| /* $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. | |
| */ | |
| 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) */ |