mtd: nand: denali: allow to override corrupted revision register

The Denali IP does not update the revision register properly.
Allow to override it with SoC data associated with compatible.

Linux had already finished big surgery of this driver, but I need
to prepare the NAND core before the full sync of the driver.
For now, I am fixing the most fatal problem on UniPhier platform.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/mtd/nand/denali.c b/drivers/mtd/nand/denali.c
index 47cf37d..54718f4 100644
--- a/drivers/mtd/nand/denali.c
+++ b/drivers/mtd/nand/denali.c
@@ -10,7 +10,7 @@
 #include <malloc.h>
 #include <nand.h>
 #include <linux/errno.h>
-#include <asm/io.h>
+#include <linux/io.h>
 
 #include "denali.h"
 
@@ -433,17 +433,13 @@
  */
 static void detect_max_banks(struct denali_nand_info *denali)
 {
-	uint32_t features = readl(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(
-				readl(denali->flash_reg + REVISION));
-	if (revision < REVISION_5_1)
-		denali->max_banks = 2 << (features & FEATURES__N_BANKS);
-	else
-		denali->max_banks = 1 << (features & FEATURES__N_BANKS);
+	uint32_t features = ioread32(denali->flash_reg + FEATURES);
+
+	denali->max_banks = 1 << (features & FEATURES__N_BANKS);
+
+	/* the encoding changed from rev 5.0 to 5.1 */
+	if (denali->revision < 0x0501)
+		denali->max_banks <<= 1;
 }
 
 static void detect_partition_feature(struct denali_nand_info *denali)
@@ -1154,6 +1150,13 @@
 static void denali_hw_init(struct denali_nand_info *denali)
 {
 	/*
+	 * The REVISION register may not be reliable.  Platforms are allowed to
+	 * override it.
+	 */
+	if (!denali->revision)
+		denali->revision = swab16(ioread32(denali->flash_reg + REVISION));
+
+	/*
 	 * tell driver how many bit controller will skip before writing
 	 * ECC code in OOB. This is normally used for bad block marker
 	 */