#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 */
