+ int last_nonzero, period;
+
+ /* Find last non-zero byte */
+ for (last_nonzero = arrlen - 1; last_nonzero >= 0; last_nonzero--)
+ if (id_data[last_nonzero])
+ break;
+
+ /* All zeros */
+ if (last_nonzero < 0)
+ return 0;
+
+ /* Calculate wraparound period */
+ for (period = 1; period < arrlen; period++)
+ if (nand_id_has_period(id_data, arrlen, period))
+ break;
+
+ /* There's a repeated pattern */
+ if (period < arrlen)
+ return period;
+
+ /* There are trailing zeros */
+ if (last_nonzero < arrlen - 1)
+ return last_nonzero + 1;
+
+ /* No pattern detected */
+ return arrlen;
+}
+
+/*
+ * 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, id_len;
+ /* 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];
+
+ id_len = nand_id_len(id_data, 8);
+
+ /*
+ * Field definitions are in the following datasheets:
+ * Old style (4,5 byte ID): Samsung K9GAG08U0M (p.32)
+ * New Samsung (6 byte ID): Samsung K9GAG08U0F (p.44)
+ * Hynix MLC (6 byte ID): Hynix H27UBG8T2B (p.22)
+ *
+ * Check for ID length, non-zero 6th byte, cell type, and Hynix/Samsung
+ * ID to decide what to do.
+ */
+ if (id_len == 6 && id_data[0] == NAND_MFR_SAMSUNG &&
+ (chip->cellinfo & NAND_CI_CELLTYPE_MSK) &&
+ id_data[5] != 0x00) {