minix/sys/arch/arm/include/lock.h

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/* $NetBSD: lock.h,v 1.25 2013/08/18 04:31:08 matt Exp $ */
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/*-
* Copyright (c) 2000, 2001 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe.
*
* 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.
*
* 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.
*/
/*
* Machine-dependent spin lock operations.
*
* NOTE: The SWP insn used here is available only on ARM architecture
* version 3 and later (as well as 2a). What we are going to do is
* expect that the kernel will trap and emulate the insn. That will
* be slow, but give us the atomicity that we need.
*/
#ifndef _ARM_LOCK_H_
#define _ARM_LOCK_H_
static __inline int
__SIMPLELOCK_LOCKED_P(__cpu_simple_lock_t *__ptr)
{
return *__ptr == __SIMPLELOCK_LOCKED;
}
static __inline int
__SIMPLELOCK_UNLOCKED_P(__cpu_simple_lock_t *__ptr)
{
return *__ptr == __SIMPLELOCK_UNLOCKED;
}
static __inline void
__cpu_simple_lock_clear(__cpu_simple_lock_t *__ptr)
{
*__ptr = __SIMPLELOCK_UNLOCKED;
}
static __inline void
__cpu_simple_lock_set(__cpu_simple_lock_t *__ptr)
{
*__ptr = __SIMPLELOCK_LOCKED;
}
#ifdef _KERNEL
#include <arm/cpufunc.h>
#define mb_read drain_writebuf /* in cpufunc.h */
#define mb_write drain_writebuf /* in cpufunc.h */
#define mb_memory drain_writebuf /* in cpufunc.h */
#endif
#if defined(_KERNEL)
static __inline unsigned char
__swp(__cpu_simple_lock_t __val, volatile __cpu_simple_lock_t *__ptr)
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{
#ifdef _ARM_ARCH_6
uint32_t __rv, __tmp;
if (sizeof(*__ptr) == 1) {
__asm volatile(
"1:\t"
"ldrexb\t%[__rv], [%[__ptr]]" "\n\t"
"cmp\t%[__rv],%[__val]" "\n\t"
#ifdef __thumb__
"itt\tne" "\n\t"
#endif
"strexbne\t%[__tmp], %[__val], [%[__ptr]]" "\n\t"
"cmpne\t%[__tmp], #0" "\n\t"
"bne\t1b" "\n\t"
#ifdef _ARM_ARCH_7
"dmb"
#else
"mcr\tp15, 0, %[__tmp], c7, c10, 5"
#endif
: [__rv] "=&r" (__rv), [__tmp] "=&r"(__tmp)
: [__val] "r" (__val), [__ptr] "r" (__ptr) : "cc", "memory");
} else {
__asm volatile(
"1:\t"
"ldrex\t%[__rv], [%[__ptr]]" "\n\t"
"cmp\t%[__rv],%[__val]" "\n\t"
#ifdef __thumb__
"itt\tne" "\n\t"
#endif
"strexne\t%[__tmp], %[__val], [%[__ptr]]" "\n\t"
"cmpne\t%[__tmp], #0" "\n\t"
"bne\t1b" "\n\t"
#ifdef _ARM_ARCH_7
"nop"
#else
"mcr\tp15, 0, %[__tmp], c7, c10, 5"
#endif
: [__rv] "=&r" (__rv), [__tmp] "=&r"(__tmp)
: [__val] "r" (__val), [__ptr] "r" (__ptr) : "cc", "memory");
}
return __rv;
#else
uint32_t __val32;
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__asm volatile("swpb %0, %1, [%2]"
: "=&r" (__val32) : "r" (__val), "r" (__ptr) : "memory");
return __val32;
#endif
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}
#else
/*
* On Cortex-A9 (SMP), SWP no longer guarantees atomic results. Thus we pad
* out SWP so that when the A9 generates an undefined exception we can replace
* the SWP/MOV instructions with the right LDREX/STREX instructions.
*
* This is why we force the SWP into the template needed for LDREX/STREX
* including the extra instructions and extra register for testing the result.
*/
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static __inline int
__swp(int __val, volatile int *__ptr)
{
int __rv, __tmp;
__asm volatile(
"1:\t"
#ifdef _ARM_ARCH_6
"ldrex\t%[__rv], [%[__ptr]]" "\n\t"
"cmp\t%[__rv],%[__val]" "\n\t"
#ifdef __thumb__
"it\tne" "\n\t"
#endif
"strexne\t%[__tmp], %[__val], [%[__ptr]]" "\n\t"
#else
"swp\t%[__rv], %[__val], [%[__ptr]]" "\n\t"
"mov\t%[__tmp], #0" "\n\t"
"cmp\t%[__rv],%[__val]" "\n\t"
#endif
"cmpne\t%[__tmp], #0" "\n\t"
"bne\t1b" "\n\t"
#ifdef _ARM_ARCH_7
"dmb"
#elif defined(_ARM_ARCH_6)
"mcr\tp15, 0, %[__tmp], c7, c10, 5"
#else
"nop"
#endif
: [__rv] "=&r" (__rv), [__tmp] "=&r"(__tmp)
: [__val] "r" (__val), [__ptr] "r" (__ptr) : "cc", "memory");
return __rv;
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}
#endif /* _KERNEL */
static __inline void __unused
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__cpu_simple_lock_init(__cpu_simple_lock_t *alp)
{
*alp = __SIMPLELOCK_UNLOCKED;
#ifdef _ARM_ARCH_7
__asm __volatile("dsb");
#endif
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}
#if !defined(__thumb__) || defined(_ARM_ARCH_T2)
static __inline void __unused
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__cpu_simple_lock(__cpu_simple_lock_t *alp)
{
while (__swp(__SIMPLELOCK_LOCKED, alp) != __SIMPLELOCK_UNLOCKED)
continue;
}
#else
void __cpu_simple_lock(__cpu_simple_lock_t *);
#endif
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#if !defined(__thumb__) || defined(_ARM_ARCH_T2)
static __inline int __unused
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__cpu_simple_lock_try(__cpu_simple_lock_t *alp)
{
return (__swp(__SIMPLELOCK_LOCKED, alp) == __SIMPLELOCK_UNLOCKED);
}
#else
int __cpu_simple_lock_try(__cpu_simple_lock_t *);
#endif
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static __inline void __unused
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__cpu_simple_unlock(__cpu_simple_lock_t *alp)
{
#ifdef _ARM_ARCH_7
__asm __volatile("dmb");
#endif
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*alp = __SIMPLELOCK_UNLOCKED;
#ifdef _ARM_ARCH_7
__asm __volatile("dsb");
#endif
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}
#endif /* _ARM_LOCK_H_ */