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>

arch/mips/include/asm/cpu-features.h

@@ -344,4 +344,8 @@
 # define cpu_has_msa		0
 #endif
 
+#ifndef cpu_has_fre
+# define cpu_has_fre		(cpu_data[0].options & MIPS_CPU_FRE)
+#endif
+
 #endif /* __ASM_CPU_FEATURES_H */

arch/mips/include/asm/cpu.h

@@ -368,6 +368,7 @@ enum cpu_type_enum {
 #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

arch/mips/kernel/cpu-probe.c

@@ -1317,6 +1317,8 @@ void cpu_probe(void)
 				    MIPS_CPU_ISA_M64R1 | MIPS_CPU_ISA_M64R2)) {
 			if (c->fpu_id & MIPS_FPIR_3D)
 				c->ases |= MIPS_ASE_MIPS3D;
+			if (c->fpu_id & MIPS_FPIR_FREP)
+				c->options |= MIPS_CPU_FRE;
 		}
 	}