mtd: create an mtd_oobavail() helper and make use of it

Currently, all MTD drivers/sublayers exposing an OOB area are
doing the same kind of test to extract the available OOB size
based on the mtd_info and mtd_oob_ops structures.
Move this common logic into an inline function and make use of it.

Signed-off-by: Boris Brezillon <[e-mail]>
Suggested-by: Priit Laes <[e-mail]>
Signed-off-by: Brian Norris <[e-mail]>

drivers/mtd/mtdpart.c

···
 	if (ops->oobbuf) {
 		size_t len, pages;
 
-		if (ops->mode == MTD_OPS_AUTO_OOB)
-			len = mtd->oobavail;
-		else
-			len = mtd->oobsize;
+		len = mtd_oobavail(mtd, ops);
 		pages = mtd_div_by_ws(mtd->size, mtd);
 		pages -= mtd_div_by_ws(from, mtd);
 		if (ops->ooboffs + ops->ooblen > pages * len)

drivers/mtd/nand/nand_base.c

···
 	int ret = 0;
 	uint32_t readlen = ops->len;
 	uint32_t oobreadlen = ops->ooblen;
-	uint32_t max_oobsize = ops->mode == MTD_OPS_AUTO_OOB ?
-		mtd->oobavail : mtd->oobsize;
+	uint32_t max_oobsize = mtd_oobavail(mtd, ops);
 
 	uint8_t *bufpoi, *oob, *buf;
 	int use_bufpoi;
···
 
 	stats = mtd->ecc_stats;
 
-	if (ops->mode == MTD_OPS_AUTO_OOB)
-		len = mtd->oobavail;
-	else
-		len = mtd->oobsize;
+	len = mtd_oobavail(mtd, ops);
 
 	if (unlikely(ops->ooboffs >= len)) {
 		pr_debug("%s: attempt to start read outside oob\n",
···
 	uint32_t writelen = ops->len;
 
 	uint32_t oobwritelen = ops->ooblen;
-	uint32_t oobmaxlen = ops->mode == MTD_OPS_AUTO_OOB ?
-				mtd->oobavail : mtd->oobsize;
+	uint32_t oobmaxlen = mtd_oobavail(mtd, ops);
 
 	uint8_t *oob = ops->oobbuf;
 	uint8_t *buf = ops->datbuf;
···
 	pr_debug("%s: to = 0x%08x, len = %i\n",
 			 __func__, (unsigned int)to, (int)ops->ooblen);
 
-	if (ops->mode == MTD_OPS_AUTO_OOB)
-		len = mtd->oobavail;
-	else
-		len = mtd->oobsize;
+	len = mtd_oobavail(mtd, ops);
 
 	/* Do not allow write past end of page */
 	if ((ops->ooboffs + ops->ooblen) > len) {

drivers/mtd/onenand/onenand_base.c

···
 	pr_debug("%s: from = 0x%08x, len = %i\n", __func__, (unsigned int)from,
 			(int)len);
 
-	if (ops->mode == MTD_OPS_AUTO_OOB)
-		oobsize = mtd->oobavail;
-	else
-		oobsize = mtd->oobsize;
-
+	oobsize = mtd_oobavail(mtd, ops);
 	oobcolumn = from & (mtd->oobsize - 1);
 
 	/* Do not allow reads past end of device */
···
 	pr_debug("%s: from = 0x%08x, len = %i\n", __func__, (unsigned int)from,
 			(int)len);
 
-	if (ops->mode == MTD_OPS_AUTO_OOB)
-		oobsize = mtd->oobavail;
-	else
-		oobsize = mtd->oobsize;
-
+	oobsize = mtd_oobavail(mtd, ops);
 	oobcolumn = from & (mtd->oobsize - 1);
 
 	/* Do not allow reads past end of device */
···
 	/* Check zero length */
 	if (!len)
 		return 0;
-
-	if (ops->mode == MTD_OPS_AUTO_OOB)
-		oobsize = mtd->oobavail;
-	else
-		oobsize = mtd->oobsize;
-
+	oobsize = mtd_oobavail(mtd, ops);
 	oobcolumn = to & (mtd->oobsize - 1);
 
 	column = to & (mtd->writesize - 1);

include/linux/mtd/mtd.h

···
 	return mtd->dev.of_node;
 }
 
+static inline int mtd_oobavail(struct mtd_info *mtd, struct mtd_oob_ops *ops)
+{
+	return ops->mode == MTD_OPS_AUTO_OOB ? mtd->oobavail : mtd->oobsize;
+}
+
 int mtd_erase(struct mtd_info *mtd, struct erase_info *instr);
 int mtd_point(struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen,
 	      void **virt, resource_size_t *phys);