1 files changed, 162 insertions, 0 deletions
diff --git a/arch/xtensa/include/asm/cmpxchg.h b/arch/xtensa/include/asm/cmpxchg.h
new file mode 100644
index 000000000..201e9009e
--- /dev/null
+++ b/arch/xtensa/include/asm/cmpxchg.h
@@ -0,0 +1,162 @@
+/*
+ * 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(TOPLEVEL)"\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(TOPLEVEL)"\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 */