atomic.h

/*
 * Based on arch/arm/include/asm/atomic.h
 *
 * Copyright (C) 1996 Russell King.
 * Copyright (C) 2002 Deep Blue Solutions Ltd.
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef __ASM_ATOMIC_H
#define __ASM_ATOMIC_H

#include <linux/compiler.h>
#include <linux/stringify.h>
#include <linux/types.h>

#include <asm/barrier.h>
#include <asm/cmpxchg.h>

#define ATOMIC_INIT(i)	{ (i) }

#ifdef __KERNEL__

#define __ARM64_IN_ATOMIC_IMPL

#ifdef CONFIG_ARM64_LSE_ATOMICS
#include <asm/atomic_lse.h>
#else
#include <asm/atomic_ll_sc.h>
#endif

#undef __ARM64_IN_ATOMIC_IMPL

/*
 * On ARM, ordinary assignment (str instruction) doesn't clear the local
 * strex/ldrex monitor on some implementations. The reason we can use it for
 * atomic_set() is the clrex or dummy strex done on every exception return.
 */
#define atomic_read(v)	ACCESS_ONCE((v)->counter)
#define atomic_set(v,i)	(((v)->counter) = (i))

#define atomic_xchg(v, new) (xchg(&((v)->counter), new))

static inline int __atomic_add_unless(atomic_t *v, int a, int u)
{
	int c, old;

	c = atomic_read(v);
	while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c)
		c = old;
	return c;
}

#define atomic_inc(v)		atomic_add(1, v)
#define atomic_dec(v)		atomic_sub(1, v)

#define atomic_inc_and_test(v)	(atomic_add_return(1, v) == 0)
#define atomic_dec_and_test(v)	(atomic_sub_return(1, v) == 0)
#define atomic_inc_return(v)    (atomic_add_return(1, v))
#define atomic_dec_return(v)    (atomic_sub_return(1, v))
#define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)

#define atomic_add_negative(i,v) (atomic_add_return(i, v) < 0)

#define atomic_andnot atomic_andnot

/*
 * 64-bit atomic operations.
 */
#define ATOMIC64_INIT(i) { (i) }

#define atomic64_read(v)	ACCESS_ONCE((v)->counter)
#define atomic64_set(v,i)	(((v)->counter) = (i))

#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))

static inline int atomic64_add_unless(atomic64_t *v, long a, long u)
{
	long c, old;

	c = atomic64_read(v);
	while (c != u && (old = atomic64_cmpxchg((v), c, c + a)) != c)
		c = old;

	return c != u;
}

#define atomic64_add_negative(a, v)	(atomic64_add_return((a), (v)) < 0)
#define atomic64_inc(v)			atomic64_add(1LL, (v))
#define atomic64_inc_return(v)		atomic64_add_return(1LL, (v))
#define atomic64_inc_and_test(v)	(atomic64_inc_return(v) == 0)
#define atomic64_sub_and_test(a, v)	(atomic64_sub_return((a), (v)) == 0)
#define atomic64_dec(v)			atomic64_sub(1LL, (v))
#define atomic64_dec_return(v)		atomic64_sub_return(1LL, (v))
#define atomic64_dec_and_test(v)	(atomic64_dec_return((v)) == 0)
#define atomic64_inc_not_zero(v)	atomic64_add_unless((v), 1LL, 0LL)

#define atomic64_andnot atomic64_andnot

#endif
#endif