[MTD] NAND: add subpage write support

Many SLC NANDs support up to 4 writes at one NAND page. Add support
of this feature.

Signed-off-by: Artem Bityutskiy <dedekind@infradead.org>
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 6fc3e07..1aeedf2 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -166,6 +166,9 @@
  * for all large page devices, as they do not support
  * autoincrement.*/
 #define NAND_NO_READRDY		0x00000100
+/* Chip does not allow subpage writes */
+#define NAND_NO_SUBPAGE_WRITE	0x00000200
+
 
 /* Options valid for Samsung large page devices */
 #define NAND_SAMSUNG_LP_OPTIONS \
@@ -193,6 +196,9 @@
 /* Nand scan has allocated controller struct */
 #define NAND_CONTROLLER_ALLOC	0x80000000
 
+/* Cell info constants */
+#define NAND_CI_CHIPNR_MSK	0x03
+#define NAND_CI_CELLTYPE_MSK	0x0C
 
 /*
  * nand_state_t - chip states
@@ -341,6 +347,7 @@
  * @chipsize:		[INTERN] the size of one chip for multichip arrays
  * @pagemask:		[INTERN] page number mask = number of (pages / chip) - 1
  * @pagebuf:		[INTERN] holds the pagenumber which is currently in data_buf
+ * @subpagesize:	[INTERN] holds the subpagesize
  * @ecclayout:		[REPLACEABLE] the default ecc placement scheme
  * @bbt:		[INTERN] bad block table pointer
  * @bbt_td:		[REPLACEABLE] bad block table descriptor for flash lookup
@@ -388,6 +395,8 @@
 	unsigned long	chipsize;
 	int		pagemask;
 	int		pagebuf;
+	int		subpagesize;
+	uint8_t		cellinfo;
 	int		badblockpos;
 
 	nand_state_t	state;