| /* $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) */ |