/*
* include/asm-s390/spinlock.h
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* Derived from "include/asm-i386/spinlock.h"
*/
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
static inline int
_raw_compare_and_swap(volatile unsigned int *lock,
unsigned int old, unsigned int new)
{
asm volatile ("cs %0,%3,0(%4)"
: "=d" (old), "=m" (*lock)
: "0" (old), "d" (new), "a" (lock), "m" (*lock)
: "cc", "memory" );
return old;
}
/*
* Simple spin lock operations. There are two variants, one clears IRQ's
* on the local processor, one does not.
*
* We make no fairness assumptions. They have a cost.
*/
typedef struct {
volatile unsigned int lock;
#ifdef CONFIG_PREEMPT
unsigned int break_lock;
#endif
} __attribute__ ((aligned (4))) spinlock_t;
#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
#define spin_lock_init(lp) do { (lp)->lock = 0; } while(0)
#define spin_unlock_wait(lp) do { barrier(); } while(((volatile spinlock_t *)(lp))->lock)
#define spin_is_locked(x) ((x)->lock != 0)
#define _raw_spin_lock_flags(lock, flags) _raw_spin_lock(lock)
extern void _raw_spin_lock_wait(spinlock_t *lp, unsigned int pc);
extern int _raw_spin_trylock_retry(spinlock_t *lp, unsigned int pc);
static inline void _raw_spin_lock(spinlock_t *lp)
{
unsigned long pc = (unsigned long) __builtin_return_address(0);
if (unlikely(_raw_compare_and_swap(&lp->lock, 0, pc) != 0))
_raw_spin_lock_wait(lp, pc);
}
static inline int _raw_spin_trylock(spinlock_t *lp)
{
unsigned long pc = (unsigned long) __builtin_return_address(0);
if (likely(_raw_compare_and_swap(&lp->lock, 0, pc) == 0))
return 1;
return _raw_spin_trylock_retry(lp, pc);
}
static inline void _raw_spin_unlock(spinlock_t *lp)
{
_raw_compare_and_swap(&lp->lock, lp->lock, 0);
}
/*
* 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.
*/
typedef struct {
volatile unsigned int lock;
volatile unsigned long owner_pc;
#ifdef CONFIG_PREEMPT
unsigned int break_lock;
#endif
} rwlock_t;
#define RW_LOCK_UNLOCKED (rwlock_t) { 0, 0 }
#define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0)
/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
#define read_can_lock(x) ((int)(x)->lock >= 0)
/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
#define write_can_lock(x) ((x)->lock == 0)
extern void _raw_read_lock_wait(rwlock_t *lp);
extern int _raw_read_trylock_retry(rwlock_t *lp);
extern void _raw_write_lock_wait(rwlock_t *lp);
extern int _raw_write_trylock_retry(rwlock_t *lp);
static inline void _raw_read_lock(rwlock_t *rw)
{
unsigned int old;
old = rw->lock & 0x7fffffffU;
if (_raw_compare_and_swap(&rw->lock, old, old + 1) != old)
_raw_read_lock_wait(rw);
}
static inline void _raw_read_unlock(rwlock_t *rw)
{
unsigned int old, cmp;
old = rw->lock;
do {
cmp = old;
old = _raw_compare_and_swap(&rw->lock, old, old - 1);
} while (cmp != old);
}
static inline void _raw_write_lock(rwlock_t *rw)
{
if (unlikely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) != 0))
_raw_write_lock_wait(rw);
}
static inline void _raw_write_unlock(rwlock_t *rw)
{
_raw_compare_and_swap(&rw->lock, 0x80000000, 0);
}
static inline int _raw_read_trylock(rwlock_t *rw)
{
unsigned int old;
old = rw->lock & 0x7fffffffU;
if (likely(_raw_compare_and_swap(&rw->lock, old, old + 1) == old))
return 1;
return _raw_read_trylock_retry(rw);
}
static inline int _raw_write_trylock(rwlock_t *rw)
{
if (likely(_raw_compare_and_swap(&rw->lock, 0, 0x80000000) == 0))
return 1;
return _raw_write_trylock_retry(rw);
}
#endif /* __ASM_SPINLOCK_H */
