summaryrefslogtreecommitdiffstats
path: root/include/asm-sparc/smpprim.h
blob: 9b9c28ed748e1d9f7426925f20c19d85358381e7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
/*  $Id: smpprim.h,v 1.5 1996/08/29 09:48:49 davem Exp $
 *  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.
 */

extern __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. */
extern __inline__ __volatile__ smp_initlock(void *spinlock)
{
	/* Unset the lock. */
	*((unsigned char *) spinlock) = 0;

	return;
}

/* This routine spins until it acquires the lock at ADDR. */
extern __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. */
extern __inline__ __volatile__ smp_unlock(void *addr)
{
	*((unsigned char *) addr) = 0;
}

#endif /* !(__SPARC_SMPPRIM_H) */
OpenPOWER on IntegriCloud