mtd: rawnand: Return an enum from of_get_nand_ecc_algo()

There is an enumeration to list ECC algorithm, let's use it instead of
returning an int.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200526195633.11543-6-miquel.raynal@bootlin.com

drivers/mtd/nand/raw/nand_base.c

@@ -5043,17 +5043,20 @@ static const char * const nand_ecc_algos[] = {
 	[NAND_ECC_RS]		= "rs",
 };
 
-static int of_get_nand_ecc_algo(struct device_node *np)
+static enum nand_ecc_algo of_get_nand_ecc_algo(struct device_node *np)
 {
+	enum nand_ecc_algo ecc_algo;
 	const char *pm;
-	int err, i;
+	int err;
 
 	err = of_property_read_string(np, "nand-ecc-algo", &pm);
 	if (!err) {
-		for (i = NAND_ECC_HAMMING; i < ARRAY_SIZE(nand_ecc_algos); i++)
-			if (!strcasecmp(pm, nand_ecc_algos[i]))
-				return i;
-		return -ENODEV;
+		for (ecc_algo = NAND_ECC_HAMMING;
+		     ecc_algo < ARRAY_SIZE(nand_ecc_algos);
+		     ecc_algo++) {
+			if (!strcasecmp(pm, nand_ecc_algos[ecc_algo]))
+				return ecc_algo;
+		}
 	}
 
 	/*
@@ -5061,15 +5064,14 @@ static int of_get_nand_ecc_algo(struct device_node *np)
 	 * for some obsoleted values that were specifying ECC algorithm.
 	 */
 	err = of_property_read_string(np, "nand-ecc-mode", &pm);
-	if (err < 0)
-		return err;
-
+	if (!err) {
 		if (!strcasecmp(pm, "soft"))
 			return NAND_ECC_HAMMING;
 		else if (!strcasecmp(pm, "soft_bch"))
 			return NAND_ECC_BCH;
+	}
 
-	return -ENODEV;
+	return NAND_ECC_UNKNOWN;
 }
 
 static int of_get_nand_ecc_step_size(struct device_node *np)
@@ -5114,7 +5116,8 @@ static bool of_get_nand_on_flash_bbt(struct device_node *np)
 static int nand_dt_init(struct nand_chip *chip)
 {
 	struct device_node *dn = nand_get_flash_node(chip);
-	int ecc_mode, ecc_algo, ecc_strength, ecc_step;
+	enum nand_ecc_algo ecc_algo;
+	int ecc_mode, ecc_strength, ecc_step;
 
 	if (!dn)
 		return 0;
@@ -5136,7 +5139,7 @@ static int nand_dt_init(struct nand_chip *chip)
 	if (ecc_mode >= 0)
 		chip->ecc.mode = ecc_mode;
 
-	if (ecc_algo >= 0)
+	if (ecc_algo != NAND_ECC_UNKNOWN)
 		chip->ecc.algo = ecc_algo;
 
 	if (ecc_strength >= 0)