linux/arch/sh/include/asm/spinlock-cas.h
Kuninori Morimoto 6a0abce4c4 sh: include: convert to SPDX identifiers
Update license to use SPDX-License-Identifier instead of verbose license
text.

Link: http://lkml.kernel.org/r/87ftvccszx.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-12-28 12:11:45 -08:00

90 lines
2.0 KiB
C

/* SPDX-License-Identifier: GPL-2.0
*
* include/asm-sh/spinlock-cas.h
*
* Copyright (C) 2015 SEI
*/
#ifndef __ASM_SH_SPINLOCK_CAS_H
#define __ASM_SH_SPINLOCK_CAS_H
#include <asm/barrier.h>
#include <asm/processor.h>
static inline unsigned __sl_cas(volatile unsigned *p, unsigned old, unsigned new)
{
__asm__ __volatile__("cas.l %1,%0,@r0"
: "+r"(new)
: "r"(old), "z"(p)
: "t", "memory" );
return new;
}
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*/
#define arch_spin_is_locked(x) ((x)->lock <= 0)
static inline void arch_spin_lock(arch_spinlock_t *lock)
{
while (!__sl_cas(&lock->lock, 1, 0));
}
static inline void arch_spin_unlock(arch_spinlock_t *lock)
{
__sl_cas(&lock->lock, 0, 1);
}
static inline int arch_spin_trylock(arch_spinlock_t *lock)
{
return __sl_cas(&lock->lock, 1, 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.
*/
static inline void arch_read_lock(arch_rwlock_t *rw)
{
unsigned old;
do old = rw->lock;
while (!old || __sl_cas(&rw->lock, old, old-1) != old);
}
static inline void arch_read_unlock(arch_rwlock_t *rw)
{
unsigned old;
do old = rw->lock;
while (__sl_cas(&rw->lock, old, old+1) != old);
}
static inline void arch_write_lock(arch_rwlock_t *rw)
{
while (__sl_cas(&rw->lock, RW_LOCK_BIAS, 0) != RW_LOCK_BIAS);
}
static inline void arch_write_unlock(arch_rwlock_t *rw)
{
__sl_cas(&rw->lock, 0, RW_LOCK_BIAS);
}
static inline int arch_read_trylock(arch_rwlock_t *rw)
{
unsigned old;
do old = rw->lock;
while (old && __sl_cas(&rw->lock, old, old-1) != old);
return !!old;
}
static inline int arch_write_trylock(arch_rwlock_t *rw)
{
return __sl_cas(&rw->lock, RW_LOCK_BIAS, 0) == RW_LOCK_BIAS;
}
#endif /* __ASM_SH_SPINLOCK_CAS_H */