NAND: rearrange ONFI revision checking, add ONFI 2.3

This patch sync with Brian's patch on Linux in nand_flash_detect_onfi()

	commit b7b1a29d94c17e4341856381bccb4d17495bea60
	Author: Brian Norris <computersforpeace@gmail.com>
	Date:   Sun Dec 12 00:23:33 2010 -0800

	    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>

Signed-off-by: Florian Fainelli <florian@openwrt.org>

drivers/mtd/nand/nand_base.c

@@ -2461,20 +2461,24 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd,
 
 	/* 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;
+	}
 
 	if (!mtd->name)
 		mtd->name = p->model;