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Diffstat (limited to 'include/asm-m68k/semaphore.h')
-rw-r--r-- | include/asm-m68k/semaphore.h | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/include/asm-m68k/semaphore.h b/include/asm-m68k/semaphore.h new file mode 100644 index 000000000..ef23201c3 --- /dev/null +++ b/include/asm-m68k/semaphore.h @@ -0,0 +1,68 @@ +#ifndef _M68K_SEMAPHORE_H +#define _M68K_SEMAPHORE_H + +#include <linux/linkage.h> + +/* + * SMP- and interrupt-safe semaphores.. + * + * (C) Copyright 1996 Linus Torvalds + * + * m68k version by Andreas Schwab + */ + +struct semaphore { + int count; + int waiting; + struct wait_queue * wait; +}; + +#define MUTEX ((struct semaphore) { 1, 0, NULL }) +#define MUTEX_LOCKED ((struct semaphore) { 0, 0, NULL }) + +asmlinkage void __down_failed(void /* special register calling convention */); +asmlinkage void __up_wakeup(void /* special register calling convention */); + +extern void __down(struct semaphore * sem); +extern void __up(struct semaphore * sem); + +/* + * This is ugly, but we want the default case to fall through. + * "down_failed" is a special asm handler that calls the C + * routine that actually waits. See arch/m68k/lib/semaphore.S + */ +extern inline void down(struct semaphore * sem) +{ + register struct semaphore *sem1 __asm__ ("%a1") = sem; + __asm__ __volatile__( + "| atomic down operation\n\t" + "lea %%pc@(1f),%%a0\n\t" + "subql #1,%0\n\t" + "jmi " SYMBOL_NAME_STR(__down_failed) "\n" + "1:" + : /* no outputs */ + : "m" (sem->count), "a" (sem1) + : "%a0", "memory"); +} + +/* + * Note! This is subtle. We jump to wake people up only if + * the semaphore was negative (== somebody was waiting on it). + * The default case (no contention) will result in NO + * jumps for both down() and up(). + */ +extern inline void up(struct semaphore * sem) +{ + register struct semaphore *sem1 __asm__ ("%a1") = sem; + __asm__ __volatile__( + "| atomic up operation\n\t" + "lea %%pc@(1f),%%a0\n\t" + "addql #1,%0\n\t" + "jle " SYMBOL_NAME_STR(__up_wakeup) "\n" + "1:" + : /* no outputs */ + : "m" (sem->count), "a" (sem1) + : "%a0", "memory"); +} + +#endif |