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Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef __ASM_SPINLOCK_H
2#define __ASM_SPINLOCK_H
Arnd Bergmann88ced032005-12-16 22:43:46 +01003#ifdef __KERNEL__
Linus Torvalds1da177e2005-04-16 15:20:36 -07004
5/*
6 * Simple spin lock operations.
7 *
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
12 *
13 * Type of int is used as a full 64b word is not necessary.
14 *
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.
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070019 *
20 * (the type definitions are in asm/spinlock_types.h)
Linus Torvalds1da177e2005-04-16 15:20:36 -070021 */
Paul Mackerras0212ddd2005-11-19 20:50:46 +110022#ifdef CONFIG_PPC64
Linus Torvalds1da177e2005-04-16 15:20:36 -070023#include <asm/paca.h>
24#include <asm/hvcall.h>
Kelly Daly1da44032005-11-01 16:59:20 +110025#include <asm/iseries/hv_call.h>
Paul Mackerras0212ddd2005-11-19 20:50:46 +110026#endif
27#include <asm/asm-compat.h>
28#include <asm/synch.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070030#define __raw_spin_is_locked(x) ((x)->slock != 0)
Linus Torvalds1da177e2005-04-16 15:20:36 -070031
Paul Mackerras0212ddd2005-11-19 20:50:46 +110032#ifdef CONFIG_PPC64
33/* use 0x800000yy when locked, where yy == CPU number */
34#define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token))
35#else
36#define LOCK_TOKEN 1
37#endif
38
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070039/*
40 * This returns the old value in the lock, so we succeeded
41 * in getting the lock if the return value is 0.
42 */
43static __inline__ unsigned long __spin_trylock(raw_spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -070044{
Paul Mackerras0212ddd2005-11-19 20:50:46 +110045 unsigned long tmp, token;
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070046
Paul Mackerras0212ddd2005-11-19 20:50:46 +110047 token = LOCK_TOKEN;
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070048 __asm__ __volatile__(
Paul Mackerras0212ddd2005-11-19 20:50:46 +110049"1: lwarx %0,0,%2 # __spin_trylock\n\
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070050 cmpwi 0,%0,0\n\
51 bne- 2f\n\
52 stwcx. %1,0,%2\n\
53 bne- 1b\n\
54 isync\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100552:" : "=&r" (tmp)
56 : "r" (token), "r" (&lock->slock)
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070057 : "cr0", "memory");
58
59 return tmp;
60}
61
62static int __inline__ __raw_spin_trylock(raw_spinlock_t *lock)
63{
64 return __spin_trylock(lock) == 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070065}
66
67/*
68 * On a system with shared processors (that is, where a physical
69 * processor is multiplexed between several virtual processors),
70 * there is no point spinning on a lock if the holder of the lock
71 * isn't currently scheduled on a physical processor. Instead
72 * we detect this situation and ask the hypervisor to give the
73 * rest of our timeslice to the lock holder.
74 *
75 * So that we can tell which virtual processor is holding a lock,
76 * we put 0x80000000 | smp_processor_id() in the lock when it is
77 * held. Conveniently, we have a word in the paca that holds this
78 * value.
79 */
80
81#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
82/* We only yield to the hypervisor if we are in shared processor mode */
83#define SHARED_PROCESSOR (get_paca()->lppaca.shared_proc)
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070084extern void __spin_yield(raw_spinlock_t *lock);
85extern void __rw_yield(raw_rwlock_t *lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086#else /* SPLPAR || ISERIES */
87#define __spin_yield(x) barrier()
88#define __rw_yield(x) barrier()
89#define SHARED_PROCESSOR 0
90#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -070091
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070092static void __inline__ __raw_spin_lock(raw_spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -070093{
94 while (1) {
95 if (likely(__spin_trylock(lock) == 0))
96 break;
97 do {
98 HMT_low();
99 if (SHARED_PROCESSOR)
100 __spin_yield(lock);
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700101 } while (unlikely(lock->slock != 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 HMT_medium();
103 }
104}
105
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700106static void __inline__ __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107{
108 unsigned long flags_dis;
109
110 while (1) {
111 if (likely(__spin_trylock(lock) == 0))
112 break;
113 local_save_flags(flags_dis);
114 local_irq_restore(flags);
115 do {
116 HMT_low();
117 if (SHARED_PROCESSOR)
118 __spin_yield(lock);
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700119 } while (unlikely(lock->slock != 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 HMT_medium();
121 local_irq_restore(flags_dis);
122 }
123}
124
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700125static __inline__ void __raw_spin_unlock(raw_spinlock_t *lock)
126{
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100127 __asm__ __volatile__(SYNC_ON_SMP" # __raw_spin_unlock"
128 : : :"memory");
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700129 lock->slock = 0;
130}
131
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100132#ifdef CONFIG_PPC64
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700133extern void __raw_spin_unlock_wait(raw_spinlock_t *lock);
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100134#else
135#define __raw_spin_unlock_wait(lock) \
136 do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
137#endif
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700138
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139/*
140 * Read-write spinlocks, allowing multiple readers
141 * but only one writer.
142 *
143 * NOTE! it is quite common to have readers in interrupts
144 * but no interrupt writers. For those circumstances we
145 * can "mix" irq-safe locks - any writer needs to get a
146 * irq-safe write-lock, but readers can get non-irqsafe
147 * read-locks.
148 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700149
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700150#define __raw_read_can_lock(rw) ((rw)->lock >= 0)
151#define __raw_write_can_lock(rw) (!(rw)->lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100153#ifdef CONFIG_PPC64
154#define __DO_SIGN_EXTEND "extsw %0,%0\n"
155#define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */
156#else
157#define __DO_SIGN_EXTEND
158#define WRLOCK_TOKEN (-1)
159#endif
160
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161/*
162 * This returns the old value in the lock + 1,
163 * so we got a read lock if the return value is > 0.
164 */
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700165static long __inline__ __read_trylock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166{
167 long tmp;
168
169 __asm__ __volatile__(
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100170"1: lwarx %0,0,%1 # read_trylock\n"
171 __DO_SIGN_EXTEND
172" addic. %0,%0,1\n\
173 ble- 2f\n"
174 PPC405_ERR77(0,%1)
175" stwcx. %0,0,%1\n\
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 bne- 1b\n\
177 isync\n\
1782:" : "=&r" (tmp)
179 : "r" (&rw->lock)
180 : "cr0", "xer", "memory");
181
182 return tmp;
183}
184
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185/*
186 * This returns the old value in the lock,
187 * so we got the write lock if the return value is 0.
188 */
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700189static __inline__ long __write_trylock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190{
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100191 long tmp, token;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100193 token = WRLOCK_TOKEN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 __asm__ __volatile__(
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100195"1: lwarx %0,0,%2 # write_trylock\n\
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 cmpwi 0,%0,0\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100197 bne- 2f\n"
198 PPC405_ERR77(0,%1)
199" stwcx. %1,0,%2\n\
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 bne- 1b\n\
201 isync\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +11002022:" : "=&r" (tmp)
203 : "r" (token), "r" (&rw->lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 : "cr0", "memory");
205
206 return tmp;
207}
208
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700209static void __inline__ __raw_read_lock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210{
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700211 while (1) {
212 if (likely(__read_trylock(rw) > 0))
213 break;
214 do {
215 HMT_low();
216 if (SHARED_PROCESSOR)
217 __rw_yield(rw);
218 } while (unlikely(rw->lock < 0));
219 HMT_medium();
220 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221}
222
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700223static void __inline__ __raw_write_lock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224{
225 while (1) {
226 if (likely(__write_trylock(rw) == 0))
227 break;
228 do {
229 HMT_low();
230 if (SHARED_PROCESSOR)
231 __rw_yield(rw);
Jake Moilanend6374132005-05-01 08:58:47 -0700232 } while (unlikely(rw->lock != 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 HMT_medium();
234 }
235}
236
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700237static int __inline__ __raw_read_trylock(raw_rwlock_t *rw)
238{
239 return __read_trylock(rw) > 0;
240}
241
242static int __inline__ __raw_write_trylock(raw_rwlock_t *rw)
243{
244 return __write_trylock(rw) == 0;
245}
246
247static void __inline__ __raw_read_unlock(raw_rwlock_t *rw)
248{
249 long tmp;
250
251 __asm__ __volatile__(
252 "eieio # read_unlock\n\
2531: lwarx %0,0,%1\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100254 addic %0,%0,-1\n"
255 PPC405_ERR77(0,%1)
256" stwcx. %0,0,%1\n\
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700257 bne- 1b"
258 : "=&r"(tmp)
259 : "r"(&rw->lock)
260 : "cr0", "memory");
261}
262
263static __inline__ void __raw_write_unlock(raw_rwlock_t *rw)
264{
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100265 __asm__ __volatile__(SYNC_ON_SMP" # write_unlock"
266 : : :"memory");
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700267 rw->lock = 0;
268}
269
Arnd Bergmann88ced032005-12-16 22:43:46 +0100270#endif /* __KERNEL__ */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271#endif /* __ASM_SPINLOCK_H */