MIPS: mm: c-r4k: Detect instruction cache aliases

The *Aptiv cores can use the CONF7/IAR bit to detect if the core
has hardware support to remove instruction cache aliasing.

This also defines the CONF7/AR bit in order to avoid using
the '16' magic number.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6499/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mipsregs.h

@@ -653,6 +653,9 @@
 
 #define MIPS_CONF7_RPS		(_ULCAST_(1) << 2)
 
+#define MIPS_CONF7_IAR		(_ULCAST_(1) << 10)
+#define MIPS_CONF7_AR		(_ULCAST_(1) << 16)
+
 /*  EntryHI bit definition */
 #define MIPS_ENTRYHI_EHINV	(_ULCAST_(1) << 10)
 

arch/mips/mm/c-r4k.c

@@ -1117,9 +1117,14 @@ static void probe_pcache(void)
 	case CPU_PROAPTIV:
 		if (current_cpu_type() == CPU_74K)
 			alias_74k_erratum(c);
-		if ((read_c0_config7() & (1 << 16))) {
-			/* effectively physically indexed dcache,
-			   thus no virtual aliases. */
+		if (!(read_c0_config7() & MIPS_CONF7_IAR) &&
+		    (c->icache.waysize > PAGE_SIZE))
+			c->icache.flags |= MIPS_CACHE_ALIASES;
+		if (read_c0_config7() & MIPS_CONF7_AR) {
+			/*
+			 * Effectively physically indexed dcache,
+			 * thus no virtual aliases.
+			*/
 			c->dcache.flags |= MIPS_CACHE_PINDEX;
 			break;
 		}