1 files changed, 143 insertions, 0 deletions
diff --git a/arch/arc/include/asm/cmpxchg.h b/arch/arc/include/asm/cmpxchg.h
new file mode 100644
index 0000000000..e138fde067
--- /dev/null
+++ b/arch/arc/include/asm/cmpxchg.h
@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ */
+
+#ifndef __ASM_ARC_CMPXCHG_H
+#define __ASM_ARC_CMPXCHG_H
+
+#include <linux/build_bug.h>
+#include <linux/types.h>
+
+#include <asm/barrier.h>
+#include <asm/smp.h>
+
+#ifdef CONFIG_ARC_HAS_LLSC
+
+/*
+ * if (*ptr == @old)
+ *      *ptr = @new
+ */
+#define __cmpxchg(ptr, old, new)					\
+({									\
+	__typeof__(*(ptr)) _prev;					\
+									\
+	__asm__ __volatile__(						\
+	"1:	llock  %0, [%1]	\n"					\
+	"	brne   %0, %2, 2f	\n"				\
+	"	scond  %3, [%1]	\n"					\
+	"	bnz     1b		\n"				\
+	"2:				\n"				\
+	: "=&r"(_prev)	/* Early clobber prevent reg reuse */		\
+	: "r"(ptr),	/* Not "m": llock only supports reg */		\
+	  "ir"(old),							\
+	  "r"(new)	/* Not "ir": scond can't take LIMM */		\
+	: "cc",								\
+	  "memory");	/* gcc knows memory is clobbered */		\
+									\
+	_prev;								\
+})
+
+#define arch_cmpxchg_relaxed(ptr, old, new)				\
+({									\
+	__typeof__(ptr) _p_ = (ptr);					\
+	__typeof__(*(ptr)) _o_ = (old);					\
+	__typeof__(*(ptr)) _n_ = (new);					\
+	__typeof__(*(ptr)) _prev_;					\
+									\
+	switch(sizeof((_p_))) {						\
+	case 4:								\
+		_prev_ = __cmpxchg(_p_, _o_, _n_);			\
+		break;							\
+	default:							\
+		BUILD_BUG();						\
+	}								\
+	_prev_;								\
+})
+
+#else
+
+#define arch_cmpxchg(ptr, old, new)				        \
+({									\
+	volatile __typeof__(ptr) _p_ = (ptr);				\
+	__typeof__(*(ptr)) _o_ = (old);					\
+	__typeof__(*(ptr)) _n_ = (new);					\
+	__typeof__(*(ptr)) _prev_;					\
+	unsigned long __flags;						\
+									\
+	BUILD_BUG_ON(sizeof(_p_) != 4);					\
+									\
+	/*								\
+	 * spin lock/unlock provide the needed smp_mb() before/after	\
+	 */								\
+	atomic_ops_lock(__flags);					\
+	_prev_ = *_p_;							\
+	if (_prev_ == _o_)						\
+		*_p_ = _n_;						\
+	atomic_ops_unlock(__flags);					\
+	_prev_;								\
+})
+
+#endif
+
+/*
+ * xchg
+ */
+#ifdef CONFIG_ARC_HAS_LLSC
+
+#define __arch_xchg(ptr, val)						\
+({									\
+	__asm__ __volatile__(						\
+	"	ex  %0, [%1]	\n"	/* set new value */	        \
+	: "+r"(val)							\
+	: "r"(ptr)							\
+	: "memory");							\
+	_val_;		/* get old value */				\
+})
+
+#define arch_xchg_relaxed(ptr, val)					\
+({									\
+	__typeof__(ptr) _p_ = (ptr);					\
+	__typeof__(*(ptr)) _val_ = (val);				\
+									\
+	switch(sizeof(*(_p_))) {					\
+	case 4:								\
+		_val_ = __arch_xchg(_p_, _val_);			\
+		break;							\
+	default:							\
+		BUILD_BUG();						\
+	}								\
+	_val_;								\
+})
+
+#else  /* !CONFIG_ARC_HAS_LLSC */
+
+/*
+ * EX instructions is baseline and present in !LLSC too. But in this
+ * regime it still needs use @atomic_ops_lock spinlock to allow interop
+ * with cmpxchg() which uses spinlock in !LLSC
+ * (llist.h use xchg and cmpxchg on sama data)
+ */
+
+#define arch_xchg(ptr, val)					        \
+({									\
+	__typeof__(ptr) _p_ = (ptr);					\
+	__typeof__(*(ptr)) _val_ = (val);				\
+									\
+	unsigned long __flags;						\
+									\
+	atomic_ops_lock(__flags);					\
+									\
+	__asm__ __volatile__(						\
+	"	ex  %0, [%1]	\n"					\
+	: "+r"(_val_)							\
+	: "r"(_p_)							\
+	: "memory");							\
+									\
+	atomic_ops_unlock(__flags);					\
+	_val_;								\
+})
+
+#endif
+
+#endif