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-rw-r--r--arch/xtensa/include/asm/cmpxchg.h162
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..370b26f38
--- /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(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 */