atomic.h

/* atomic.h: atomic operation emulation for FR-V
 *
 * For an explanation of how atomic ops work in this arch, see:
 *   Documentation/frv/atomic-ops.txt
 *
 * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * 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.
 */
#ifndef _ASM_ATOMIC_H
#define _ASM_ATOMIC_H

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

#ifdef CONFIG_SMP
#error not SMP safe
#endif

#include <asm/atomic_defs.h>

/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 *
 * We do not have SMP systems, so we don't have to deal with that.
 */

#define ATOMIC_INIT(i)		{ (i) }
#define atomic_read(v)		READ_ONCE((v)->counter)
#define atomic_set(v, i)	WRITE_ONCE(((v)->counter), (i))

static inline int atomic_inc_return(atomic_t *v)
{
	return __atomic_add_return(1, &v->counter);
}

static inline int atomic_dec_return(atomic_t *v)
{
	return __atomic_sub_return(1, &v->counter);
}

static inline int atomic_add_return(int i, atomic_t *v)
{
	return __atomic_add_return(i, &v->counter);
}

static inline int atomic_sub_return(int i, atomic_t *v)
{
	return __atomic_sub_return(i, &v->counter);
}

static inline int atomic_add_negative(int i, atomic_t *v)
{
	return atomic_add_return(i, v) < 0;
}

static inline void atomic_inc(atomic_t *v)
{
	atomic_inc_return(v);
}

static inline void atomic_dec(atomic_t *v)
{
	atomic_dec_return(v);
}

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

/*
 * 64-bit atomic ops
 */
typedef struct {
	long long counter;
} atomic64_t;

#define ATOMIC64_INIT(i)	{ (i) }

static inline long long atomic64_read(const atomic64_t *v)
{
	long long counter;

	asm("ldd%I1 %M1,%0"
	    : "=e"(counter)
	    : "m"(v->counter));

	return counter;
}

static inline void atomic64_set(atomic64_t *v, long long i)
{
	asm volatile("std%I0 %1,%M0"
		     : "=m"(v->counter)
		     : "e"(i));
}

static inline long long atomic64_inc_return(atomic64_t *v)
{
	return __atomic64_add_return(1, &v->counter);
}

static inline long long atomic64_dec_return(atomic64_t *v)
{
	return __atomic64_sub_return(1, &v->counter);
}

static inline long long atomic64_add_return(long long i, atomic64_t *v)
{
	return __atomic64_add_return(i, &v->counter);
}

static inline long long atomic64_sub_return(long long i, atomic64_t *v)
{
	return __atomic64_sub_return(i, &v->counter);
}

static inline long long atomic64_add_negative(long long i, atomic64_t *v)
{
	return atomic64_add_return(i, v) < 0;
}

static inline void atomic64_inc(atomic64_t *v)
{
	atomic64_inc_return(v);
}

static inline void atomic64_dec(atomic64_t *v)
{
	atomic64_dec_return(v);
}

#define atomic64_sub_and_test(i,v)	(atomic64_sub_return((i), (v)) == 0)
#define atomic64_dec_and_test(v)	(atomic64_dec_return((v)) == 0)
#define atomic64_inc_and_test(v)	(atomic64_inc_return((v)) == 0)
#define atomic64_inc_not_zero(v)	atomic64_add_unless((v), 1, 0)

#define atomic_cmpxchg(v, old, new)	(cmpxchg(&(v)->counter, old, new))
#define atomic_xchg(v, new)		(xchg(&(v)->counter, new))
#define atomic64_cmpxchg(v, old, new)	(__cmpxchg_64(old, new, &(v)->counter))
#define atomic64_xchg(v, new)		(__xchg_64(new, &(v)->counter))

static __inline__ int __atomic_add_unless(atomic_t *v, int a, int u)
{
	int c, old;
	c = atomic_read(v);
	for (;;) {
		if (unlikely(c == (u)))
			break;
		old = atomic_cmpxchg((v), c, c + (a));
		if (likely(old == c))
			break;
		c = old;
	}
	return c;
}

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

	c = atomic64_read(v);
	for (;;) {
		if (unlikely(c == u))
			break;
		old = atomic64_cmpxchg(v, c, c + i);
		if (likely(old == c))
			break;
		c = old;
	}
	return c != u;
}

static inline long long atomic64_dec_if_positive(atomic64_t *v)
{
	long long c, old, dec;

	c = atomic64_read(v);
	for (;;) {
		dec = c - 1;
		if (unlikely(dec < 0))
			break;
		old = atomic64_cmpxchg((v), c, dec);
		if (likely(old == c))
			break;
		c = old;
	}
		return dec;
}

#define ATOMIC_OP(op)							\
static inline int atomic_fetch_##op(int i, atomic_t *v)			\
{									\
	return __atomic32_fetch_##op(i, &v->counter);			\
}									\
static inline void atomic_##op(int i, atomic_t *v)			\
{									\
	(void)__atomic32_fetch_##op(i, &v->counter);			\
}									\
									\
static inline long long atomic64_fetch_##op(long long i, atomic64_t *v)	\
{									\
	return __atomic64_fetch_##op(i, &v->counter);			\
}									\
static inline void atomic64_##op(long long i, atomic64_t *v)		\
{									\
	(void)__atomic64_fetch_##op(i, &v->counter);			\
}

ATOMIC_OP(or)
ATOMIC_OP(and)
ATOMIC_OP(xor)
ATOMIC_OP(add)
ATOMIC_OP(sub)

#undef ATOMIC_OP

#endif /* _ASM_ATOMIC_H */