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>

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index 16bb17f..e017af0 100644 (file)
--- 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.