MIPS: detect presence of the FRE & UFR bits

Detect the presence of the Config5 FRE & UFE bits, as indicated by the
FREP bit in FPIR. Record this as a CPU option bit, and provide a
cpu_has_fre macro to ease checking of that option bit.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/7678/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h
index dfdc77e..11025bf 100644
--- a/arch/mips/include/asm/cpu.h
+++ b/arch/mips/include/asm/cpu.h
@@ -368,6 +368,7 @@
 #define MIPS_CPU_HTW		0x100000000ull /* CPU support Hardware Page Table Walker */
 #define MIPS_CPU_RIXIEX		0x200000000ull /* CPU has unique exception codes for {Read, Execute}-Inhibit exceptions */
 #define MIPS_CPU_MAAR		0x400000000ull /* MAAR(I) registers are present */
+#define MIPS_CPU_FRE		0x800000000ull /* FRE & UFE bits implemented */
 
 /*
  * CPU ASE encodings