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/* * 1,2 and 4 byte cmpxchg and xchg implementations for OpenRISC. * * Copyright (C) 2014 Stefan Kristiansson <stefan.kristiansson@saunalahti.fi> * Copyright (C) 2017 Stafford Horne <shorne@gmail.com> * * This file is licensed under the terms of the GNU General Public License * version 2. This program is licensed "as is" without any warranty of any * kind, whether express or implied. * * Note: * The portable implementations of 1 and 2 byte xchg and cmpxchg using a 4 * byte cmpxchg is sourced heavily from the sh and mips implementations. */ #ifndef __ASM_OPENRISC_CMPXCHG_H #define __ASM_OPENRISC_CMPXCHG_H #include <linux/bits.h> #include <linux/compiler.h> #include <linux/types.h> #define __HAVE_ARCH_CMPXCHG 1 static inline unsigned long cmpxchg_u32(volatile void *ptr, unsigned long old, unsigned long new) { __asm__ __volatile__( "1: l.lwa %0, 0(%1) \n" " l.sfeq %0, %2 \n" " l.bnf 2f \n" " l.nop \n" " l.swa 0(%1), %3 \n" " l.bnf 1b \n" " l.nop \n" "2: \n" : "=&r"(old) : "r"(ptr), "r"(old), "r"(new) : "cc", "memory"); return old; } static inline unsigned long xchg_u32(volatile void *ptr, unsigned long val) { __asm__ __volatile__( "1: l.lwa %0, 0(%1) \n" " l.swa 0(%1), %2 \n" " l.bnf 1b \n" " l.nop \n" : "=&r"(val) : "r"(ptr), "r"(val) : "cc", "memory"); return val; } static inline u32 cmpxchg_small(volatile void *ptr, u32 old, u32 new, int size) { int off = (unsigned long)ptr % sizeof(u32); volatile u32 *p = ptr - off; #ifdef __BIG_ENDIAN int bitoff = (sizeof(u32) - size - off) * BITS_PER_BYTE; #else int bitoff = off * BITS_PER_BYTE; #endif u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff; u32 load32, old32, new32; u32 ret; load32 = READ_ONCE(*p); while (true) { ret = (load32 & bitmask) >> bitoff; if (old != ret) return ret; old32 = (load32 & ~bitmask) | (old << bitoff); new32 = (load32 & ~bitmask) | (new << bitoff); /* Do 32 bit cmpxchg */ load32 = cmpxchg_u32(p, old32, new32); if (load32 == old32) return old; } } /* xchg */ static inline u32 xchg_small(volatile void *ptr, u32 x, int size) { int off = (unsigned long)ptr % sizeof(u32); volatile u32 *p = ptr - off; #ifdef __BIG_ENDIAN int bitoff = (sizeof(u32) - size - off) * BITS_PER_BYTE; #else int bitoff = off * BITS_PER_BYTE; #endif u32 bitmask = ((0x1 << size * BITS_PER_BYTE) - 1) << bitoff; u32 oldv, newv; u32 ret; do { oldv = READ_ONCE(*p); ret = (oldv & bitmask) >> bitoff; newv = (oldv & ~bitmask) | (x << bitoff); } while (cmpxchg_u32(p, oldv, newv) != oldv); return ret; } /* * This function doesn't exist, so you'll get a linker error * if something tries to do an invalid cmpxchg(). */ extern unsigned long __cmpxchg_called_with_bad_pointer(void) __compiletime_error("Bad argument size for cmpxchg"); static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size) { switch (size) { case 1: case 2: return cmpxchg_small(ptr, old, new, size); case 4: return cmpxchg_u32(ptr, old, new); default: return __cmpxchg_called_with_bad_pointer(); } } #define cmpxchg(ptr, o, n) \ ({ \ (__typeof__(*(ptr))) __cmpxchg((ptr), \ (unsigned long)(o), \ (unsigned long)(n), \ sizeof(*(ptr))); \ }) /* * This function doesn't exist, so you'll get a linker error if * something tries to do an invalidly-sized xchg(). */ extern unsigned long __xchg_called_with_bad_pointer(void) __compiletime_error("Bad argument size for xchg"); static inline unsigned long __xchg(volatile void *ptr, unsigned long with, int size) { switch (size) { case 1: case 2: return xchg_small(ptr, with, size); case 4: return xchg_u32(ptr, with); default: return __xchg_called_with_bad_pointer(); } } #define xchg(ptr, with) \ ({ \ (__typeof__(*(ptr))) __xchg((ptr), \ (unsigned long)(with), \ sizeof(*(ptr))); \ }) #endif /* __ASM_OPENRISC_CMPXCHG_H */
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