mtd: rawnand: Rework of_get_nand_bus_width()

of_get_nand_bus_width() had a wrong behavior because:
1/ it ignored the -ENODATA and -EOVERFLOW return values of
   of_property_read_u32(). "nand-bus-width" without value was tolerated
   while it shouldn't have been according to the devicetree bindings.
2/ returned -EIO when the nand-bus-width was neither 8 nor 16, when it
   should have returned -EINVAL instead.
3/ returned the 8 or 16 bus-width integer, but it was never used it its
   caller. A simply return 0 on success is enough.
Rework of_get_nand_bus_width() and address all the above. The execution
is now stopped in case of errors.

Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220106131610.225661-2-tudor.ambarus@microchip.com

diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c
index dd276df..3e4a525 100644 (file)
--- a/drivers/mtd/nand/raw/nand_base.c
+++ b/drivers/mtd/nand/raw/nand_base.c
@@ -5274,20 +5274,24 @@ static void of_get_nand_ecc_legacy_user_config(struct nand_chip *chip)
                user_conf->placement = of_get_rawnand_ecc_placement_legacy(dn);
 }
 
-static int of_get_nand_bus_width(struct device_node *np)
+static int of_get_nand_bus_width(struct nand_chip *chip)
 {
+       struct device_node *dn = nand_get_flash_node(chip);
        u32 val;
+       int ret;
 
-       if (of_property_read_u32(np, "nand-bus-width", &val))
-               return 8;
+       ret = of_property_read_u32(dn, "nand-bus-width", &val);
+       if (ret == -EINVAL)
+               /* Buswidth defaults to 8 if the property does not exist .*/
+               return 0;
+       else if (ret)
+               return ret;
 
-       switch (val) {
-       case 8:
-       case 16:
-               return val;
-       default:
-               return -EIO;
-       }
+       if (val == 16)
+               chip->options |= NAND_BUSWIDTH_16;
+       else if (val != 8)
+               return -EINVAL;
+       return 0;
 }
 
 static int of_get_nand_secure_regions(struct nand_chip *chip)
@@ -5363,12 +5367,14 @@ static int rawnand_dt_init(struct nand_chip *chip)
 {
        struct nand_device *nand = mtd_to_nanddev(nand_to_mtd(chip));
        struct device_node *dn = nand_get_flash_node(chip);
+       int ret;
 
        if (!dn)
                return 0;
 
-       if (of_get_nand_bus_width(dn) == 16)
-               chip->options |= NAND_BUSWIDTH_16;
+       ret = of_get_nand_bus_width(chip);
+       if (ret)
+               return ret;
 
        if (of_property_read_bool(dn, "nand-is-boot-medium"))
                chip->options |= NAND_IS_BOOT_MEDIUM;