1 files changed, 88 insertions, 0 deletions
diff --git a/arch/sh/include/asm/atomic-llsc.h b/arch/sh/include/asm/atomic-llsc.h
new file mode 100644
index 000000000..b63dcfbfa
--- /dev/null
+++ b/arch/sh/include/asm/atomic-llsc.h
@@ -0,0 +1,88 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_SH_ATOMIC_LLSC_H
+#define __ASM_SH_ATOMIC_LLSC_H
+
+/*
+ * SH-4A note:
+ *
+ * We basically get atomic_xxx_return() for free compared with
+ * atomic_xxx(). movli.l/movco.l require r0 due to the instruction
+ * encoding, so the retval is automatically set without having to
+ * do any special work.
+ */
+/*
+ * To get proper branch prediction for the main line, we must branch
+ * forward to code at the end of this object's .text section, then
+ * branch back to restart the operation.
+ */
+
+#define ATOMIC_OP(op)							\
+static inline void arch_atomic_##op(int i, atomic_t *v)			\
+{									\
+	unsigned long tmp;						\
+									\
+	__asm__ __volatile__ (						\
+"1:	movli.l @%2, %0		! atomic_" #op "\n"			\
+"	" #op "	%1, %0				\n"			\
+"	movco.l	%0, @%2				\n"			\
+"	bf	1b				\n"			\
+	: "=&z" (tmp)							\
+	: "r" (i), "r" (&v->counter)					\
+	: "t");								\
+}
+
+#define ATOMIC_OP_RETURN(op)						\
+static inline int arch_atomic_##op##_return(int i, atomic_t *v)		\
+{									\
+	unsigned long temp;						\
+									\
+	__asm__ __volatile__ (						\
+"1:	movli.l @%2, %0		! atomic_" #op "_return	\n"		\
+"	" #op "	%1, %0					\n"		\
+"	movco.l	%0, @%2					\n"		\
+"	bf	1b					\n"		\
+"	synco						\n"		\
+	: "=&z" (temp)							\
+	: "r" (i), "r" (&v->counter)					\
+	: "t");								\
+									\
+	return temp;							\
+}
+
+#define ATOMIC_FETCH_OP(op)						\
+static inline int arch_atomic_fetch_##op(int i, atomic_t *v)		\
+{									\
+	unsigned long res, temp;					\
+									\
+	__asm__ __volatile__ (						\
+"1:	movli.l @%3, %0		! atomic_fetch_" #op "	\n"		\
+"	mov %0, %1					\n"		\
+"	" #op "	%2, %0					\n"		\
+"	movco.l	%0, @%3					\n"		\
+"	bf	1b					\n"		\
+"	synco						\n"		\
+	: "=&z" (temp), "=&r" (res)					\
+	: "r" (i), "r" (&v->counter)					\
+	: "t");								\
+									\
+	return res;							\
+}
+
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op) ATOMIC_FETCH_OP(op)
+
+ATOMIC_OPS(add)
+ATOMIC_OPS(sub)
+
+#undef ATOMIC_OPS
+#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_FETCH_OP(op)
+
+ATOMIC_OPS(and)
+ATOMIC_OPS(or)
+ATOMIC_OPS(xor)
+
+#undef ATOMIC_OPS
+#undef ATOMIC_FETCH_OP
+#undef ATOMIC_OP_RETURN
+#undef ATOMIC_OP
+
+#endif /* __ASM_SH_ATOMIC_LLSC_H */