nand: Move the sub-page read support enable to a flag

Use a flag instead of a hard-coded macro so that sub-page reads can be
enabled in other cases (such as on-die ecc).

This is the same as a5ff4f102937a3492bca4a9ff0c341d78813414c in Linux

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/mtd/nand/nand_base.c

@@ -1245,7 +1245,8 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 			if (unlikely(ops->mode == MTD_OOB_RAW))
 				ret = chip->ecc.read_page_raw(mtd, chip,
 							      bufpoi, page);
-			else if (!aligned && NAND_SUBPAGE_READ(chip) && !oob)
+			else if (!aligned && NAND_HAS_SUBPAGE_READ(chip) &&
+			    !oob)
 				ret = chip->ecc.read_subpage(mtd, chip,
 							col, bytes, bufpoi);
 			else
@@ -1256,7 +1257,7 @@ static int nand_do_read_ops(struct mtd_info *mtd, loff_t from,
 
 			/* Transfer not aligned data */
 			if (!aligned) {
-				if (!NAND_SUBPAGE_READ(chip) && !oob &&
+				if (!NAND_HAS_SUBPAGE_READ(chip) && !oob &&
 				    !(mtd->ecc_stats.failed - stats.failed))
 					chip->pagebuf = realpage;
 				memcpy(buf, chip->buffers->databuf + col, bytes);
@@ -3150,6 +3151,10 @@ int nand_scan_tail(struct mtd_info *mtd)
 	/* Invalidate the pagebuffer reference */
 	chip->pagebuf = -1;
 
+	/* Large page NAND with SOFT_ECC should support subpage reads */
+	if ((chip->ecc.mode == NAND_ECC_SOFT) && (chip->page_shift > 9))
+		chip->options |= NAND_SUBPAGE_READ;
+
 	/* Fill in remaining MTD driver data */
 	mtd->type = MTD_NANDFLASH;
 	mtd->flags = (chip->options & NAND_ROM) ? MTD_CAP_ROM :

include/linux/mtd/nand.h

@@ -194,6 +194,9 @@ typedef enum {
 /* Device behaves just like nand, but is readonly */
 #define NAND_ROM		0x00000800
 
+/* Device supports subpage reads */
+#define NAND_SUBPAGE_READ       0x00001000
+
 /* Options valid for Samsung large page devices */
 #define NAND_SAMSUNG_LP_OPTIONS \
 	(NAND_NO_PADDING | NAND_CACHEPRG | NAND_COPYBACK)
@@ -203,9 +206,7 @@ typedef enum {
 #define NAND_MUST_PAD(chip) (!(chip->options & NAND_NO_PADDING))
 #define NAND_HAS_CACHEPROG(chip) ((chip->options & NAND_CACHEPRG))
 #define NAND_HAS_COPYBACK(chip) ((chip->options & NAND_COPYBACK))
-/* Large page NAND with SOFT_ECC should support subpage reads */
-#define NAND_SUBPAGE_READ(chip) ((chip->ecc.mode == NAND_ECC_SOFT) \
-					&& (chip->page_shift > 9))
+#define NAND_HAS_SUBPAGE_READ(chip) ((chip->options & NAND_SUBPAGE_READ))
 
 /* Non chip related options */
 /*