163 lines
3.9 KiB
C
163 lines
3.9 KiB
C
/*
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* Atomic xchg and cmpxchg operations.
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2001 - 2005 Tensilica Inc.
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*/
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#ifndef _XTENSA_CMPXCHG_H
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#define _XTENSA_CMPXCHG_H
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#ifndef __ASSEMBLY__
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#include <linux/stringify.h>
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/*
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* cmpxchg
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*/
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static inline unsigned long
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__cmpxchg_u32(volatile int *p, int old, int new)
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{
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#if XCHAL_HAVE_S32C1I
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__asm__ __volatile__(
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" wsr %2, scompare1\n"
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" s32c1i %0, %1, 0\n"
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: "+a" (new)
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: "a" (p), "a" (old)
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: "memory"
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);
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return new;
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#else
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__asm__ __volatile__(
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" rsil a15, "__stringify(TOPLEVEL)"\n"
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" l32i %0, %1, 0\n"
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" bne %0, %2, 1f\n"
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" s32i %3, %1, 0\n"
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"1:\n"
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" wsr a15, ps\n"
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" rsync\n"
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: "=&a" (old)
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: "a" (p), "a" (old), "r" (new)
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: "a15", "memory");
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return old;
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#endif
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}
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/* This function doesn't exist, so you'll get a linker error
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* if something tries to do an invalid cmpxchg(). */
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extern void __cmpxchg_called_with_bad_pointer(void);
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static __inline__ unsigned long
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__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
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{
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switch (size) {
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case 4: return __cmpxchg_u32(ptr, old, new);
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default: __cmpxchg_called_with_bad_pointer();
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return old;
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}
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}
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#define cmpxchg(ptr,o,n) \
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({ __typeof__(*(ptr)) _o_ = (o); \
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__typeof__(*(ptr)) _n_ = (n); \
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(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
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(unsigned long)_n_, sizeof (*(ptr))); \
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})
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#include <asm-generic/cmpxchg-local.h>
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static inline unsigned long __cmpxchg_local(volatile void *ptr,
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unsigned long old,
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unsigned long new, int size)
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{
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switch (size) {
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case 4:
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return __cmpxchg_u32(ptr, old, new);
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default:
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return __cmpxchg_local_generic(ptr, old, new, size);
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}
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return old;
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}
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/*
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* cmpxchg_local and cmpxchg64_local are atomic wrt current CPU. Always make
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* them available.
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*/
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#define cmpxchg_local(ptr, o, n) \
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((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
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(unsigned long)(n), sizeof(*(ptr))))
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#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
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#define cmpxchg64(ptr, o, n) cmpxchg64_local((ptr), (o), (n))
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/*
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* xchg_u32
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*
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* Note that a15 is used here because the register allocation
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* done by the compiler is not guaranteed and a window overflow
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* may not occur between the rsil and wsr instructions. By using
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* a15 in the rsil, the machine is guaranteed to be in a state
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* where no register reference will cause an overflow.
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*/
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static inline unsigned long xchg_u32(volatile int * m, unsigned long val)
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{
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#if XCHAL_HAVE_S32C1I
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unsigned long tmp, result;
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__asm__ __volatile__(
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"1: l32i %1, %2, 0\n"
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" mov %0, %3\n"
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" wsr %1, scompare1\n"
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" s32c1i %0, %2, 0\n"
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" bne %0, %1, 1b\n"
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: "=&a" (result), "=&a" (tmp)
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: "a" (m), "a" (val)
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: "memory"
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);
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return result;
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#else
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unsigned long tmp;
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__asm__ __volatile__(
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" rsil a15, "__stringify(TOPLEVEL)"\n"
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" l32i %0, %1, 0\n"
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" s32i %2, %1, 0\n"
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" wsr a15, ps\n"
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" rsync\n"
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: "=&a" (tmp)
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: "a" (m), "a" (val)
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: "a15", "memory");
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return tmp;
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#endif
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}
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#define xchg(ptr,x) \
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((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
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/*
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* This only works if the compiler isn't horribly bad at optimizing.
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* gcc-2.5.8 reportedly can't handle this, but I define that one to
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* be dead anyway.
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*/
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extern void __xchg_called_with_bad_pointer(void);
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static __inline__ unsigned long
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__xchg(unsigned long x, volatile void * ptr, int size)
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{
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switch (size) {
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case 4:
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return xchg_u32(ptr, x);
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}
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__xchg_called_with_bad_pointer();
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return x;
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}
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#endif /* __ASSEMBLY__ */
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#endif /* _XTENSA_CMPXCHG_H */
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