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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 int lock;
} __attribute__ ((aligned (4))) 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(" bras 1,1f\n"
"0: # diag 0,0,68\n"
"1: slr 0,0\n"
" cs 0,1,0(%0)\n"
" jl 0b\n"
: : "a" (&lp->lock) : "0", "1", "cc", "memory" );
}
extern inline int spin_trylock(spinlock_t *lp)
{
unsigned int result;
__asm__ __volatile(" slr %0,%0\n"
" basr 1,0\n"
"0: cs %0,1,0(%1)"
: "=&d" (result)
: "a" (&lp->lock) : "1", "cc", "memory" );
return !result;
}
extern inline void spin_unlock(spinlock_t *lp)
{
__asm__ __volatile(" xc 0(4,%0),0(%0)\n"
" bcr 15,0"
: : "a" (&lp->lock) : "memory", "cc" );
}
/*
* 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 rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0)
#define read_lock(rw) \
asm volatile(" lg 2,0(%0)\n" \
" j 1f\n" \
"0: # diag 0,0,68\n" \
"1: nihh 2,0x7fff\n" /* clear high (=write) bit */ \
" la 3,1(2)\n" /* one more reader */ \
" csg 2,3,0(%0)\n" /* try to write new value */ \
" jl 0b" \
: : "a" (&(rw)->lock) : "2", "3", "cc", "memory" );
#define read_unlock(rw) \
asm volatile(" lg 2,0(%0)\n" \
" j 1f\n" \
"0: # diag 0,0,68\n" \
"1: lgr 3,2\n" \
" bctgr 3,0\n" /* one less reader */ \
" csg 2,3,0(%0)\n" \
" jl 0b" \
: : "a" (&(rw)->lock) : "2", "3", "cc", "memory" );
#define write_lock(rw) \
asm volatile(" llihh 3,0x8000\n" /* new lock value = 0x80...0 */ \
" j 1f\n" \
"0: # diag 0,0,68\n" \
"1: slgr 2,2\n" /* old lock value must be 0 */ \
" csg 2,3,0(%0)\n" \
" jl 0b" \
: : "a" (&(rw)->lock) : "2", "3", "cc", "memory" );
#define write_unlock(rw) \
asm volatile(" slgr 3,3\n" /* new lock value = 0 */ \
" j 1f\n" \
"0: # diag 0,0,68\n" \
"1: llihh 2,0x8000\n" /* old lock value must be 0x8..0 */\
" csg 2,3,0(%0)\n" \
" jl 0b" \
: : "a" (&(rw)->lock) : "2", "3", "cc", "memory" );
#endif /* __ASM_SPINLOCK_H */
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