mtd: rawnand: Expose _notsupp() helpers for raw page accessors

Some implementations simply can't disable their ECC engine. Expose
helpers returning -ENOTSUPP so that the caller knows that raw accesses
are not supported instead of silently falling back to non-raw
accessors.
Signed-off-by: NBoris Brezillon <boris.brezillon@bootlin.com>
Signed-off-by: NMiquel Raynal <miquel.raynal@bootlin.com>

drivers/mtd/nand/raw/nand_base.c

@@ -2966,6 +2966,23 @@ int nand_check_erased_ecc_chunk(void *data, int datalen,
 }
 EXPORT_SYMBOL(nand_check_erased_ecc_chunk);
 
+/**
+ * nand_read_page_raw_notsupp - dummy read raw page function
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @buf: buffer to store read data
+ * @oob_required: caller requires OOB data read to chip->oob_poi
+ * @page: page number to read
+ *
+ * Returns -ENOTSUPP unconditionally.
+ */
+int nand_read_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
+			       u8 *buf, int oob_required, int page)
+{
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL(nand_read_page_raw_notsupp);
+
 /**
  * nand_read_page_raw - [INTERN] read raw page data without ecc
  * @mtd: mtd info structure
@@ -3960,6 +3977,22 @@ static int nand_read_oob(struct mtd_info *mtd, loff_t from,
 	return ret;
 }
 
+/**
+ * nand_write_page_raw_notsupp - dummy raw page write function
+ * @mtd: mtd info structure
+ * @chip: nand chip info structure
+ * @buf: data buffer
+ * @oob_required: must write chip->oob_poi to OOB
+ * @page: page number to write
+ *
+ * Returns -ENOTSUPP unconditionally.
+ */
+int nand_write_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
+				const u8 *buf, int oob_required, int page)
+{
+	return -ENOTSUPP;
+}
+EXPORT_SYMBOL(nand_write_page_raw_notsupp);
 
 /**
  * nand_write_page_raw - [INTERN] raw page write function

include/linux/mtd/rawnand.h

@@ -1681,10 +1681,14 @@ int nand_get_set_features_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
 /* Default read_page_raw implementation */
 int nand_read_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
 		       uint8_t *buf, int oob_required, int page);
+int nand_read_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
+			       u8 *buf, int oob_required, int page);
 
 /* Default write_page_raw implementation */
 int nand_write_page_raw(struct mtd_info *mtd, struct nand_chip *chip,
 			const uint8_t *buf, int oob_required, int page);
+int nand_write_page_raw_notsupp(struct mtd_info *mtd, struct nand_chip *chip,
+				const u8 *buf, int oob_required, int page);
 
 /* Reset and initialize a NAND device */
 int nand_reset(struct nand_chip *chip, int chipnr);