55 lines
1.2 KiB
C
55 lines
1.2 KiB
C
/*
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* smpprim.h: SMP locking primitives on the Sparc
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*
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* God knows we won't be actually using this code for some time
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* but I thought I'd write it since I knew how.
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*
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* Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu)
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*/
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#ifndef __SPARC_SMPPRIM_H
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#define __SPARC_SMPPRIM_H
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/* Test and set the unsigned byte at ADDR to 1. Returns the previous
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* value. On the Sparc we use the ldstub instruction since it is
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* atomic.
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*/
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static inline __volatile__ char test_and_set(void *addr)
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{
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char state = 0;
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__asm__ __volatile__("ldstub [%0], %1 ! test_and_set\n\t"
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"=r" (addr), "=r" (state) :
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"0" (addr), "1" (state) : "memory");
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return state;
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}
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/* Initialize a spin-lock. */
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static inline __volatile__ smp_initlock(void *spinlock)
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{
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/* Unset the lock. */
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*((unsigned char *) spinlock) = 0;
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return;
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}
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/* This routine spins until it acquires the lock at ADDR. */
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static inline __volatile__ smp_lock(void *addr)
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{
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while(test_and_set(addr) == 0xff)
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;
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/* We now have the lock */
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return;
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}
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/* This routine releases the lock at ADDR. */
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static inline __volatile__ smp_unlock(void *addr)
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{
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*((unsigned char *) addr) = 0;
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}
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#endif /* !(__SPARC_SMPPRIM_H) */
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