MIPS: MIPS16e2: Identify ASE presence

Identify the presence of the MIPS16e2 ASE as per the architecture
specification[1], by checking for CP0 Config5.CA2 bit being 1[2].

References:

[1] "MIPS32 Architecture for Programmers: MIPS16e2 Application-Specific
    Extension Technical Reference Manual", Imagination Technologies
    Ltd., Document Number: MD01172, Revision 01.00, April 26, 2016,
    Section 1.2 "Software Detection of the ASE", p. 5

[2] "MIPS32 interAptiv Multiprocessing System Software User's Manual",
    Imagination Technologies Ltd., Document Number: MD00904, Revision
    02.01, June 15, 2016, Section 2.2.1.6 "Device Configuration 5 --
    Config5 (CP0 Register 16, Select 5)", pp. 71-72
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Reviewed-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16094/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

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

@@ -138,6 +138,9 @@
 #ifndef cpu_has_mips16
 #define cpu_has_mips16		(cpu_data[0].ases & MIPS_ASE_MIPS16)
 #endif
+#ifndef cpu_has_mips16e2
+#define cpu_has_mips16e2	(cpu_data[0].ases & MIPS_ASE_MIPS16E2)
+#endif
 #ifndef cpu_has_mdmx
 #define cpu_has_mdmx		(cpu_data[0].ases & MIPS_ASE_MDMX)
 #endif

arch/mips/include/asm/cpu.h

@@ -436,5 +436,6 @@ enum cpu_type_enum {
 #define MIPS_ASE_VZ		0x00000080 /* Virtualization ASE */
 #define MIPS_ASE_MSA		0x00000100 /* MIPS SIMD Architecture */
 #define MIPS_ASE_DSP3		0x00000200 /* Signal Processing ASE Rev 3*/
+#define MIPS_ASE_MIPS16E2	0x00000400 /* MIPS16e2 */
 
 #endif /* _ASM_CPU_H */

arch/mips/include/asm/mipsregs.h

@@ -652,6 +652,7 @@
 #define MIPS_CONF5_SBRI		(_ULCAST_(1) << 6)
 #define MIPS_CONF5_FRE		(_ULCAST_(1) << 8)
 #define MIPS_CONF5_UFE		(_ULCAST_(1) << 9)
+#define MIPS_CONF5_CA2		(_ULCAST_(1) << 14)
 #define MIPS_CONF5_MSAEN	(_ULCAST_(1) << 27)
 #define MIPS_CONF5_EVA		(_ULCAST_(1) << 28)
 #define MIPS_CONF5_CV		(_ULCAST_(1) << 29)

arch/mips/kernel/cpu-probe.c

@@ -845,6 +845,8 @@ static inline unsigned int decode_config5(struct cpuinfo_mips *c)
 		c->options |= MIPS_CPU_MVH;
 	if (cpu_has_mips_r6 && (config5 & MIPS_CONF5_VP))
 		c->options |= MIPS_CPU_VP;
+	if (config5 & MIPS_CONF5_CA2)
+		c->ases |= MIPS_ASE_MIPS16E2;
 
 	return config5 & MIPS_CONF_M;
 }