#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. * * (the type definitions are in asm/spinlock_types.h) */ #include <linux/config.h> #include <asm/paca.h> #include <asm/hvcall.h> #include <asm/iseries/hv_call.h> #define __raw_spin_is_locked(x) ((x)->slock != 0) /* * 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(raw_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->slock), "i" (offsetof(struct paca_struct, lock_token)) : "cr0", "memory"); return tmp; } static int __inline__ __raw_spin_trylock(raw_spinlock_t *lock) { return __spin_trylock(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(raw_spinlock_t *lock); extern void __rw_yield(raw_rwlock_t *lock); #else /* SPLPAR || ISERIES */ #define __spin_yield(x) barrier() #define __rw_yield(x) barrier() #define SHARED_PROCESSOR 0 #endif static void __inline__ __raw_spin_lock(raw_spinlock_t *lock) { while (1) { if (likely(__spin_trylock(lock) == 0)) break; do { HMT_low(); if (SHARED_PROCESSOR) __spin_yield(lock); } while (unlikely(lock->slock != 0)); HMT_medium(); } } static void __inline__ __raw_spin_lock_flags(raw_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 (unlikely(lock->slock != 0)); HMT_medium(); local_irq_restore(flags_dis); } } static __inline__ void __raw_spin_unlock(raw_spinlock_t *lock) { __asm__ __volatile__("lwsync # __raw_spin_unlock": : :"memory"); lock->slock = 0; } extern void __raw_spin_unlock_wait(raw_spinlock_t *lock); /* * 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 __raw_read_can_lock(rw) ((rw)->lock >= 0) #define __raw_write_can_lock(rw) (!(rw)->lock) /* * 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(raw_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; } /* * 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(raw_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 void __inline__ __raw_read_lock(raw_rwlock_t *rw) { while (1) { if (likely(__read_trylock(rw) > 0)) break; do { HMT_low(); if (SHARED_PROCESSOR) __rw_yield(rw); } while (unlikely(rw->lock < 0)); HMT_medium(); } } static void __inline__ __raw_write_lock(raw_rwlock_t *rw) { while (1) { if (likely(__write_trylock(rw) == 0)) break; do { HMT_low(); if (SHARED_PROCESSOR) __rw_yield(rw); } while (unlikely(rw->lock != 0)); HMT_medium(); } } static int __inline__ __raw_read_trylock(raw_rwlock_t *rw) { return __read_trylock(rw) > 0; } static int __inline__ __raw_write_trylock(raw_rwlock_t *rw) { return __write_trylock(rw) == 0; } static void __inline__ __raw_read_unlock(raw_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"); } static __inline__ void __raw_write_unlock(raw_rwlock_t *rw) { __asm__ __volatile__("lwsync # write_unlock": : :"memory"); rw->lock = 0; } #endif /* __ASM_SPINLOCK_H */