MIPS: mm: c-r4k: Panic if IL or DL fields have a reserved value

According to MIPS32 and MIPS64 PRA documents,
a value of 7 in IL and DL fields is marked as "Reserved"
so panic if the core uses this value in the config1 register.
Also simplify the code a little bit.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/5861/

arch/mips/mm/c-r4k.c

@@ -1013,10 +1013,14 @@ static void probe_pcache(void)
 		 */
 		config1 = read_c0_config1();
 
-		if ((lsize = ((config1 >> 19) & 7)))
-			c->icache.linesz = 2 << lsize;
-		else
-			c->icache.linesz = lsize;
+		lsize = (config1 >> 19) & 7;
+
+		/* IL == 7 is reserved */
+		if (lsize == 7)
+			panic("Invalid icache line size");
+
+		c->icache.linesz = lsize ? 2 << lsize : 0;
+
 		c->icache.sets = 32 << (((config1 >> 22) + 1) & 7);
 		c->icache.ways = 1 + ((config1 >> 16) & 7);
 
@@ -1033,10 +1037,14 @@ static void probe_pcache(void)
 		 */
 		c->dcache.flags = 0;
 
-		if ((lsize = ((config1 >> 10) & 7)))
-			c->dcache.linesz = 2 << lsize;
-		else
-			c->dcache.linesz= lsize;
+		lsize = (config1 >> 10) & 7;
+
+		/* DL == 7 is reserved */
+		if (lsize == 7)
+			panic("Invalid dcache line size");
+
+		c->dcache.linesz = lsize ? 2 << lsize : 0;
+
 		c->dcache.sets = 32 << (((config1 >> 13) + 1) & 7);
 		c->dcache.ways = 1 + ((config1 >> 7) & 7);