1 #ifndef __ASM_SPINLOCK_H
2 #define __ASM_SPINLOCK_H
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>
25 #include <asm/hvcall.h>
26 #include <asm/iseries/hv_call.h>
28 #include <asm/asm-compat.h>
29 #include <asm/synch.h>
31 #define arch_spin_is_locked(x) ((x)->slock != 0)
34 /* use 0x800000yy when locked, where yy == CPU number */
35 #define LOCK_TOKEN (*(u32 *)(&get_paca()->lock_token))
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)) { \
45 get_paca()->io_sync = 0; \
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 __arch_spin_trylock(arch_spinlock_t
*lock
)
59 unsigned long tmp
, token
;
70 : "r" (token
), "r" (&lock
->slock
)
76 static inline int arch_spin_trylock(arch_spinlock_t
*lock
)
79 return __arch_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
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(arch_spinlock_t
*lock
);
100 extern void __rw_yield(arch_rwlock_t
*lock
);
101 #else /* SPLPAR || ISERIES */
102 #define __spin_yield(x) barrier()
103 #define __rw_yield(x) barrier()
104 #define SHARED_PROCESSOR 0
107 static inline void arch_spin_lock(arch_spinlock_t
*lock
)
111 if (likely(__arch_spin_trylock(lock
) == 0))
115 if (SHARED_PROCESSOR
)
117 } while (unlikely(lock
->slock
!= 0));
123 void arch_spin_lock_flags(arch_spinlock_t
*lock
, unsigned long flags
)
125 unsigned long flags_dis
;
129 if (likely(__arch_spin_trylock(lock
) == 0))
131 local_save_flags(flags_dis
);
132 local_irq_restore(flags
);
135 if (SHARED_PROCESSOR
)
137 } while (unlikely(lock
->slock
!= 0));
139 local_irq_restore(flags_dis
);
143 static inline void arch_spin_unlock(arch_spinlock_t
*lock
)
146 __asm__
__volatile__("# arch_spin_unlock\n\t"
147 LWSYNC_ON_SMP
: : :"memory");
152 extern void arch_spin_unlock_wait(arch_spinlock_t
*lock
);
154 #define arch_spin_unlock_wait(lock) \
155 do { while (arch_spin_is_locked(lock)) cpu_relax(); } while (0)
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
169 #define __raw_read_can_lock(rw) ((rw)->lock >= 0)
170 #define __raw_write_can_lock(rw) (!(rw)->lock)
173 #define __DO_SIGN_EXTEND "extsw %0,%0\n"
174 #define WRLOCK_TOKEN LOCK_TOKEN /* it's negative */
176 #define __DO_SIGN_EXTEND
177 #define WRLOCK_TOKEN (-1)
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 arch_read_trylock(arch_rwlock_t
*rw
)
188 __asm__
__volatile__(
199 : "cr0", "xer", "memory");
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 arch_write_trylock(arch_rwlock_t
*rw
)
212 token
= WRLOCK_TOKEN
;
213 __asm__
__volatile__(
222 : "r" (token
), "r" (&rw
->lock
)
228 static inline void __raw_read_lock(arch_rwlock_t
*rw
)
231 if (likely(arch_read_trylock(rw
) > 0))
235 if (SHARED_PROCESSOR
)
237 } while (unlikely(rw
->lock
< 0));
242 static inline void __raw_write_lock(arch_rwlock_t
*rw
)
245 if (likely(arch_write_trylock(rw
) == 0))
249 if (SHARED_PROCESSOR
)
251 } while (unlikely(rw
->lock
!= 0));
256 static inline int __raw_read_trylock(arch_rwlock_t
*rw
)
258 return arch_read_trylock(rw
) > 0;
261 static inline int __raw_write_trylock(arch_rwlock_t
*rw
)
263 return arch_write_trylock(rw
) == 0;
266 static inline void __raw_read_unlock(arch_rwlock_t
*rw
)
270 __asm__
__volatile__(
280 : "cr0", "xer", "memory");
283 static inline void __raw_write_unlock(arch_rwlock_t
*rw
)
285 __asm__
__volatile__("# write_unlock\n\t"
286 LWSYNC_ON_SMP
: : :"memory");
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 arch_spin_relax(lock) __spin_yield(lock)
294 #define arch_read_relax(lock) __rw_yield(lock)
295 #define arch_write_relax(lock) __rw_yield(lock)
297 #endif /* __KERNEL__ */
298 #endif /* __ASM_SPINLOCK_H */