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Diffstat (limited to 'include/asm-ppc64/spinlock.h')
| -rw-r--r-- | include/asm-ppc64/spinlock.h | 260 |
1 files changed, 260 insertions, 0 deletions
diff --git a/include/asm-ppc64/spinlock.h b/include/asm-ppc64/spinlock.h new file mode 100644 index 00000000000..a9b2a1162cf --- /dev/null +++ b/include/asm-ppc64/spinlock.h @@ -0,0 +1,260 @@ +#ifndef __ASM_SPINLOCK_H +#define __ASM_SPINLOCK_H + +/* + * Simple spin lock operations. + * + * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM + * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM + * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM + * Rework to support virtual processors + * + * Type of int is used as a full 64b word is not necessary. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +#include <linux/config.h> +#include <asm/paca.h> +#include <asm/hvcall.h> +#include <asm/iSeries/HvCall.h> + +typedef struct { + volatile unsigned int lock; +#ifdef CONFIG_PREEMPT + unsigned int break_lock; +#endif +} spinlock_t; + +typedef struct { + volatile signed int lock; +#ifdef CONFIG_PREEMPT + unsigned int break_lock; +#endif +} rwlock_t; + +#ifdef __KERNEL__ +#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 } + +#define spin_is_locked(x) ((x)->lock != 0) +#define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0) + +static __inline__ void _raw_spin_unlock(spinlock_t *lock) +{ + __asm__ __volatile__("lwsync # spin_unlock": : :"memory"); + lock->lock = 0; +} + +/* + * On a system with shared processors (that is, where a physical + * processor is multiplexed between several virtual processors), + * there is no point spinning on a lock if the holder of the lock + * isn't currently scheduled on a physical processor. Instead + * we detect this situation and ask the hypervisor to give the + * rest of our timeslice to the lock holder. + * + * So that we can tell which virtual processor is holding a lock, + * we put 0x80000000 | smp_processor_id() in the lock when it is + * held. Conveniently, we have a word in the paca that holds this + * value. + */ + +#if defined(CONFIG_PPC_SPLPAR) || defined(CONFIG_PPC_ISERIES) +/* We only yield to the hypervisor if we are in shared processor mode */ +#define SHARED_PROCESSOR (get_paca()->lppaca.shared_proc) +extern void __spin_yield(spinlock_t *lock); +extern void __rw_yield(rwlock_t *lock); +#else /* SPLPAR || ISERIES */ +#define __spin_yield(x) barrier() +#define __rw_yield(x) barrier() +#define SHARED_PROCESSOR 0 +#endif +extern void spin_unlock_wait(spinlock_t *lock); + +/* + * This returns the old value in the lock, so we succeeded + * in getting the lock if the return value is 0. + */ +static __inline__ unsigned long __spin_trylock(spinlock_t *lock) +{ + unsigned long tmp, tmp2; + + __asm__ __volatile__( +" lwz %1,%3(13) # __spin_trylock\n\ +1: lwarx %0,0,%2\n\ + cmpwi 0,%0,0\n\ + bne- 2f\n\ + stwcx. %1,0,%2\n\ + bne- 1b\n\ + isync\n\ +2:" : "=&r" (tmp), "=&r" (tmp2) + : "r" (&lock->lock), "i" (offsetof(struct paca_struct, lock_token)) + : "cr0", "memory"); + + return tmp; +} + +static int __inline__ _raw_spin_trylock(spinlock_t *lock) +{ + return __spin_trylock(lock) == 0; +} + +static void __inline__ _raw_spin_lock(spinlock_t *lock) +{ + while (1) { + if (likely(__spin_trylock(lock) == 0)) + break; + do { + HMT_low(); + if (SHARED_PROCESSOR) + __spin_yield(lock); + } while (likely(lock->lock != 0)); + HMT_medium(); + } +} + +static void __inline__ _raw_spin_lock_flags(spinlock_t *lock, unsigned long flags) +{ + unsigned long flags_dis; + + while (1) { + if (likely(__spin_trylock(lock) == 0)) + break; + local_save_flags(flags_dis); + local_irq_restore(flags); + do { + HMT_low(); + if (SHARED_PROCESSOR) + __spin_yield(lock); + } while (likely(lock->lock != 0)); + HMT_medium(); + local_irq_restore(flags_dis); + } +} + +/* + * Read-write spinlocks, allowing multiple readers + * but only one writer. + * + * NOTE! it is quite common to have readers in interrupts + * but no interrupt writers. For those circumstances we + * can "mix" irq-safe locks - any writer needs to get a + * irq-safe write-lock, but readers can get non-irqsafe + * read-locks. + */ +#define RW_LOCK_UNLOCKED (rwlock_t) { 0 } + +#define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0) + +#define read_can_lock(rw) ((rw)->lock >= 0) +#define write_can_lock(rw) (!(rw)->lock) + +static __inline__ void _raw_write_unlock(rwlock_t *rw) +{ + __asm__ __volatile__("lwsync # write_unlock": : :"memory"); + rw->lock = 0; +} + +/* + * This returns the old value in the lock + 1, + * so we got a read lock if the return value is > 0. + */ +static long __inline__ __read_trylock(rwlock_t *rw) +{ + long tmp; + + __asm__ __volatile__( +"1: lwarx %0,0,%1 # read_trylock\n\ + extsw %0,%0\n\ + addic. %0,%0,1\n\ + ble- 2f\n\ + stwcx. %0,0,%1\n\ + bne- 1b\n\ + isync\n\ +2:" : "=&r" (tmp) + : "r" (&rw->lock) + : "cr0", "xer", "memory"); + + return tmp; +} + +static int __inline__ _raw_read_trylock(rwlock_t *rw) +{ + return __read_trylock(rw) > 0; +} + +static void __inline__ _raw_read_lock(rwlock_t *rw) +{ + while (1) { + if (likely(__read_trylock(rw) > 0)) + break; + do { + HMT_low(); + if (SHARED_PROCESSOR) + __rw_yield(rw); + } while (likely(rw->lock < 0)); + HMT_medium(); + } +} + +static void __inline__ _raw_read_unlock(rwlock_t *rw) +{ + long tmp; + + __asm__ __volatile__( + "eieio # read_unlock\n\ +1: lwarx %0,0,%1\n\ + addic %0,%0,-1\n\ + stwcx. %0,0,%1\n\ + bne- 1b" + : "=&r"(tmp) + : "r"(&rw->lock) + : "cr0", "memory"); +} + +/* + * This returns the old value in the lock, + * so we got the write lock if the return value is 0. + */ +static __inline__ long __write_trylock(rwlock_t *rw) +{ + long tmp, tmp2; + + __asm__ __volatile__( +" lwz %1,%3(13) # write_trylock\n\ +1: lwarx %0,0,%2\n\ + cmpwi 0,%0,0\n\ + bne- 2f\n\ + stwcx. %1,0,%2\n\ + bne- 1b\n\ + isync\n\ +2:" : "=&r" (tmp), "=&r" (tmp2) + : "r" (&rw->lock), "i" (offsetof(struct paca_struct, lock_token)) + : "cr0", "memory"); + + return tmp; +} + +static int __inline__ _raw_write_trylock(rwlock_t *rw) +{ + return __write_trylock(rw) == 0; +} + +static void __inline__ _raw_write_lock(rwlock_t *rw) +{ + while (1) { + if (likely(__write_trylock(rw) == 0)) + break; + do { + HMT_low(); + if (SHARED_PROCESSOR) + __rw_yield(rw); + } while (likely(rw->lock != 0)); + HMT_medium(); + } +} + +#endif /* __KERNEL__ */ +#endif /* __ASM_SPINLOCK_H */ |