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/*
* include/asm-s390/spinlock.h
*
* S390 version
* Copyright (C) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
* Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
*
* Derived from "include/asm-i386/spinlock.h"
*/
#ifndef __ASM_SPINLOCK_H
#define __ASM_SPINLOCK_H
/*
* Simple spin lock operations. There are two variants, one clears IRQ's
* on the local processor, one does not.
*
* We make no fairness assumptions. They have a cost.
*/
typedef struct {
volatile unsigned long lock;
} spinlock_t;
#define SPIN_LOCK_UNLOCKED (spinlock_t) { 0 }
#define spin_lock_init(lp) do { (lp)->lock = 0; } while(0)
#define spin_unlock_wait(lp) do { barrier(); } while((volatile spinlock_t *)(lp)->lock)
#define spin_is_locked(x) ((x)->lock != 0)
extern inline void spin_lock(spinlock_t *lp)
{
__asm__ __volatile(" lhi 1,-1\n"
"0: slr 0,0\n"
" cs 0,1,%1\n"
" jl 0b"
: "=m" (lp->lock)
: "0" (lp->lock) : "0", "1");
}
extern inline int spin_trylock(spinlock_t *lp)
{
unsigned long result;
__asm__ __volatile(" slr %1,%1\n"
" lhi 0,-1\n"
"0: cs %1,0,%0"
: "=m" (lp->lock), "=&d" (result)
: "0" (lp->lock) : "0");
return !result;
}
extern inline void spin_unlock(spinlock_t *lp)
{
__asm__ __volatile(" xc 0(4,%0),0(%0)\n"
" bcr 15,0"
: /* no output */ : "a" (lp) );
}
/*
* Read-write spinlocks, allowing multiple readers
* but only one writer.
*
* NOTE! it is quite common to have readers in interrupts
* but no interrupt writers. For those circumstances we
* can "mix" irq-safe locks - any writer needs to get a
* irq-safe write-lock, but readers can get non-irqsafe
* read-locks.
*/
typedef struct {
volatile unsigned long lock;
volatile unsigned long owner_pc;
} rwlock_t;
#define RW_LOCK_UNLOCKED (rwlock_t) { 0, 0 }
#define read_lock(rw) \
asm volatile(" l 2,%0\n" \
"0: sll 2,1\n" \
" srl 2,1\n" /* clear high (=write) bit */ \
" lr 3,2\n" \
" ahi 3,1\n" /* one more reader */ \
" cs 2,3,%0\n" /* try to write new value */ \
" jl 0b" \
: "+m" ((rw)->lock) : : "2", "3" );
#define read_unlock(rw) \
asm volatile(" l 2,%0\n" \
"0: lr 3,2\n" \
" ahi 3,-1\n" /* one less reader */ \
" cs 2,3,%0\n" \
" jl 0b" \
: "+m" ((rw)->lock) : : "2", "3" );
#define write_lock(rw) \
asm volatile(" lhi 3,1\n" \
" sll 3,31\n" /* new lock value = 0x80000000 */ \
"0: slr 2,2\n" /* old lock value must be 0 */ \
" cs 2,3,%0\n" \
" jl 0b" \
: "+m" ((rw)->lock) : : "2", "3" );
#define write_unlock(rw) \
asm volatile(" slr 3,3\n" /* new lock value = 0 */ \
"0: lhi 2,1\n" \
" sll 2,31\n" /* old lock value must be 0x80000000 */ \
" cs 2,3,%0\n" \
" jl 0b" \
: "+m" ((rw)->lock) : : "2", "3" );
#endif /* __ASM_SPINLOCK_H */
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