1/* $NetBSD: sync_bool_compare_and_swap_2.S,v 1.1 2013/11/08 22:42:52 matt Exp $ */
2/*-
3 * Copyright (c) 2013 The NetBSD Foundation, Inc.
4 * All rights reserved.
5 *
6 * This code is derived from software contributed to The NetBSD Foundation
7 * by Matt Thomas <matt@3am-software.com>
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
20 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
22 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 */
30
31#include "atomic_op_asm.h"
32
33#if defined(_ARM_ARCH_6)
34/*
35 * ARMv6 has load-exclusive/store-exclusive which works for both user
36 * and kernel.
37 */
38ENTRY_NP(__sync_bool_compare_and_swap_2)
39	mov	ip, r0			/* we need r0 for return value */
40	movs	r0, #0			/* assume failure */
411:
42	ldrexh	r3, [ip]		/* load old value */
43	cmp	r3, r1			/*   compare? */
44#ifdef __thumb__
45	bne	2f
46#else
47	RETc(ne)			/*     return if different */
48#endif
49	strexh	r0, r2, [ip]		/* store new value */
50	cmp	r0, #0			/*   succeed? */
51	bne	1b			/*     nope, try again. */
52	movs	r0, #1			/* indicate success */
53#ifdef _ARM_ARCH_7
54	dsb				/* data synchronization barrier */
55#else
56	mcr	p15, 0, r3, c7, c10, 4	/* data synchronization barrier */
57#endif
582:	RET				/* return. */
59END(__sync_bool_compare_and_swap_2)
60
61#endif /* _ARM_ARCH_6 */
62