Commit e4e3b5cc authored by Tom Rini's avatar Tom Rini Committed by Paul Mundt
Browse files

sh: Add a simple cmpxchg(). 



We didn't have one of these before, a simple implementation
borrowed from MIPS as well as the __HAVE_ARCH_CMPXCHG bits.

Signed-off-by: default avatarTom Rini <trini@kernel.crashing.org>
Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 0c91c1a7

include/asm-sh/system.h

+40 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
 * Copyright (C) 2002 Paul Mundt

 */



#include <asm/types.h>



/*

 *	switch_to() should switch tasks to task nr n, first
@@ -260,6 +261,45 @@ static __inline__ unsigned long __xchg(unsigned long x, volatile void * ptr, int 
	return x;

}



static inline unsigned long __cmpxchg_u32(volatile int * m, unsigned long old,

	unsigned long new)

{

	__u32 retval;

	unsigned long flags;



	local_irq_save(flags);

	retval = *m;

	if (retval == old)

		*m = new;

	local_irq_restore(flags);       /* implies memory barrier  */

	return retval;

}



/* This function doesn't exist, so you'll get a linker error

 * if something tries to do an invalid cmpxchg(). */

extern void __cmpxchg_called_with_bad_pointer(void);



#define __HAVE_ARCH_CMPXCHG 1



static inline unsigned long __cmpxchg(volatile void * ptr, unsigned long old,

		unsigned long new, int size)

{

	switch (size) {

	case 4:

		return __cmpxchg_u32(ptr, old, new);

	}

	__cmpxchg_called_with_bad_pointer();

	return old;

}



#define cmpxchg(ptr,o,n)						 \

  ({									 \

     __typeof__(*(ptr)) _o_ = (o);					 \

     __typeof__(*(ptr)) _n_ = (n);					 \

     (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_,		 \

				    (unsigned long)_n_, sizeof(*(ptr))); \

  })



/* XXX

 * disable hlt during certain critical i/o operations

 */