mtd: nand: rearrange ONFI revision checking, add ONFI 2.3

In checking for the ONFI revision, the first conditional (for checking
"unsupported" ONFI) seems unnecessary.  All ONFI revisions should be
backwards-compatible; even if this is not the case on some newer ONFI
revision, it should simply fail the second version-checking if-else block
(i.e., the bit-fields for 1.0, 2.0, etc. would not be set to 1). Thus, we
move our "unsupported" condition after having checked each bit field.

Also, it's simple enough to add a condition for ONFI revision 2.3. Note
that this does *NOT* mean we handle all new features of ONFI versions
above 1.0.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Acked-by: Florian Fainelli <ffainelli@freebox.fr>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

drivers/mtd/nand/nand_base.c

@@ -2865,20 +2865,24 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 
 	/* check version */
 	val = le16_to_cpu(p->revision);
-	if (val == 1 || val > (1 << 4)) {
-		printk(KERN_INFO "%s: unsupported ONFI version: %d\n",
-								__func__, val);
-		return 0;
-	}
-
-	if (val & (1 << 4))
+	if (val & (1 << 5))
+		chip->onfi_version = 23;
+	else if (val & (1 << 4))
 		chip->onfi_version = 22;
 	else if (val & (1 << 3))
 		chip->onfi_version = 21;
 	else if (val & (1 << 2))
 		chip->onfi_version = 20;
-	else
+	else if (val & (1 << 1))
 		chip->onfi_version = 10;
+	else
+		chip->onfi_version = 0;
+
+	if (!chip->onfi_version) {
+		printk(KERN_INFO "%s: unsupported ONFI version: %d\n",
+								__func__, val);
+		return 0;
+	}
 
 	sanitize_string(p->manufacturer, sizeof(p->manufacturer));
 	sanitize_string(p->model, sizeof(p->model));