MIPS: Probe for presence of KScratch registers.

Probe c0_config4 for KScratch registers and report them in /proc/cpuinfo.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1877/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/cpu-probe.c

@@ -739,6 +739,8 @@ static inline unsigned int decode_config4(struct cpuinfo_mips *c)
 	    && cpu_has_tlb)
 		c->tlbsize += (config4 & MIPS_CONF4_MMUSIZEEXT) * 0x40;
 
+	c->kscratch_mask = (config4 >> 16) & 0xff;
+
 	return config4 & MIPS_CONF_M;
 }