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[linux-2.6/linux-acpi-2.6.git] / arch / powerpc / include / asm / spinlock.h
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1 #ifndef __ASM_SPINLOCK_H
2 #define __ASM_SPINLOCK_H
3 #ifdef __KERNEL__
5 /*
6 * Simple spin lock operations.
8 * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
9 * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
10 * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
11 * Rework to support virtual processors
13 * Type of int is used as a full 64b word is not necessary.
15 * This program is free software; you can redistribute it and/or
16 * modify it under the terms of the GNU General Public License
17 * as published by the Free Software Foundation; either version
18 * 2 of the License, or (at your option) any later version.
20 * (the type definitions are in asm/spinlock_types.h)
22 #include <linux/irqflags.h>
23 #ifdef CONFIG_PPC64
24 #include <asm/paca.h>
25 #include <asm/hvcall.h>
26 #include <asm/iseries/hv_call.h>
27 #endif
28 #include <asm/asm-compat.h>
29 #include <asm/synch.h>
31 #define __raw_spin_is_locked(x) ((x)->slock != 0)
33 #ifdef CONFIG_PPC64
34 /* use 0x800000yy when locked, where yy == CPU number */
35 #define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token))
36 #else
37 #define LOCK_TOKEN 1
38 #endif
40 #if defined(CONFIG_PPC64) && defined(CONFIG_SMP)
41 #define CLEAR_IO_SYNC (get_paca()->io_sync = 0)
42 #define SYNC_IO do { \
43 if (unlikely(get_paca()->io_sync)) { \
44 mb(); \
45 get_paca()->io_sync = 0; \
46 } \
47 } while (0)
48 #else
49 #define CLEAR_IO_SYNC
50 #define SYNC_IO
51 #endif
54 * This returns the old value in the lock, so we succeeded
55 * in getting the lock if the return value is 0.
57 static inline unsigned long __spin_trylock(raw_spinlock_t *lock)
59 unsigned long tmp, token;
61 token = LOCK_TOKEN;
62 __asm__ __volatile__(
63 "1: lwarx %0,0,%2\n\
64 cmpwi 0,%0,0\n\
65 bne- 2f\n\
66 stwcx. %1,0,%2\n\
67 bne- 1b\n\
68 isync\n\
69 2:" : "=&r" (tmp)
70 : "r" (token), "r" (&lock->slock)
71 : "cr0", "memory");
73 return tmp;
76 static inline int __raw_spin_trylock(raw_spinlock_t *lock)
78 CLEAR_IO_SYNC;
79 return __spin_trylock(lock) == 0;
83 * On a system with shared processors (that is, where a physical
84 * processor is multiplexed between several virtual processors),
85 * there is no point spinning on a lock if the holder of the lock
86 * isn't currently scheduled on a physical processor. Instead
87 * we detect this situation and ask the hypervisor to give the
88 * rest of our timeslice to the lock holder.
90 * So that we can tell which virtual processor is holding a lock,
91 * we put 0x80000000 | smp_processor_id() in the lock when it is
92 * held. Conveniently, we have a word in the paca that holds this
93 * value.
96 #if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
97 /* We only yield to the hypervisor if we are in shared processor mode */
98 #define SHARED_PROCESSOR (get_lppaca()->shared_proc)
99 extern void __spin_yield(raw_spinlock_t *lock);
100 extern void __rw_yield(raw_rwlock_t *lock);
101 #else /* SPLPAR || ISERIES */
102 #define __spin_yield(x) barrier()
103 #define __rw_yield(x) barrier()
104 #define SHARED_PROCESSOR 0
105 #endif
107 static inline void __raw_spin_lock(raw_spinlock_t *lock)
109 CLEAR_IO_SYNC;
110 while (1) {
111 if (likely(__spin_trylock(lock) == 0))
112 break;
113 do {
114 HMT_low();
115 if (SHARED_PROCESSOR)
116 __spin_yield(lock);
117 } while (unlikely(lock->slock != 0));
118 HMT_medium();
122 static inline
123 void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
125 unsigned long flags_dis;
127 CLEAR_IO_SYNC;
128 while (1) {
129 if (likely(__spin_trylock(lock) == 0))
130 break;
131 local_save_flags(flags_dis);
132 local_irq_restore(flags);
133 do {
134 HMT_low();
135 if (SHARED_PROCESSOR)
136 __spin_yield(lock);
137 } while (unlikely(lock->slock != 0));
138 HMT_medium();
139 local_irq_restore(flags_dis);
143 static inline void __raw_spin_unlock(raw_spinlock_t *lock)
145 SYNC_IO;
146 __asm__ __volatile__("# __raw_spin_unlock\n\t"
147 LWSYNC_ON_SMP: : :"memory");
148 lock->slock = 0;
151 #ifdef CONFIG_PPC64
152 extern void __raw_spin_unlock_wait(raw_spinlock_t *lock);
153 #else
154 #define __raw_spin_unlock_wait(lock) \
155 do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
156 #endif
159 * Read-write spinlocks, allowing multiple readers
160 * but only one writer.
162 * NOTE! it is quite common to have readers in interrupts
163 * but no interrupt writers. For those circumstances we
164 * can "mix" irq-safe locks - any writer needs to get a
165 * irq-safe write-lock, but readers can get non-irqsafe
166 * read-locks.
169 #define __raw_read_can_lock(rw) ((rw)->lock >= 0)
170 #define __raw_write_can_lock(rw) (!(rw)->lock)
172 #ifdef CONFIG_PPC64
173 #define __DO_SIGN_EXTEND "extsw %0,%0\n"
174 #define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */
175 #else
176 #define __DO_SIGN_EXTEND
177 #define WRLOCK_TOKEN (-1)
178 #endif
181 * This returns the old value in the lock + 1,
182 * so we got a read lock if the return value is > 0.
184 static inline long __read_trylock(raw_rwlock_t *rw)
186 long tmp;
188 __asm__ __volatile__(
189 "1: lwarx %0,0,%1\n"
190 __DO_SIGN_EXTEND
191 " addic. %0,%0,1\n\
192 ble- 2f\n"
193 PPC405_ERR77(0,%1)
194 " stwcx. %0,0,%1\n\
195 bne- 1b\n\
196 isync\n\
197 2:" : "=&r" (tmp)
198 : "r" (&rw->lock)
199 : "cr0", "xer", "memory");
201 return tmp;
205 * This returns the old value in the lock,
206 * so we got the write lock if the return value is 0.
208 static inline long __write_trylock(raw_rwlock_t *rw)
210 long tmp, token;
212 token = WRLOCK_TOKEN;
213 __asm__ __volatile__(
214 "1: lwarx %0,0,%2\n\
215 cmpwi 0,%0,0\n\
216 bne- 2f\n"
217 PPC405_ERR77(0,%1)
218 " stwcx. %1,0,%2\n\
219 bne- 1b\n\
220 isync\n\
221 2:" : "=&r" (tmp)
222 : "r" (token), "r" (&rw->lock)
223 : "cr0", "memory");
225 return tmp;
228 static inline void __raw_read_lock(raw_rwlock_t *rw)
230 while (1) {
231 if (likely(__read_trylock(rw) > 0))
232 break;
233 do {
234 HMT_low();
235 if (SHARED_PROCESSOR)
236 __rw_yield(rw);
237 } while (unlikely(rw->lock < 0));
238 HMT_medium();
242 static inline void __raw_write_lock(raw_rwlock_t *rw)
244 while (1) {
245 if (likely(__write_trylock(rw) == 0))
246 break;
247 do {
248 HMT_low();
249 if (SHARED_PROCESSOR)
250 __rw_yield(rw);
251 } while (unlikely(rw->lock != 0));
252 HMT_medium();
256 static inline int __raw_read_trylock(raw_rwlock_t *rw)
258 return __read_trylock(rw) > 0;
261 static inline int __raw_write_trylock(raw_rwlock_t *rw)
263 return __write_trylock(rw) == 0;
266 static inline void __raw_read_unlock(raw_rwlock_t *rw)
268 long tmp;
270 __asm__ __volatile__(
271 "# read_unlock\n\t"
272 LWSYNC_ON_SMP
273 "1: lwarx %0,0,%1\n\
274 addic %0,%0,-1\n"
275 PPC405_ERR77(0,%1)
276 " stwcx. %0,0,%1\n\
277 bne- 1b"
278 : "=&r"(tmp)
279 : "r"(&rw->lock)
280 : "cr0", "xer", "memory");
283 static inline void __raw_write_unlock(raw_rwlock_t *rw)
285 __asm__ __volatile__("# write_unlock\n\t"
286 LWSYNC_ON_SMP: : :"memory");
287 rw->lock = 0;
290 #define __raw_read_lock_flags(lock, flags) __raw_read_lock(lock)
291 #define __raw_write_lock_flags(lock, flags) __raw_write_lock(lock)
293 #define _raw_spin_relax(lock) __spin_yield(lock)
294 #define _raw_read_relax(lock) __rw_yield(lock)
295 #define _raw_write_relax(lock) __rw_yield(lock)
297 #endif /* __KERNEL__ */
298 #endif /* __ASM_SPINLOCK_H */