mtd: nand: denali: max_banks calculation changed in revision 5.1

Read Denali hardware revision number and use it to
calculate max_banks,  The encoding of max_banks changed
in Denali revision 5.1.
Signed-off-by: Graham Moore <grmoore@opensource.altera.com>
[Brian: parentheses around macro arg]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/denali.c

@@ -458,8 +458,17 @@ static void find_valid_banks(struct denali_nand_info *denali)
 static void detect_max_banks(struct denali_nand_info *denali)
 {
 	uint32_t features = ioread32(denali->flash_reg + FEATURES);
+	/*
+	 * Read the revision register, so we can calculate the max_banks
+	 * properly: the encoding changed from rev 5.0 to 5.1
+	 */
+	u32 revision = MAKE_COMPARABLE_REVISION(
+				ioread32(denali->flash_reg + REVISION));
 
-	denali->max_banks = 2 << (features & FEATURES__N_BANKS);
+	if (revision < REVISION_5_1)
+		denali->max_banks = 2 << (features & FEATURES__N_BANKS);
+	else
+		denali->max_banks = 1 << (features & FEATURES__N_BANKS);
 }
 
 static void detect_partition_feature(struct denali_nand_info *denali)

drivers/mtd/nand/denali.h

@@ -178,6 +178,8 @@
 
 #define REVISION				0x370
 #define     REVISION__VALUE				0xffff
+#define MAKE_COMPARABLE_REVISION(x)		swab16((x) & REVISION__VALUE)
+#define REVISION_5_1				0x00000501
 
 #define ONFI_DEVICE_FEATURES			0x380
 #define     ONFI_DEVICE_FEATURES__VALUE			0x003f