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/* SPDX-License-Identifier: GPL-2.0 */
/*
* S390 version
* Copyright IBM Corp. 1999
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* Derived from "include/asm-i386/spinlock.h"
*/
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
#include <linux/smp.h>
#include <asm/atomic_ops.h>
#include <asm/barrier.h>
#include <asm/processor.h>
#include <asm/alternative.h>
#define SPINLOCK_LOCKVAL (S390_lowcore.spinlock_lockval)
extern int spin_retry;
#ifndef CONFIG_SMP
static inline bool arch_vcpu_is_preempted(int cpu) { return false; }
#else
bool arch_vcpu_is_preempted(int cpu);
#endif
#define vcpu_is_preempted arch_vcpu_is_preempted
/*
* 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.
*
* (the type definitions are in asm/spinlock_types.h)
*/
void arch_spin_relax(arch_spinlock_t *lock);
void arch_spin_lock_wait(arch_spinlock_t *);
int arch_spin_trylock_retry(arch_spinlock_t *);
void arch_spin_lock_setup(int cpu);
static inline u32 arch_spin_lockval(int cpu)
{
return cpu + 1;
}
static inline int arch_spin_value_unlocked(arch_spinlock_t lock)
{
return lock.lock == 0;
}
static inline int arch_spin_is_locked(arch_spinlock_t *lp)
{
return READ_ONCE(lp->lock) != 0;
}
static inline int arch_spin_trylock_once(arch_spinlock_t *lp)
{
barrier();
return likely(__atomic_cmpxchg_bool(&lp->lock, 0, SPINLOCK_LOCKVAL));
}
static inline void arch_spin_lock(arch_spinlock_t *lp)
{
if (!arch_spin_trylock_once(lp))
arch_spin_lock_wait(lp);
}
static inline void arch_spin_lock_flags(arch_spinlock_t *lp,
unsigned long flags)
{
if (!arch_spin_trylock_once(lp))
arch_spin_lock_wait(lp);
}
static inline int arch_spin_trylock(arch_spinlock_t *lp)
{
if (!arch_spin_trylock_once(lp))
return arch_spin_trylock_retry(lp);
return 1;
}
static inline void arch_spin_unlock(arch_spinlock_t *lp)
{
typecheck(int, lp->lock);
asm volatile(
ALTERNATIVE("", ".long 0xb2fa0070", 49) /* NIAI 7 */
" sth %1,%0\n"
: "=Q" (((unsigned short *) &lp->lock)[1])
: "d" (0) : "cc", "memory");
}
/*
* 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.
*/
/**
* read_can_lock - would read_trylock() succeed?
* @lock: the rwlock in question.
*/
#define arch_read_can_lock(x) (((x)->cnts & 0xffff0000) == 0)
/**
* write_can_lock - would write_trylock() succeed?
* @lock: the rwlock in question.
*/
#define arch_write_can_lock(x) ((x)->cnts == 0)
#define arch_read_lock_flags(lock, flags) arch_read_lock(lock)
#define arch_write_lock_flags(lock, flags) arch_write_lock(lock)
#define arch_read_relax(rw) barrier()
#define arch_write_relax(rw) barrier()
void arch_read_lock_wait(arch_rwlock_t *lp);
void arch_write_lock_wait(arch_rwlock_t *lp);
static inline void arch_read_lock(arch_rwlock_t *rw)
{
int old;
old = __atomic_add(1, &rw->cnts);
if (old & 0xffff0000)
arch_read_lock_wait(rw);
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
__atomic_add_const_barrier(-1, &rw->cnts);
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
if (!__atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000))
arch_write_lock_wait(rw);
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
__atomic_add_barrier(-0x30000, &rw->cnts);
}
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
int old;
old = READ_ONCE(rw->cnts);
return (!(old & 0xffff0000) &&
__atomic_cmpxchg_bool(&rw->cnts, old, old + 1));
}
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
int old;
old = READ_ONCE(rw->cnts);
return !old && __atomic_cmpxchg_bool(&rw->cnts, 0, 0x30000);
}
#endif /* __ASM_SPINLOCK_H */
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