NetBSD/sys/arch/sparc/include/lock.h

121 lines
3.9 KiB
C

/* $NetBSD: lock.h,v 1.10 2000/05/05 20:12:00 hannken Exp $ */
/*-
* Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Paul Kranenburg.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _MACHINE_LOCK_H
#define _MACHINE_LOCK_H
/*
* Machine dependent spin lock operations.
*/
/*
* The value for __SIMPLELOCK_LOCKED is what ldstub() naturally stores
* `lock_data' given its address (and the fact that SPARC is big-endian).
*/
typedef __volatile int __cpu_simple_lock_t;
#define __SIMPLELOCK_LOCKED 0xff000000
#define __SIMPLELOCK_UNLOCKED 0
/* XXX So we can expose this to userland. */
#ifdef __lint__
#define __ldstub(__addr) (__addr)
#else /* !__lint__ */
#define __ldstub(__addr) \
({ \
int __v; \
\
__asm __volatile("ldstub [%1],%0" \
: "=r" (__v) \
: "r" (__addr) \
: "memory"); \
\
__v; \
})
#endif /* __lint__ */
static __inline void __cpu_simple_lock_init __P((__cpu_simple_lock_t *))
__attribute__((__unused__));
static __inline void __cpu_simple_lock __P((__cpu_simple_lock_t *))
__attribute__((__unused__));
static __inline int __cpu_simple_lock_try __P((__cpu_simple_lock_t *))
__attribute__((__unused__));
static __inline void __cpu_simple_unlock __P((__cpu_simple_lock_t *))
__attribute__((__unused__));
static __inline void
__cpu_simple_lock_init(__cpu_simple_lock_t *alp)
{
*alp = __SIMPLELOCK_UNLOCKED;
}
static __inline void
__cpu_simple_lock(__cpu_simple_lock_t *alp)
{
/*
* If someone else holds the lock use simple reads until it
* is released, then retry the atomic operation. This reduces
* memory bus contention because the cache-coherency logic
* does not have to broadcast invalidates on the lock while
* we spin on it.
*/
while (__ldstub(alp) != __SIMPLELOCK_UNLOCKED) {
while (*alp != __SIMPLELOCK_UNLOCKED)
/* spin */ ;
}
}
static __inline int
__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
{
return (__ldstub(alp) == __SIMPLELOCK_UNLOCKED);
}
static __inline void
__cpu_simple_unlock(__cpu_simple_lock_t *alp)
{
*alp = __SIMPLELOCK_UNLOCKED;
}
#endif /* _MACHINE_LOCK_H */