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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
Paul Mackerrasf007cac2006-09-13 22:08:26 +100039#if defined(CONFIG_PPC64) && defined(CONFIG_SMP)
40#define CLEAR_IO_SYNC (get_paca()->io_sync = 0)
41#define SYNC_IO do { \
42 if (unlikely(get_paca()->io_sync)) { \
43 mb(); \
44 get_paca()->io_sync = 0; \
45 } \
46 } while (0)
47#else
48#define CLEAR_IO_SYNC
49#define SYNC_IO
50#endif
51
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070052/*
53 * This returns the old value in the lock, so we succeeded
54 * in getting the lock if the return value is 0.
55 */
56static __inline__ unsigned long __spin_trylock(raw_spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -070057{
Paul Mackerras0212ddd2005-11-19 20:50:46 +110058 unsigned long tmp, token;
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070059
Paul Mackerras0212ddd2005-11-19 20:50:46 +110060 token = LOCK_TOKEN;
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070061 __asm__ __volatile__(
Anton Blanchard144b9c12006-01-13 15:37:17 +110062"1: lwarx %0,0,%2\n\
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070063 cmpwi 0,%0,0\n\
64 bne- 2f\n\
65 stwcx. %1,0,%2\n\
66 bne- 1b\n\
67 isync\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100682:" : "=&r" (tmp)
69 : "r" (token), "r" (&lock->slock)
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070070 : "cr0", "memory");
71
72 return tmp;
73}
74
75static int __inline__ __raw_spin_trylock(raw_spinlock_t *lock)
76{
Paul Mackerrasf007cac2006-09-13 22:08:26 +100077 CLEAR_IO_SYNC;
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070078 return __spin_trylock(lock) == 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -070079}
80
81/*
82 * On a system with shared processors (that is, where a physical
83 * processor is multiplexed between several virtual processors),
84 * there is no point spinning on a lock if the holder of the lock
85 * isn't currently scheduled on a physical processor. Instead
86 * we detect this situation and ask the hypervisor to give the
87 * rest of our timeslice to the lock holder.
88 *
89 * So that we can tell which virtual processor is holding a lock,
90 * we put 0x80000000 | smp_processor_id() in the lock when it is
91 * held. Conveniently, we have a word in the paca that holds this
92 * value.
93 */
94
95#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES)
96/* We only yield to the hypervisor if we are in shared processor mode */
David Gibson3356bb9f72006-01-13 10:26:42 +110097#define SHARED_PROCESSOR (get_lppaca()->shared_proc)
Ingo Molnarfb1c8f92005-09-10 00:25:56 -070098extern void __spin_yield(raw_spinlock_t *lock);
99extern void __rw_yield(raw_rwlock_t *lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100#else /* SPLPAR || ISERIES */
101#define __spin_yield(x) barrier()
102#define __rw_yield(x) barrier()
103#define SHARED_PROCESSOR 0
104#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700106static void __inline__ __raw_spin_lock(raw_spinlock_t *lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700107{
Paul Mackerrasf007cac2006-09-13 22:08:26 +1000108 CLEAR_IO_SYNC;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 while (1) {
110 if (likely(__spin_trylock(lock) == 0))
111 break;
112 do {
113 HMT_low();
114 if (SHARED_PROCESSOR)
115 __spin_yield(lock);
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700116 } while (unlikely(lock->slock != 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 HMT_medium();
118 }
119}
120
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700121static void __inline__ __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122{
123 unsigned long flags_dis;
124
Paul Mackerrasf007cac2006-09-13 22:08:26 +1000125 CLEAR_IO_SYNC;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126 while (1) {
127 if (likely(__spin_trylock(lock) == 0))
128 break;
129 local_save_flags(flags_dis);
130 local_irq_restore(flags);
131 do {
132 HMT_low();
133 if (SHARED_PROCESSOR)
134 __spin_yield(lock);
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700135 } while (unlikely(lock->slock != 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136 HMT_medium();
137 local_irq_restore(flags_dis);
138 }
139}
140
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700141static __inline__ void __raw_spin_unlock(raw_spinlock_t *lock)
142{
Paul Mackerrasf007cac2006-09-13 22:08:26 +1000143 SYNC_IO;
Anton Blanchard144b9c12006-01-13 15:37:17 +1100144 __asm__ __volatile__("# __raw_spin_unlock\n\t"
145 LWSYNC_ON_SMP: : :"memory");
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700146 lock->slock = 0;
147}
148
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100149#ifdef CONFIG_PPC64
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700150extern void __raw_spin_unlock_wait(raw_spinlock_t *lock);
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100151#else
152#define __raw_spin_unlock_wait(lock) \
153 do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
154#endif
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156/*
157 * Read-write spinlocks, allowing multiple readers
158 * but only one writer.
159 *
160 * NOTE! it is quite common to have readers in interrupts
161 * but no interrupt writers. For those circumstances we
162 * can "mix" irq-safe locks - any writer needs to get a
163 * irq-safe write-lock, but readers can get non-irqsafe
164 * read-locks.
165 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700167#define __raw_read_can_lock(rw) ((rw)->lock >= 0)
168#define __raw_write_can_lock(rw) (!(rw)->lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100170#ifdef CONFIG_PPC64
171#define __DO_SIGN_EXTEND "extsw %0,%0\n"
172#define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */
173#else
174#define __DO_SIGN_EXTEND
175#define WRLOCK_TOKEN (-1)
176#endif
177
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178/*
179 * This returns the old value in the lock + 1,
180 * so we got a read lock if the return value is > 0.
181 */
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700182static long __inline__ __read_trylock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700183{
184 long tmp;
185
186 __asm__ __volatile__(
Anton Blanchard144b9c12006-01-13 15:37:17 +1100187"1: lwarx %0,0,%1\n"
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100188 __DO_SIGN_EXTEND
189" addic. %0,%0,1\n\
190 ble- 2f\n"
191 PPC405_ERR77(0,%1)
192" stwcx. %0,0,%1\n\
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 bne- 1b\n\
194 isync\n\
1952:" : "=&r" (tmp)
196 : "r" (&rw->lock)
197 : "cr0", "xer", "memory");
198
199 return tmp;
200}
201
Linus Torvalds1da177e2005-04-16 15:20:36 -0700202/*
203 * This returns the old value in the lock,
204 * so we got the write lock if the return value is 0.
205 */
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700206static __inline__ long __write_trylock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207{
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100208 long tmp, token;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100210 token = WRLOCK_TOKEN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 __asm__ __volatile__(
Anton Blanchard144b9c12006-01-13 15:37:17 +1100212"1: lwarx %0,0,%2\n\
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 cmpwi 0,%0,0\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100214 bne- 2f\n"
215 PPC405_ERR77(0,%1)
216" stwcx. %1,0,%2\n\
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 bne- 1b\n\
218 isync\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +11002192:" : "=&r" (tmp)
220 : "r" (token), "r" (&rw->lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 : "cr0", "memory");
222
223 return tmp;
224}
225
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700226static void __inline__ __raw_read_lock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227{
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700228 while (1) {
229 if (likely(__read_trylock(rw) > 0))
230 break;
231 do {
232 HMT_low();
233 if (SHARED_PROCESSOR)
234 __rw_yield(rw);
235 } while (unlikely(rw->lock < 0));
236 HMT_medium();
237 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700238}
239
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700240static void __inline__ __raw_write_lock(raw_rwlock_t *rw)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241{
242 while (1) {
243 if (likely(__write_trylock(rw) == 0))
244 break;
245 do {
246 HMT_low();
247 if (SHARED_PROCESSOR)
248 __rw_yield(rw);
Jake Moilanend6374132005-05-01 08:58:47 -0700249 } while (unlikely(rw->lock != 0));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700250 HMT_medium();
251 }
252}
253
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700254static int __inline__ __raw_read_trylock(raw_rwlock_t *rw)
255{
256 return __read_trylock(rw) > 0;
257}
258
259static int __inline__ __raw_write_trylock(raw_rwlock_t *rw)
260{
261 return __write_trylock(rw) == 0;
262}
263
264static void __inline__ __raw_read_unlock(raw_rwlock_t *rw)
265{
266 long tmp;
267
268 __asm__ __volatile__(
Anton Blanchard144b9c12006-01-13 15:37:17 +1100269 "# read_unlock\n\t"
270 LWSYNC_ON_SMP
271"1: lwarx %0,0,%1\n\
Paul Mackerras0212ddd2005-11-19 20:50:46 +1100272 addic %0,%0,-1\n"
273 PPC405_ERR77(0,%1)
274" stwcx. %0,0,%1\n\
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700275 bne- 1b"
276 : "=&r"(tmp)
277 : "r"(&rw->lock)
278 : "cr0", "memory");
279}
280
281static __inline__ void __raw_write_unlock(raw_rwlock_t *rw)
282{
Anton Blanchard144b9c12006-01-13 15:37:17 +1100283 __asm__ __volatile__("# write_unlock\n\t"
284 LWSYNC_ON_SMP: : :"memory");
Ingo Molnarfb1c8f92005-09-10 00:25:56 -0700285 rw->lock = 0;
286}
287
Martin Schwidefskycdc39362006-09-30 23:27:44 -0700288#define _raw_spin_relax(lock) __spin_yield(lock)
289#define _raw_read_relax(lock) __rw_yield(lock)
290#define _raw_write_relax(lock) __rw_yield(lock)
Martin Schwidefskyef6edc92006-09-30 23:27:43 -0700291
Arnd Bergmann88ced032005-12-16 22:43:46 +0100292#endif /* __KERNEL__ */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293#endif /* __ASM_SPINLOCK_H */