[PATCH 1/4] MIPS: Introduce isa-rev.h to define MIPS_ISA_REV

[Matt Redfearn]

There are multiple instances in the kernel where we need to include or
exclude particular instructions based on the ISA revision of the target
processor. For MIPS32 / MIPS64, the compiler exports a __mips_isa_rev
define. However, when targeting MIPS I - V, this define is absent. This
leads to each use of __mips_isa_rev having to check that it is defined
first. To simplify this, introduce the isa-rev.h header which always
exports MIPS_ISA_REV. The name is changed so as to avoid confusion with
the compiler builtin and to avoid accidentally using the builtin.
MIPS_ISA_REV is defined to the compilers builtin if provided, or 0,
which satisfies all current usages.

Suggested-by: Paul Burton <paul.burton@xxxxxxxx>
Signed-off-by: Matt Redfearn <matt.redfearn@xxxxxxxx>

---

 arch/mips/include/asm/isa-rev.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 arch/mips/include/asm/isa-rev.h

diff --git a/arch/mips/include/asm/isa-rev.h b/arch/mips/include/asm/isa-rev.h
new file mode 100644
index 000000000000..683ea3454dcb
--- /dev/null
+++ b/arch/mips/include/asm/isa-rev.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2018 MIPS Tech, LLC
+ * Author: Matt Redfearn <matt.redfearn@xxxxxxxx>
+ */
+
+#ifndef __MIPS_ASM_ISA_REV_H__
+#define __MIPS_ASM_ISA_REV_H__
+
+/*
+ * The ISA revision level. This is 0 for MIPS I to V and N for
+ * MIPS{32,64}rN.
+ */
+
+/* If the compiler has defined __mips_isa_rev, believe it. */
+#ifdef __mips_isa_rev
+#define MIPS_ISA_REV __mips_isa_rev
+#else
+/* The compiler hasn't defined the isa rev so assume it's MIPS I - V (0) */
+#define MIPS_ISA_REV 0
+#endif
+
+
+#endif /* __MIPS_ASM_ISA_REV_H__ */
-- 
2.7.4