MIPS: mipsregs.h: Add write_32bit_cp1_register()

Add a write_32bit_cp1_register() macro to compliment the
read_32bit_cp1_register() macro. This is to abstract whether .set
hardfloat needs to be used based on GAS_HAS_SET_HARDFLOAT.

The implementation of _read_32bit_cp1_register() .sets mips1 due to
failure of gas v2.19 to assemble cfc1 for Octeon (see commit
25c3000 ("MIPS: Override assembler target architecture for
octeon.")). I haven't copied this over to _write_32bit_cp1_register() as
I'm uncertain whether it applies to ctc1 too, or whether anybody cares
about that version of binutils any longer.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9172/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mipsregs.h

@@ -1386,12 +1386,27 @@ do {									\
 	__res;								\
 })
 
+#define _write_32bit_cp1_register(dest, val, gas_hardfloat)		\
+do {									\
+	__asm__ __volatile__(						\
+	"	.set	push					\n"	\
+	"	.set	reorder					\n"	\
+	"	"STR(gas_hardfloat)"				\n"	\
+	"	ctc1	%0,"STR(dest)"				\n"	\
+	"	.set	pop					\n"	\
+	: : "r" (val));							\
+} while (0)
+
 #ifdef GAS_HAS_SET_HARDFLOAT
 #define read_32bit_cp1_register(source)					\
 	_read_32bit_cp1_register(source, .set hardfloat)
+#define write_32bit_cp1_register(dest, val)				\
+	_write_32bit_cp1_register(dest, val, .set hardfloat)
 #else
 #define read_32bit_cp1_register(source)					\
 	_read_32bit_cp1_register(source, )
+#define write_32bit_cp1_register(dest, val)				\
+	_write_32bit_cp1_register(dest, val, )
 #endif
 
 #ifdef HAVE_AS_DSP