mtd: nand: split extended ID decoding into its own function

When detecting NAND parameters, the code gets a little ugly so that the
logic is obscured. Try to remedy that by moving code to separate functions
that have well-defined purposes.

This patch splits out the extended ID decode functionality, which handles
decoding the 3rd-8th ID bytes to determine NAND device parameters.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 67 insertions, 55 deletions

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 16bb17f93997..e017af02da1c 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -2906,6 +2906,71 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip,
 }
 
 /*
+ * Many new NAND share similar device ID codes, which represent the size of the
+ * chip. The rest of the parameters must be decoded according to generic or
+ * manufacturer-specific "extended ID" decoding patterns.
+ */
+static void nand_decode_ext_id(struct mtd_info *mtd, struct nand_chip *chip,
+                                u8 id_data[8], int *busw)
+{
+        int extid;
+        /* The 3rd id byte holds MLC / multichip data */
+        chip->cellinfo = id_data[2];
+        /* The 4th id byte is the important one */
+        extid = id_data[3];
+
+        /*
+         * Field definitions are in the following datasheets:
+         * Old style (4,5 byte ID): Samsung K9GAG08U0M (p.32)
+         * New style   (6 byte ID): Samsung K9GBG08U0M (p.40)
+         *
+         * Check for wraparound + Samsung ID + nonzero 6th byte
+         * to decide what to do.
+         */
+        if (id_data[0] == id_data[6] && id_data[1] == id_data[7] &&
+                        id_data[0] == NAND_MFR_SAMSUNG &&
+                        (chip->cellinfo & NAND_CI_CELLTYPE_MSK) &&
+                        id_data[5] != 0x00) {
+                /* Calc pagesize */
+                mtd->writesize = 2048 << (extid & 0x03);
+                extid >>= 2;
+                /* Calc oobsize */
+                switch (extid & 0x03) {
+                case 1:
+                        mtd->oobsize = 128;
+                        break;
+                case 2:
+                        mtd->oobsize = 218;
+                        break;
+                case 3:
+                        mtd->oobsize = 400;
+                        break;
+                default:
+                        mtd->oobsize = 436;
+                        break;
+                }
+                extid >>= 2;
+                /* Calc blocksize */
+                mtd->erasesize = (128 * 1024) <<
+                        (((extid >> 1) & 0x04) | (extid & 0x03));
+                *busw = 0;
+        } else {
+                /* Calc pagesize */
+                mtd->writesize = 1024 << (extid & 0x03);
+                extid >>= 2;
+                /* Calc oobsize */
+                mtd->oobsize = (8 << (extid & 0x01)) *
+                        (mtd->writesize >> 9);
+                extid >>= 2;
+                /* Calc blocksize. Blocksize is multiples of 64KiB */
+                mtd->erasesize = (64 * 1024) << (extid & 0x03);
+                extid >>= 2;
+                /* Get buswidth information */
+                *busw = (extid & 0x01) ? NAND_BUSWIDTH_16 : 0;
+        }
+}
+
+/*
  * Set the bad block marker/indicator (BBM/BBI) patterns according to some
  * heuristic patterns using various detected parameters (e.g., manufacturer,
  * page size, cell-type information).
@@ -3016,61 +3081,8 @@ static struct nand_flash_dev *nand_get_flash_type(struct mtd_info *mtd,
                 /* Set the pagesize, oobsize, erasesize by the driver */
                 busw = chip->init_size(mtd, chip, id_data);
         } else if (!type->pagesize) {
-                int extid;
-                /* The 3rd id byte holds MLC / multichip data */
-                chip->cellinfo = id_data[2];
-                /* The 4th id byte is the important one */
-                extid = id_data[3];
-
-                /*
-                 * Field definitions are in the following datasheets:
-                 * Old style (4,5 byte ID): Samsung K9GAG08U0M (p.32)
-                 * New style   (6 byte ID): Samsung K9GBG08U0M (p.40)
-                 *
-                 * Check for wraparound + Samsung ID + nonzero 6th byte
-                 * to decide what to do.
-                 */
-                if (id_data[0] == id_data[6] && id_data[1] == id_data[7] &&
-                                id_data[0] == NAND_MFR_SAMSUNG &&
-                                (chip->cellinfo & NAND_CI_CELLTYPE_MSK) &&
-                                id_data[5] != 0x00) {
-                        /* Calc pagesize */
-                        mtd->writesize = 2048 << (extid & 0x03);
-                        extid >>= 2;
-                        /* Calc oobsize */
-                        switch (extid & 0x03) {
-                        case 1:
-                                mtd->oobsize = 128;
-                                break;
-                        case 2:
-                                mtd->oobsize = 218;
-                                break;
-                        case 3:
-                                mtd->oobsize = 400;
-                                break;
-                        default:
-                                mtd->oobsize = 436;
-                                break;
-                        }
-                        extid >>= 2;
-                        /* Calc blocksize */
-                        mtd->erasesize = (128 * 1024) <<
-                                (((extid >> 1) & 0x04) | (extid & 0x03));
-                        busw = 0;
-                } else {
-                        /* Calc pagesize */
-                        mtd->writesize = 1024 << (extid & 0x03);
-                        extid >>= 2;
-                        /* Calc oobsize */
-                        mtd->oobsize = (8 << (extid & 0x01)) *
-                                (mtd->writesize >> 9);
-                        extid >>= 2;
-                        /* Calc blocksize. Blocksize is multiples of 64KiB */
-                        mtd->erasesize = (64 * 1024) << (extid & 0x03);
-                        extid >>= 2;
-                        /* Get buswidth information */
-                        busw = (extid & 0x01) ? NAND_BUSWIDTH_16 : 0;
-                }
+                /* Decode parameters from extended ID */
+                nand_decode_ext_id(mtd, chip, id_data, &busw);
         } else {
                 /*
                  * Old devices have chip data hardcoded in the device id table.