1 files changed, 144 insertions, 0 deletions
diff --git a/arch/m68k/include/asm/cmpxchg.h b/arch/m68k/include/asm/cmpxchg.h
new file mode 100644
index 000000000..38e1d7acc
--- /dev/null
+++ b/arch/m68k/include/asm/cmpxchg.h
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ARCH_M68K_CMPXCHG__
+#define __ARCH_M68K_CMPXCHG__
+
+#include <linux/irqflags.h>
+
+struct __xchg_dummy { unsigned long a[100]; };
+#define __xg(x) ((volatile struct __xchg_dummy *)(x))
+
+extern unsigned long __invalid_xchg_size(unsigned long, volatile void *, int);
+
+#ifndef CONFIG_RMW_INSNS
+static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
+{
+	unsigned long flags, tmp;
+
+	local_irq_save(flags);
+
+	switch (size) {
+	case 1:
+		tmp = *(u8 *)ptr;
+		*(u8 *)ptr = x;
+		x = tmp;
+		break;
+	case 2:
+		tmp = *(u16 *)ptr;
+		*(u16 *)ptr = x;
+		x = tmp;
+		break;
+	case 4:
+		tmp = *(u32 *)ptr;
+		*(u32 *)ptr = x;
+		x = tmp;
+		break;
+	default:
+		tmp = __invalid_xchg_size(x, ptr, size);
+		break;
+	}
+
+	local_irq_restore(flags);
+	return x;
+}
+#else
+static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size)
+{
+	switch (size) {
+	case 1:
+		__asm__ __volatile__
+			("moveb %2,%0\n\t"
+			 "1:\n\t"
+			 "casb %0,%1,%2\n\t"
+			 "jne 1b"
+			 : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
+		break;
+	case 2:
+		__asm__ __volatile__
+			("movew %2,%0\n\t"
+			 "1:\n\t"
+			 "casw %0,%1,%2\n\t"
+			 "jne 1b"
+			 : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
+		break;
+	case 4:
+		__asm__ __volatile__
+			("movel %2,%0\n\t"
+			 "1:\n\t"
+			 "casl %0,%1,%2\n\t"
+			 "jne 1b"
+			 : "=&d" (x) : "d" (x), "m" (*__xg(ptr)) : "memory");
+		break;
+	default:
+		x = __invalid_xchg_size(x, ptr, size);
+		break;
+	}
+	return x;
+}
+#endif
+
+#define xchg(ptr,x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
+
+#include <asm-generic/cmpxchg-local.h>
+
+#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
+
+extern unsigned long __invalid_cmpxchg_size(volatile void *,
+					    unsigned long, unsigned long, int);
+
+/*
+ * Atomic compare and exchange.  Compare OLD with MEM, if identical,
+ * store NEW in MEM.  Return the initial value in MEM.  Success is
+ * indicated by comparing RETURN with OLD.
+ */
+#ifdef CONFIG_RMW_INSNS
+
+static inline unsigned long __cmpxchg(volatile void *p, unsigned long old,
+				      unsigned long new, int size)
+{
+	switch (size) {
+	case 1:
+		__asm__ __volatile__ ("casb %0,%2,%1"
+				      : "=d" (old), "=m" (*(char *)p)
+				      : "d" (new), "0" (old), "m" (*(char *)p));
+		break;
+	case 2:
+		__asm__ __volatile__ ("casw %0,%2,%1"
+				      : "=d" (old), "=m" (*(short *)p)
+				      : "d" (new), "0" (old), "m" (*(short *)p));
+		break;
+	case 4:
+		__asm__ __volatile__ ("casl %0,%2,%1"
+				      : "=d" (old), "=m" (*(int *)p)
+				      : "d" (new), "0" (old), "m" (*(int *)p));
+		break;
+	default:
+		old = __invalid_cmpxchg_size(p, old, new, size);
+		break;
+	}
+	return old;
+}
+
+#define cmpxchg(ptr, o, n)						    \
+	((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),	    \
+			(unsigned long)(n), sizeof(*(ptr))))
+#define cmpxchg_local(ptr, o, n)					    \
+	((__typeof__(*(ptr)))__cmpxchg((ptr), (unsigned long)(o),	    \
+			(unsigned long)(n), sizeof(*(ptr))))
+
+#define cmpxchg64(ptr, o, n)	cmpxchg64_local((ptr), (o), (n))
+
+#else
+
+/*
+ * 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))))
+
+#include <asm-generic/cmpxchg.h>
+
+#endif
+
+#endif /* __ARCH_M68K_CMPXCHG__ */