diff options
| -rw-r--r-- | drivers/mtd/nand/nand_base.c | 72 |
1 files changed, 65 insertions, 7 deletions
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index 4e1ea7283a95..5365ad569f5a 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -2906,6 +2906,65 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, } /* + * nand_id_has_period - Check if an ID string has a given wraparound period + * @id_data: the ID string + * @arrlen: the length of the @id_data array + * @period: the period of repitition + * + * Check if an ID string is repeated within a given sequence of bytes at + * specific repetition interval period (e.g., {0x20,0x01,0x7F,0x20} has a + * period of 2). This is a helper function for nand_id_len(). Returns non-zero + * if the repetition has a period of @period; otherwise, returns zero. + */ +static int nand_id_has_period(u8 *id_data, int arrlen, int period) +{ + int i, j; + for (i = 0; i < period; i++) + for (j = i + period; j < arrlen; j += period) + if (id_data[i] != id_data[j]) + return 0; + return 1; +} + +/* + * nand_id_len - Get the length of an ID string returned by CMD_READID + * @id_data: the ID string + * @arrlen: the length of the @id_data array + + * Returns the length of the ID string, according to known wraparound/trailing + * zero patterns. If no pattern exists, returns the length of the array. + */ +static int nand_id_len(u8 *id_data, int arrlen) +{ + 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. @@ -2913,24 +2972,23 @@ static int nand_flash_detect_onfi(struct mtd_info *mtd, struct nand_chip *chip, static void nand_decode_ext_id(struct mtd_info *mtd, struct nand_chip *chip, u8 id_data[8], int *busw) { - int extid; + 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 style (6 byte ID): Samsung K9GBG08U0M (p.40) * - * Check for wraparound + Samsung ID + nonzero 6th byte - * to decide what to do. + * Check for ID length + Samsung ID 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) { + if (id_len == 6 && id_data[0] == NAND_MFR_SAMSUNG && + (chip->cellinfo & NAND_CI_CELLTYPE_MSK)) { /* Calc pagesize */ mtd->writesize = 2048 << (extid & 0x03); extid >>= 2; |