mtd: rawnand: helper function for setting up ECC configuration

Abhishek Sahu · miquelraynal · commit 181ace9e1b2e · 2018-07-18T09:24:05.000+02:00
commit 2c8f8af ("mtd: nand: add generic helpers to check, match, maximize ECC settings") provides generic helpers which drivers can use for setting up ECC parameters. Since same board can have different ECC strength nand chips so following is the logic for setting up ECC strength and ECC step size, which can be used by most of the drivers. 1. If both ECC step size and ECC strength are already set (usually by DT) then just check whether this setting is supported by NAND controller. 2. If NAND_ECC_MAXIMIZE is set, then select maximum ECC strength supported by NAND controller. 3. Otherwise, try to match the ECC step size and ECC strength closest to the chip's requirement. If available OOB size can't fit the chip requirement then select maximum ECC strength which can be fit with available OOB size. This patch introduces nand_ecc_choose_conf function which calls the required helper functions for the above logic. The drivers can use this single function instead of calling the 3 helper functions individually. Signed-off-by: Abhishek Sahu <absahu@codeaurora.org> Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
@@ -6295,6 +6295,39 @@ int nand_maximize_ecc(struct nand_chip *chip,
 }
 EXPORT_SYMBOL_GPL(nand_maximize_ecc);
 
+/**
+ * nand_ecc_choose_conf - Set the ECC strength and ECC step size
+ * @chip: nand chip info structure
+ * @caps: ECC engine caps info structure
+ * @oobavail: OOB size that the ECC engine can use
+ *
+ * Choose the ECC configuration according to following logic
+ *
+ * 1. If both ECC step size and ECC strength are already set (usually by DT)
+ *    then check if it is supported by this controller.
+ * 2. If NAND_ECC_MAXIMIZE is set, then select maximum ECC strength.
+ * 3. Otherwise, try to match the ECC step size and ECC strength closest
+ *    to the chip's requirement. If available OOB size can't fit the chip
+ *    requirement then fallback to the maximum ECC step size and ECC strength.
+ *
+ * On success, the chosen ECC settings are set.
+ */
+int nand_ecc_choose_conf(struct nand_chip *chip,
+			 const struct nand_ecc_caps *caps, int oobavail)
+{
+	if (chip->ecc.size && chip->ecc.strength)
+		return nand_check_ecc_caps(chip, caps, oobavail);
+
+	if (chip->ecc.options & NAND_ECC_MAXIMIZE)
+		return nand_maximize_ecc(chip, caps, oobavail);
+
+	if (!nand_match_ecc_req(chip, caps, oobavail))
+		return 0;
+
+	return nand_maximize_ecc(chip, caps, oobavail);
+}
+EXPORT_SYMBOL_GPL(nand_ecc_choose_conf);
+
 /*
  * Check if the chip configuration meet the datasheet requirements.
 
diff --git a/include/linux/mtd/rawnand.h b/include/linux/mtd/rawnand.h
@@ -1672,6 +1672,9 @@ int nand_match_ecc_req(struct nand_chip *chip,
 int nand_maximize_ecc(struct nand_chip *chip,
 		      const struct nand_ecc_caps *caps, int oobavail);
 
+int nand_ecc_choose_conf(struct nand_chip *chip,
+			 const struct nand_ecc_caps *caps, int oobavail);
+
 /* Default write_oob implementation */
 int nand_write_oob_std(struct mtd_info *mtd, struct nand_chip *chip, int page);
 
