %2 \n"
151 " bltz %1, 1b \n"
152 " addu %1, 1 \n"
153 " sc %1, %0 \n"
154 " beqzl %1, 1b \n"
155 " nop \n"
156 " sync \n"
157 " .set reorder \n"
158 : "=m" (rw->lock), "=&r" (tmp)
159 : "m" (rw->lock)
160 : "memory");
161 } else {
162 __asm__ __volatile__(
163 " .set noreorder # _raw_read_lock \n"
164 "1: ll %1, %2 \n"
165 " bltz %1, 1b \n"
166 " addu %1, 1 \n"
167 " sc %1, %0 \n"
168 " beqz %1, 1b \n"
169 " sync \n"
170 " .set reorder \n"
171 : "=m" (rw->lock), "=&r" (tmp)
172 : "m" (rw->lock)
173 : "memory");
174 }
175}
176
177/* Note the use of sub, not subu which will make the kernel die with an
178 overflow exception if we ever try to unlock an rwlock that is already
179 unlocked or is being held by a writer. */
180static inline void _raw_read_unlock(rwlock_t *rw)
181{
182 unsigned int tmp;
183
184 if (R10000_LLSC_WAR) {
185 __asm__ __volatile__(
186 "1: ll %1, %2 # _raw_read_unlock \n"
187 " sub %1, 1 \n"
188 " sc %1, %0 \n"
189 " beqzl %1, 1b \n"
190 " sync \n"
191 : "=m" (rw->lock), "=&r" (tmp)
192 : "m" (rw->lock)
193 : "memory");
194 } else {
195 __asm__ __volatile__(
196 " .set noreorder # _raw_read_unlock \n"
197 "1: ll %1, %2 \n"
198 " sub %1, 1 \n"
199 " sc %1, %0 \n"
200 " beqz %1, 1b \n"
201 " sync \n"
202 " .set reorder \n"
203 : "=m" (rw->lock), "=&r" (tmp)
204 : "m" (rw->lock)
205 : "memory");
206 }
207}
208
209static inline void _raw_write_lock(rwlock_t *rw)
210{
211 unsigned int tmp;
212
213 if (R10000_LLSC_WAR) {
214 __asm__ __volatile__(
215 " .set noreorder # _raw_write_lock \n"
216 "1: ll %1, %2 \n"
217 " bnez %1, 1b \n"
218 " lui %1, 0x8000 \n"
219 " sc %1, %0 \n"
220 " beqzl %1, 1b \n"
221 " nop \n"
222 " sync \n"
223 " .set reorder \n"
224 : "=m" (rw->lock), "=&r" (tmp)
225 : "m" (rw->lock)
226 : "memory");
227 } else {
228 __asm__ __volatile__(
229 " .set noreorder # _raw_write_lock \n"
230 "1: ll %1, %2 \n"
231 " bnez %1, 1b \n"
232 " lui %1, 0x8000 \n"
233 " sc %1, %0 \n"
234 " beqz %1, 1b \n"
235 " nop \n"
236 " sync \n"
237 " .set reorder \n"
238 : "=m" (rw->lock), "=&r" (tmp)
239 : "m" (rw->lock)
240 : "memory");
241 }
242}
243
244static inline void _raw_write_unlock(rwlock_t *rw)
245{
246 __asm__ __volatile__(
247 " sync # _raw_write_unlock \n"
248 " sw $0, %0 \n"
249 : "=m" (rw->lock)
250 : "m" (rw->lock)
251 : "memory");
252}
253
254#define _raw_read_trylock(lock) generic_raw_read_trylock(lock)
255
256static inline int _raw_write_trylock(rwlock_t *rw)
257{
258 unsigned int tmp;
259 int ret;
260
261 if (R10000_LLSC_WAR) {
262 __asm__ __volatile__(
263 " .set noreorder # _raw_write_trylock \n"
264 " li %2, 0 \n"
265 "1: ll %1, %3 \n"
266 " bnez %1, 2f \n"
267 " lui %1, 0x8000 \n"
268 " sc %1, %0 \n"
269 " beqzl %1, 1b \n"
270 " nop \n"
271 " sync \n"
272 " li %2, 1 \n"
273 " .set reorder \n"
274 "2: \n"
275 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
276 : "m" (rw->lock)
277 : "memory");
278 } else {
279 __asm__ __volatile__(
280 " .set noreorder # _raw_write_trylock \n"
281 " li %2, 0 \n"
282 "1: ll %1, %3 \n"
283 " bnez %1, 2f \n"
284 " lui %1, 0x8000 \n"
285 " sc %1, %0 \n"
286 " beqz %1, 1b \n"
287 " sync \n"
288 " li %2, 1 \n"
289 " .set reorder \n"
290 "2: \n"
291 : "=m" (rw->lock), "=&r" (tmp), "=&r" (ret)
292 : "m" (rw->lock)
293 : "memory");
294 }
295
296 return ret;
297}
298
299#endif /* _ASM_SPINLOCK_H */