/*
* Atomic xchg and cmpxchg operations.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2001 - 2005 Tensilica Inc.
*/

#ifndef _XTENSA_CMPXCHG_H
#define _XTENSA_CMPXCHG_H

#ifndef __ASSEMBLY__

#include <linux/stringify.h>

/*
* cmpxchg
*/

static inline unsigned long
__cmpxchg_u32(volatile int *p, int old, int new)
{
#if XCHAL_HAVE_S32C1I
__asm__ __volatile__(
" wsr %2, scompare1\n"
" s32c1i %0, %1, 0\n"
: "+a" (new)
: "a" (p), "a" (old)
: "memory"
);

return new;
#else
__asm__ __volatile__(
" rsil a15, "__stringify(LOCKLEVEL)"\n"
" l32i %0, %1, 0\n"
" bne %0, %2, 1f\n"
" s32i %3, %1, 0\n"
"1:\n"
" wsr a15, ps\n"
" rsync\n"
: "=&a" (old)
: "a" (p), "a" (old), "r" (new)
: "a15", "memory");
return old;
#endif
}
/* 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);

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);
default: __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))); \
})

#include <asm-generic/cmpxchg-local.h>

static inline unsigned long __cmpxchg_local(volatile void *ptr,
unsigned long old,
unsigned long new, int size)
{
switch (size) {
case 4:
return __cmpxchg_u32(ptr, old, new);
default:
return __cmpxchg_local_generic(ptr, old, new, size);
}

return old;
}

/*
* cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
* them available.
*/
#define cmpxchg_local(ptr, o, n) \
((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
(unsigned long)(n), sizeof(*(ptr))))
#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))

/*
* xchg_u32
*
* Note that a15 is used here because the register allocation
* done by the compiler is not guaranteed and a window overflow
* may not occur between the rsil and wsr instructions. By using
* a15 in the rsil, the machine is guaranteed to be in a state
* where no register reference will cause an overflow.
*/

static inline unsigned long xchg_u32(volatile int * m, unsigned long val)
{
#if XCHAL_HAVE_S32C1I
unsigned long tmp, result;
__asm__ __volatile__(
"1: l32i %1, %2, 0\n"
" mov %0, %3\n"
" wsr %1, scompare1\n"
" s32c1i %0, %2, 0\n"
" bne %0, %1, 1b\n"
: "=&a" (result), "=&a" (tmp)
: "a" (m), "a" (val)
: "memory"
);
return result;
#else
unsigned long tmp;
__asm__ __volatile__(
" rsil a15, "__stringify(LOCKLEVEL)"\n"
" l32i %0, %1, 0\n"
" s32i %2, %1, 0\n"
" wsr a15, ps\n"
" rsync\n"
: "=&a" (tmp)
: "a" (m), "a" (val)
: "a15", "memory");
return tmp;
#endif
}

#define xchg(ptr,x) \
((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))

/*
* This only works if the compiler isn't horribly bad at optimizing.
* gcc-2.5.8 reportedly can't handle this, but I define that one to
* be dead anyway.
*/

extern void __xchg_called_with_bad_pointer(void);

static __inline__ unsigned long
__xchg(unsigned long x, volatile void * ptr, int size)
{
switch (size) {
case 4:
return xchg_u32(ptr, x);
}
__xchg_called_with_bad_pointer();
return x;
}

#endif /* __ASSEMBLY__ */

#endif /* _XTENSA_CMPXCHG_H */