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