MIPS: Define the legacy-NaN and 2008-NaN features

Allocate CPU option bits and define macros for the legacy-NaN and
2008-NaN IEEE Std 754 MIPS architecture features.  Unconditionally mark
the legacy-NaN feature as present across hardware and emulated
floating-point configurations.

Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Fortune <Matthew.Fortune@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/11475/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

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

@@ -414,4 +414,11 @@
 # define cpu_has_small_pages	(cpu_data[0].options & MIPS_CPU_SP)
 #endif
 
+#ifndef cpu_has_nan_legacy
+#define cpu_has_nan_legacy	(cpu_data[0].options & MIPS_CPU_NAN_LEGACY)
+#endif
+#ifndef cpu_has_nan_2008
+#define cpu_has_nan_2008	(cpu_data[0].options & MIPS_CPU_NAN_2008)
+#endif
+
 #endif /* __ASM_CPU_FEATURES_H */

arch/mips/include/asm/cpu.h

@@ -386,6 +386,8 @@ enum cpu_type_enum {
 #define MIPS_CPU_BP_GHIST	0x8000000000ull /* R12K+ Branch Prediction Global History */
 #define MIPS_CPU_SP		0x10000000000ull /* Small (1KB) page support */
 #define MIPS_CPU_FTLB		0x20000000000ull /* CPU has Fixed-page-size TLB */
+#define MIPS_CPU_NAN_LEGACY	0x40000000000ull /* Legacy NaN implemented */
+#define MIPS_CPU_NAN_2008	0x80000000000ull /* 2008 NaN implemented */
 
 /*
  * CPU ASE encodings

arch/mips/kernel/cpu-probe.c

@@ -137,6 +137,7 @@ static void cpu_set_fpu_opts(struct cpuinfo_mips *c)
 	}
 
 	cpu_set_fpu_fcsr_mask(c);
+	c->options |= MIPS_CPU_NAN_LEGACY;
 }
 
 /*
@@ -147,6 +148,7 @@ static void cpu_set_nofpu_opts(struct cpuinfo_mips *c)
 	c->options &= ~MIPS_CPU_FPU;
 	c->fpu_msk31 = mips_nofpu_msk31;
 
+	c->options |= MIPS_CPU_NAN_LEGACY;
 	cpu_set_nofpu_id(c);
 }