mtd: nand: provide several helpers to do common NAND operations

This is part of the process of removing direct calls to ->cmdfunc()
outside of the core in order to introduce a better interface to execute
NAND operations.

Here we provide several helpers and make use of them to remove all
direct calls to ->cmdfunc(). This way, we can easily modify those
helpers to make use of the new ->exec_op() interface when available.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
[miquel.raynal@free-electrons.com: rebased and fixed some conflicts]
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/drivers/mtd/nand/cafe_nand.c b/drivers/mtd/nand/cafe_nand.c
index bc558c4..95c2cfa 100644
--- a/drivers/mtd/nand/cafe_nand.c
+++ b/drivers/mtd/nand/cafe_nand.c
@@ -353,23 +353,15 @@
 static int cafe_nand_write_oob(struct mtd_info *mtd,
 			       struct nand_chip *chip, int page)
 {
-	int status = 0;
-
-	chip->cmdfunc(mtd, NAND_CMD_SEQIN, mtd->writesize, page);
-	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
-	chip->cmdfunc(mtd, NAND_CMD_PAGEPROG, -1, -1);
-	status = chip->waitfunc(mtd, chip);
-
-	return status & NAND_STATUS_FAIL ? -EIO : 0;
+	return nand_prog_page_op(chip, page, mtd->writesize, chip->oob_poi,
+				 mtd->oobsize);
 }
 
 /* Don't use -- use nand_read_oob_std for now */
 static int cafe_nand_read_oob(struct mtd_info *mtd, struct nand_chip *chip,
 			      int page)
 {
-	chip->cmdfunc(mtd, NAND_CMD_READOOB, 0, page);
-	chip->read_buf(mtd, chip->oob_poi, mtd->oobsize);
-	return 0;
+	return nand_read_oob_op(chip, page, 0, chip->oob_poi, mtd->oobsize);
 }
 /**
  * cafe_nand_read_page_syndrome - [REPLACEABLE] hardware ecc syndrome based page read